Progresses on RNA-based therapeutics for genetic diseases / 浙江大学学报·医学版

RNA therapeutics inhibit the expression of specific proteins/RNAs by targeting complementary sequences of corresponding genes, or synthesize proteins encoded by the desired genes to treat genetic diseases. RNA-based therapeutics are categorized as oligonucleotide drugs (antisense oligonucleotides, small interfering RNA, RNA aptamers), and mRNA drugs. The antisense oligonucleotides and small interfering RNA for treatment of genetic diseases have been approved by the FDA in the United State, while RNA aptamers and mRNA drugs are still in clinical trials. Chemical modifications are applied to RNA drugs, such as pseudouridine modification of mRNA, to reduce immunogenicity and improve the efficacy. The secure and effective delivery systems like lipid-based nanoparticles, extracellular vesicles, and virus-like particles are under development to address stability, specificity, and safety issues of RNA drugs. This article provides an overview of the specific molecular mechanisms of 11 RNA drugs currently used for treating genetic diseases, and discusses the research progress of chemical modifications and delivery systems of RNA drugs.

Advances in aptamer-based nuclear medicine / 中华核医学与分子影像杂志

Aptamers are single-stranded DNA or RNA that can bind to different targets with high specificity and affinity, including small molecules, ions, viruses, and cells. This article focuses on the progress of aptamer in nuclear medicine, including SPECT and PET imaging researches. With the development of nuclear medicine related equipment and isotope labeling technology, the aptamer will have broader application prospects in nuclear medicine.

Progress on RNA-based therapeutics for genetic diseases / 浙江大学学报·医学版

RNA therapeutics inhibit the expression of specific proteins/RNAs by targeting complementary sequences of corresponding genes or encode proteins for the synthesis desired genes to treat genetic diseases. RNA-based therapeutics are categorized as oligonucleotide drugs (antisense oligonucleotides, small interfering RNA, RNA aptamers), and mRNA drugs. The antisense oligonucleotides and small interfering RNA for treatment of genetic diseases have been approved by the FDA in the United States, while RNA aptamers and mRNA drugs are still in clinical trials. Chemical modifications can be applied to RNA drugs, such as pseudouridine modification of mRNA, to reduce immunogenicity and improve the efficacy. The secure and effective delivery systems such as lipid-based nanoparticles, extracellular vesicles, and virus-like particles are under development to address stability, specificity, and safety issues of RNA drugs. This article provides an overview of the specific molecular mechanisms of eleven RNA drugs currently used for treating genetic diseases, and discusses the research progress of chemical modifications and delivery systems of RNA drugs.

Identification of new human mesenchymal stem cell biomarker by aptamers / Identificação de novos biomarcadores de células tronco mesenquimais de origem humana por meio de aptâmeros

Stem cells are undifferentiated cells that can be distinguished from others by their ability to self-renew and to differentiate into new specific cell types. Mesenchymal stem cells (MSC) are adult stem cells that can be obtained from different sources, such as adipose tissue, bone marrow, dental pulp, and umbilical cord. They can either replicate, originating new identical cells, or differentiate into cells of mesodermal origin and from other germ layers. MSC have been studied as new tools for regenerative therapy. Although encouraging results have been demonstrated, MSC-based therapies still face a great barrier: the difficulty of isolating these cells from heterogeneous environments. MSC are currently characterized by immunolabelling through a set of multiple surface membrane markers, including CD29, CD73, CD90 and CD105, which are also expressed by other cell types. Hence, the present work aimed to identify new specific biomarkers for the characterization of human MSC using DNA aptamers produced by the SELEX (Systematic Evolution of Ligands by EXponential Enrichment) technique. Our results showed that MSC from different origins bound to DNA candidate aptamers, that is, DNA or RNA oligonucleotides selected from random libraries that bind specifically to biological targets. Aptamer-bound MSC could be isolated by fluorescenceactivated cell sorting (FACS) procedures, enhancing the induction of differentiation into specific phenotypes (chondrocytes, osteocytes and adipocytes) when compared to the whole MSC population. Flow cytometry analyses revealed that candidate aptamers bound to 50% of the MSC population from dental pulp and did not present significant binding rates to human fibroblasts or lymphocytes, both used as negative control. Moreover, immunofluorescence images and confocal analyses revealed staining of MSC by aptamers localized in the surfacemembrane of these cells. The results also showed internal staining of human monocytes by our investigated aptamers. A non-specific control aptamer (CNTR APT) obtained from the random pool was then utilized to compare the specificity of the aptamers bound to the analyzed non-apoptotic cells, showing no staining for MSC. However, 40% of the monocytes bound to the CNTR APT. Normalized data based on the cells bound to candidate aptamers compared to those bound to the CNTR APT, revealed a 10 to 16-fold higher binding rate for MSC against 2-fold for monocytes. Despite its low specificity, monocyte-aptamer binding occurs probably due to the expression of shared markers with MSC, since monocytes are derived from hematopoietic stem cells and are important for the immune system ability to internalize/phagocyte external molecules. Given that, we performed a pull-down assay followed by mass spectrometry analysis to detect which MSC-specific protein or other target epitope not coexpressed by monocytes or the CNTR APT would bind to the candidate aptamer. Distinguishing between MSC and monocyte epitopes is important, as both cells are involved in immunomodulatory effects after MSC transplantations. ADAM17 was found to be a target of the APT10, emerging as a possible biomarker of MSC, since its involvement in the inhibition of the TGF signaling cascade, which is responsible for the differentiation of MSC. Thus, MSC with a higher stemness profile should overexpress the protein ADAM17, which presents a catalytic site with affinity to APT10. Another target of Apt 10 is VAMP3, belonging to a transmembrane protein complex that is involved in endocytosis and exocytosis processes during immune and inflammatory responses. Overall, proteins identified as targets of APT10 may be cell surface MSC biomarkers, with importance for MSC-based cell and immune therapies

