[Show abstract][Hide abstract] ABSTRACT: Although various parts of J. curcas (Jatropha curcas L., Euphorbiaceae) have long been used as traditional folk medicines for their antiviral, analgesic, and/or antidotal efficacies, we are the first to investigate the role of anti-carcinogenicity of isoamericanol A (IAA) from the seed extract. Our results showed that IAA is capable of inhibiting cell proliferation in a dose-dependent manner on the human cancer cell lines of MCF-7, MDA-MB231, HuH-7, and HeLa. Flow cytometry analysis showed IAA significantly induces cell cycle arrest at G2/M on MCF-7 cells. At both protein and mRNA levels examined by western blot and real-time PCR, the results revealed increased expression of BTG2 (B-cell translocation gene 2), p21 (p21WAF1/CIPI), and GADD45A (growth arrest and DNA-damage-inducible, alpha) after IAA treatment, but inversed expression in CDK1 (cyclin-dependent kinase 1) and cyclins B1 and B2. All these effects contribute to G2/M cell cycle arrest. Furthermore, these results coincide with the changes in molecular expressions determined by DNA-microarray analysis. Our findings indicate that IAA has an inhibitory effect on cell proliferation of MCF-7 through cell cycle arrest, giving it great potential as a future therapeutic reagent for cancers.
[Show abstract][Hide abstract] ABSTRACT: Glucose is a major energy source for mammalian cells and is transported into cells via cell-specific expression of various glucose transporters (GLUTs). Especially, cancer cells require massive amounts of glucose as an energy source for their dysregulated growth and thus over-express GLUTs. d-allose, a C-3 epimer of d-glucose, is one of rare sugars that exist in small quantities in nature. We have shown that d-allose induces the tumor suppressor gene coding for thioredoxin interacting protein (TXNIP) and inhibits cancer cell growth by G1 cell cycle arrest. It has also been reported that GLUTs including GLUT1 are over-expressed in many cancer cell lines, which may contribute to larger glucose utilization. Since d-allose suppresses the growth of cancer cells through the upregulation of TXNIP expression, our present study focused on whether d-allose down-regulates GLUT1 expression via TXNIP expression and thus suppresses cancer cell growth. Western blot and real-time PCR analyses revealed that d-allose significantly induced TXNIP expression and inhibited GLUT1 expression in a dose-dependent manner in three human cancer cell lines: hepatocellular carcinoma (HuH-7), Caucasian breast adenocarcinoma (MDA-MB-231), and neuroblastoma (SH-SY5Y). In these cell lines, d-allose treatment inhibited cell growth. Importantly, d-allose treatment decreased glucose uptake, as measured by the uptake of 2-deoxy d-glucose. Moreover, the reporter assays showed that d-allose decreased the expression of luciferase through the hypoxia response element present in the tested promoter region. These results suggest that d-allose may cause the inhibition of cancer growth by reducing both GLUT1 expression and glucose uptake.
Preview · Article · Jan 2016 · The Tohoku Journal of Experimental Medicine
[Show abstract][Hide abstract] ABSTRACT: Background:
Pretransplant restoration of islets damaged during isolation remains to be solved. In this study, we examined the effect of D-allose on islets isolated from rat pancreata prior to islet transplantation.
Rat islets isolated from fresh pancreata were cultured overnight in Roswell Park Memorial Institute 1640 solution in the absence (group 1) or presence (group 2) of D-allose. Then we assessed stimulation index of insulin, and cure rate after islet transplantation to diabetic nude mice. We also measured malondialdehyde level and caspase 3 activity of islets after the overnight culture for assessment of the oxidative stress and the apoptosis.
D-allose significantly improved insulin secretion of islets. The stimulation index in group 2 was significantly higher than in group 1. Cure rate after transplantation in group 2 was higher than in group 1 especially in the first week. The malondialdehyde level in group 2 was significantly lower than in group 1. But the caspase 3 activities in both groups didn't differ.
D-allose treatment of isolated islet culture prior to transplantation restored islet function and increased successful transplant rate. The results of this study suggested that D-allose improved function of damaged islets through its anti-oxidative activity.
