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Metastasis cascade. L-R formation of primary tumor: cancer cells start to invade the local epithelial tissue and undergo the EMT. Intravasation and circulation: these cells enter the bloodstream with some of them eliminated by macrophages. The rest of CTCs will exit the blood in a process called extravasation. Secondary tumor formation: after they exit the blood, circulating cancer cells undergo a MET and start to invade distant organs forming a secondary tumor. CTC, circulating tumor cells; EMT, epithelial to mesenchymal transition; MET, mesenchymal to epithelial transition. Color images available online at www.liebertpub.com/nat
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Circulating tumor cells (CTCs) are cells that shed from a primary tumor and freely circulate in the blood, retaining the ability to initiate metastasis and form a secondary tumor in distant organs in the body. CTCs reflect the molecular profile of the primary tumor, therefore studying CTCs can allow for an understanding of the mechanism of metastas...
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... is formed due to the accumulation of multiple mutations in the malignant cells, which lead to uncontrolled growth of the cells [7]. In general, mutant cells acquire the ability to independently synthesize or overexpress certain growth factors or proteins [7]. Moreover, the mutant cells are insensitive to inhibitory signals from signaling pathways [7]. Together, those mutations alter mitotic division resulting in abnormal cell division and elevated resistance to apoptosis (programmed cell death) leading to the formation of the solid tumor [7] (Fig. ...
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... cells are heterogeneous and, thus, not all cancer cells are capable of initiating metastasis [8]. A small subset of CTCs gain stem cell-like properties (self-renewable, ability to initiate and sustain cancer growth) and thus have the ability to initiate metastasis through transformation from differen- tiated epithelial cancer cells into dedifferentiated cells that have more mesenchymal characteristics. This occurs via an epithelial to mesenchymal transition (EMT), which is con- sidered to be a crucial event in the metastatic process [8,9] ( Fig. 1). This facilitates their invasion into the bloodstream [7,8]. Downregulation of some of the cell adhesion proteins on the surface of the cancer cell (eg, E-cadherin), decreased expression of epithelial markers (eg, cytokeratin) [10], in- creased expression of mesenchymal markers (eg, vimentin), and change of the expression of the extracellular matrix (ECM) molecules (eg, integrin) are the most critical events in the EMT process [11][12][13][14]. The EMT cells break through the basement membrane, blood vessels, or interstitial spaces and start entering the circulation in a process called intravasation, allowing them to initiate distant or regional metastasis ...
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... play an important role in cancer metastasis. There- fore, their enumeration and detection may be used to under- stand the mechanism by which they initiate metastasis, thus leading to the development of more effective therapies, more accurate cancer diagnoses and prognoses, and improved 4. Schematic of bar- code particles used to capture different types of CTCs: apta- mers were immobilized on the surface of three types of bar- code particles (reflecting red, green, and blue) using a PA- MAM dendrimer. The apta- mers were TD05 that bind to Ramos cells, while Sgc8 and Sgd5 both bind to lymphoma cells with high specificity. Captured CTCs were released from aptamers using exonu- clease I enzyme. Released CTCs could then be cultured and analyzed by microscopy. (Adapted from 116). Color images available online at www.liebertpub.com/nat cancer treatment. There is no ideal marker that can reliably and efficiently differentiate all CTCs from other blood cells. Therefore, new markers are still needed to capture and isolate these cells. Moreover, increasing the sensitivity and specificity by investigating new ligands is required. Aptamers have great potential for the future of CTC detection as they bind to their targets with high affinity and selectivity. Cell-SELEX pro- duces aptamers that detect CTCs, and identify new biomark- ers. Aptamers are preferable to use in CTC detection platforms as they are more stable than antibodies and they bind to their targets with high specificity and selectivity. Aptamers also can be used with a wider range of experimental conditions. Aptamer detection platforms show great potential in the detection of CTCs. Some of them show improvement of the sensitivity when using multiple aptamers to capture CTCs, for example, micro-devices. For these platforms to be used in a clinical environment, they should provide high purity and higher throughput. Also, most of the platforms mentioned above have only been tested using spiked cells in a diluted buffer or blood sample, which does not reflect the true complexity of a real clinical sample. Some of the reviewed platforms have the ability to recover viable CTCs from a real blood sample with high efficiency and thus allow further analysis of the molecular profile and the phenotype of the captured CTCs at the single cell level. Although antibodies and peptides were used in some of these platforms as tar- geting ligands to capture CTCs, aptamers could increase the sensitivity, selectivity, and stability of these platforms, thus improving their chances of success in the ...
