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Lectins as Bioactive Plant Proteins: A Potential in Cancer Treatment
Abstract
Plant lectins, a unique group of proteins and glycoproteins with potent biological activity, occur in foods like wheat, corn, tomato, peanut, kidney bean, banana, pea, lentil, soybean, mushroom, rice, and potato. Thus, dietary intakes by humans can be significant. Many lectins resist digestion, survive gut passage, and bind to gastrointestinal cells and/or enter the circulation intact, maintaining full biological activity. Several lectins have been found to possess anticancer properties in vitro, in vivo, and in human case studies; they are used as therapeutic agents, preferentially binding to cancer cell membranes or their receptors, causing cytotoxicity, apoptosis, and inhibition of tumor growth. These compounds can become internalized into cells, causing cancer cell agglutination and/or aggregation. Ingestion of lectins also sequesters the available body pool of polyamines, thereby thwarting cancer cell growth. They also affect the immune system by altering the production of various interleukins, or by activating certain protein kinases. Lectins can bind to ribosomes and inhibit protein synthesis. They also modify the cell cycle by inducing non-apoptotic G1-phase accumulation mechanisms, G2/M phase cell cycle arrest and apoptosis, and can activate the caspase cascade. Lectins can also downregulate telomerase activity and inhibit angiogenesis. Although lectins seem to have great potential as anticancer agents, further research is still needed and should include a genomic and proteomic approach.
... Some lectins can be internalized, causing cell death through ribosomal inactivation, or they can initiate signaling cascades that lead to apoptosis [5,7]. The most recognized mechanisms of action are the following: 1) At a physiological level, lectin-lymphocyte binding has been observed as well as release of blood cytokines, activation and release of spleen lymphocytes, activation of NK cells and macrophages, production of antiangiogenic factors, combination of intestinal hyperplasia and antiangiogenic effects reducing nutrient availability and cytotoxic effects on tumor cells [8,9]. 2) At the biochemical and molecular level, different mechanisms of action are proposed. ...
... Some lectins have been studied against colon cancer because of their effects on cell growth and promotion of cell death in different cell lines [13,15,16], such as lectins of Arisaema helleborifolium (AHL), Arisaema tortuosum (ATL), Arachis hypogaea (PNA), Viscum album (VAL, VAA, VAA-1), Sauromatum venosum (SVA), Phaseolus vulgaris L. (PVA) and Vicia faba (VFA) [4][5][6]8,14,15,17]. A Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) has shown differential cytotoxic effects on breast, cervix and colon cancer cell lines as well as on non-malignant cells from the intestinal tract [15,18]. ...
... Between the observed adverse effects are loss of body weight, small intestinal villus and colonic crypt atrophy and exocrine pancreas hypertrophy, without systemic adverse effects. Negative effects could be reversible after a recovery period [8]. When TBLF was tested against colon cancer (chemically induced using dimethylhydrazine (DMH) or azoxymethane (AOM) in rats), early tumorigenesis inhibition was linked with modulation of apoptotic pathways [23]. ...
A Tepary bean lectin fraction (TBLF) has been studied because it exhibits differential cytotoxic and anticancer effects on colon cancer. The present work focuses on the evaluation of the apoptotic mechanism of action on colon cancer cells. Initially, lethal concentrations (LC50) were obtained for the three studied cell lines (HT-29, RKO and SW-480). HT-29 showed the highest LC50, 10 and 100 times higher than that of RKO and SW-480 cells, respectively. Apoptosis was evaluated by flow cytometry, where HT-29 cells showed the highest levels of early and total apoptosis, caspases activity was confirmed and necrosis was discarded. The effect on cell cycle arrest was shown in the G0/G1 phase. Specific apoptosis-related gene expression was determined, where an increase in p53 and a decrease in Bcl-2 were observed. Expression of p53 gene showed the maximum level at 8 h with an important decrease at 12 and 24 h, also the phosphorylated p53(ser46) increased at 8 h. Our results show that TBLF induces apoptosis in colon cancer cells by p-p53(ser46) involvement. Further studies will focus on studying the specific signal transduction pathway.
... Besides antiviral activity, lectins display anticancer activity in vivo and in vitro. They preferentially recognize the carbohydrates expressed on the membrane surface of cancer cells, causing tumor growth inhibition, apoptosis, and cytotoxicity [26]. Anticarcinogenic and antitumor activities of lectins are owing to diverse mechanisms as a direct cytotoxic effect on malignant cells, inducing remission in certain tumors, stimulating restoration of normal growth in tumor cells, inhibiting the neoplastic effect of chemotherapy and radiation and augmenting tumor cell immunogenicity [27]. ...
... Wheat germ lectin (WGA) had shown an inhibitory effect on tumor growth of lymphoma cells [30], while its isolectins displayed different cytotoxic activities and differential interaction with leukemic cells [31]. Some cyanobacterial lectins were found to inhibit tumor proliferation in vitro and in vivo by attaching to cell membranes of tumor cells and their cellular receptors [26,32]. This antitumor activity leads to many effects, e.g. ...
In the present study, a novel lectin was purified from the newly isolated cyanobacterium, Lyngabya confervoides MK012409 and tested for its antiviral and anticancer activity. Out of 30 isolates, Mabroka-s isolate which identified as Lyngabya confervoides MK012409 showed the highest agglutination titer. Lyngabyal lectin showed the greatest haemagglutination activity with pigeon/rabbit erythrocytes with a minimum concentration of 2.4 μg/ml. Physical characterization of Lyngabyal lectin showed ability to keep the activity at a higher temperature up to 80 °C with stability over a wide pH range (4–8) as well as its stability toward chemical denaturants. Carbohydrate specificity test revealed that the sugar alcohols completely inhibited the lectin haemagglutination activity. The electrophoretic analysis revealed that the lyngabyal lectin is a 140 kDa composed of two 70 kDa subunits. Lyngabyal lectin was able to inhibit the proliferation of MCF-7 and Caco-2 cancer cell lines with IC50 values of 246 ± 0.17 and 376.4 ± 0.34 μg/ml, respectively. Lyngabyal lectin also showed virucidal activity against HSV-1 with EC50 of 167 ± 0.52 ng/ml and inhibited plaque formation in the HSV-1 infected Vero cells with EC50 of 84.94 ± 0.34 ng/ml. These findings emphasize the ability of the lyngabyal lectin to fight breast and colon cancer besides it represents a promising antiviral agent.
... 3,6,8 Lectins and trypsin inhibitors can both reduce protein digestibility and nutrient absorption. 16,17 Favin, a particular lectin in faba beans, was purified by Wang et al. 18 and was also found to be mitogenic for lymphocytes in rats. However, studies on mice showed that a lectin from kidney beans possesses anticarcinogenic effects. ...
... Reduction of protein digestibility and nutrient absorption 3,17 Extrusion, germination 41,42 Saponins Bitter and astringent taste, bloat symptoms in animals 3 Soaking, germination 42 Lectins Decrease of protein digestibility and nutrient absorption 16,26 Dehulling 42 Phytate degradation was tackled by means of enzymatic treatment. The mineral bioavailability of zinc and iron of faba bean flour significantly improved when the content of phytate was decreased, clearly proportional to the degradation of phytic acid. ...
... Legume lectins emerge in human diet, being present in foods like tomato, peanut, banana, lentil, soybean, rice, potato, and others. When consumed, lectins' biological activity may be preserved, as they are resistant to gut digestion, enabling their possible function, even in the circulation system [1]. Plants lectins are used as potential biomarkers for several diseases as they are associated with antimicrobial, insecticidal, and antitumor activity [1][2][3]. ...
... When consumed, lectins' biological activity may be preserved, as they are resistant to gut digestion, enabling their possible function, even in the circulation system [1]. Plants lectins are used as potential biomarkers for several diseases as they are associated with antimicrobial, insecticidal, and antitumor activity [1][2][3]. As lectins bind to carbohydrates moieties, they detect large and heterogeneous group of proteins in tumor cancer tissues, since glycosylated proteins are commonly upregulated in cancer, where their various functions tend to increase tumor progression and other aberrant conditions [4][5][6]. ...
Currently available drugs for treatment of glioblastoma, the most aggressive brain tumor, remain inefficient, thus a plethora of natural compounds have already been shown to have antimalignant effects. However, these have not been tested for their impact on tumor cells in their microenvironment-simulated cell models, e.g., mesenchymal stem cells in coculture with glioblastoma cell U87 (GB). Mesenchymal stem cells (MSC) chemotactically infiltrate the glioblastoma microenvironment. Our previous studies have shown that bone-marrow derived MSCs impair U87 growth and invasion via paracrine and cell–cell contact-mediated cross-talk. Here, we report on a plant-derived protein, obtained from Crataeva tapia tree Bark Lectin (CrataBL), having protease inhibitory/lectin activities, and demonstrate its effects on glioblastoma cells U87 alone and their cocultures with MSCs. CrataBL inhibited U87 cell invasion and adhesion. Using a simplified model of the stromal microenvironment, i.e., GB/MSC direct cocultures, we demonstrated that CrataBL, when added in increased concentrations, caused cell cycle arrest and decreased cocultured cells’ viability and proliferation, but not invasion. The cocultured cells’ phenotypes were affected by CrataBL via a variety of secreted immunomodulatory cytokines, i.e., G-CSF, GM-CSF, IL-6, IL-8, and VEGF. We hypothesize that CrataBL plays a role by boosting the modulatory effects of MSCs on these glioblastoma cell lines and thus the effects of this and other natural lectins and/or inhibitors would certainly be different in the tumor microenvironment compared to tumor cells alone. We have provided clear evidence that it makes much more sense testing these potential therapeutic adjuvants in cocultures, mimicking heterogeneous tumor–stroma interactions with cancer cells in vivo. As such, CrataBL is suggested as a new candidate to approach adjuvant treatment of this deadly tumor.
... 17 Plant lectins are common in food and dietary intake can be significant. 16,28 Many non-legume plant lectins, including MBL, maintain full biological activity after consumption as they are typically not inactivated by cooking, resist digestion, and enter the circulation intact. 16,28,29 An example where an active lectin supplement may be demonstrating its anti-coronaviral properties is the Nictaba lectin from the tobacco plant (Nicotiana tabacum). ...
... 16,28 Many non-legume plant lectins, including MBL, maintain full biological activity after consumption as they are typically not inactivated by cooking, resist digestion, and enter the circulation intact. 16,28,29 An example where an active lectin supplement may be demonstrating its anti-coronaviral properties is the Nictaba lectin from the tobacco plant (Nicotiana tabacum). Nictaba is a GlcNAc-specific agglutinin that is active against SARS-CoV-1, which exposes many glycans enabling interference with virus entry and virus release. ...
Increasing consumption of plant lectins (e.g., eating fruits and vegetables) may reduce COVID-19 risks. Mannose binding lectins (MBL), a key molecule in our innate immune response, contributes to host defense against coronaviruses such as SARS-CoV. This article reviews the role of MBL in the innate immune response against coronavirus infections, highlights evidence of MBL’s significance, and suggests dietary MBL supplementation through increased consumption of fruits and vegetables as an accessible and viable approach to minimizing COVID-19 infection risk.
... Lectins agglutinate erythrocytes or aggregate cells and inhibit protein synthesis. They also induce apoptosis and cell cycle arrest and thus inhibit angiogenesis and cell proliferation (Beztsinna et al., 2018;Ferriz-Martinez et al., 2010;González De Mejía and Prisecaru, 2007;. Moreover lectins affect the immune system by activating the immune cells (González De Mejía and Prisecaru, 2007). ...
... They also induce apoptosis and cell cycle arrest and thus inhibit angiogenesis and cell proliferation (Beztsinna et al., 2018;Ferriz-Martinez et al., 2010;González De Mejía and Prisecaru, 2007;. Moreover lectins affect the immune system by activating the immune cells (González De Mejía and Prisecaru, 2007). ...
Ethnopharmacological relevance: Mistletoe has been used since ancient times in Europe mostly for medicinal purposes. Since 1917, mistletoe preparations have been applied in cancer therapy and today are the most frequently used complementary medicine in tumor treatment. The main cytotoxic constituents of Viscum album are lectins and viscotoxins. Aim of the study: The aim of this in vitro study was to investigate the antiproliferative potential of Viscum album preparations from different host trees and to assess the impact of mistletoe lectin 1 (ML-1) and viscotoxin A (VT-A) in comparison to a structurally similar lectin and thionin. Materials and methods: By means of widely accepted 2D Alamar Blue Assay, based on population counting of living cells using a fluorescent cell viability dye, the potential impact to inhibit tumor cell of the mistletoe preparations (Iscucin ® ) and their single compounds (ML-1 and VT-A) on the cell growth of six human cancer cell lines were evaluated. Also the mixture of ML-1 and VT-A corresponding to the contents in the specific mistletoe preparations were monitored. Ricin and purothionin were used as reference lectin and reference thionin, respectively. Results: The lung carcinoma cell line HCC827 was very sensitive to the Iscucin ® preparations. Very strong antiproliferative effects were found with Iscucin ® Salicis and Tiliae and a strong with Iscucin ® Crataegi, Mali and Populi. The IC 50 concentrations of the Iscucin ® preparations correlated with their respective ML-1 contents, but the ML-1 levels were much lower than the IC 50 concentration of isolated ML-1 (1 ng/ml – 56 ng/ml). ML-1 was much more effective than ricin. Iscucin ® preparations, ML-1 and ricin showed antiproliferative activity on human tumor cells. VT-A and purothionin had no effect on cell viability in the concentration ranges tested. Conclusion: The complete mistletoe extract is more potent to inhibit tumor cell proliferation than isolated ML-1 at an equivalent concentration level. Phenolic compounds found in all Iscucin ® preparations might contribute to uphold the cytotoxic activity of ML-1 by antioxidative action. However, further studies are necessary to evaluate the role of VT-A and possible synergistic actions to the antiproliferative effect of aqueous mistletoe extracts.
... Lectins are proteins that bind to carbohydrates, either free or bound to cell membranes as part of glycoproteins, glycolipids, or polysaccharides. Since these interactions are reversible and highly specific, lectins have been widely used to elucidate alterations in the composition of carbohydrates during pathological processes such as cancer, where the cell glycosylation machinery is frequently altered, leading to the exposure of aberrant carbohydrates on cellular surfaces [1][2][3][4][5]. ...
... These changes vary depending on the cancer type and are often related to tumor progression and lifespan [4]. Some of the most common tumor-associated glycan changes described to date include (1) increased β1-4 branched tetra-antennary N-glycans [4,5]; (2) α2-6 sialylation on the outer poly-N-acetyllactosamines (LacNAc) of N-glycans [6]; (3) increase of α1-6 fucosylation [7,8]; (4) overexpression of mucins and truncated O-glycans [9]; (5) altered expression of blood groups and sialyl-Lewis antigens [10]; (6) increase in bisecting GlcNAc [11]; (7) overexpression of hyaluronan [12,13]; and (8) increased β1-6 branching of N-glycans [4,5]. The latter is one of the most important glycan modifications in colorectal cancer cells. ...
Herein, we report the production of a recombinant Tepary bean lectin (rTBL-1), its three-dimensional (3D) structure, and its differential recognition for cancer-type glycoconjugates. rTBL-1 was expressed in Pichia pastoris, yielding 316 mg per liter of culture, and was purified by nickel affinity chromatography. Characterization of the protein showed that rTBL-1 is a stable 120 kDa homo-tetramer folded as a canonical leguminous lectin with two divalent cations (Ca 2+ and Mn 2+) attached to each subunit, confirmed in its 3D structure solved by X-ray diffraction at 1.9 Å resolution. Monomers also presented a~2.5 kDa N-linked glycan located on the opposite face of the binding pocket. It does not participate in carbohydrate recognition but contributes to the stabilization of the interfaces between protomers. Screening for potential rTBL-1 targets by glycan array identified 14 positive binders, all of which correspond to β1-6 branched N-glycans' characteristics of cancer cells. The presence of α1-6 core fucose, also tumor-associated, improved carbohydrate recognition. rTBL-1 affinity for a broad spectrum of mono-and disaccharides was evaluated by isothermal titration calorimetry (ITC); however, no interaction was detected, corroborating that carbohydrate recognition is highly specific and requires larger ligands for binding. This would explain the differential recognition between healthy and cancer cells by Tepary bean lectins.