Células tronco são células indiferenciadas que podem ser distinguidas de outros tipos celulares por meio da habilidade de se auto renovarem e de se diferenciarem em novos tipos celulares. Células tronco mesenquimais (MSC) são células tronco adultas encontradas em diferentes tecidos como tecido adiposo, polpa de dente e cordão umbilical. Estas células podem se autodividir em células idênticas ou se diferenciarem em células de origem mesodermal. Estas células têm sido estudadas em novas aplicações que envolvem terapia regenerativas. Embora resultados encorajadores tenham sido demonstrados, terapias que utilizam MSC ainda encontram uma grande barreira: a dificuldade no isolamento destas células a partir de um ambiente heterogêneo. MSC são caracterizadas por populações positivas em ensaios de imunomarcação para os epítopos membranares CD29, CD73, CD90 e CD105, presentes também em outros tipos celulares. Assim, o presente trabalho tem o objetivo de identificar novos biomarcadores de MSC de origem humana, utilizando aptâmeros de DNA produzidos pela técnica SELEX (Systematic Evolution of Ligands by EXponential Enrichment) como ferramenta. Nossos resultados mostraram que MSC de diferentes origens ligam-se a aptâmeros (oligonucleotídeos de DNA ou RNA que atuam como ligantes específicos de alvos moleculares) de DNA candidatos que atuam no isolamento de MSC por meio da técnica FACS de separação celular, promovendo uma maior indução de diferenciação em células específicas (condrócitos, osteócitos e adipócitos) comparada com a população total de MSC. Análises de citometria de fluxo mostraram que os aptâmeros candidatos se ligam a 50% das MSC de polpa de dente e não apresentam taxa de ligação significante para fibroblastos e linfócitos de origem humana - utilizados como controles negativo. Além domais, imagens de imunofluorescência e confocal mostraram ligação na superfície da membrana de MSC e a marcação interna de monócitos a estes aptâmeros. Portanto, um aptâmero controle (CNTR APT) foi utilizado para comparar a especificidade dos aptâmeros ligados a células viáveis, mostrando a não ligação deste aptâmero a MSC. Porém, 40% da população de monócitos ligou-se ao CNTR APT. Uma normalização baseada na comparação entre as taxas de ligação entre células ligadas com aptâmeros candidatos e o aptâmero controle gerou uma taxa de especificidade entre 10-16 vezes maior para MSC contra 2,5 vezes para os monócitos. Deste modo, embora os resultados tenham mostrado uma taxa de ligação entre monócitos e aptâmeros, as MSC ligadas aos aptâmeros candidatos possuem uma maior taxa de especificidade devido a uma maior presença de antígenos que são expressos em ambas as células. Um ensaio de Pull Down seguido de espectrometria de massas foi utilizado para a identificação de biomarcadores que se ligariam aos aptâmeros candidatos, e que não seriam co-expressos por monócitos e por antígenos ligados ao aptâmero controle. Deste modo, a proteína ADAM17 foi identificada nas amostras de APT10 ligadas às MSC. Tal proteína está relacionada à inibição de uma cascata de sinalização da família de proteínas TGF, responsável pela diferenciação de MSC. Assim, MSC com maior potencial tronco deveriam expressar ADAM17 em maior quantidade. Tal proteína apresenta um sítio catalítico que demonstra interagir com o APT10, de acordo com predição Docking entre proteína e DNA. Foi identificada também, a proteína VAMP3, que pertence a um complexo proteico transmembranar responsável pelos processos de endocitose e exocitose, e que podem ter um papel importante na liberação de citocinas e outras moléculas relacionadas às respostas imune e inflamatórias. Deste modo, o APT10 identificou proteínas importantes que devem estar relacionas com a melhora de imunoterapias que utilizam MSC