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... ancer is among the leading causes of death in economically developed countries and the second cause of death in developing countries [1]. In 2012, there were 14.1 million new cancer cases, 8.2 million cancer deaths, and 32.6 million people living with cancer (within 5 years of diagnosis) worldwide [2]. More than 90% of cancer-related mortalities are due to metastasis [3]. In 1869, Thomas Ashworth was the first to describe the presence of cells, similar to those of the tumor, in blood after death [4]. These cells were termed circulating tumor cells (CTCs), which have the capability to detach from a primary tumor, circulate with the blood cells and then invade other distant organs in the body forming a secondary tumor ( Fig. 1) [5]. The topic of CTCs was not well understood in cancer research until the last 20 years, due to the fact that CTCs are very rare events in blood (just a few CTCs mixed with the *10 million leukocytes and 5 billion erythrocytes in 1 mL of blood) [5]. However, despite their rarity, CTCs could be ideal samples that (a) can be easily obtained in a regular manner (liquid biopsy), and (b) help to effectively identify therapeutic targets by providing real-time single-cell level data ...
Citations
... For the fluorescent cytotoxicity assays, HaCaT cells were seeded at a density of 5000 cells/well in 384-well plates in RPMI medium supplemented with 10% FBS. After seeding, the cells were incubated with serial dilutions of PMPC 35 , PDMAEMA 80 and PDMAEMA-b-PMPC 10:1 . The cells were incubated with 1 μg/ml PI, MitoTracker probe 500 nM and 5 μg/ml Hoechst 33342 for 40 min in serum-free medium, at 37 • C in 5% CO 2 . ...
Aim: To synthesize HER2 aptamer-conjugated iron oxide nanoparticles with a coating of poly(2-(dimethylamino) ethyl methacrylate)–poly(2-methacryloyloxyethylphosphorylcholine) block copolymer (IONPPPs). Methods: Characterization covered molecular structure, chemical composition, thermal stability, magnetic characteristics, aptamer interaction, crystalline nature and microscopic features. Subsequent investigations focused on IONPPPs for in vitro cancer cell identification. Results: Results demonstrated high biocompatibility of the diblock copolymer with no significant toxicity up to 150 μg/ml. The facile coating process yielded the IONPP complex, featuring a 13.27 nm metal core and a 3.10 nm polymer coating. Functionalized with a HER2-targeting DNA aptamer, IONPPP enhanced recognition in HER2-amplified SKBR3 cells via magnetization separation. Conclusion: These findings underscore IONPPP’s potential in cancer research and clinical applications, showcasing diagnostic efficacy and HER2 protein targeting in a proof-of-concept approach.
... Aptamers have demonstrated their potentials in both diagnostics and therapy, such as binding to circulating tumor cells for early metastasis detection and blocking the activity of specific membrane proteins to induce effects like apoptosis and disruption of cancer cell growth and division. Clinical trials, including the phase II trial of AS1411, highlight the progress and potential of aptamer-based therapies (Bates et al., 2009;Hassan et al., 2016). ...