... Lectins bind with cell surface carbohydrates when it comes into contract of the cell or can be internalized into the cells which can trigger a wide variety of signals those includes induction of cell cycle arrest or apoptosis, suppression of telomerase activity, and inhibition of angiogenesis and ribosomal inactivation [32][33][34][35][36][37][38][39][40]. Proliferation of T lymphocytes can be stimulated, tumour necrosis factor alpha (TNF)-a activity can be raised and anti-inflammatory interleukin (IL)-10 activity can be also inhibited by lectin as a result immune system can be activated [39]. ...
Kaempferia rotunda Linn. is a plant of ginger family and has many medicinal values in traditional applications, including as antimicrobial and anticancer agents. The present study aims to examine the anticancer activity of Kaempferia rotunda tuberous rhizome lectin (KRL, MW 29 ± 1.0 kDa) against colon cancer cells SW480 and SW48. KRL inhibited 67% and 59% of SW480 and SW48 cells growth respectively at the concentration of 1.0 mg/ml. The cells growth inhibition was a dose dependent manner. KRL treatments notably inhibited the colony formation capacity of the cancer cells. The surviving fractions of SW480 and SW48 cells treated with KRL significantly (p < 0.001) reduced compared to that of control cells. Significant increment of the apoptotic cells were noted following by G0/G1 or G2/M cell cycle arrest in KRL treated SW480 and SW48 cells, respectively. Modulation of PARP1, p53, p21, Bax and Bcl2 proteins expression was observed in treated cells in comparison to that of untreated cells. Furthermore, activation of caspase-3 and caspase-9 was noted in KRL treated cells and caspase-3 and caspase-9 inhibitors pre-treated cells were shown insensitive to KRL treatment. The results implied that KRL prevents SW480 and SW48 cells proliferation by the induction of apoptosis in the mitochondrial intrinsic pathway.
... The affinity of lectins towards cancer cell is higher than that of healthy cells (20). Thereafter, lectin exhibited EAC growth inhibition by altering cell cycle, inducing non-apoptotic G1phase accumulation mechanisms, G2/M phase cell cycle arrest, and apoptosis (21). According to a previous study, lectin from Pisum sativum seed reduced the EAC cell growth by 44 and 63% at 1.4 mg/kg/day and 2.8 mg/kg/ day respectively (22). ...
Citrus macroptera (Rutaceae) has long been used in folk medicine in Bangladesh. Considering the folkloric context , this study was aimed to scrutinize anti-proliferative activity of C. macroptera fruit pulp juice (CMFPJ) against Ehrlich's ascites carcinoma (EAC). The anti-proliferative capacity of CMFPJ was investigated and confirmed primarily using MTT assay. In vivo anti-proliferative aptitude of CMFPJ was investigated with 25, 50, and 100 mg/kg/day intraperitoneal (i.p.) treatment. Anti-proliferative efficacy of CMFPJ was assessed based on EAC growth inhibition. CMFPJ inhibited EAC growth in vitro in a dose-dependent manner. And the percentages of in vivo EAC growth inhibition were 19.53, 49.2, and 68.9% at 25, 50, and 100 mg/kg CMFPJ respectively. CMFPJ significantly induced expression of apoptosis regulatory genes caspase-8, caspase-9, cytochrome-c, and caspase-3. This considerable anti-cancer activity was perhaps due to combinatorial effect of lectin, polyphenols, and flavo-noids present in CMFPJ.
... Several plant lectins such as mistletoe lectins (MLs) and ricin have been well-studied and shown to possess antiproliferative and apoptosis-inducing activities towards cancer cells [9]. In addition, other lectins such as Con A [4,10,11] and PCL [12,13] can result in autophagic cell death after internalization or binding certain sugar-containing receptors on the surface of cancer cells [14]. ...
Experiments conducted in vitro and in vivo, as well as some preclinical trials for cancer therapeutics, support the antineoplastic properties of lectins. A screening of antitumoral activity on HT29 colon cancer cells, based on polypeptide characterization and specific lectin binding to HT29 cells membrane receptors, was performed in order to assess the bioactivities present in four Mediterranean plant species: Juniperus oxycedrus subsp. oxycedrus, Juniperus oxycedrus subsp. badia, Arbutus unedo and Corema album. Total leaf proteins from each species were evaluated with respect to cell viability and inhibitory activities on HT29 cells (cell migration, matrix metalloproteinase –MMP proteolytic activities). A discussion is presented on a possible mechanism justifying the specific binding of lectins to HT29 cell receptors. All species revealed the presence of proteins with affinity to HT29 cell glycosylated receptors, possibly explaining the differential antitumor activity exhibited by the two most promising species, Juniperus oxycedrus subsp. badia and Arbutus unedo.
... This fact generally occurs when lectins link to glycan chains in the tumor cell membrane to produce various effects. Mechanical details are not yet known, but there are so many pieces of evidence that lectins may inhibit or activate protein function by binding to glycan chains of glycoproteins in different cellular compartments (17). Thus, the lectin interaction in different cellular compartments can give rise to some toxic effects such as decrease in protein synthesis or cell death stimulation. ...
... Recently, there has been an increased interest in lectin-containing edible mushrooms for different biological significant activities of lectins including antiproliferative, anti-tumour and immunomodulatory function [2]. Lectins are non-immune proteins or glycoproteins that are specifically bound to the carbohydrates of the cell surface [3,4]. Increasing numbers of lectins from plant and animal origin have been extracted and characterized; furthermore, research on lectins derived from fungal sources stays limited [1]. ...
The acidic microenvironment of tumour cells requires a pH-sensitive delivery mechanism for improving drug release. In this study, we investigated the feasibility of using pH-sensitive ACC nanoparticles with sustained-release performance and slow degradability as carriers for lectins isolated from edible mushroom Agaricus bis-porus (ABL) that exhibited anti-proliferating effects on tumour cells. ABL was purified and characterized using ion-exchange, gel filtration chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. ABL-ACC nanoparticles were synthesized through a simple precipitation process coupled with mechanical grinding. The conjugated ABL-ACC-NPs were characterized using Fourier-transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscope, transmission electron microscope and zeta potential. Cytotoxicity of ABL-ACC-NPs was analyzed using methylthiazol tetrazolium assay against MCF-7 cells compared with ABL and ACC-NPs. The results indicated biostability of ACC-NPs and low toxicity toward MCF-7 cells, and induced increased reduction in MCF-7 viability compared with ABL. ABL-ACC-NPs-FITC showed fully internalization and accumulation inside the nucleus comparing with ABL-FITC which showed only accumulation around the nuclear envelope. Inclusively, conjugation of ABL with ACC-NPs has improved its cytotoxicity, enhanced its bioavailability, internalization into the tumour cells, accumulation in cell organelles which may promote cell responses and subsequently triggered cell death.
... Lectins are one kind of carbohydrates binding protein that normally found in whole plant or plant parts [40]. It is well known that the plant lectins are able to bind with cell membrane of different types of cancer cells leading to stun their multiplication [41,42]. A few researches evident that the lectin has anti-proliferative activity against EAC cell line [43,44]. ...
Cancer is the second death causing disease all over the world and until today 100 different types of cancer have been identified whose treatment methods consist of serious side effects on human body. To reduce the frequency of adverse effects of
cancer treatment, nowadays plant derived natural components are getting priority. The plant Morus latifolia is widely available in northern part of Bangladesh. The earlier researches suggested that popular varieties of some Morus sp. like Morus alba, Morus indica etc. have good anti-proliferative activity. Hence, this study was designed to evaluate the anti-proliferative activity of leaf and bark extracts of M. latifolia against Ehrlich’s ascites carcinoma (EAC) in vivo. The leaf and bark extracts of M. latifolia were used in several bioassays including Brine shrimp lethality test, hemagglutination activity test, antioxidant activity test, and cell growth inhibition test. Besides, fluorescence microscopy was performed to study apoptotic features in EAC cells, and molecular analysis like real-time PCR were also conducted. The results of Brine shrimp lethality test, hemagglutination activity test, and antioxidant activity assay supported the cell growth inhibition capability of leaf and bark extracts which was confirmed by in vivo cell growth inhibition bioassay. Moreover, the experimental extracts were able to induce cell apoptotis through altering the expression pattern of Bcl-2 and Bax genes. All of the results of this study suggest that several noble compounds are present in M. latifolia plant extracts which are capable for healing cancer cells.
... The capacity of lectins to recognize and interact with specific glycans makes them interesting molecules for detecting modifications in surface glycans during the transformation of normal cells into cancer cells [84,85], and these molecules have been used to study several properties of cancer [86]. Pinto Dioclea grandiflora (DGL), Dioclea guianensis (DGuiL), Dioclea virgata (DvirL), Dioclea violacea (DVL) and Dioclea rostrata (DRL) lectins, were also tested in this study and presented differential binding to the tested cell lines, enabling their use as biomarkers. ...
Curr Protein Pept Sci. 2019 Jan 4. doi: 10.2174/1389203720666190104123210. [Epub ahead of print]
ConBr, The Lectin From Canavalia brasiliensis Mart. Seeds: Forty Years Of Research.
Cavada BS1, Osterne VJS1, Pinto-Junior VR1, Nascimento KS1.
Abstract
Lectins are defined as proteins or glycoproteins capable of specific and reversible binding to carbohydrates. Inside this group of proteins, the most well studied lectins belong to the family Leguminosae, and inside this family, the Diocleinae subtribe presents the extensively characterized lectin Concanavalin A (ConA), as well as ConBr, the lectin from Canavalia brasiliensis, the subject of this review. Since 1979, several studies have been published in the literature regarding this lectin, from its isolation and characterization to its several biological activities. This year, 2019, will mark 40 years since researchers have begun to study ConBr and 100 years since the discovery of ConA, making 2019 a momentous year for lectinology. Owing to the abundance of studies involving ConBr, this review will focus on ConBr's purification, physicochemical properties, functional and structural analyses, biological activities and biotechnological applications. This will give researchers a broad glimpse into the potential of this lectin, as well as it characteristics, as we look ahead to its expanding applications in glycomics and biotechnology.
KEYWORDS:
Biological Activities; Canavalia brasiliensis; ConBr; Lectin; Lectinology. ; Properties
... Studies have reported on the application of plant lectins as anticancer agents owing to their potent inhibitory effects, cytotoxicity and the ability to induce apoptosis and autophagy in several tumor cell lines [57,58]. These lectins can inhibit tumorigenesis by binding to glycosylated proteins on the membrane of cancer cells. ...
Lectins are a widely studied group of proteins capable of specific and reversible binding to carbohydrates. Undoubtedly, the best characterized are those extracted from plants of the Leguminosae family. Inside this group of proteins, those from the Diocleinae subtribe have attracted attention, in particular Concanavalin A (ConA), the best-studied lectin of the group. Diocleinae lectins, also called ConA-like lectins, present a high similarity of sequence and three-dimensional structure and are known to present inflammatory, vasoactive, antibiotic, immunomodulatory and antitumor activities, among others. This high similarity of lectins inside the ConA-like group makes it possible to use them to study structure/biological activity relationships by the variability of both carbohydrate specificity and biological activities results. It is in this context the following review aims to summarize the most recent data on the biochemical and structural properties, as well as biological activities, of ConA-like lectins and the use of these lectins as models to study structure/biological activity relationships.
... In many places of Argentina, there is a rich tradition of using herbal medicine for the treatment of various infectious diseases like 4 inflammations 5 , and injuries 6 . Some plant lectins have been found to possess remarkable anticancer properties in in vivo, in vitro and in human case studies 7 and have also been successfully adopted for alternative cancer therapy 8,9 . Plant cause cytotoxicity in cancer cells via different mechanisms namely, by inducing apoptosis, autophagy or necrosis and inhibiting cells growth, preferentially binding to cancer cells membrane or their receptors 10 . ...
... Hemagglutination assay was carried out to find out the presence of lectin protein which is considered to have potent anticancer and growth inhibitory activity [11,43]. The hemagglutination activity of leaf and seed extracts of B. alba was represented in Figure 2. ...
Cancer is a class of diseases characterized by uncontrolled cell growth. The current treatment options of cancer are radiotherapy, chemotherapy, hormone therapy, and surgery, where all of them have unpleasant side effects. Due to their adverse side effects, it is challenging to develop new drug for cancer treatment. Hence, the scientists are trying to seek for noble compounds from natural sources to treat cancer. Therefore, in the present investigation, a widely consumable vegetable Basella alba was subjected to evaluate its antiproliferative effect along with molecular signaling of apoptosis in Ehrlich ascites carcinoma (EAC) cell line. Cell growth inhibition was determined by haemocytometer whereas apoptosis of cancer cells were studied by florescence microscope using Hoechst-33342 stain and result was supported by DNA fragmentation and certain cancer related genes expression through PCR analysis. B. alba leaf and seed extract exhibit a considerable scavenging activity in comparison to a standard antioxidant BHT. Moreover, the leaf and seed extracts were able to agglutinate 2% RBC of goat blood at minimum 12.5 μ g/ml and 50.0 μ g/ml concentration, respectively. A significant cytotoxic activity was also found in both leaf and seed extract. In haemocytometic observation, the leaf and seed extracts exhibit about 62.54±2.41% and 53.96±2.34% cell growth inhibition, respectively, whereas standard anticancer drug Bleomycin showed 79.43±1.92% growth inhibition. Morphological alteration under fluorescence microscope showed nuclear condensation and fragmentation which is the sign of apoptosis. Apoptosis induction was also confirmed by DNA laddering in leaf and seed treated EAC cells. Upregulation of the tumor suppressor gene P ⁵³ and downregulation of antiapoptotic gene Bcl-2 enumerate apoptosis induction. Therefore, current study manifested that leaf and seed extracts of B. alba have antiproliferative activity against EAC cell line and can be a potent source of anticancer agents to treat cancer.
... Las lentejas poseen un grupo de prote?nas y glicoprote?nas con una potente actividad biol?gica, las lectinas, las cuales son usadas para profilaxis de infecciones retrovirales (incluido el VIH) y c?ncer ( Alexandre et al., 2010;De Mej?a & Prisecaru, 2005). Tambi?n se ha encontrado que en los pa?ses donde se consume menos carne y m?s prote?nas vegetales, existe menor cantidad de personas enfermas con c?ncer de colon, de pecho y de la pr?stata (Correa, 1981). ...
Las tendencias del consumo de alimentos en la época contemporánea están orientadas por el interés en conservar la salud y contribuir a la conservación del ambiente. Consumir menos carne de vacuno y más proteínas de origen vegetal es una de las opciones de alimentación en crecimiento.
Esta investigación tuvo como objetivo desarrollar una hamburguesa para vegetarianos que
cumpliera la proporción de aminoácidos esenciales similar a la del huevo (como referencia
estándar), a la cual se le determinaron propiedades texturales, de color, humedad, grasa y
características sensoriales.
La hamburguesa se elaboró a escala de laboratorio y se calculó el puntaje de aminoácidos esenciales teórico. Se encontró que es posible elaborar una hamburguesa vegetariana que cumpla con la proporción de aminoácidos iguales o superiores a los del huevo como referencia estándar, y que además tenga una aceptabilidad sensorial.