Los aptámeros como novedosa herramienta diagnóstica y terapéutica y su potencial uso en parasitología / Aptamers as a novel diagnostic and therapeutic tool and their potential use in parasitology

Los aptámeros son secuencias de ADN o ARN de cadena sencilla que adoptan la forma de estructuras tridimensionales únicas, lo cual les permite reconocer un blanco específico con gran afinidad. Sus usos potenciales abarcan, entre otros, el diagnóstico de enfermedades, el desarrollo de nuevos agentes terapéuticos, la detección de riesgos alimentarios, la producción de biosensores, la detección de toxinas, el transporte de fármacos en el organismo y la señalización de nanopartículas. El pegaptanib es el único aptámero aprobado para uso comercial por la Food and Drug Administration (FDA). Otros aptámeros para el tratamiento de enfermedades están en la fase clínica de desarrollo. En parasitología, se destacan los estudios que se vienen realizando en Leishmania spp., con la obtención de aptámeros que reconocen la proteína de unión a poliA (LiPABP) y que pueden tener potencial utilidad en la investigación, el diagnóstico y el tratamiento de la leishmaniasis. En cuanto a la malaria, se han obtenido aptámeros que permiten identificar eritrocitos infectados e inhiben la formación de rosetas, y otros que prometen ser alternativas para el diagnóstico al detectar de forma específica la proteína lactato deshidrogenasa (PfLDH). Para Cryptosporidium parvuum se han seleccionado aptámeros que detectan ooquistes a partir de alimentos o aguas contaminadas. Para Entamoeba histolytica se han aislado dos aptámeros llamados C4 y C5, que inhiben la proliferación in vitro de los trofozoítos y tienen potencial terapéutico. Los aptámeros contra Trypanosoma cruzi inhiben la invasión de células LLC-MK2 (de riñón de mono) en un 50 a 70 % y aquellos contra T. brucei transportan moléculas tóxicas al lisosoma parasitario como una novedosa estrategia terapéutica. Los datos recopilados en esta revisión destacan los aptámeros como una alternativa para la investigación, el diagnóstico y el tratamiento contra parásitos de interés nacional.

Aptamers are single-stranded DNA or RNA sequences that adopt unique three-dimensional structures that allow them to recognize a specific target with high affinity. They can potentially be used for the diagnosis of diseases, as new therapeutic agents, for the detection of food risks, as biosensors, for the detection of toxins, and as drug carriers and nanoparticle markers, among other applications. To date, an aptamer called pegaptanib is the only aptamer approved by the Food and Drug Administration (FDA) for commercial use. Other aptamers are in different clinical stages of development for the treatment of different diseases. In parasitology, investigations carried out with parasites such as Leishmania spp. allowed the acquisition of aptamers that recognize the polyA-binding protein LiPABP and may have potential applications in research and diagnosis and even as therapeutic agents. Regarding malaria, aptamers have been obtained that allow the identification of infected erythrocytes or inhibit the formation of rosettes, along with those that provide promising alternatives for diagnosis by specifically detecting the protein lactate dehydrogenase (PfLDH). In Cryptosporidium parvum allow the detection of oocysts in contaminated food or water. In Entamoeba histolytica, two aptamers called C4 and C5, which inhibit the proliferation of trophozoites in vitro and have potential use as therapeutic agents, have been isolated. Aptamers obtained against Trypanosoma cruzi inhibit the invasion of LLC-MK2 (from monkey kidney) cells by 50-70%, and in T. brucei, aptamers with the potential to transport toxic molecules to the parasitic lysosome were identified as a novel therapeutic strategy. The data collected in this review highlight aptamers as a novel alternative in the research, diagnosis, and treatment of parasites of national interest.