Hybrid nanoparticles have shown promise in biomedical applications; however, their seamless integration into clinical settings remains challenging. Here, we introduce a novel metal oxide polymer hybrid nanoparticle (NP) with a high affinity for nucleic acids. Iron oxide nanoparticles (IONP) were initially synthesized via the co-precipitation method and subjected to comprehensive characterization. Subsequently, block copolymers were synthesized using the Reversible Addition−Fragmentation Chain Transfer (RAFT) technique, employing the zwitterionic PMPC (Poly (2 Methacryloyloxyethyl Phosphorylcholine)) and the cationic PDMAEMA (Poly(2 (Dimethylamino) Ethyl Methacrylate)) with varying degrees of polymerization. In vitro cytotoxicity studies demonstrated the biocompatibility of the synthesized nanoparticles, with no observed toxicity up to a concentration of 150 µg/mL. The cationic polymer PDMAEMA facilitated the facile coating of IONP, forming the IONPP complex, consisting of a 13.27 metal core and a 3.1 nm block-copolymer coating. Subsequently, the IONPP complex was functionalized with a DNA aptamer specifically targeting the human epidermal growth factor receptor 2 (HER2) in breast cancer, forming IONPPP. The block-copolymer exhibited an EC 50 of 7.07 µg/mL and demonstrated enhanced recognition efficiency in HER2-amplified SKBR3 cells. Our study presents a comprehensive IONPPP characterization capable of binding short DNA sequences and targeting proteins such as HER2. This newly developed nanoparticle holds significant potential for cancer cell identification and isolation, offering promising prospects in cancer research and clinical applications.
1.
Statement of significance
Despite recent advancements in biomedical research, developing sensitive and specific tools for recognizing biological motifs, such as cell receptors and proteins in complex biological solutions, remains a challenge. Furthermore, current approaches often rely on complex biological derivatives like antibodies, lacking a cost-effective delivery strategy. Our study proposes creating and characterizing a novel hybrid metal oxide polymer nanoparticle named IONPPP, functionalized with a DNA aptamer designed to recognize HER2-positive cells. HER2 is a clinically actionable marker for gastric, gastroesophageal, and, particularly, breast cancers. This unique combination of a metal core with an external polymeric structure offers the potential for identification, isolation, and even theragnostic applications, benefiting from its low toxicity and high specificity.
2.
Graphical Abstract
... Aptamers have demonstrated their potentials in both diagnostics and therapy, such as binding to circulating tumor cells for early metastasis detection and blocking the activity of specific membrane proteins to induce effects like apoptosis and disruption of cancer cell growth and division. Clinical trials, including the phase II trial of AS1411, highlight the progress and potential of aptamer-based therapies (Bates et al., 2009;Hassan et al., 2016). ...
This descriptive narrative review demonstrates state-of-the-art epidemiological research in glioblastoma (GB). We discussed the case number and deaths worldwide and the intrinsic and extrinsic risk factors (RF) in cancer analytical epidemiology. GB is the most common glioma, with increased cases in recent decades. Despite much research in the last decades, GB is a disease with a poor survival prognosis. The difference in the amount of data between developed and other countries is notable, as shown in our review. Many intrinsic and extrinsic RF have been studied for GB in recent years, resulting in few conclusions, with cases being more common in older, white, and male patients. In contrast to other review articles, which include more than one neuro-oncological disease, this paper concentrates on GB epidemiological data, including neglected countries. Moreover, we demonstrate and discuss GB’s most recent molecular classification for discovering new molecular markers for prognosis and treatment. More studies are needed to understand extrinsic RF and elucidate contradictory results from the literature. While highlighting the differences between developed and in-development countries, this review can provide grounds for future research in neglected regions, helping improve the quality of living in GB patients.
... Moreover, aptamers can be chemically synthesized with flexible customization providing an opportunity to improve pharmacokinetics and meet a wide range of applications needed (53,54). They can bind diverse targets, ranging from small molecules, proteins to viruses and cells (55)(56)(57)(58). From a therapeutic perspective, aptamers can be used to exert pharmacological action by themselves as agonists (target activation), antagonists (target inhibition), or to act as ligands for targeted delivery of therapeutics (12) (Fig. 2). ...
Cancer‑related deaths remain a challenging and devastating obstacle to defeat despite the tremendous advances in cancer treatment. Cancer metastasis is the major cause of these cancer‑related deaths. Metastasis involves sequential steps during cancer cells' journey to a new site. These steps are coordinately regulated by specific intracellular regulators and cellular interactions between the cancer cells and the supporting microenvironment of the different organs. The development of aptamer‑based therapeutics is a promising strategy to fight cancer metastasis as it holds potential advantages. Oligonucleotide and peptide aptamers are short sequences of single‑stranded nucleic acids or amino acids, respectively, that target proteins, genetic materials, and cells. Antimetastatic aptamer‑based therapeutics exert their pharmacological effect by direct interaction with the signaling pathways inside the cancer cells or the communications between cancer cells and the tumor microenvironment. In addition, aptamers have been utilized as a guiding ligand to deliver a therapeutic moiety to cancer cells or the supporting microenvironment. The selected aptamer possesses high specificity since it is designed to recognize and interact with its target. This review summarizes recent advances in the development of aptamer‑based therapeutics targeting mediators of cancer metastasis. In addition, potential opportunities are discussed to inspire researchers in the field to develop novel aptamer‑based antimetastatic treatments.