Palabras clave: Hamburguesa, vegetarianos, aminoácidos esenciales, análisis sensorial, TPA
... Lectins can be used as blood typing agents, for the identification of sugar components of the normal and cancerous cells and for the estimation of virus particles [43]. According to the properties of lectins, the haemagglutination activity of Q. semecarpifolia was determined against human RBCs. ...
The development of reliable and green methods for the fabrication of metallic nanoparticles has many
advantages in the field of nanotechnology. In this direction, the present work describes eco-friendly and costeffective
protocol for the production of silver nanoparticles (AgNPs) using aqueous extract of Quercus
semecarpifolia leaves. Different techniques were carried out for characterization of the synthesized AgNPs.
The UV-visible spectroscopic analysis showed highest absorbance peak at 430 nm. The particle size and structure
was confirmed by Scanning Electron Microscope (SEM) as well as Transmission Electron Microscope (TEM)
analysis. From TEM imaging, it was revealed that the formed particles were spherical with average size of 20-50
nm. Crystalline nature of the nanoparticles (NPs) was determined by X-ray powder diffraction (XRD)
pattern. Thermogravimetry and Differential Thermal Analysis (TG-DTA) was also evaluated by
temperature increment from 100 to 1000oC. Bio-inspired synthesis of AgNPs was investigated for their
pharmacological evaluation in relation to the activities of the crude methanolic, n-hexane, chloroform, ethyl
acetate and aqueous extracts. Good cytotoxic activity was exhibited by the green-synthesized AgNPs (77%).
Furthermore, the AgNPs were found to exhibit significant antioxidant activity at 300 μg/ml (82%). At highest
concentration, AgNPs showed good phytotoxic potential (75%). The test samples showed no haemagglutination
activity.
... Several researches have shown the use of Lectins to inhibit tumor growth, especially by causing cytotoxicity, apoptosis and, down-regulation of telomerase activity and inhibition of angiogenesis. In addition, lectins have also been found to sequester the pool of available polyamines in the body; thereby help in thwarting cancer cell growth [16]. ...
Novel Lectin gene was isolated from the seeds of an indigenous plant Piliostigma thonningii (PTL) using Zymo Research Plant/Seed Kit. Agglutination reaction for confirmation of the lectin was performed using chicken erythrocytes. Galactose-specific lectin coding protein was detected by optimized Polymerase Chain Reaction using a primer pair LEC5 (Forward) and LEC6 (Reverse). The lectin was partially purified under a working condition of phosphate-buffered saline (PBS, pH 7.0) followed by ammonium sulfate precipitation and gel filtration on Sephadex G-75 column. Electrophoresis of the purified protein under denaturing conditions was performed on 12% Acrylamide gel using a tris-glycine buffer, pH 8.3. The crude protein of the plant seeds and the partially purified lectin were tested for antimicrobial activity against certain microorganisms. The PTL DNA was isolated using Zymo Research Plant/Seed Kit. The result revealed a 195bp product, confirming the presence of lectin gene in PTL seeds. The purified protein had an estimated molecular weight of 21kDa. The result revealed no antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Bacillus subitilis and a fungi, Candida albicans. The novelty of this study presents lectin gene in an indigenous PTL and the use of conventional hemagglutination and Polymerase Chain Reaction, as sensitive and specific detection methods.
... They are extremely used for diagnostic and therapeutic purposes in cancer research. Lectins have different carbohydratebinding specificities, the effects of which have been studied in human hepatoma (H3B), human choriocarcinoma, mouse melanoma, and rat osteosarcoma cell lines [12,13]. Lectins are considered as one of the potent natural sources for the treatment of cancer which causing apoptosis and cell growth inhibition proved by in vitro and in vivo experiment [14]. ...
Legume lectins are carbohydrate-binding protein and widely distributed in a variety of species of leguminous plants and have drawn increased attention toward cancer. Nowadays, the lectins have been studied for the screening of potential biomarkers which increased its importance in cancer research. Few plant lectins have been shown to destroy cancer cells, suggesting that lectins may have biological potential in cancer treatments. In this review, we present a focused outline of legume lectins in descriptive their complex anti-cancer mechanisms on the bases of their properties of recognition and interacting specifically with carbohydrates binding sites. Existing reports suggested the binding of lectins to cancerous cells with their cell surface markers speculated by histochemistry in vitro and in vivo. In this review, we illuminate the use of legume lectins as a natural source for diagnostics and therapeutics purpose against cancer.
... Numerous authors have reviewed the role of lectins, including those existing in plants which are currently used in cancer treatment. (De Mejía and Prisecaru 2005;Ferriz-Martinez et al. 2010;Liu et al. 2010;Fu et al. 2011;Zhang et al. 2012;Dan et al. 2016;Coelho et al. 2017;de Oliveira Figueiroa et al. 2017;Poiroux et al. 2017). To cite a few examples, Con A binds tumor cells in a mannosespecific manner inducing autophagy against hepatoma (Mice-P) (Chang et al. 2007). ...
Medicinal plants host numerous therapeutic low molecular weight phytochemicals and macromolecules such as polysaccharides and proteins. Lectins are glycan binding proteins ubiquitous in the cell and the extracellular surface of all living organisms. Plant parts contain lectins with diverse glycan binding specificities. This review highlights the occurrence of lectins in herbal remedies, their persistence, and bioactivity. Lectins’ roles in plants include signaling, defense, and stress responses. The species, plant part, biotic and abiotic factors influence the type and concentration of lectins. Many lectins withstand herbal portions preparation procedures, resist degradation in the alimentary canal and crossover to the circulatory system. Exogenous plant lectins bind glycans with high specificity eliciting cellular responses that include antimicrobial, antitumor and immunomodulation effects. Some lectins are deleterious to normal physiology.
... In plants, these proteins are found mainly in seeds and storage tissues, where they reach up to 10% of the total proteins, whereas in leaves, roots, and stems, their concentration is lower (Liener, 1976;Etzler, 1985;Chrispeels and Raikhel, 1991). Lectins from some species, mainly legumes, have shown an ability to selectively adhere to tumor-cell oligosaccharides and inhibit their growth (Díaz et al., 1999;De Mejía and Prisecaru, 2005;Ferriz Martínez et al., 2010). ...
Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) has been shown to specifically bind and induce cell death of different types of cancer cells and also has exhibited an effect on early colon tumorigenesis. However, the development of a pharmaceutical formula is not possible yet because the production process is expensive and slow and provides low yields. Therefore, the purpose of the present work was to develop a strategy to produce one bioactive lectin by rhizosecretion through root exudates on genetically modified plants. Amplification of Tepary bean transcripts was performed using degenerate primers, and the products obtained were sequenced. Multiple alignments of sequences led to elucidating one of the lectins present in TBLF. Its coding sequence was flanked by an N-terminal secretion signal peptide and a 6xHis-tail. This construction was introduced into P. acutifolius plants using Agrobacterium tumefaciens to subsequently carry out the in vitro growth of the plants. When roots grew, plants were transferred to hydroponic conditions and root exudates were analyzed. Results showed the presence of a glycosylated cisgenic lectin with biological activity, confirming that the strategy followed provides an alternative for the synthetic production and purification of this lectin.
... The rationale to use lectins for cancer therapy arises from their ability to target multiple cellular components, so as to allow cancer treatment by different approaches. It has been demonstrated that lectins are able to affect apoptosis by interacting with signalling pathways involving Bcl-2 and caspase families, p53, PI3K/Akt, ERK, BNIp3, Ras-Raf and ATG families [8]. It is known that the transcription factor RUNX2 is involved in p53 regulation, in the crosstalk between Mek/Erk and PI3K/Akt pathways, and it is also linked to Ras in mechanical stress induction. ...
RUNX2, a master osteogenic transcript ion factor, is overexpressed in several cancer cells; in melanoma it promotes cells migration and invasion as well as neoangiogenesis. The annual mortality rates related to metastatic melanoma are high and novel agents are needed to improve melanoma patients’ survival. It has been shown that lectins specifically target malignant cells since they present the Thomsen–Friedenreich antigen. This disaccharide is hidden in normal cells, while it allows selective lectins binding in transformed cells. Recently, an edible lectin named BEL β-trefoil has been obtained from the wild mushroom Boletus edulis. Our previous study showed BEL β-trefoil effects on transcription factor RUNX2 downregulation as well as on the migration ability in melanoma cells treated in vitro. Therefore, to better understand the role of this lectin, we investigated the BEL β-trefoil effects in a zebrafish in vivo model, transplanted with human melanoma cells expressing RUNX2. Our data showed that BEL β-trefoil is able to spread in the tissues and to reduce the formation of metastases in melanoma xenotransplanted zebrafish. In conclusion, BEL β-trefoil can be considered an effective biomolecule to counteract melanoma disease.
... Recently, there has been an increased interest in lectin-containing edible mushrooms for different biological significant activities of lectins including antiproliferative, anti-tumour and immunomodulatory function [2]. Lectins are non-immune proteins or glycoproteins that are specifically bound to the carbohydrates of the cell surface [3,4]. Increasing numbers of lectins from plant and animal origin have been extracted and characterized; furthermore, research on lectins derived from fungal sources stays limited [1]. ...
The acidic microenvironment of tumour cells requires a pH-sensitive delivery mechanism for improving drug release. In this study, we investigated the feasibility of using pH-sensitive ACC nanoparticles with sustained-release performance and slow degradability as carriers for lectins isolated from edible mushroom Agaricus bisporus (ABL) that exhibited anti-proliferating effects on tumour cells. ABL was purified and characterized using ion-exchange, gel filtration chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. ABL-ACC nanoparticles were synthesized through a simple precipitation process coupled with mechanical grinding. The conjugated ABL-ACC-NPs were characterized using Fourier-transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscope, transmission electron microscope and zeta potential. Cytotoxicity of ABL-ACC-NPs was analyzed using methylthiazol tetrazolium assay against MCF-7 cells compared with ABL and ACC-NPs. The results indicated biostability of ACC-NPs and low toxicity toward MCF-7 cells, and induced increased reduction in MCF-7 viability compared with ABL. ABL-ACC-NPs-FITC showed fully internalization and accumulation inside the nucleus comparing with ABL-FITC which showed only accumulation around the nuclear envelope. Inclusively, conjugation of ABL with ACC-NPs has improved its cytotoxicity, enhanced its bioavailability, internalization into the tumour cells, accumulation in cell organelles which may promote cell responses and subsequently triggered cell death.
... Compounds that exemplify the extremes of this classification range are shown in Fig. 4. Mycalolide B (entry ID JQV, Fig. 4a) Identifying saccharide binding proteins. Lectins and saccharide binding proteins are involved in many biological processes, including cell recognition, cell-cell adhesion, and immune functions [31][32][33][34][35] . In this section, we show another application of CTPIC for identification of these macromolecules by probabilistic annotation of small molecule with saccharide origin that bind to the proteins. ...
The chemical composition of saccharide complexes underlies their biomedical activities as biomarkers for cardiometabolic disease, various types of cancer, and other conditions. However, because these molecules may undergo major structural modifications, distinguishing between compounds of saccharide and non-saccharide origin becomes a challenging computational problem that hinders the aggregation of information about their bioactive moieties. We have developed an algorithm and software package called “Cheminformatics Tool for Probabilistic Identification of Carbohydrates” (CTPIC) that analyzes the covalent structure of a compound to yield a probabilistic measure for distinguishing saccharides and saccharide-derivatives from non-saccharides. CTPIC analysis of the RCSB Ligand Expo (database of small molecules found to bind proteins in the Protein Data Bank) led to a substantial increase in the number of ligands characterized as saccharides. CTPIC analysis of Protein Data Bank identified 7.7% of the proteins as saccharide-binding. CTPIC is freely available as a webservice at (http://ctpic.nmrfam.wisc.edu).
... These well-known protein-bound polysaccharides contain substantial amounts of carbohydrates (50-90%). They could kill cancer cells by binding to the cell membranes (De Mejía and Prisecaru 2005) leading to extrinsic (death receptor) or intrinsic (mitochondrial) apoptotic pathways. In addition, recent studies reported anticancer activity of protein extracts or protein fractions isolated from medicinal mushrooms without identifying the exact structures of active proteins, such as Calvatia lilacina, Pleurotus ostreatus, Volvariella volvacea , Lentinus squarrosulus (Sumkhemthong et al. 2016;Prateep et al. 2017), and Lentinus tigrinus (Mohammadnejad et al. 2019). ...
Severe side effects of chemotherapy as well as drug resistance highlight the ongoing need to discover novel natural bioactive compounds with anticancer potentiality. Mushroom-derived proteins are among the naturally occurring compounds that have been the subject of a body of research on their potentiality in cancer therapy. The greatest attention in relevant review articles has been paid to well-known mushroom-derived glycoproteins such as lectins and protein-bound polysaccharide complexes such as polysaccharide-K (PSK) or krestin and polysaccharopeptide (PSP), which contain substantial amounts of carbohydrates (50–90%). These complex compounds exert their anticancer activity mainly by binding to cell membranes leading to extrinsic (death receptor) apoptosis or intrinsic (mitochondrial) apoptotic pathways. However, several other research studies have reported pure, well-characterized, proteins or peptides from mushrooms, which are carbohydrate-free or have very low amounts of carbohydrate. These proteins may fall into four categories including fungal immunomodulatory proteins, ubiquitin-like proteins, enzymes, and unclassified proteins. Well-defined chemical structure, elucidated full amino acid or N-terminal sequences, purity, and having some distinct and specific pathways compared to glycoproteins have made these low-carbohydrate proteins attractive for cancer research. The aim of this review was therefore to improve the current understanding of mushroom-derived low-carbohydrate proteins and to consolidate the existing knowledge of the most promising mushroom species from which low-carbohydrate proteins have been derived, characterized, and examined for their anticancer activity. In addition, molecular targets and mechanisms of action of these proteins have been discussed.Key points
• Mushroom-derived low-carbohydrate proteins lack or have low carbohydrate.
• Low-carbohydrate proteins show potent anticancer activities in vitro and in vivo.
• There are specific pathways for low-carbohydrate proteins to inhibit cancer cells.
... The first is due to the ability of lectins to recognize tumor glycosylations, which allows for a better diagnosis and prognosis of cancer tumors [8,9]. The therapeutic potential of lectins is based on their antitumor and cytotoxic effects subsequent to their surface binding through the induction of apoptosis or autophagy [10][11][12][13]. Increased core fucosylation on many serum glycoproteins like Alphafetoprotein (AFP) and membrane receptors is observed in gastrointestinal cancer, hence it is becoming an important diagnostic marker [14]. ...
Cephalosporium curvulum lectin (CSL), a lectin from pathogenic fungus has exquisite specificity towards α1–6 linkage of core fucosylated glycans, expressed in hepatocellular and pancreatic cancer. Interaction and effect of CSL and other fucose specific lectins LCA and AOL on HepG2 and PANC-1 cells was investigated. CSL, LCA and AOL exhibited strong binding to PANC-1 cells which could be effectively blocked by competing glycoprotein mucin. Effect of CSL, LCA and AOL on PANC-1 and HepG2 cells was determined by MTT assay and all the three lectins inhibited the cell growth which could be blocked by mucin, cell cycle analysis revealed that CSL increased hypodiploid HepG2 cell population indicating cellular apoptosis. CSL induced apoptosis in HepG2 cells was confirmed by Annexin V/PI assay. CSL induced increase in early apoptotic HepG2 cell population, a time dependent increase in the expression of caspases-3, 9 and cytochrome-c was observed by western blotting suggesting the possible involvement of intrinsic caspase dependent apoptosis. Increase in ROS and decrease in MMP demonstrated involvement of intrinsic caspase dependent apoptosis. Quantification of AFP in HCC patients using CSL lectin-antibody sandwich ELISA, supports diagnostic potential of CSL.
... It also includes inhibition of growth and kinase activity and induction of apoptosis (Kanadaswami et al., 2005). Foods like wheat, beans, rice, potatoes etc contain plant lectin, which exhibit anticancer activity (De Mejia et al. 2005). Plant derived tyrosine kinase inhibitors are the potential anticancer agents. ...