Evolution of specific RNA aptamers via SELEX targeting recombinant human CD36 protein: A candidate therapeutic target in severe malaria

Objective: To isolate and characterize RNA aptamers that are specific to human CD36 protein using systematic evolution of ligands by exponential enrichment (SELEX) technology to identify candidates for adjunct therapy to reverse the binding of Plasmodium-infected erythrocytes. Methods: RNA aptamers were isolated using nitrocellulose membrane-based SELEX and binding analysis was screened using an electrophoretic mobility shift assay and enzyme-linked oligonucleotide assay. Results: Thirteen cycles of nitrocellulose membrane-based SELEX yielded three aptamers (RC60, RC25, RC04) exhibiting high binding against CD36 protein as shown on electrophoretic mobility shift assay. The sequence analysis revealed a G-quadruplex sequence within all the isolated aptamers that might contribute to aptamer binding and thermodynamic stability. The specificity assay further showed that RC60 and RC25 were highly specific to CD36. The competitive inhibition assay demonstrated that RC60 and RC25 shared a similar binding epitope recognized by mAb FA6-152, a specific monoclonal antibody against CD36. Conclusions: RC60 and RC25 are promising candidates as anti-cytoadherence for severe malaria adjunct therapy.

Aptamers specific for biotoxins: research advances / 国际药学研究杂志

Biotoxins widely exist in foods and environments, posing a serious threat to human health. Specific and sensitive detection of biotoxins is the most effective way to prevent unexpected problems caused by biotoxins. In recent years, aptamer-based bio-toxin detections have gradually been prevailing. Aptamers, a new type of recognition molecules with high affinity and specificity, have been used to produce a variety of biosensors. In addition, some aptamers can neutralize the toxicity of biotoxins and inhibit their activities, with the effect to replace the antibody to some extent. This article briefly describes the research advances on biotoxin aptamers and prospects the development and application of aptamers targeting biotoxins in the future.

Evolution of specific RNA aptamers via SELEX targeting recombinant human CD36 protein: A candidate therapeutic target in severe malaria

To isolate and characterize RNA aptamers that are specific to human CD36 protein using systematic evolution of ligands by exponential enrichment (SELEX) technology to identify candidates for adjunct therapy to reverse the binding of Plasmodiuminfected erythrocytes. Methods: RNA aptamers were isolated using nitrocellulose membrane-based SELEX and binding analysis was screened using an electrophoretic mobility shift assay and enzyme-linked oligonucleotide assay. Results: Thirteen cycles of nitrocellulose membrane-based SELEX yielded three aptamers (RC60, RC25, RC04) exhibiting high binding against CD36 protein as shown on electrophoretic mobility shift assay. The sequence analysis revealed a G-quadruplex sequence within all the isolated aptamers that might contribute to aptamer binding and thermodynamic stability. The specificity assay further showed that RC60 and RC25 were highly specific to CD36. The competitive inhibition assay demonstrated that RC60 and RC25 shared a similar binding epitope recognized by mAb FA6-152, a specific monoclonal antibody against CD36. Conclusions: RC60 and RC25 are promising candidates as anticytoadherence for severe malaria adjunct therapy.

Isolation of MLL1 Inhibitory RNA Aptamers

Mixed lineage leukemia proteins (MLL) are the key histone lysine methyltransferases that regulate expression of diverse genes. Aberrant activation of MLL promotes leukemia as well as solid tumors in humans, highlighting the urgent need for the development of an MLL inhibitor. We screened and isolated MLL1-binding ssRNAs using SELEX (Systemic Evolution of Ligands by Exponential enrichment) technology. When sequences in sub-libraries were obtained using next-generation sequencing (NGS), the most enriched aptamers—APT1 and APT2—represented about 30% and 26% of sub-library populations, respectively. Motif analysis of the top 50 sequences provided a highly conserved sequence: 5′-A[A/C][C/G][G/U][U/A]ACAGAGGG[U/A]GG[A/C] GAGUGGGU-3′. APT1, APT2, and APT5 embracing this motif generated secondary structures with similar topological characteristics. We found that APT1 and APT2 have a good binding activity and the analysis using mutated aptamer variants showed that the site information in the central region was critical for binding. In vitro enzyme activity assay showed that APT1 and APT2 had MLL1 inhibitory activity. Three-dimensional structure prediction of APT1-MLL1 complex indicates multiple weak interactions formed between MLL1 SET domain and APT1. Our study confirmed that NGS-assisted SELEX is an efficient tool for aptamer screening and that aptamers could be useful in diagnosis and treatment of MLL1-mediated diseases.

Research progress of aptamer and organic nanomaterials based tumor targeting drug delivery systems / 国际生物医学工程杂志

Aptamers are DNA or RNA fragments that can specifically bind to target substances.Because of the excellent properties such as strong binding force,high specificity,small physical size,chemical synthesis and modification,good biocompatibility,and low immunogenicity aptamers show wide application propects in biomedical researches.Aptamers can also bind specifically to receptors on the surface of cell membranes,and mediate the endocytosis of nanoparticles into cells,making them ideal drug targeting ligands.Organic nanomaterials have excellent application value in nanodrug delivery system because of their good biocompatibility and degradability.In this paper,the recent research progress of aptamers and organic nanomaterials drug delivery systems was reviewed.