No preview · Article · Oct 2015 · Journal of Hepato-Biliary-Pancreatic Sciences
[Show abstract][Hide abstract] ABSTRACT: We examined and compared the inhibitory effects of D-tagatose on the growth, acid production, and water-insoluble glucan synthesis of GS5, a bacterial strain of Streptococcus mutans, with those of xylitol, D-psicose, L-psicose and L-tagatose. GS5 was cultured for 12h in a medium containing 10% (w/v) of xylitol, D-psicose, L-psicose, D-tagatose or L-tagatose, and the inhibitory effect of GS5 growth was assessed. Each sugar showed different inhibitory effects on GS5. Both D-tagatose and xylitol significantly inhibited the acid production and water-insoluble glucan synthesis of GS5 in the presence of 1% (w/v) sucrose. However, the inhibitory effect of acid production by D-tagatose was significantly stronger than that of xylitol in presence of sucrose.
[Show abstract][Hide abstract] ABSTRACT: The fundamental cause of overweight and obesity is consumption of calorie-dense foods. We have introduced a zero-calorie sweet sugar, d-psicose (d-allulose), a rare sugar that has been proven to have strong antihyperglycemic and antihyperlipidemic effects, and could be used as a replacement of natural sugar for the obese and diabetic subjects.
Above mentioned efficacy of d-psicose (d-allulose) has been confirmed in our previous studies on type 2 diabetes mellitus (T2DM) model Otsuka Long-Evans Tokushima Fatty (OLETF) rats with short-term treatment. In this study we investigated the long-term effect of d-psicose in preventing the commencement and progression of T2DM with the mechanism of preservation of pancreatic β-cells in OLETF rats.
Treated OLETF rats were fed 5% d-psicose dissolved in water and control rats only water. Nondiabetic control rats, Long-Evans Tokushima Otsuka (LETO), were taken as healthy control and fed water. To follow the progression of diabetes, periodic measurements of blood glucose, plasma insulin, and body weight changes were continued till sacrifice at 60 weeks. Periodic in vivo body fat mass was measured. On sacrifice, pancreas, liver, and abdominal adipose tissues were collected for various staining tests.
d-Psicose prevented the commencement and progression of T2DM till 60 weeks through the maintenance of blood glucose levels, decrease in body weight gain, and the control of postprandial hyperglycemia, with decreased levels of HbA1c in comparison to nontreated control rats. This improvement in glycemic control was accompanied by the maintenance of plasma insulin levels and the preservation of pancreatic β-cells with the significant reduction in inflammatory markers. Body fat accumulation was significantly lower in the treatment group, with decreased infiltration of macrophages in the abdominal adipose tissue.
Our findings suggest that the rare sugar d-psicose could be beneficial for the prevention and control of obesity and hyperglycemia with the preservation of β-cells in the progression of T2DM.
Full-text · Article · Jan 2015 · Drug Design, Development and Therapy
[Show abstract][Hide abstract] ABSTRACT: Recently, phototherapy which utilizes artificial light source like laser and light-emitting diode (LED) has attracted much attention. Among such phototherapies, photodynamic therapy (PDT) is well-known and used in hospitals to cure cancer. The PDT is utilized for lung cancer and skin disease and it combines a photosensitive agent, e.g. Photofrin or Laserphyrin, and laser with a particular wavelength. In this research, we noticed the bilirubin as a photosensitive agent. The bilirubin has a photosensitivity and exists in human body as a metabolite of blood. Experiments were carried out in vitro to inhibit leukemia cells using high efficiency LED light irradiation and bilirubin administration. Experimental results showed that the activated bilirubin by blue LED light irradiation remarkably suppressed the proliferation of leukemia cells in the culture vessel. This fact may pave a new way to natural cure using sunlight or artificial light for leukemia therapy.
No preview · Article · Nov 2014 · IEEJ Transactions on Electronics Information and Systems
[Show abstract][Hide abstract] ABSTRACT: Rare sugar syrup is a sweetener obtained from high-fructose corn syrup under slightly alkaline conditions, which promotes the formation of rare sugars. Here, the physiological impact and safety of rare sugar syrup in humans was investigated by a randomized double-blind parallel experiment. Thirty-four subjects with an average body mass index of 25.6 kg/m2 were divided into two groups. Subjects consumed either a test drink containing rare sugar syrup or an isocaloric control drink containing high-fructose corn syrup on a daily basis for 12 weeks. Results showed significant decreases in body weight, body fat percentage and waist circumference in the rare sugar syrup group compared to the control. No adverse events with regard to hepatic and renal function or blood parameters were observed. Our study conclusively suggests, for the first time, that rare sugar syrup is a safe sweetener, and that continuous consumption of this syrup could help weight management.