Discovery of the medicine or drug is time consuming and labour intensive process. Natural products have vast chemical diversity and it has ability to act on various biological systems. Plants and its products are the important elements in the plant medicine system. Many of the plant extracts currently used in the treatment of cancer therapy and those agents were also isolated from plants. Here the main objective of this review is to introduce the plants and its products used in the treatment of the leukemia effectively.
... The effect of lectins on the immune system by altering the production of various interleukins has been well-documented. There is also data showing that some lectins down-regulate the activity of telomere, thereby inhibiting angiogenesis (Choi et al., 2004;De Mejía and Prisecaru, 2005). Cancerlectins can induce cytotoxicity, apoptosis, and inhibit tumor growth by binding to receptors on the surface of cancer cells. ...
The cancerlectin plays an important role in the initiation, survival, growth, metastasis, and spread of cancer. Therefore, to study the function of cancerlectin is greatly significant because it can help to identify tumor markers and tumor prevention, treatment, and prognosis. However, plenty of studies have generated a large amount of protein data. Traditional prediction methods have been unable to meet the needs of analysis. Developing powerful computational models based on these data to discriminate cancerlectins and non-cancerlectins on a large scale has been treated as one of the most important topics. In this study, we developed a feature extraction method to identify cancerlectins based on fusion of g-gap dipeptides. The analysis of variance was used to select the optimal feature set and a support vector machine was used to classify the data. The rigorous nested 10-fold cross-validation results, demonstrated that our method obtained the prediction accuracy of 83.91% and sensitivity of 83.15%. At the same time, in order to evaluate the performance of the classification model constructed in this work, we constructed a new data set. The prediction accuracy of the new data set reaches 83.3%. Experimental results show that the performance of our method is better than the state-of-the-art methods.
... Lectins can inhibit proliferation and have a cytotoxic effect on tumor cells. 22 Moreover, ConA induces apoptosis in human melanoma Fig. 2 ConA can increase the proliferation of DPSCs. DPSCs were cultured in osteogenic medium with 5 and 10 µg/mL ConA being added for 24 hours. ...
Objective Dental pulp stem cells (DPSCs) can be used as a component in the formation of regenerative dentine during direct pulp capping therapy. Concanavalin A (ConA) is a type of lectin with a molecular weight of 26 kDa derived from the Canavalia ensiformis plant. Lectins possess strong proliferation and differentiation abilities in various animal cells including lymphocytes, osteoblasts, and chondrocytes. The aim of study was to determine the effect of ConA on the proliferation and osteogenic differentiation of DPSCs in vitro.
Materials and Methods In this in vitro study, DPSCs were isolated from third molars before ConA induction was performed at concentrations of 5 and 10 μg/mL. The proliferation assay was determined by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Osteogenic differentiation was determined by means of mineralization.
Statistical Analysis Data were analyzed using analysis of variance and a Student’s t-test. The p-value was set at 0.05.
Results The addition of 5 and 10 µg/mL of ConA to DPSCs can significantly increase the proliferation and osteogenic differentiation of DPSCs (p ≤0.05).
Conclusion ConA can increase the proliferation and osteogenic differentiation of DPSCs.
... Abrin is extremely toxic to eukaryotic cells, whereas AAG has low toxicity (Liu et al., 2000). Despite this, abrin is much more toxic to some transformed cell lines than to normal cells and is therefore attractive as a potential anticancer agent (Mejía and Prisecaru, 2005). The antitumor activity of abrin has been reported in in vitro (Bhutia et al., 2016) and in vivo (Ramnath et al., 2009) conditions. ...
Plants are rich sources of compounds with varied structures and potent
biological effects against diseases, including cancer. Many studies have been performed to investigate plant-derived compounds with the ability to impair tumor formation or control cancer progression such as lectins (carbohydrate-binding proteins). This review discusses the in vitro and/or in vivo effects of these bioactive proteins from plants against cancer cells or models. Lectins interfere with cell growth and survival by binding to specific membrane receptors or internalization via endocytosis. In both cases, they can block the pathways involved in cell growth and survival (e.g., PI3K/Akt/mTOR, ERK, and NF-κB signaling), induce oxidative stress, trigger apoptosis through the induction of an imbalance of pro- apoptotic and anti-apoptotic proteins and/or the activation of death receptors, induce autophagy-related gene expression, and cause necrosis. Although some lectins have been studied in clinical trials, there are many others that deserve attention. The current study indicates such proteins that
have a promising future as new anticancer drugs.
... Chickpea lectin is also involved in lowering the blood glucose level by binding to and disrupting the intestinal mucosal cells resulting in a hindrance to nutrient absorption. The lectins from lentil, pea and chickpea were found to be non-toxic (Gonzalez and Prisecaru, 2005). Previous studies on the lectin activity of various leguminous crops demonstrated that chickpea and pigeon pea have lectin activity, though the activity was reported to be below toxic levels (Singh 1988). ...
Lectins are proteins with carbohydrate-binding ability. In plants, they have been obtained from leaves, weeds, roots, rhizomes, bulbs, pods, seeds, fruits and flowers. The interaction of lectins with carbohydrates from cell surfaces can trigger diverse intracellular responses, resulting in a range of biological activities that have been exploited for various biotechnological purposes. Among the biological activities of plant lectins, it is possible to mention immunomodulatory action that can be given through the interaction between lectin to surface glycoproteins of immune cells. Immunomodulators may exhibit positive (immune-stimulation) or negative (immunosuppression) activities over a specific immunological function. It is known that lectins can stimulate pro-inflammatory or anti- inflammatory responses. In this paper, we review plant lectins able to induce both profiles, in vitro and/or in vivo, and their possible mechanisms of action. Plant lectins are capable to alter the release of cytokines, chemokines and nitric oxide by immune cells. One of the mechanisms that may be involved in the pro-inflammatory action of lectins is the activation of Toll-like receptors (TLR). Also, it was observed that the lectin-induced cytokines profile may vary according to the model, the type of immune cell and the route of administration. Moreover, plant lectins can stimulate the differentiation, activation and proliferation of immune cells. More studies are needed to determine in more details the pathways and mechanisms involved in the immune-modulatory action presented by these biomolecules as well as on their effective application in immunotherapy.
... This binding allows the detection of malignant cells [10,11] and, additionally, triggers cytotoxic activity through apoptosis and autophagy induction, resulting in the inhibition of tumour growth [2,[12][13][14]. Although the complete mechanism of lectin activation has not been described, some signalling pathways have been proposed [4,[15][16][17], and the cytotoxic effects of different lectins on cancer cells have also been reported [4,14,15,[18][19][20][21]. ...
Lectins are bioactive proteins with the ability to recognize cell membrane carbohydrates in a specific way. Diverse plant lectins have shown diagnostic and therapeutic potential against cancer, and their cytotoxicity against transformed cells is mediated through the induction of apoptosis. Previous works have determined the cytotoxic activity of a Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) and its anti-tumorigenic effect on colon cancer. In this work, lectins from the TBLF were additionally purified by ionic-exchange chromatography. Two peaks with agglutination activity were obtained: one of them was named TBL-IE2 and showed a single protein band in two-dimensional electrophoresis; this one was thus selected for coupling to quantum dot (QD) nanoparticles by microfluidics (TBL-IE2-QD). The microfluidic method led to low sample usage, and resulted in homogeneous complexes, whose visualization was achieved using multiphoton and transmission electron microscopy. The average particle size (380 nm) and the average zeta potential (−18.51 mV) were determined. The cytotoxicity of the TBL-IE2 and TBL-IE2-QD was assayed on HT-29 colon cancer cells, showing no differences between them (p ≤ 0.05), where the LC50 values were 1.0 × 10−3 and 1.7 × 10−3 mg/mL, respectively. The microfluidic technique allowed control of the coupling between the QD and the protein, substantially improving the labelling process, providing a rapid and efficient method that enabled the traceability of lectins. Future studies will focus on the potential use of the QD-labelled lectin to recognize tumor tissues.
... Research on biosynthesized nanomaterials has increased due to their significance in biomedical and pharmaceutical applications. Efforts have been made to biologically synthesize different metal nanoparticles such as zinc [1][2], gold [3] and silver [4][5] for use in the biomedical field because of their antioxidant and antimicrobial potential [6][7]. Nanoparticles have a scope in cancer therapeutics because of their anticancer properties [8][9]. ...
Background and Objectives
Present years biogenic nanomaterials are deeply concerned in biomedicine because of their antioxidant, antimicrobial and anti-inflammatory or antitumor performance. This study was intended to biologically synthesize gold nanoparticles using N. foetida, a camptothecin producing plant and evaluation of their potent cytotoxic activity against cancer cells and antimicrobial activities against human pathogenic bacteria.
Methods
The gold nanoparticles were characterized by UV-visible spectroscopy, Scaning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform-infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Dynamic Light Scattering (DLS). Antimicrobial activity of gold nanoparticles was determined by minimum inhibitory concentration (MIC) assay on Gram positive and negative bacteria whereas cytotoxicity against cancer cells was assessed by MTT assay and genotoxicity was assayed by DNA fragmentation.
Results
Results of TEM and DLS showed synthesis of 20-200 nm sized NFAuNPs. The NFAuNPs exerted growth inhibitory effects on Gram negative bacteria where MIC for inhibition of E.coli was 0.15 mg/mL where as the MIC of AuNPs to inhibit growth of P. aeruginosa was 0.25 mg/mL. The cytotoxicity results indicated that the sublethal concentration NFAuNPs required to inhibit 50 % of cell growth (IC50) of cancer cells including HeLa, MCF-7 and HCT-15 are 7.2, 9.67 and 5.28 µg/mL after 48h of exposure. DNA fragmentation in cells exposed to 10 to 75 µg/mL concentrations of AuNPs revealed the genotoxic effects of NFAuNPs.
Conclusion
Thus, the study revealed the biogenic synthesis of gold nanoparticles using N. foetida plant extract and its biological potential as antimicrobial and anticancer agent.
... Plant-derived lectin present in corn, wheat, tomato, potato, soybean, rice, mushroom, peanut and banana and plays a significant role in the improvement of immune system functions. Numerous lectins acquire anticancer and immunomodulatory activity in vivo, in vitro and in clinical trials, hence used as the therapeutic agent [93,94]. Viscum album agglutinin-I (VAA-I) is a plant lectin exhibits immunomodulatory activity by altering mitochondrial transmembrane potential and increasing intracellular levels of ROS [95]. ...
A well-functioning immune system of the host body plays pivotal role in the maintenance of ordinary physiological and immunological functions as well as internal environment. Balanced immunity enhances defense mechanism against infection, diseases and unwanted pathogens to avoid hypersensitivity reactions and immune related diseases. The ideal immune responses are the results of corrective interaction between the innate immune cells and acquired components of the immune system. Recently, the interest towards the immune system increased as significant target of toxicity due to exposure of chemicals, drugs and environmental pollutants. Numerous factors are involved in altering the immune responses of the host such as sex, age, stress, malnutrition, alcohol, genetic variability, life styles, environmental-pollutants and chemotherapy exposure. Immunomodula-tion is any modification of immune responses, often involved induction, amplification, attenuation or inhibition of immune responses. Several synthetic or traditional medicines are available in the market which promptly have many serious adverse effects and create pathogenic resistance. Phytochemicals are naturally occurring molecules , which significantly play an imperative role in modulating favorable immune responses. The present review emphasizes on the risk factors associated with alterations in immune responses, and immunomodulatory activity of phytochemicals specifically, glycosides, alkaloids, phenolic acids, flavonoids, saponins, tannins and sterols and sterolins.
Plant-based diets are associated with reduced risk of lifestyle-induced chronic diseases. The thousands of phytochemicals they contain are implicated in cellular-based mechanisms to promote antioxidant defense and reduce inflammation. While recommendations encourage the intake of fruits and vegetables, most people fall short of their target daily intake. Despite the need to increase plant-food consumption, there have been some concerns raised about whether they are beneficial because of the various 'anti-nutrient' compounds they contain. Some of these anti-nutrients that have been called into question included lectins, oxalates, goitrogens, phytoestrogens, phytates, and tannins. As a result, there may be select individuals with specific health conditions who elect to decrease their plant food intake despite potential benefits. The purpose of this narrative review is to examine the science of these 'anti-nutrients' and weigh the evidence of whether these compounds pose an actual health threat.
Nanotechnology is a fast-growing field with numerous applications in the field of medical science. One such application comprises nanoparticle biosynthesis from plant extracts and their compounds with their potential applications in cancer therapy. These plant-based nanoparticles have been observed to be effective against various types of cancerous cells both in vitro and animal models. Another application of nanotechnology is the herbal therapeutics comprising the use of novel nano-based drug delivery systems in the treatment of cancer. These novel drug delivery systems aid in increasing the therapeutic value and bioavailability of the herbal medicine. The application of nanoherbal formulations as novel drug delivery systems (NDDS) is more valuable as compared to other therapies. These novel drug delivery systems include phytosomes, liposomes, microsphere, nanocapsules, ethosomes, transfersomes, nanoemulsions, and polymeric nanoparticles. The effectiveness of these different plant-based nanodrug delivery systems has been studied against various cancer types. These alternative drug delivery systems help in increasing the efficiency of a drug delivery and safeguard the drug from metabolic processes alongside its sustained delivery, proper distribution, and protection from physical and chemical deterioration. In addition, they reduce the possible side effects of the drugs. In spite of the advancements, cancer endures to be a predominant and fatal disease. This has led to the increased use of nano-based anticancer drugs and their delivery systems, also known as nanotherapies against tumors due to their ability of site-specific targeting and multifunctionality. In this chapter, recent advancements in application of plant-based nanomaterials in cancer therapy and impending strategies are discussed.
Grain legumes, also called pulses, are plants belonging to the family Leguminosae (alternatively Fabaceae) which are grown primarily for their edible seeds.
Lectins are proteins or glycoproteins of non-immune origin which have at least one non-catalytic domain that bind reversibly to specific mono or oligosaccharides. Traditional Chinese Medicine (TCM) involves a broad range of medicinal practices sharing common concepts which have been developed in China and are based on a tradition of more than thousands of years. Plant materials which are commonly used in TCM as a complementary or alternative for Western medical treatments contain a considerable number of important lectins. These lectins have been reported to have various applications and uses such as cancer treatment, glycoconjugate research, biomarker development, and others. Here, we summarize the available literature related to lectins from TCM and recent trends in their potential biomedical applications.
This Proceeding or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. The organizing committee would like to thanks all participants in IPSB 2017 for the manuscript submitted. The Editors have made every effort to ensure the accuracy and completeness of information contained in this Proceedings. However, due to limited time, it was not possible for the Editors to thoroughly edit all submissions. The Editors are therefore not liable for any errors, inaccuracies, omissions or any inconsistencies in the published manuscripts in this Proceeding.
TF antigen binding lectins from dietary sources PNA, ACA, ABL, JAC, and SRL from Sclerotium rolfsii have been reported to induce diverse effects on cancer cell proliferation by different mechanisms. This study aimed to compare effects of these lectins on growth and cell cycle progression in colon cancer HT29 and SW620 cells. As reported SRL, ABL, and JAC inhibited while PNA and ACA increased cell proliferation. ABL and JAC treated HT29 cells showed increased cell population in G0/G1 phase. PNA, ACA, ABL, and JAC increased SW620 cell population in S and decreased in G2/M phase. In contrast, SRL and JAC increased hypodiploid population in both the cells. PNA and ACA reduced whereas SRL and ABL diminished cell cyclin D1 expression. SRL, PNA, and ACA also reduced cellular cyclin D3 level while SRL, ABL, and JAC reduced cyclin E levels. ABL decreased CDK5 levels while SRL and ACA completely abolished CDK5 expression. All the lectins completely abolished cyclin D2 expression. These results not only confirms growth regulatory effects of TF-binding lectins but also indicates different effects of these lectins on cell growth is associated with regulation on expression of cell cycle associated proteins in G1-S phase and on cell cycle progression.