... An aptamer with high specificity and affinity discerns and connects to their targets, such as antibodies, and has been used to establish affinity-based isolation of exosomes [137]. For instance, a coating agent composed of EpCAM-affinity peptide aptamer (Ep114) and zwitterionic poly-2-methacryloyloxyethyl phosphorylcholine (MPC) polymer has been used for exosome isolation [138]. ...
Exosomes derived from tumor cells contain various molecular components, such as proteins, RNA, DNA, lipids, and carbohydrates. These components play a crucial role in all stages of tumorigenesis and development. Moreover, they reflect the physiological and pathological status of parental tumor cells. Recently, tumor-derived exosomes have become popular biomarkers for non-invasive liquid biopsy and the diagnosis of numerous cancers. The interdisciplinary significance of exosomes research has also attracted growing enthusiasm. However, the intrinsic nature of tumor-derived exosomes requires advanced methods to detect and evaluate the complex biofluid. This review analyzes the relationship between exosomes and tumors. It also summarizes the exosomal biological origin, composition, and application of molecular markers in clinical cancer diagnosis. Remarkably, this paper constitutes a comprehensive summary of the innovative research on numerous detection strategies for tumor-derived exosomes with the intent of providing a theoretical basis and reference for early diagnosis and clinical treatment of cancer.
... -Obtained by chemical synthesis, which leads to reproducible properties and facilitates modification with functional groups and different labels -Simple and cost-effective production -Aptamers are stable under various conditions (pH, temperature) [55,56] -Cells captured using aptamers can be released using nucleases or the aptamer's complementary strand -Low to no immunogenicity -Long-shelf life -Application of aptamer is still in development phase, due to well-established use of antibodies -Time consuming selection process -Possible endocytosis of the aptamer-magnetic particle conjugates [57] (although this is exploited for therapeutic applications). [58][59][60][61] [62,63] Fishing -Applicable to unculturable cells for which antibodies are not available cell genetic content is preserved inside the cell but the latter is no longer viable due to treatment with chemical fixative such as paraformaldehyde. ...
Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells.
... A number of methods have been developed for detection of tumor cells at the earliest. For detection of circulating tumor cells and disseminated tumor cells, techniques such as laser detection, 32 cell search system, 33 EPithelial ImmunoSPOT (EPISPOT), 34 AdnaTest, 35 TelomeScan, 36 aptamers 37 and others have been used. However, these techniques require accessibility and expertise for detecting Circulating Tumor Cells. ...
Microfluidics is an exponentially growing area and is being used for numerous applications from basic science to advanced biotechnology and medicines. Microfluidics provides a platform to the research community for studying and building new strategies for the diagnosis and therapeutics applications. In the last decade, microfluidic have enriched the field of diagnostics by providing new solutions which was not possible with conventional detection and treatment methods. Microfluidics has the ability to precisely control and perform high-throughput functions. It has been proven as an efficient and rapid method for biological sample preparation, analysis and controlled drug delivery system. Microfluidics plays significant role in personalized medicine. These personalized medicines are used for medical decisions, practices and other interventions as well as for individual patients based on their predicted response or risk of disease. This chapter highlights microfluidics in developing personalized medical applications for its applications in diseases such as cancer, cardiovascular disease, diabetes, pulmonary disease and several others.
... Aptamers are oligonucleotide ligands (single-stranded DNA or RNA) with desired properties [13] including high stability, biocompatibility, resistance to harsh conditions, etc. which be able to stick on their targets, specifically. So they can be used as an alternative capture agent. ...