Preview · Article · Nov 2014 · Journal of Functional Foods
[Show abstract][Hide abstract] ABSTRACT: Background
The purpose of this study was to evaluate intestinal absorption, organ distribution, and urinary elimination of the rare sugar D-psicose, a 3-carbon stereoisomer of D-fructose that is currently being investigated and which has been found to be strongly effective against hyperglycemia and hyperlipidemia.
This study was performed using radioactive D-psicose, which was synthesized enzymatically from radioactive D-allose. Concentrations in whole blood, urine, and organs were measured at different time points until 2 hours after both oral and intravenous administrations and 7 days after a single oral administration (100 mg/kg body weight) to Wistar rats. Autoradiography was also performed by injecting 100 mg/kg body weight of 14C-labeled D-psicose or glucose intravenously to C3H mice.
Following oral administration, D-psicose easily moved to blood. The maximum blood concentration (48.5±15.6 μg/g) was observed at 1 hour. Excretion to urine was 20% within 1 hour and 33% within 2 hours. Accumulation to organs was detected only in the liver. Following intravenous administration, blood concentration was decreased with the half-life=57 minutes, and the excretion to urine was up to almost 50% within 1 hour. Similarly to the results obtained with oral administration, accumulation to organs was detected only in the liver. Seven days after the single-dose oral administration, the remaining amounts in the whole body were less than 1%. Autoradiography of mice showed results similar to those in rats. High signals of 14C-labeled D-psicose were observed in liver, kidney, and bladder. Interestingly, no accumulation of D-psicose was observed in the brain.
D-psicose was absorbed well after oral administration and eliminated rapidly after both oral and intravenous administrations, with short duration of action. The study provides valuable pharmacokinetic data for further drug development of D-psicose. Because the findings were mainly based on animal study, it is necessary to implement human trials to study the metabolism pathway, which would give an important guide for human intake and food application of D-psicose.
Full-text · Article · Oct 2014 · Drug Design, Development and Therapy
[Show abstract][Hide abstract] ABSTRACT: The present study investigates the neuroprotective effects of D-allose, a rare sugar, against ischemia/reperfusion injury in a gerbil model. Transient forebrain ischemia was induced by occlusion of the bilateral common carotid arteries for 5 min. D-Allose was intravenously injected before and after ischemia (200 mg/kg). Extracellular glutamate and lactate release from the gerbil brain, and PO2 profiles were monitored during ischemia and reperfusion. We also examined neuronal death and oxidative damage in the hippocampus one week after ischemia reperfusion, and investigated functional outcome. D-Allose administration suppressed glutamate and lactate release compared to vehicle controls. Brain damage, 8-OHdG levels (a marker of oxidative stress) and locomotor activities were significantly decreased by D-allose treatment. The present results suggest that D-allose reduces delayed neuronal death and behavioral deficits after transient ischemia by changing cerebral metabolism and inhibiting oxidative stress.
No preview · Article · Oct 2014 · Brain Research Bulletin
[Show abstract][Hide abstract] ABSTRACT: S100 proteins bind to numerous target proteins, as well as other S100 proteins and activate signaling cascades. S100 proteins can be modified by various post‑translational modifications, such as phosphorylation, methylation and acetylation. In addition, oxidation is important for modulating their activities. Previous studies have shown that S100A1 interacts with S100A4 in vitro and in vivo. Due to this potential cross‑talk among the S100 proteins, the aim of the present study was to examine whether S100A4 modulates the activity of S100A1. S100A4 was readily oxidized and formed disulfide‑linked dimers and oligomers. Although non‑oxidized S100A4 bound to protein phosphatase 5 (PP5), the Cu‑oxidized S100A4 failed to bind PP5. Instead, the Cu‑oxidized S100A4 directly interacted with S100A1 and prevented PP5 activation. Hydrogen peroxide induced S100A4 oxidation in MKN‑45 gastric adenocarcinoma cells and decreased S100A1‑PP5 interaction, resulted in the inhibition of PP5 activation by S100A1. These data indicate that oxidized S100A4 regulates PP5 activity in a unique manner under oxidative stress conditions.