Abelmoschus esculentus (Okra) is one of the most utilize species of the Malvaceae family and garnered tremendous attention in the scientific community due to the myriad biological functions. Besides the health benefit, around the worldwide, this plant has been reported to be used extensively in traditional medicine. Meanwhile, very few studies have been conducted to evaluate the molecular mechanism in cancer, thus, ongoing research conducting to evaluate the role of okra in cancer. Recently active constituent of okra has been reported to combat the diverse type of cancer. The purpose of this review was to summarize the findings of recent publications of okra with regard to cancer and to discuss the importance of this as a possible therapeutic agent.
It has been shown that a concentrated fraction in lectins (FCL) of Tepari bean (Phaseolus acutifolius) has the ability to induce programmed cell death on different types of human cancer cells, mainly colon and breast cancer. This effect derives from the differential recognition exhibited by lectins on glyco-conjugates present on the membrane of healthy and cancerous cells because their interaction with the latter is greater and decreases the risk of collateral damage on surrounding tissues. When administered orally, the lectins present in the FCL have the ability to cross the gastrointestinal tract without being degraded by the pH conditions and/or the enzymes present in the stomach and intestine, so they have been considered as potential chemotherapeutic agents to fight malignant transformations of the gastrointestinal tract. However, they are not currently used because the procurement process is expensive, slow and has very low yields. Therefore, the purpose of this work was to generate a heterologous production system independent of beans, which constitutes a continuous obtaining platform and allows the implementation of strategies that contribute to facilitate the purification process. For this, the coding sequence of one of the lectins presumably responsible for the biological effect of FCL was coupled to a hexahistidine tail and fused in phase with the "α-factor" of S. cerevisiae under the regulation of the constitutive PGAP promoter. This genetic material was introduced into the yeast Pichia pastoris which, in turn, was transferred to liquid culture under controlled conditions to favor the production of the protein. The final yield obtained was 316 mg of recombinant lectin (LR)/L of culture medium. After purification, it was possible to obtain a single protein of approximately 30.8 kDa that contains an N-glycosidic antenna covalently linked to asparagine13 of its polypeptide sequence and does not possess O-glycosylations. Said lectin showed no binding activity with fresh rabbit erythrocytes; however, its cytotoxic activity on colon cancer cells remained similar to its native counterpart, with a lethal concentration 50 (LC50) of approximately 2.47 μg / mL, which is similar to that reported for FCL (2.71 μg / mL). Finally, through the development of LR mutants, it was demonstrated that the conservative substitution of the Arg132 and Arg103 residues leads to a significant decrease in their cytotoxicity on colon cancer cells, suggesting that these residues are fundamental for the recognition of the lectin on the glycoconjugates of tumor cells. The evidence found confirms that the strategy followed provides a successful alternative for the synthetic obtaining of FCL lectins and also opens a range of possibilities for the study of the interactions that are established between said lectins and the glycoconjugates of transformed cells.
Una fracción de lectinas (FCL) de frijol Tépari (Phaseolus acutifolius) estudiada previamente, ha mostrado importantes efectos inhibiendo la proliferación en células de diferentes tipos de cáncer humano. No obstante, estas moléculas no se utilizan actualmente como agentes terapéuticos debido a que el proceso de obtención es costoso, lento y presenta muy bajos rendimientos. Por otra parte, la obtención heteróloga de dichas lectinas no es una alternativa viable debido a que sus patrones de glicosilación están sujetos a la maquinaria enzimática de cada especie, aunado al hecho de que sus secuencias polipeptídicas no se encuentran completamente elucidadas. Por lo anterior, la finalidad del presente trabajo fue realizar la síntesis de una lectina de frijol Tépari mediante la modificación genética de plantas, con una novedosa estrategia que permite conservar su patrón de glicosilación nativo y, por ende, su actividad citotóxica diferencial. Para ello, se obtuvo la secuencia nucleotídica de una de las lectinas presuntamente responsables del efecto biológico de la FCL de frijol Tépari, la cual fue flanqueada por un péptido señal de rizo-secreción en el extremo 5´ y una cola de hexahistidinas en el extremo 3´. Este material genético fue introducido en plantas de Phaseolus acutifolius por medio de Agrobacterium tumefaciens, para posteriormente efectuar el crecimiento in-vitro de las plantas transgénicas. Al alcanzar la edad adulta, fueron transferidas a condiciones hidropónicas con la finalidad de analizar el producto obtenido de los exudados radiculares. Los resultados obtenidos confirmaron la presencia de una lectina recombinante con actividad biológica y sugieren que la estrategia seguida provee una alternativa exitosa para la obtención sintética de estos elementos.
A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.
The Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) exhibits differential cytotoxicity on colon cancer cells and inhibition of early tumorigenesis in the colon (50 mg/kg, three times per week, for 6 weeks). TBLF showed low toxicity with the ability to activate the immune system; however, some adverse effects are the loss in body weight gain, intestinal atrophy, and pancreatic hyperplasia. After a recovery period of 2 weeks after treatment, reversion of pancreatic hyperplasia but no recovery of intestinal atrophy was observed. As TBLF has shown anticancer effects on the colon, it is important to characterize the adverse effects and how they can be reversed. Sprague Dawley rats were administered with TBLF (50 mg/kg) for 6 weeks, three times per week, and then allowed to recover for 6 weeks post-treatment. After TBLF administration, small intestine atrophy, villus atrophy, and cryptic hyperplasia were confirmed, as well as increased intestinal mucus production, increased permeability and a decrease in the apparent ileal digestibility of crude proteins. The colon showed damage in the simple prismatic tissue and decreased crypt depth, and changes in microbiota and a decrease in the apparent fecal digestibility of crude protein were determined. Our results show that the adverse effects provoked by TBLF were partially reversed after 6 weeks of recovery post-treatment, suggesting that increasing the recovery period it could be possible to reverse all adverse effects observed.
Pleurotus ostreatus Lectin (POL) is a 353 amino acid chain lectin that can be purified from the fruiting bodies of the very well-known and widely diffused edible oyster mushrooms (Pleurotus ostreatus). The lectin has been partially characterized by different groups and, although it was crystallized about 20 years ago, its three-dimensional structure and the details of its interactions with carbohydrates are still unknown. This paper reports the three-dimensional structure and ligand-binding properties of POL. We have determined the X-ray structure of the apo-protein purified from the fruiting bodies of the mushroom and that of the recombinant protein in complex with melibiose to a resolution of about 2 Å. The lectin is a homodimer in which the two polypeptide chains are linked by a disulfide bridge. A POL monomer is composed of two highly homologous β-jellyroll domains each of which containing a calcium-dependent carbohydrate binding site. A high degree of sequence similarity is observed between the two carbohydrate binding modules present in each monomer. The structure of the lectin in complex with melibiose reveals that a POL dimer has four calcium dependent carbohydrate-binding sites. The interaction with sugars in solution has been characterized by ITC and Saturation transfer difference (STD) NMR and it sheds new light on the molecular determinants of POL specificity. The lectin exhibits in vitro antiproliferative effects against human cancer cell lines and presents structural similarity with the prototype member of the CBM67 family, the non-catalytic domain of Streptomyces avermitilis α-Rhamnosidase.
The high prevalence of cancer has been increased the rate of studying about the new formulation of chemotherapeutic drugs. In this regards, one of the suitable options is the use of metal nanoparticles for formulating these drugs. In the recent study, Lens culinaris seed aqueous extract conjugated gold nanoparticles (AuNPs) are reported for the first time to exert a dietary therapeutic potential compared to mitoxantrone in an animal model of acute myeloid leukemia. The synthesized AuNPs were characterized using different techniques including UV–Vis., FT‐IR, XRD, FE‐SEM, and TEM. DPPH free radical scavenging test was done to evaluate the antioxidant potentials of HAuCl4, L. culinaris, AuNPs, and mitoxantrone. For the analyzing of cytotoxicity effects of HAuCl4, L. culinaris, AuNPs, and mitoxantrone, MTT assay was used on HUVEC, 32D‐FLT3‐ITD, Human HL‐60/vcr, and Murine C1498 cell lines. In vivo assay, induction of acute myeloid leukemia was done by 7,12‐Dimethylbenz[a]anthracene (DMBA) in 75 mice. Then, the animals were randomly divided into six subgroups, including control, untreated, HAuCl4, L. culinaris, AuNPs, and mitoxantrone. SEM and TEM images showed uniform spherical morphology and average diameters of 10–40 nm for the nanoparticles. DPPH test revealed similar antioxidant potentials for mitoxantrone and AuNPs. Similar to mitoxantrone, AuNPs had low cell viability dose‐dependently against 32D‐FLT3‐ITD, Human HL‐60/vcr, and Murine C1498 cell lines without any cytotoxicity on HUVEC cell line. AuNPs and mitoxantrone significantly (p ≤ 0.05) reduced the weight and volume of liver and spleen, the pro‐inflammatory cytokines, and the total WBC, blast, neutrophil, monocyte, eosinophil, and basophil counts and increased the mRNA expression of Sphingosine‐1‐phosphate receptor‐1 and Sphingosine‐1‐phosphate receptor‐5, the anti‐inflammatory cytokines, and the lymphocyte, platelet, and RBC parameters as compared to the untreated mice. It looks that AuNPs can be administrated as a chemotherapeutic supplement or drug for the treatment of acute myeloid leukemia in the clinical trial. Formulation a modern chemotherapeutic drug.
The monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins, which until now have been isolated from species of the Amaryllidaceae, Alliaceae, Araceae, Orchidaceae, and Liliaceae. To explain the obvious differences in biological activities, the structure-function relationships of the monocot mannose-binding lectins were studied by a combination of glycan-binding studies and molecular modeling using the deduced amino acid sequences of the currently known lectins. Molecular modeling indicated that the number of active mannose-binding sites per monomer varies between three and zero. Since the number of binding sites is fairly well correlated with the binding activity measured by surface plasmon resonance, and is also in good agreement with the results of previous studies of the biological activities of the mannose-binding lectins, molecular modeling is of great value for predicting which lectins are best suited for a particular application.
The epithelial glycoprotein 40 (EGP40, also known as GA733-2, ESA, KSA, and the 17-1A antigen), encoded by the GA-733-2 gene, is expressed on the baso-lateral cell surface in most human simple epithelia. The protein is also expressed in the vast majority of carcinomas and has attracted attention as a tumor marker. The function of the protein is unknown. We demonstrate here that EGP40 is an epithelium-specific intercellular adhesion molecule. The molecule mediates, in a Ca(2+)-independent manner, a homophilic cell-cell adhesion of murine cells transfected with the complete EGP40 cDNA. Two murine cell lines were tested for the effects of EGP40 expression: fibroblastic L cells and dedifferentiated mammary carcinoma L153S cells. The expression of the EGP40 protein causes morphological changes in cultures of transfected cells--increasing intercellular adhesion of the transfectants--and has a clear effect on cell aggregating behavior in suspension aggregation assays. EGP40 directs sorting in mixed cell populations, in particular, causes segregation of the transfectants from the corresponding parental cells. EGP40 expression suppresses invasive colony growth of L cells in EHS-matrigel providing tight adhesions between cells in growing colonies. EGP40 can thus be considered a new member of the intercellular adhesion molecules. In its biological behavior EGP40 resembles to some extent the molecules of the immunoglobulin superfamily of cell adhesion molecules (CAMs), although no immunoglobulin-like repeats are present in the EGP40 molecule. Certain structural similarities in general organization of the molecule exist between EGP40 and the lin-12/Notch proteins. A possible role of this adhesion molecule in formation of architecture of epithelial tissues is discussed. To reflect the function of the molecule the name Ep-CAM for EGP40 seems appropriate.
Endocytosis and intracellular transport of ricin were studied in stable transfected HeLa cells where overexpression of wild-type (WT) or mutant dynamin is regulated by tetracycline. Overexpression of the temperature-sensitive mutant dynG273D at the nonpermissive temperature or the dynK44A mutant inhibits clathrin-dependent endocytosis (Damke, H., T. Baba, A.M. van der Blieck, and S.L. Schmid. 1995. J. Cell Biol. 131: 69–80; Damke, H., T. Baba, D.E. Warnock, and S.L. Schmid. 1994. J. Cell Biol. 127:915–934). Under these conditions, ricin was endocytosed at a normal level. Surprisingly, overexpression of both mutants made the cells less sensitive to ricin. Butyric acid and trichostatin A treatment enhanced dynamin overexpression and increased the difference in toxin sensitivity between cells with normal and mutant dynamin. Intoxication with ricin seems to require toxin transport to the Golgi apparatus (Sandirg, K., and B. van Deurs. 1996. Physiol. Rev. 76:949–966), and this process was monitored by measuring the incorporation of radioactive sulfate into a modified ricin molecule containing a tyrosine sulfation site. The sulfation of ricin was much greater in cells expressing dynWT than in cells expressing dynK44A. Ultrastructural analysis using a ricin-HRP conjugate confirmed that transport to the Golgi apparatus was severely inhibited in cells expressing dynK44A. In contrast, ricin transport to lysosomes as measured by degradation of ¹²⁵I-ricin was essentially unchanged in cells expressing dynK44A. These data demonstrate that although ricin is internalized by clathrin-independent endocytosis in cells expressing mutant dynamin, there is a strong and apparently selective inhibition of ricin transport to the Golgi apparatus. Also, in cells with mutant dynamin, there is a redistribution of the mannose-6-phosphate receptor.
The ability of ricin, a type II ribosome-inactivating protein, to induce hepatoma cell (BEL7404) to apoptosis in vitro was examined by fluorescence microscopy, flow cytometry, and DNA fragmentation assay. As a Bcl-2 lacking model, BEL7404 bore unique advantage to study the effect of over-expressing Bcl-2 on the apoptosis induced by the inhibitor of protein synthesis. By establishing a Bcl-2 over-expressing cell line (BEL7404/ Bcl-2), we found that Bcl-2 could promote the survival of the hepatoma cell against ricin insult. The ricin-induced apoptosis of BEL7404 was accompanied by increased expression of Bak and decreased levels of Bcl-xl and Bax. Caspases and PARP cleavage activity were found to be implicated in the death process. Through the inhibitor tests, our results excluded the participation of calcium-dependent proteases or protein kinase C in the apoptotic process induced by ricin, though an elevation of intracellular calcium did occur as an immediate response to ricin treatment. Cycloheximide, another protein synthesis inhibitor, did synergistically enhance rather than inhibit the cytotoxicity of ricin to hepatoma cell BEL7404. Actually, cycloheximide alone was able to induce hepatoma cell BEL7404 to death that could also be inhibited by over-expressing Bcl-2. The elevation of apoptotic protein Bak was discussed to challenge the notion that ricin exerted its cytotoxicity through nonspecific inhibition of all the de novo protein synthesis. J. Cell. Biochem. 81: 583–593, 2001. © 2001 Wiley-Liss, Inc.