It has been proved that most of the deaths due to cancer are related to metastasis. This process occurs through the separation of cells from the primary tumor and maintenance in the circulation systems in the body. Finally, if the condition for the relocalizing of them in other sites becomes appropriate, they produce new tumors in various parts of the body. The number of these circulating tumor cells (CTCs) in the blood is very rare. So, detecting and counting them is difficult, but very vital. There are various techniques for the detection of CTCs, which along with them, nanomaterials are suitable tools for this purpose due to their small sizes and unique properties. Because of the high efficiency of these materials, it is possible to exceed the other mentioned methods. In this review, we aim to render a comprehensive study about recent advances in the capture and subsequent release of the CTCs using different types of nanomaterials.
... Aptamers are single-stranded DNA/RNA sequences owing to unique binding features to their targets, and they have been widely applied in diverse fields of research [1][2][3][4][5][6][7]. They are short nucleotide sequences with the molecular weight ranging from 10 to 30 kDa, much smaller than that of antibodies [8,9]. ...
Surface-enhanced Raman spectroscopy, due to its high sensitivity, unique vibrational fingerprint identification of molecules and easy operation, has been extensively applied in different fields. Aptamers, being the unique single stranded DNA/RNA sequences that can specifically recognize and seize the target analytes, combined with Surface-enhanced Raman spectroscopy (SERS), can offer potent multiplex detection capacity with high specificity and sensitivity. In this review, we summarize and classify the general working strategies of different types of aptamer-based SERS biosensors with diversified protocols which either take aptamer conformational change as intrinsic reporter, or make use of various extrinsic Raman reporters in different sensor designs via on/off approach, sandwich-type and magnetic nanoparticles (NPs)-assisted approach, and catalytic reaction assisted approach with amplification of alternative Raman signals. The advantages, applications and perspectives of these aptamer-based SERS biosensors are also discussed.
... Currently, aptamers have been emerged as a new powerful tool for targeting molecules since it was first discovered in 1990, 1 which are being reviewed as a next-generation technology for capture and detection of biomolecules including cells and biomarkers. 2,3 As an alternative to antibody, aptamers that are generated from oligonucleotides by a process termed SELEX possess many intrinsic merits, such as small size, chemically automated synthesis, flexible structure, long-term stability, lack of immunogenicity, and controllable modification. Due to these advantages, aptamers may overcome the inherent disadvantages of antibody-based biotechnology that suffers from its inherent drawbacks including instability, immunogenicity, high cost and big molecular size. ...
Background/objective:
Circulating tumor cells (CTCs) are known as the root of cancer metastasis. Capture and inhibition of CTCs may prevent metastasis. Due to the rarity of CTCs in vivo, the current technology about CTCs capture is still challenging. The aim of our study was to conjugate the enhanced biostable double-strand (ds) circular aptamer (dApR) with dendrimers for capturing and restraining CTCs in vitro and in vivo.
Methods:
CEM-targeting aptamer (Ap) was looped by ligation after phosphorylation to form circular ds aptamer dApR, which was then conjugated to dendrimers by biotin-streptavidin affinity reaction and named as G-dApR. The physicochemical properties of G-dApR were characterized by using PAGE gel electrophoresis, UV, DLS, AFM, fluorophotometer and laser confocal microscope. Biostability of G-dApR was also analyzed by gel electrophoresis. Confocal microscopy and flow cytometry were then performed to determine the binding specificity of G-dApR to CEM cells and the captured CTCs in mice and in human blood. Apoptosis of the captured cells was finally evaluated by using MTT assay, DAPI staining, AO/EB staining, cell cycle analysis and Annexin V-FITC/PI staining.
Results:
Physicochemical characterization demonstrated the entity of dApR and G-dApR, and the nano-size of G-dApR (about 180 nm in aqueous phase). G-dApR exhibited the excellent biostability that confers their resistance to nuclease-mediated biodegradation in serum for at least 6 days. In our established CTCs model, we found that G-dApR could specifically and sensitively capture CTCs not non-target cells even in the presence of millions of interfering cells (108), in mice and in human blood. Finally, the activity of captured CTCs was significantly down-regulated by G-dApR, resulting in apoptosis.
Conclusion:
We created the enhanced biostable dApR-coated dendrimers (G-dApR) that could specifically capture and restrain CTCs in vitro and in vivo for preventing CTC-mediated cancer metastasis.