Full-text · Article · Sep 2014 · International Journal of Molecular Medicine
[Show abstract][Hide abstract] ABSTRACT: In this study we investigated the combined effects of docetaxel and d-allose in HSC3 human oral carcinoma cells. The dose enhancement ratios at the 25% survival level were 1.3 and 1.71 for combined treatment with 10 or 25 mM D-allose, respectively. Apoptosis was significantly increased by addition of D-allose. Additionally, a synchronous increase in the G2/M-phase population was observed after docetaxel plus D-allose treatment. In vivo experiments revealed that docetaxel plus D-allose was more effective than either agent alone. Thus, D-allose enhanced the anticancer effects of docetaxel, and combined treatment may be useful to achieve clinical efficacy with reduced toxicity.
Preview · Article · Aug 2014 · International Journal of Oncology
[Show abstract][Hide abstract] ABSTRACT: Background
Previous reports showed the presence of limited numbers of stem cells in neonatal murine cochlear sensory epithelia and these cells are progressively lost during the postnatal development. The goal of this study was to investigate whether stem cells can be derived from mature mouse cochleae under suspension culture conditions, and to analyze the expression of the stem cell and inner ear progenitor cell markers in cells dissociated from neonatal and adult mouse organs of Corti.
Organs of Corti were dissected from postnatal day 1 (P1) or postnatal day 60 (P60) mouse. The dissociated cells were cultivated under suspension cultures conditions. Reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry were conducted for phenotype characterization.
The number of cochlear stem cells (otospheres) yielded from P1 organ of Corti was significantly higher than that of the P60 organ of Corti. RT-PCR analyses showed that the stem markers, such as nanog, sox2, klf4, and nestin can be found to be distributed similarly in the cells derived from both of organisms, but the inner ear developmental/progenitor cell markers showed lower expression in P60 organ of Corti compared to P1. Immunocytochemistry results also revealed the evidence that P60 otospheres lacking of differentiation potential in vitro, which opposed to the strong differentiation potential of otospheres at P1 stage.
Our findings suggest that the loss of numbers and features of stem cells in the adult organ of Corti is associated with the substantial down-regulation of inner ear progenitor key-markers during maturation of the cells in organ of Corti.
Full-text · Article · May 2014 · Journal of Translational Medicine
[Show abstract][Hide abstract] ABSTRACT: High fructose intake is associated with increased plasma triglyceride concentration, hepatic steatosis, impaired glucose tolerance, insulin resistance, and high blood pressure. In addition, increased fructose intake has recently been supposed to be a risk factor for dementia. However, direct effects of fructose on the brain function remain to be clarified. The localization of glucose transporter 5 (Glut5), a representative transporter of fructose, was immunohistochemically examined in brains of humans, rats, and mice to clarify whether fructose was transported from the blood into the brain. Glut5 immunoreactivity was demonstrated to be located in the epithelial cells of choroid plexus and the ependymal cells in the brains of humans and rats using commercial antibodies for Glut5. In addition, mRNA expression of mouse Glut5 was confirmed in the brains of mice. Immunohistochemical examination using a custom-made antibody against two regions of amino acid sequences of mouse Glut5 revealed that Glut5 immunoreactivity was also seen in the epithelial cells of choroid plexus and the ependymal cells in the brains of mice. These findings show that Glut5 immunoreactivity is located in the epithelial cells of choroid plexus and the ependymal cells, suggesting the possibility of the direct transportation of intravascular fructose into the brain parenchyma.
[Show abstract][Hide abstract] ABSTRACT: Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates various cell processes including proliferation, growth, synaptogenesis, neural and glioma stem/progenitor cell renewal. In addition, PTEN can regulate sensory cell proliferation and differentiation of hair bundles in the mammalian cochlea. In this study we use immunofluorescence, western blot and RT-PCR to reveal the expression of PTEN in the developing cochlear lateral wall, which is crucial for regulating K(+) homeostasis. Relatively high levels of PTEN are initially expressed in the marginal cells (MCs) of the lateral wall at embryonic day (E) 17.5 when they start to differentiate. Similarly high levels are subsequently expressed in differentiating root cells (RCs) at postnatal day (P) 3 and then in spiral ligament fibrocytes (SLFs) at postnatal day (P) 10. In the mature cochlea, PTEN expression is low or undetectable in MCs and SLFs but it remains high in RCs and their processes. The expression pattern for PTEN in the developing lateral wall suggests that it plays a critical role in the differentiation of the cellular pathways that regulate K(+) homeostasis in the cochlea.