Protease inhibitor and lectin concentrations and N and lipid levels were evaluated in 27 soya bean samples. All contained trypsin and chymotrypsin inhibiting activity and lectin. Shinano midori, Shinano wasediro, Shinano-oomame and Tsuronoku had high protein contents and average lipid levels, and their lectin and trypsin and chymotrypsin inhibitory activities were not unduly high. These lines, in particular, merit further nutritional evaluation. Food intake, feed conversion efficiency and growth by rats was reduced when soya bean was included in their diet, but the extent to which these parameters were affected did not appear to depend only on the protease inhibitor or lectin content. In contrast, pancreatic and small intestinal growth did seem to reflect the levels of these factors in the diet. Chymotrypsin inhibitor activity in soya bean was more readily abolished by heat-treatment than was trypsin inhibitory activity. Lectin activity was also relatively heat-resistant. However, all of these activities could be abolished by aqueous heat-treatment of fully imbibed seeds at 100°C for 10 min. The effects of a soya diet on pancreas and small intestine weights were also abolished by this pre-treatment, and food intake and nutrient utilisation by rats was greatly improved. © 1998 Society of Chemical Industry
One of the predominant proteins in the pulp of ripe bananas (Musa acuminata L.) and plantains (Musa spp.) has been identified as a lectin. The banana and plantain agglutinins (called BanLec and PlanLec, respectively) were
purified in reasonable quantities using a novel isolation procedure, which prevented adsorption of the lectins onto insoluble
endogenous polysaccharides. Both BanLec and PlanLec are dimeric proteins composed of two identical subunits of 15 kDa. They
readily agglutinate rabbit erythrocytes and exhibit specificity towards mannose. Molecular cloning revealed that BanLec has
sequence similarity to previously described lectins of the family of jacalin-related lectins, and according to molecular modelling
studies has the same overall fold and three-dimensional structure. The identification of BanLec and PlanLec demonstrates the
occurrence of jacalin-related lectins in monocot species, suggesting that these lectins are more widespread among higher plants
than is actually believed. The banana and plantain lectins are also the first documented examples of jacalin-related lectins,
which are abundantly present in the pulp of mature fruits but are apparently absent from other tissues. However, after treatment
of intact plants with methyl jasmonate, BanLec is also clearly induced in leaves. The banana lectin is a powerful murine T-cell
mitogen. The relevance of the mitogenicity of the banana lectin is discussed in terms of both the physiological role of the
lectin and the impact on food safety.
Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.
The protein peanut agglutinin (PNA) is a galactose-binding lectin whose receptor, the Thomsen-Friedenreich (TF) blood-group antigen, shows increased expression in hyperplastic and neoplastic colonic epithelium.
Our hypothesis was that, under these conditions, increased lectin receptors could interact with dietary lectins, which would act as tumor promoters by stimulating cell proliferation. This study was designed to confirm whether active PNA is recoverable from feces after ingestion of peanuts and to assess the mitogenic effect of PNA on proliferation of epithelial cells in the colon.
Peanut lectin was extracted from feces by lactose-agarose affinity chromatography and was assayed for hemagglutinating activity. Cultured explants of histologically normal biopsy specimens of colonic mucosa from 31 patients were examined. Crypt cell production rate and incorporation of [3H]N-acetylglucosamine into mucin were assessed as indicators of proliferative and metabolic responses to PNA. In addition, we evaluated the separate and combined effects of PNA and epidermal growth factor (EGF) on cell proliferation in human HT29 colorectal cancer cells, by using tritiated thymidine incorporation and cell counts.
Peanut lectin extracted from feces showed hemagglutinating activity toward desialylated red blood cells similar to that of a lectin preparation extracted from raw peanuts. Evaluation of biopsy specimens of normal colonic mucosa demonstrated that PNA at a concentration of 25 micrograms/mL caused statistically significant increases in crypt cell production (31% [mean] +/- 5% [SD]; P = .00005) and mucus synthesis (77% +/- 12%; P less than .000001). At 7.5-100 micrograms/mL, PNA was mitogenic for the HT29 colorectal cancer cell line. At 25 micrograms/mL, PNA alone produced a statistically significant increase in thymidine incorporation (44% [mean] +/- 3.7% [SD]; P = .002). For PNA in combination with EGF at 100 pg/mL, the increase was significantly greater (222% +/- 11.2%) than that for EGF alone (57% +/- 5%; P = .003).
These results suggest that expression of the PNA receptor, TF antigen, by hyperplastic or neoplastic colonic epithelium may affect cell proliferation.
It is possible that dietary lectins such as PNA, which bind to the TF antigen, promote cell proliferation and thus cancerous growth, while galactose-containing vegetable fiber would inhibit this effect by competing for binding by these lectins.
The sialic acid-specific leukoagglutinating lectin from the seeds of Maackia amurensis (MAL) has been studied by the techniques of quantitative precipitin formation, hapten inhibition of precipitation, hapten inhibition using an enzyme-linked immunosorbent assay, and lectin affinity chromatography. The ability of the immobilized lectin to fractionate oligosaccharides based on their content of sialic acid has also been investigated. Our results indicate that MAL reacts with greatest affinity with the trisaccharide sequence Neu5Ac/Gc alpha 2,3Gal beta 1,4GlcNAc/Glc. The lectin requires three intact sugar units for binding and does not interact when the beta 1,4-linkage is replaced by a beta 1,3-linkage nor when the "reducing sugar" of the trisaccharide is reduced. Results from enzyme-linked immunosorbent assays show that an N-acetyllactosamine repeating sequence is not required; however, the N-acetyllactosamine repeating sequence does appear to enhance the binding of MAL to a series of glycolipids. In addition, the sialic acid may be substituted with either N-acetyl or N-glycolyl groups without reduction in binding. The C-8 and C-9 hydroxyl groups of sialic acid do not play a role in binding as shown by the strong reaction of periodate-treated glycoproteins. Comparison of the specificity of the three sialic acid-binding lectins indicates that Limax flavus agglutinin binds to Neu5Ac in any linkage and in any position in a glycoconjugate, Sambucus nigra lectin requires a disaccharide of the structure Neu5Ac alpha 2,6Gal/GalNAc, and MAL has a binding site complimentary to the trisaccharide Neu5Ac alpha 2,3Gal beta 1,4GlcNAc/Glc, to which sialic acid contributes less to the total binding affinity than for either S. nigra lectin or L. flavus agglutinin.
A new lectin was purified from tubers of Arum maculatum L. by affinity chromatography on immobilized asialofetuin. Although this lectin is also retained on mannose-Sepharose 4B, under the appropriate conditions free mannose is a poor inhibitor of its agglutination activity. Pure preparations of the Arum lectin apparently yielded a single polypeptide band of approximately 12 kD upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, N-terminal sequencing of the purified protein combined with molecular cloning of the lectin have shown that the lectin is composed of two different 12-kD lectin subunits that are synthesized on a single large precursor translated from an mRNA of approximately 1400 nucleotides. Lectins with similar properties were also isolated from the Araceae species Colocasia esculenta (L.) Schott, Xanthosoma sagittifolium (L.) Schott, and Dieffenbachia sequina Schott. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration of the different Araceae lectins have shown that they are tetrameric proteins composed of lectin subunits of 12 to 14 kD. Interestingly, these lectins are the most prominent proteins in the tuber tissue. Evidence is presented that a previously described major storage protein of Colocasia tubers corresponds to the lectin.
Characterization of the lectins from onion (Allium cepa), shallot (A. ascalonicum) and leek (A. porrum) has shown that these lectins differ from previously isolated Alliaceae lectins not only in their molecular structure but also in their ability to inhibit retrovirus infection of target cells.
cDNA libraries constructed from poly(A)-rich RNA isolated from young shoots of onion, shallot and leek were screened for lectin cDNA clones using colony hybridization. Sequence analysis of the lectin cDNA clones from these three species revealed a high degree of sequence similarity both at the nucleotide and at the amino acid level.
Apparently the onion, shallot and leek lectins are translated from mRNAs of ca. 800 nucleotides. The primary translation products are preproproteins (ca. 19 kDa) which are converted into the mature lectin polypeptides (12.5–13 kDa) after post-translational modifications.
Southern blot analysis of genomic DNA has shown that the lectins are most probably encoded by a family of closely related genes which is in good agreement with the sequence heterogeneity found between different lectin cDNA clones of one species.
The epithelial glycoprotein 40 (EGP40, also known as GA733-2, ESA, KSA, and the 17-1A antigen), encoded by the GA-733-2 gene, is expressed on the baso-lateral cell surface in most human simple epithelia. The protein is also expressed in the vast majority of carcinomas and has attracted attention as a tumor marker. The function of the protein is unknown. We demonstrate here that EGP40 is an epithelium-specific intercellular adhesion molecule. The molecule mediates, in a Ca(2+)-independent manner, a homophilic cell-cell adhesion of murine cells transfected with the complete EGP40 cDNA. Two murine cell lines were tested for the effects of EGP40 expression: fibroblastic L cells and dedifferentiated mammary carcinoma L153S cells. The expression of the EGP40 protein causes morphological changes in cultures of transfected cells--increasing intercellular adhesion of the transfectants--and has a clear effect on cell aggregating behavior in suspension aggregation assays. EGP40 directs sorting in mixed cell populations, in particular, causes segregation of the transfectants from the corresponding parental cells. EGP40 expression suppresses invasive colony growth of L cells in EHS-matrigel providing tight adhesions between cells in growing colonies. EGP40 can thus be considered a new member of the intercellular adhesion molecules. In its biological behavior EGP40 resembles to some extent the molecules of the immunoglobulin superfamily of cell adhesion molecules (CAMs), although no immunoglobulin-like repeats are present in the EGP40 molecule. Certain structural similarities in general organization of the molecule exist between EGP40 and the lin-12/Notch proteins. A possible role of this adhesion molecule in formation of architecture of epithelial tissues is discussed. To reflect the function of the molecule the name Ep-CAM for EGP40 seems appropriate.
The reversible and dose-dependent hyperplastic growth of the small intestine and accelerated epithelial cell turnover caused by feeding rats with diets containing kidney bean lectin (PHA) increased the proportion of immature cells on the villi whose membrane and/or cytoplasm contained mainly simple, polymannosylated glycans. These new alpha-linked mannosyl terminals, particularly of the damaged epithelium, facilitated the preferential adherence of opportunistic Escherichia coli with mannose-sensitive Type 1 fimbriae, and other coliforms, to the glycocalyx. Accordingly, the growth of the gut was accompanied by a reversible and PHA dose-dependent overgrowth with E. coli. As expected from their common carbohydrate specificity, the inclusion in the diet of the mannose-specific agglutinin from snowdrop (Galanthus nivalis) bulbs (GNA) significantly reduced the extent of E. coli overgrowth, but abolished neither the growth nor the damage caused by PHA to the small intestine. Thus, GNA and perhaps other mannose-specific lectins, especially when used in a preventive mode, can be used to specifically block the proliferation of Type 1 E. coli in the small intestine.
Mistletoe lectin is thought to constitute the active principle in extract preparations from mistletoe, which are widely used as immunomodulators in adjuvant tumor therapy. However, no study exists which compares the immunological potency of different well‐defined mistletoe lectin preparations on human immune cells. Therefore, in the present study the biological effects of an aqueous mistletoe extract, standardized for mistletoe lectin I (eML), the isolated natural mistletoe lectin (nML), and the recombinant form of this lectin (rML) on human peripheral blood monocytes and lymphocytes were compared with respect to cell viability and cytokine induction. After 48‐hr incubation of peripheral blood mononuclear cells (PBMC) with rML, nML, and eML, a continuous concentration‐dependent decrease in cell viability was found with an IC50 of about 3 ng/ml for rML and nML and 10 ng/ml for eML, respectively. This effect also was seen when isolated lymphocytes and monocytes were separately incubated with the lectin preparations. After incubation of PBMC and isolated monocytes of 5/10 blood donors with eML, an increase in cell viability was found at lectin concentrations between 10 and 1,000 pg/ml. This effect was not seen with the pure lectin preparations nML and rML. After 48‐hr incubation of PBMC with rML, nML, and eML, induction of IL‐1‐β, TNF‐α, IL‐2, IL‐6, and IL‐10 but not IFN‐γ was measured. For IL‐1‐β it could be shown that cytokine induction took place at a broad lectin concentration range (0.1–100 ng/ml). Cytokine levels varied greatly in the PBMC cultures of the different blood donors. When monocytes were separately incubated with eML, nML, and rML for 48 hr, high levels of IL‐1‐β were found. In contrast, in cultures of separated lymphocytes from the same donors only a minimal production of IL‐1‐β and no production of IFN‐γ was found after incubation with rML, nML, and eML. It is concluded that there are quantitative differences in the immunomodulatory effects of the mistletoe lectin preparations on human monocytes and lymphocytes. Therefore, measurement of cell viability and cytokine induction may be a diagnostic laboratory tool to determine the immunological potency of various mistletoe preparations and may help to clarify the clinical benefit of therapies with these substances. J. Clin. Lab. Anal. 14:255–259, 2000. © 2000 Wiley‐Liss, Inc.
Two cultivars of Phaseolus vulgaris, FM-RMC, showing resistance to some plant pathogens and its progenitor, FM-C, without such resistance, were used to study the thermal inactivation of seed haemagglutinating activity (HA). FM-RMC showed a higher level of HA as compared to the FM-C. However, conventional cooking conditions practically abolished HA of both materials. Thermal inactivation of raw extracts of lectins showed biphasic patterns. A developed kinetic model fitted the experimental observations and showed that the HA loss rate of the improved cultivar differed only in a temperature constant.
An improved method was developed to determine active soybean lectin in processed foods containing soybean. Freeze drying of crude extracts followed by affinity chromatography allowed the authors to purify and quantitate active lectin. After dialysis, concentrated extracts from products were loaded on to a chromatography column of immobilized N-acetyl-galactosamine. Active lectin content of soybean flours depended on the processing method used. The highest level found was for raw seeds (3600 μg/g), and the lowest for texturized flour (12·9 μg/g). Direct human consumption foods contained various lectin concentrations. While meat substitutes were free of active lectin, milk substitutes, and bakery products had low levels. A cereal type food and a cookie showed the highest lectin concentrations (187·2 and 24·2 μg/g, respectively).
Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267 ± 13.6 and 283 ± 18.8 g kg -1 respectively, which did not differ significantly at P < 0.05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg- 1, 88 to 143 g kg -1, 407 to 485 g kg -1 and 32 to 42 g kg -1, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P < 0.001) than those of the colour-flowering cultivars (OMD: 889.1 ± 26.6 g kg -1 vs 797.5 ± 17.1 g kg -1; ME: 13.97 ± 0.49 vs 12.30 ± 0.34 MJ kg -1). In all cultivars, sulphur amine acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2-5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P < 0.01) compared to that of white-flowering cultivars (71.4 ± 9.3% vs 88.0 ± 11.1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28.3, 21.0 and 35.4 g kg -1 respectively). The contents of TP and T were similar (about 15 and 10 g kg -1, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor > Herz Freya > Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4.0-4.9 g kg -1). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3.05 ± 0.34 and 1.85 ± 0.09 mg trypsin inhibited g -1; lectin 27.2 ± 9.4 and 27.1 ± 5.1 mg ml -1 assay medium producing haemagglutination; phytate 15.0 ± 2.7 and 16.6 ± 2.3 g kg -1) were very low. A strong negative correlation (r= -0.92, P < 0.001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r =-0.89; P < 0.001) and organic matter digestibility (r = -0.89; P < 0.001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r = -0.88, P < 0.001), whereas between tannins and saponins it was significantly positive (r = 0.96, P < 0.001).
An elevation of β-galactoside α2,6-sialyltransferase (ST6Gal.I) enzyme activity and an increased α2,6-sialylation of cell membranes are among the most prominent glycosylation changes associated with colon cancer; both modifications correlate with a worse prognosis. In our previous studies, we have frequently observed a discrepancy between the ST6Gal.I level within a colon cancer sample or cell line and the respective level of reactivity with the α2,6-sialyl-specific lectin from Sambucus nigra (SNA). In this study, we have investigated quantitatively the biosynthesis of the sialyl-α2,6-lactosaminyl epitope in two colon cancer cell types expressing the ST6Gal.I cDNA under the control of a constitutive promoter. By measuring the amount of ST6Gal.I mRNA using competitive RT-PCR, the expression of α2,6-sialylated lactosaminic structures with SNA and anti-CDw75 Ig, and the presence of unsubstituted lactosaminic termini by Erythrina cristagalli lectin, we reached the following conclusions: (a) a high proportion of the cell surface lactosaminic termini remains unsubstituted, even in the presence of a very high ST6Gal.I activity. This proportion is strongly dependent on the cell type; (b) ST6Gal.I-transfected colon cancer cells do not express the CDw75 epitope; (c) the level of ST6Gal.I enzyme activity only partially correlates with the mRNA level; (d) despite the control by a constitutive promoter, the ST6Gal.I mRNA is not constantly expressed over time; and (e) a very large portion of the enzyme molecules is secreted in the extracellular milieu. These results indicate that post-transcriptional and post-translational mechanisms play a pivotal role in the control of α2,6-sialylation in colon cancer cells.
Numerous fndings indicate that specifc plant lecftns acting against cancer could be major active components of Viscum album extracts, although actiwty of low molecular weight components (peptides, carbohydrates and alkaloids) might be as essentialfor the benefcial activity of the plain plant extracts, too. Thus, active principle of Viscum album extracts is still not understood, and is dfficult to be analysed because of the complex composition of the extracts and uncertainty of the standardised ffictiveness (batch consistency) of the extracts. Ihe aims of this study were to compore the concentration dependent effects of the pure mistletoe lectin (IttL-l) with the fresh plant Viscum album extract (lsorel) and its drfferent MW components on the in vitro growth of ConA stimulated lymphocytes, on the growth and tumorigenicity (artificial lung metastases development) of murine melanoma B16FI0 cells, and to compare concentration dependent fficts of the different types of the Viscum album extrocts in vitro (applying novel type ofMTT assay). The results obtained indicate that the effects of Isorel used at high dose could be result of toric actüty of the mistletoe lectins ('ML-l like" activity). Unlike ML-1, if used at low concentrations, Isorel selectively inhibited tumor cells, due the activity of the low MW components. On the other hand, the number of tumor nodules was reduced (in compaison to the control) equally in the lungs of mice injected with BI6FI0 cells pre-treated in vitro with the plain Viscum album extact or any ofits modifcations or ML-1. Hence, it is supposed that the benefcial therapeutic effects of Isorel might resultfrom the combined b.iologrcal actüty of the high and the low Mll components not lectins only. Similarly, in MTT assay low concentrations of all types of the Viscum album extract showed stronger inhibiting activity for Bl6Fl0 and HeLa cells than pure ML-|. According to these results we propose a standardisation of aqueous Viscam album extracts by comparing their and ML-l concentration dependent activity on the tumor cells in vitro applying MTT bioassay described which should be relevant for further evaluation of their active principle andfor improvement of biotherapy of cancer.
The effects of natural fermentation upon the lectin in the seeds of Lens culinaris cultivar Magda 20 were investigated. Suspensions of lentil flour were allowed to ferment naturally at different lentil flour concentrations (79, 150 and 221 g l -1 ) and temperatures (28, 35 and 42°C). During fermentation, samples were taken at daily intervals (0, 24, 48, 72, and 96 h) and lentil lectin activity was measured by haemagglutination test. With the progress of fermentation there was a rapid decline in haemagglutination activity in all the batches. The largest decrease occurred between 0 h and 24 h of fermentation in all the conditions. The lectin concentration showed the maximum reduction at 72 and 96 h, under the fermentation conditions of 79 g l- 1 and 42°C, when the initial lectin content measured by ELISA was reduced by 98 and 97.8%, respectively. The changes in lentil lectin were also followed by SDS-polyacrylamide gel electrophoresis and immunoblotting. The results confirmed those obtained by ELISA and indicated that the lectin almost disappeared after 72 h of natural fermentation under the optimum conditions of flour concentration and temperature.
Mistletoe lectin-II, a major composition of Korean mistletoe (Viscum album coloratum), is known as a potent apoptosis inducer. The previous research has demonstrated that Korean mistletoe lectin-II induces apoptosis via c-Jun N terminal kinase (JNK) activation in human myeloid U937 cells. The purpose of this research is to prove the synergistic action of mistletoe lectin-II and interferon-γ (IFN-γ) in the apoptotic cytotoxicity of U937. When U937 cells were treated with mistletoe lectin-II after being differentiated by IFN-γ, the proteolytic activity of caspase-3 and 9 was markedly elevated and that of caspase-8 was prolonged for 18 hr. The activation of caspase-3-like protease requires the earlier cleavage of poly(ADP-ribose) polymerase(PARP). Caspase-1 was, however, not activated during the resting phase and nor in IFN-γ-differentiated U937 cells. Western blot analysis revealed that, in IFN-γ-differentiated U937 cells, the expression of Fas (CD95/APO-1) & Fas ligand(FasL) increases the apoptotic sensitivity against Mistletoe lectin-II. Fas (CD95/APO-1) & FasL were not significantly induced solely by mistletoe lectin-II. Furthermore the activity of JNK1 in U937 cells was also markedly increased with IFN-γ-differentiation, compared to that of the control. These results suggest that the IFN-γ-differentiation of U937 cells increases the susceptibility to mistletoe lectin-II-induced apoptosis.
Two fractions with agglutinating activity, F-I and F-II, were isolated from Jalo beans (Phaseolus vulgaris). The effect of chemical modification on biological activity was studied in fraction F-I. Polyacrylamide gel electrophoresis showed that fraction F-I migrated more slowly to the anode and had higher agglutinating activity and toxicity, whereas fraction F-II migrated more quickly toward the anode and had lower agglutinating activity and toxicity. Both fractions lost their agglutinating activity and maintained their toxicity after modification of amino groups. Tryptophan oxidation with N-bromosuccinimide eliminated the agglutinating, mitogenic, and toxic activities of the two fractions. Keywords: Chemical modifications; lectins; Phaseolus vulgaris; proteins
The antinutrient composition of 19 varieties of Phaseolus vulgaris (L) grown in different localities of Spain was determined. Moreover, eight of the 19 varieties were grown in two different environmental areas with the aim of studying the influence of variety and environment on antinutrients and the existence of relationships between some antinutritional factors. The content of sucrose and raffinose oligosaccharides was determined by HPLC. Stachyose was the predominant -galactoside in all the samples. Raffinose and verbascose were also present in significant quantities. Capillary-gas chromatography of the bean samples revealed only one peak corresponding to soyasapogenol B, which is common to both saponins I and V. The content of lectins (PHA) determined by ELISA methodology showed a high variation. Statistical analyses of data established that the compounds analysed were influenced by both variety and environment. The possibility of selecting some varieties to be used for large-scale cultivation in Spain is discussed.© 1999 Society of Chemical Industry
Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg−1, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg−1, 88 to 143 g kg−1, 407 to 485 g kg−1 and 32 to 42 g kg−1, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg−1 vs 797·5±17·1 g kg−1; ME: 13·97±0·49 vs 12·30±0·34 MJ kg−1). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg−1, respectively). The contents of TP and T were similar (about 15 and 10 g kg−1, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg−1). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g−1; lectin 27·2±9·4 and 27·1±5·1 mg ml−1 assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg−1) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI
Abstract Introduction Materials and Methods Results Discussion
Five different recently released Brazilian soybean cultivars (Bays, BR-10, Rio Balsas, Serido and Tropical) were compared for their proximate analyses and presence of antinutritional or toxic factors. As expected, the seeds are rich in proteins, varying from 360·7 to 485·4 g kg−1 flour, and they also have a high amount of fat (from 183·0 to 215·3 g kg−1 flour). Crude extracts from seeds of Bays, BR-10, Serido and Tropical were highly toxic to mice within 1–12 h, depending on the administration route (intraperitoneal, intramuscular or subcutaneous) and dose used while Rio Balsas was not. These acute effects were very similar to those produced by the soytoxin, a neurotoxin that has been recently purified from the commercial soybean sold in Brazil. The amount of trypsin inhibited in the presence of crude extracts ranged from 28·5 to 62·5 g kg−1 flour. Urease was also present and the seed lectin agglutinated preferentially rabbit erythrocytes. A heat treatment at 92°C for 1 min destroyed completely the toxic activity while the haemagglutinating and trypsin inhibitor activities were abolished within 5 min. At these conditions urease was still active. Due to its high protein content, lack of soytoxin, and low levels of trypsin inhibitor, lectin, and urease it is suggested that Rio Balsas could be an alternative for breeding programmes aimed to improve the nutritional quality of soybeans. ©1997 SCI
Colon cancer tissues display an increased activity of β-galactoside α2,6 sialyltransferase (ST6Gal.I) and an increased reactivity with the lectin from Sambucus nigra (SNA), specific for α2,6-sialyl-linkages. Experimental and clinical studies indicate a contribution of these alterations to tumor progression, but their molecular bases are largely unknown. In many tissues, ST6Gal.I is transcriptionally regulated through the usage of different promoters that originate mRNAs diverging in the 5`-untranslated regions. RT-PCR analysis of 14 carcinoma samples, all expressing an increased ST6Gal.I enzyme activity, and of the corresponding normal mucosa revealed the presence of at least 2 transcripts. One, containing the 5`-untranslated exons, Y+Z, is thought to represent the “housekeeping” expression, and another previously described in hepatic tissues. Both the Y+Z and the hepatic transcripts were detectable in normal and cancer tissues but that latter form had a marked tendency to accumulate in cancer. The extent of α2,6-sialylation of glycoconjugates, as determined by SNA-dot blot analysis, was markedly enhanced in all cancer specimens, but the level of reactivity only partially correlated with the level of enzyme expression. Western blot analysis revealed a strikingly heterogeneous pattern of SNA reactivity among cancer tissues. These data indicate that: i) during neoplastic transformation of colonic cells, ST6Gal.I expression may be modulated through a differential promoter usage; ii) the extent of α2,6-sialylation of cancer cell membranes is not a direct function of the ST6Gal.I activity, strongly suggesting the existence of other, more complex mechanisms of regulation. Int. J. Cancer 88:58–65, 2000. © 2000 Wiley-Liss, Inc.
Increased cell surface expression of the Thomsen-Friedenreich antigen (TF antigen, Galβ1-3GalNAc-) is a common feature in malignant and pre-malignant epithelia. Our previous studies have shown that dietary TF-binding lectins from peanut (Arachis hypogea) and edible mushroom (Agaricus bisporus) produce marked but different effects on human intestinal epithelial cell proliferation. This study investigates the proliferative effects of the other two known dietary TF-binding lectins: jacalin (Artocarpus integrifolia, JAC) and amaranth lectin (Amaranthus caudatus, ACA). JAC produced dose-dependent and non-cytotoxic inhibition of proliferation in HT29 human colon cancer cells with maximal effects of 46 ± 4% at 20 μg/ml, whereas ACA produced dose-dependent stimulation of proliferation with maximal effects of 22 ± 3% at 20 μg/ml when assessed both by incorporation of [3H]thymidine into DNA and by cell counting. The lectin-mediated effects were inhibitable by the presence of appropriate Galβ1-3GalNAc-expressing glycoproteins but differences existed between JAC and ACA in their patterns of inhibition by such substances. Ligand binding equilibrium studies using iodinated lectins revealed different Kd of the two lectins for HT29 cell surface glycoproteins. Lectin blots of cell membrane extracts showed different binding patterns in all the four TF-binding lectins. These results provide further evidence that dietary TF-binding lectins can have marked effects on the proliferation of human malignant gastro-intestinal epithelial cells and hence may play a role in intestinal cancer development, and also show that the biological effects of dietary lectins cannot be predicted solely from their carbohydrate binding properties. J. Cell. Physiol. 186:282–287, 2001. © 2001 Wiley-Liss, Inc.
This paper extends our knowledge of the rather bizarre carbohydrate binding poperties of the banana lectin (Musa acuminata). Although a glucose/mannose binding protein which recognizes α-linked gluco-and manno-pyranosyl groups of polysaccharide chain ends, the banana lectin was shown to bind to internal 3-O-α-d-glucopyranosyl units. Now we report that this lectin also binds to the reducing glucosyl groups of β-1,3-linked glucosyl oligosaccharides (e.g. laminaribiose oligomers). Additionally, banana lectin also recognizes β1,6-linked glucosyl end groups (gentiobiosyl groups) as occur in many fungal β1,3/1,6-linked polysaccharides. This behavior clearly distinguishes the banana lectin from other mannose/glucose binding lectins, such as concanavalin A and the pea, lentil and Calystegia sepium lectins.
Normal colonic epithelial cells undergo maturation as they traverse the crypt to the lumenal surface. The binding of lectins to goblet cell mucins and other glycoconjugates changes as the cells migrate and differentiate. Additional stepwise modifications in glycoconjugate expression occur in premalignant and malignant neoplasms that may be detected by lectin binding studies. The lectins Dolichos biflorus agglutinin (DBA) and soybean agglutinin (SBA) have been developed as markers of differentiation in normal-appearing colonic epithelium. Using a quantitative biometric system to score tissues, reduced levels of lectin binding have been found in rectal tissue from patiensts with familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer. The lectin Amaranthus caudatus agglutinin (ACA) binds to a cytoplasmic glycoconjugate expressed at the base of the colonic crypt and serves as a possible proliferation marker in the distal, but not proximal, colon. ACA binding increases in tandem with increased levels of proliferation (using Brdu incorporation ) in neoplastic tissues. Binding by the peanut lectin (PNA) occurs late in the adenoma-to-carcinoma sequence - in larger adenomas and in cancers - and serves as a marker of advancing neoplasia. Lectins identity the stepwise changes that occur during normal diferentation, proliferation and in advancing neoplasia. By selecting the appropriate probe, biomarkers may be developed for early, intermediate, and late events in colorectal cancer.
Purpose:
The aim of our study is to investigate the in vitro effects of plant lectins, galectins and neoglycoconjugates on the proliferation of three human sarcoma cell lines.
Methods:
Proliferation was assessed by means of the tetrazolium derivative reduction (MTT) assay. In addition, glycohistochemistry was used to make visible the plant-lectin-specific binding sites; the intensity of the lectin binding pattern was quantified by means of image analysis.
Results:
Depending on the cell lines, the staining intensity and the percentage of labelled cells were different. With respect to growth modulation, the cell lines also responded differently to the probes used. Besides a predominant inhibitory effect elicited by the probes at 50 microg/ml, dose-dependent effects, including growth stimulation, were detectable in several instances. These effects relate to the animal galectins tested and several neoglycoconjugates, e.g. the lactose- and blood-group-A-trisaccharide-bearing probes.
Conclusions:
Endogenous lectins and lectin-reactive cellular glycoconjugates can apparently affect the regulation of the growth of human sarcoma cells. We suggest that these results are relevant for further histopathological monitoring in correlation with prognosis and in vitro assays to reveal possible clinical applications.
Extracts of mistletoe (Viscum album var. coloratum) have been used for several decades as an anticancer immunomodulating agent in clinical fields. However, the mechanism by which the plant extracts kill tumor cells has remained elusive. We investigated the direct effects of beta-galactoside- and N-acetyl-d-galactosamine-specific mistletoe lectin II in inducing apoptotic death of U937 cells. Three distinct components of mistletoe, including beta-galactoside- and N-acetyl-d-galactosamine-specific lectin II (60 kDa), polysaccharides, and viscotoxin (5 kDa), induced apoptotic cell death, characterized by DNA ladder pattern fragmentation of U937 cells at 12 hr after treatment. Consistent with apoptosis of the cells, mistletoe extracts markedly increased the phosphotransferase activity of c-Jun N-terminal kinase 1 (JNK1)/stress-activated protein kinase (SAPK) in U937 cells. Among the three components, lectin II was the most potent in inducing apoptosis as well as JNK1 activation of U937 cells in a dose- and time-dependent manner. Catalytic activation of JNK1 induced by mistletoe lectin II was inhibited by the addition of peptide aC-DEVD-CHO, but not by aC-YVAD-CHO. In addition, mistletoe lectin II induced apoptosis in a variety of cell types including Jurkat T cells, RAW 264.7 cells, HL-60 cells, DLD-1 cells, and primary acute myelocytic leukemic cells.