[Show abstract][Hide abstract] ABSTRACT: Accumulating evidence has suggested the importance of glutamate signaling in cancer growth, yet the signaling pathway has not been fully elucidated. N-methyl-D-aspartic acid (NMDA) receptor activates intracellular signaling pathways such as the extracellular-signal-regulated kinase (ERK) and forkhead box, class O (FOXO). Suppression of lung carcinoma growth by NMDA receptor antagonists via the ERK pathway has been reported. However, series of evidences suggested the importance of FOXO pathways for the regulation of normal and cancer cell growth. In the liver, FOXO1 play important roles for the cell proliferation such as hepatic stellate cells as well as liver metabolism. Our aim was to investigate the involvement of the FOXO pathway and the target genes in the growth inhibitory effects of NMDA receptor antagonist MK-801 in human hepatocellular carcinoma.
Expression of NMDAR1 in cancer cell lines from different tissues was examined by Western blot. NMDA receptor subunits in HepG2, HuH-7, and HLF were examined by reverse transcriptase polymerase chain reaction (RT-PCR), and growth inhibition by MK-801 and NBQX was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of MK-801 on the cell cycle were examined by flow cytometry and Western blot analysis. Expression of thioredoxin-interacting protein (TXNIP) and p27 was determined by real-time PCR and Western blotting. Activation of the FOXO pathway and TXNIP induction were examined by Western blotting, fluorescence microscopy, Chromatin immunoprecipitation (ChIP) assay, and reporter gene assay. The effects of TXNIP on growth inhibition were examined using the gene silencing technique.
NMDA receptor subunits were expressed in all cell lines examined, and MK-801, but not NBQX, inhibited cell growth of hepatocellular carcinomas. Cell cycle analysis showed that MK-801 induced G1 cell cycle arrest by down-regulating cyclin D1 and up-regulating p27. MK-801 dephosphorylated Thr24 in FOXO1 and induced its nuclear translocation, thus increasing transcription of TXNIP, a tumor suppressor gene. Knock-down of TXNIP ameliorated the growth inhibitory effects of MK-801.
Our results indicate that functional NMDA receptors are expressed in hepatocellular carcinomas and that the FOXO pathway is involved in the growth inhibitory effects of MK-801. This mechanism could be common in hepatocellular carcinomas examined, but other mechanisms such as ERK pathway could exist in other cancer cells as reported in lung carcinoma cells. Altered expression levels of FOXO target genes including cyclin D1 and p27 may contribute to the inhibition of G1/S cell cycle transition. Induction of the tumor suppressor gene TXNIP plays an important role in the growth inhibition by MK-801. Our report provides new evidence that FOXO-TXNIP pathway play a role in the inhibition of the hepatocellular carcinoma growth by MK-801.
[Show abstract][Hide abstract] ABSTRACT: Suramin is an activator of ryanodine receptors and competitively binds to the calmodulin-binding site. In addition, S100A1 and calmodulin compete for the same binding site on ryanodine receptors. We therefore studied the effects of suramin on protein phosphatase 5 (PP5) and S100-activated PP5. In the absence of S100 proteins, suramin bound to the tetratricopeptide repeat (TPR) domain of PP5 and activated the enzyme in a dose-dependent manner. In the presence of S100A2/Ca(2+), lower concentrations of suramin dose-dependently inhibited PP5 activity as an S100 antagonist, whereas higher concentrations of suramin reactivated PP5. Although the C-terminal fragment of heat shock protein 90 (HspC90) also weakly activated PP5, the binding site of suramin and HspC90 may be different, and addition of suramin showed no clear effect on the phosphatase activity of PP5. Similar biphasic effects of suramin were observed with S100A1-, S100B- or S100P-activated PP5. However, the inhibitory effects of lower concentrations of suramin on S100A6-activated PP5 are weak and high concentrations of suramin further activated PP5. SPR and the cross-linking study showed inhibition of the interaction between S100 protein and PP5 by suramin. Our results revealed that suramin is a novel PP5 activator and modulates S100-activated PP5 activity by competitively binding to the TPR domain.
No preview · Article · Sep 2013 · Applied biochemistry and biotechnology