We here demonstrated the prophylactic effect of an extract (KM-110) from Viscum album coloratum, a Korean mistletoe, on tumor metastasis produced by highly metastatic tumor cells, colon 26-M3.1 carcinoma, B16-BL6 melanoma and L5178Y-ML25 lymphoma cells, using experimental models in mice. Intravenous (i.v.) adminstration of KM-110 (100 μg/mouse) 2 days before tumor inoculation significantly inhibited lung metastasis of B16-BL6 and colon 26-M3.1 cells, and liver and spleen metastasis of L5178Y-ML25 cells. The prophylactic effect of KM-110 on tumor metastasis was evident with various administration routes, i.e. subcutaneous, oral, intranasal as well as i.v., and was dependent upon the dose of KM-110 administered. Furthermore, mice given KM-110 (100 μg) 2 days before tumor inoculation showed significantly prolonged survival rates compared with the untreated mice. In a time course analysis of NK activity, i.v. administration of KM-110 (100 μg) significantly augmented NK cytotoxicity to Yac-a tumor cells from 1 to 3 days after KM-110 treatment. Furthermore, depletion NK cells by injection of rabbit anti-asialo GM1 serum completely abolished the inhibitory effect of KM-110 on lung metastasis of colon 26-M3.1 cells. These results suggest that KM-110 possesses immunopotentiating activity which enhances the host defense system against tumors, and that its prophylactic effect on tumor metastasis is mediated by NK cell activation.
Saracin, a seed integument lectin from Saraca indica is highly specific for binding N-acetyl-neuraminyl-N-acetyllactosamine [Neu5Ac-α-(2-6)/(2-3)-d-Gal-β-(1-4)-d-GlcNAc]. This lectin has been found to be mitogenic for human lymphocytes, and this mitogenic activity could be inhibited in presence of fetuin. Further, treatment with saracin could induce secretion of IL-2 in a culture of resting human peripheral blood mononuclear cells (PBMC) after 48 h. Saracin has a higher affinity for the CD8+ than CD4+ T cells as revealed by FACS analysis. Agarose gel electrophoresis of DNA isolated from lymphocytes cultured under different conditions has shown that this lectin could induce apoptosis in activated T-lymphocytes, as also confirmed by flow cytometric studies. Phenotypic analysis of the apoptotic cells reveals that they belong to CD8+ T cells lineage. Four surface glycoproteins of PBMC have been found to interact with saracin in a trisaccharide [Neu5Ac-α-(2-6)/(2-3)-d-Gal-β-(1-4)-d-GlcNAc]-sequence specific manner. Saracin seems to be an interesting immunomodulator for the mammalian immune system.
The seeds of Abrus pulchellus, sub-specie tenuiflorus, belonging to the Leguminosae, subfamily Papilionoideae contain highly toxic lectins exhibiting specificity for galactose and galactose-containing structures. The toxins which agglutinate rabbit erythrocytes, present a highly toxic activity in vivo when injected in the peritoneal cavity of mice (LD50=31 μg·kg−1) or when tested with the microcrustacean Arthemia salina (LD50=3.5 μg·ml−1). The active fraction was purified in a single step, by affinity chromatography on a Sepharose-4B column. The purified toxins migrated as two single bands of Mr 63 000 and 61 500 Da (SDS-PAGE) and Mr 31 500 and 29 000 Da (SDS-PAGE with 2-mercaptoethanol), respectively, suggesting the presence of disulphide-bridge interchains as occurs in other plant toxins. The antibodies anti-A. pulchellus toxins did not recognize ricin preparation and only partial identity was observed to A. precatorius toxic lectins prepared in a similar way to ricin and A. pulchellus toxins.
From mistletoe Viscum album L. extracts three chitin-binding lectin isoforms, cbML1, cbML2, and cbML3, were isolated and their primary structure determined. All three cbML isoforms are composed of two protein chains of 48 or 49 amino acid residues, linked by an intermolecular disulfide bond. The sequence of each single cbML chain is characterized by a relatively high number of cysteine and glycine residues, 9 and 6, respectively, and contains four intramolecular disulfide bridges. On the basis of the combined interpretation of sequencing and MALDI MS data, the following results for the three cbML isoforms were obtained: the first one consists of two identical truncated polypeptide chains (1–48), the second is a heterodimer, containing one truncated (1–48) and one full-length chain (1–49), and the third is composed of two full length chains (1–49). The cbML sequence shows 55% identity to hevein, a single-chain chitin-binding protein of 43 amino acids, one of the most predominant proteins in natural rubber latex. On the basis of the NMR data on hevein from Hevea brasiliensis the three-dimensional structure of cbML3 was modelled. The 26 sequence changes between cbML3 and hevein were accommodated with only little perturbation in the main chain folding. A comparison of the primary structures of cbML3 and hevein is shown and the effects of the sequence changes are discussed. Differences have been identified in the loop region of the molecule and the potential interface region of cbML3 supporting the dimer formation. The high-affinity chitin-binding site seems to be highly conserved.
The effects of lectins with different carbohydrate-binding specificities on human hepatoma (H3B), human choriocarcinoma (JAr), mouse melanoma (B16) and rat osteosarcoma (ROS) cell lines were investigated. Cell viability was estimated by uptake of crystal violet. Wheat germ lectin was the lectin with the most deleterious effect on the viability of H3B, JAr and ROS cell lines. The cytotoxicity of lectins with similar sugar-binding specificity to wheat germ lectin, including Maackia amurensis lectin and Solanum tuberosum lectin, was weaker than that of wheat germ lectin. N-acetylgalactosamine-and galactose-binding Tricholoma mongolicum lectin ranked third, after wheat germ lectin and Maackia amurensis lectin, with regard to its effect on H3B, and ranked, together with Maackia amurensis lectin, as the lectins with the second most pronounced effects on ROS. However, the cytotoxic effects of Tricholoma mongolicum lectin on JAr were much weaker than those of Maackia amurensis lectin, Solanum tuberosum lectin and Anguilla anguilla lectin. Artocarpus integrifolia lectin, Lens culinaris lectin and Anguilla anguilla lectin possessed milder cytotoxicity than the remaining lectins, which were approximately equipotent. The mannose-binding Narcissus pseudonarcissus and Lens culinaris lectins were only weakly cytotoxic, the exception being a stronger effect on H3B. The N-acetylgalactosamine-binding Glycine max lectin and methylgalactose-binding Artocarpus integrifolia lectin similarly exhibited low cytotoxicity. It can thus be concluded that in general the ranking was wheat germ lectin>Maackia amurensis lectin⋍Tricholoma mongolicum lectins>other aforementioned lectins in cytotoxicity. A particular lectin may manifest more conspicuous toxicity on certain cell lines and less on others.
There is evidence from recent data that mistletoe extracts exert immunostimulatory properties which could explain their therapeutic effects observed in some tumor patients. Aim of our study was, therefore, to investigate the effect of a subcutaneous 16-weeks therapy with a mistletoe extract (ABNOBAviscum Mali, AM) on the cellular and humoral immune responses in eight breast cancer patients. Mistletoe therapy induced a strong initial proliferation of peripheral blood mononuclear cells (PBMC) in all individuals, which, however, decreased in six patients during the observation period, indicating that not only activating but also inhibitory mechanisms have been induced. In all supernatants of AM-stimulated cell cultures TNF-alpha or IL-6 were found, indicating the activation of cells of the monocyte-/macrophage lineage by mistletoe extracts. Further analyses revealed, that AM induced in vitro also the release of low amounts of IFN-gamma and IL-4 with individual variations. At the end of the therapy, a shift to Th1- related cytokines could be observed in the in vitro cell culture system. All patients produced anti-mistletoe lectin 1 antibodies of the IgG-type during therapy and in four of them additionally antibodies of the IgE-type were found. It, therefore, seems that AM can influence the Th1/Th2 balance and, in case of a Th1 shift, this may favourably influence the tumor growth.
Antinutritional factors of anasazi bean were compared to traditional pinto bean (Phaseolus vulgaris L.). Anasazi beans contained less (p<0.001) soluble and bound condensed tannins compared to pinto beans. No differences (p>0.05) in stachyose and raffinose content were found between the two bean types; verbascose was not detected at all. Significant (p<0.05) differences in lectin content were observed between anasazi and pinto bean. The lectins of anasazi beans were classified as non toxic and those of the pinto beans as toxic types. No differences (p>0.05) in inhibitor activity against human and bovine trypsin and chymotrypsin were found between the two bean types.
The aim of this study was to identify receptors present on the buccal mucosa in order to select appropriate lectins that will allow the retention of a dosage form within the oral cavity. Studies using human buccal cells, the avidin-biotin-complex/diaminobenzidine method for identifying lectin binding and a microdensitometer to allow a semi-quantitative analysis of stain intensity, showed a wide diversity of lectin receptors. Kinetic studies of lectin binding to buccal cells revealed significant binding after 20 s, particularly for lectins from Pisum sativum and Arachis hypogaea. A significant reduction in lectin binding was observed after exposing buccal cells to a series of lectin solutions pre-treated with a large excess of secretor or non-secretor saliva. However when bound to the buccal cells, there was little displacement of lectins on exposure to either saliva types. Further studies on rat oral tissue suggested that the lectins appeared to bind to varying degrees on whole oral epithelial surfaces although differences in binding between this and the human buccal cell model were evident. It was concluded that a wide range of possible target receptors for lectins are present on rat oral epithelium and human buccal cells. Lectin binding to these receptors can be affected by the exposure time and the presence of saliva.
Effects of rice bran agglutinin (RBA) on human monoblastic leukemia U937 cells were examined in comparison with those of wheat germ agglutinin (WGAJ and Viscum album agglutinin (VAA). These lectins inhibit cell growth, and several lines of evidence indicate that the growth inhibition is caused by the induction of apoptosis. We observed that RBA induces chromatin condensation, externalization of membrane phosphatidylserine, and DNA ladder formation, features of apoptosis. DNA ladder formation was inhibited by a general inhibitor against caspases, which are known to play essential roles in apoptosis. Flow cytometric analysis revealed that RBA and WGA cause GSVM phase cell cycle arrest with increased expression of Wafl/p21, while cell cycle arrest was not observed for VAA. These data indicate that RBA induces apoptosis associated with cell cycle arrest in U937 cells, and suggest that the induction mechanism for RBA is similar to that for WGA, but different from that for VAA
Normal colonic epithelial cells undergo maturation as they traverse the crypt to the lumenal surface. The binding of lectins to goblet cell mucins and other glycoconjugates changes as the cells migrate and differentiate. Additional stepwise modifications in glycoconjugate expression occur in premalignant and malignant neoplasms that may be detected by lectin binding studies. The lectins Dolichos biflorus agglutinin (DBA) and soybean agglutinin (SBA) have been developed as markers of differentiation in normal-appearing colonic epithelium. Using a quantitative biometric system to score tissues, reduced levels of lectin binding have been found in rectal tissue from patients with familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer. The lectin Amaranthus caudatus agglutinin (ACA) binds to a cytoplasmic glycoconjugate expressed at the base of the colonic crypt and serves as a possible proliferation marker in the distal, but not proximal, colon. ACA binding increases in tandem with increased levels of proliferation (using BrdU incorporation) in neoplastic tissues. Binding by the peanut lectin (PNA) occurs late in the adenoma-to-carcinoma sequence--in larger adenomas and in cancers--and serves as a marker of advancing neoplasia. Lectins identify the stepwise changes that occur during normal differentiation, proliferation and in advancing neoplasia. By selecting the appropriate probe, biomarkers may be developed for early, intermediate, and late events in colorectal cancer.
More than 70 lectins from leguminous plants belonging to different suborders and tribes have been isolated, mostly from seeds, and characterized to varying degrees. Although they differ in their carbohydrate specificities, they resemble each other in their physicochemical properties. They usually consist of two or four subunits (25-30 kDa), each with one carbohydrate binding site. Interaction with carbohydrates requires tightly bound Ca2+ and Mn2+ (or another transition metal). The primary sequences of more than 15 legume lectins have been established by chemical or molecular genetic techniques. They exhibit remarkable homologies, with a significant number of invariant amino acid residues, among them most of those involved in metal binding. The 3-dimensional structures of the legume lectins are similar, too, and are characterized by a high content of beta-sheets and a lack of alpha-helix. The location of the metal and carbohydrate binding sites, established unequivocally in concanavalin A by high resolution X-ray crystallography, appears to be the same in the other legume lectins. Several of the lectin genes have been cloned and expressed in heterologous systems. This opens the way for the application of molecular genetics to the investigation of the atomic structure of the carbohydrate binding sites of the lectins, and of the relationship between their structure and biological activity. The new approaches may also provide information on the mechanisms that control gene expression in plants and on the role of lectins in nature.
The wild-type seed lima bean lectin (LBL), and recombinant LBL expressed in Escherichia coli show specificity for the human blood group A immunodominant trisaccharide GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-R. We have generated four site-specific mutants of LBL, two of which show altered specificity for extended carbohydrate structures. Four mutants, [C127Y]LBL, [H128P]LBL, [H128R]LBL and [W132F]LBL were expressed in E. coli. Two mutants show altered specificity for the substituent at the C2 hydroxy group of the penultimate Gal in the wild-type ligand which is alpha-L-fucose in the A trisaccharide. The mutant [C127Y]LBL showed specificity for the A disaccharide (GalNAc alpha 1-3Gal) and GalNAc alpha 1-4Gal, with free hydroxyl groups at the C2 position of Gal. The mutant [H128P]LBL bound the Forssman disaccharide structure GalNAc alpha 1-3GalNAc, in which the C2 hydroxyl group is substituted with an acetamido group. The third and fourth mutants, [H128R]LBL and [W132F]LBL, exhibited wild-type specificities, both recognizing the A trisaccharide. All of these mutant lectins bound the terminal GalNAc residues exposed on asialoovine submaxillary mucin, thus indicating that the monosaccharide-binding site had not been altered. We also determined that all but one mutant ([C127Y]LBL) retained the high-affinity binding site for N6 derivatives of adenine, indicative of tetramer formation; each mutant also expressed the low-affinity binding site for 8-anilinonaphthalene 1-sulfonate (1/monomer). Thus, by targeting two residues in LBL, we have identified a region of the protein that is part of the extended carbohydrate-binding site and which is specifically involved in the binding/recognition of substituents at the C2 position of the penultimate Gal of the A disaccharide. We have determined, by site-directed mutagenesis, that an essential Cys residue is involved in the specificity of LBL for the A trisaccharide.
The antitumour activities of four plant lectins, phytohaemagglutinin, pokeweed mitogen, soybean agglutinin, and wheat germ agglutinin, were evaluated on a murine ascitic lymphoma. The effects of lectin treatment on mitogenic response of peripheral blood lymphocytes and macrophage-mediated tumour cell lysis were also assessed. All four lectins studied were found to be able to restrict tumour growth and to improve the life expectancy of the host. The response of peripheral blood lymphocytes towards mitogenic stimulation was found to be improved and enhancement of tumour cytolysis by peritoneal macrophages was noted following lectin treatment.
Mice injected intraperitoneally with Krebs II cells and then fed on a diet containing the lectin phytohaemagglutinin (PHA) developed ascites tumours more slowly than mice fed on a control diet. After an 8-day period following injection the number of cells recovered from mice maintained on the PHA diet was half that from those fed the control diet. A switch of diet from control to PHA on day 4 after injection resulted in a large decrease in number of tumour cells recovered. Mice injected s.c. also developed tumours at later times when fed on the PHA diet. A quantitative of ribosomes in polysome-containing fractions showed no major differences in protein synthesis in control mice and those fed the PHA diet.