Application of aptamers for assessment of vaccine efficacy

Assessing antigen concentration of vaccine is essential step in determining the quality of the vaccine prior to vaccination. After vaccination, vaccine-induced antibody titer should also be measured to verify the vaccine efficacy. Since conventional assay used for vaccine concentrations and induced Ab-titers is antibody-based enzyme-linked immunosorbent assay, the assay inevitably brings drawbacks of antibody such as high cost for production, limited stability, and inconsistent quality between lot-to-lots. Aptamer is single-stranded nucleic acid having three-dimensional structure and has features overcoming limitations of antibody. This review will briefly introduce the features of aptamer and potential of aptamer-based system for evaluation of vaccine efficacy.

Review of Studies on the Chinese Medicine combined with Nucleoside (acid) Drugs for Chronic Hepatitis B / 国际中医中药杂志

Recent studies showed that Chinese medicine combined with nucleoside (acid) treatments could benefit chronic hepatitis B (CHB). Many patients have gained the benefits from these treatments. This paper summarized the recent studies of Chinese medicine combined with nucleoside (acid) drugs for chronic hepatitis B, and discussed the status of the researches, in order to explore an integrated treatment for chronic hepatitis B.

Nucleic acid aptamer and its research progress in glioma / 国际肿瘤学杂志

Nucleic acid aptamer is an oligonucleotide generated by the systematic evolution of ligands by exponential enrichment (SELEX)process from oligonucleotide library.Nucleic acid aptamer can bind to various targets with high specificity and can recognize or inhibit the biological activity of targeting molecular. Glioma-specific aptamers are developed by either targeting the glioma cells or known biomarkers,which can be coupled with nanoparticles,drugs or molecular probes,and can be applied in the imaging,targeted therapy and drug delivery of glioma.

Enhancement of thermal damage to EpCAM-positive tumor cells by novel aptamer-guided magnetic nanoparticles / 中华肿瘤杂志

Objective@#To explore the thermal damage to epithelial cell adhesion molecule(EpCAM)-positive tumor cells by novel aptamer-guided magnetic nanoparticles(AptNPs).@*Methods@#EpCAM aptamer SYL3C was connected to NPs via biotin-streptavidin reaction. The diameter of AptNPs were characterized by Dynamic Light Scattering(DLS). The binding feature of the aptamer to EpCAM-positive tumor cells was evaluated by Prussian blue dyeing. Thermal damage under alternative magnetic field was measured bylactate dehydrogenase (LDH). The apoptosis of EpCAM-positive tumor cells was detected by acridine orange/ethidium bromide (AO/EB) double staining.@*Results@#The average size of AptNPs was 282 nm. Flow cytometry and Prussian blue dyeing showed that AptNPs exhibited strong binding to the EpCAM-positive tumor cells but not to the EpCAM-negative tumor cells. Moreover, when incubated with 1.5×108 AptNPs under alternative electromagnetic fieldfor 5 hours, the viability of EpCAM-positive HCT116 cells and A549 cells was 28.9% and 54.4%, respectively, significantly lower than 76.7% of EpCAM-negative HepG2 cells (P<0.05).@*Conclusions@#AptNPs can improve the thermal damage to EpCAM-positive tumor cells, and may have potential utility in the development of tumor targeted therapy.

Application of Nucleic Acid Aptamers in Polypeptides Researches / 分析化学

Polypeptides play a vital role in physiological processes of life. The pharmacological and medical value of polypeptides has attracted the attention of researchers in recent years. Aptamers are short, single stranded DNA or RNA which developed by an in vitro process called systematic evolution of ligands by exponential enrichment ( SELEX ) . Aptamers can bind targets with high affinity and specificity. Hence, aptamer is also called "chemical antibody" or "chemist's antibody". To date, there are two main application aspects for polypeptides-targeted aptamers. First, aptamer can be used as specific affinitive elements based on their ability of recognition, which would be applied to polypeptides detection or imaging. The other one is that aptamer can also be used as antagonists based on their ability of inhibiting, which can restrict the activity of polypeptides and block the downstream signaling pathways in vivo, thus can be used to treat the disease associated with polypeptides. In this review, we summarize the numbers of polypeptides-targeted aptamers and the related applications in vitro and in vivo. Current issues and development trends throughout the screening, characterizing and applying of polypeptides-targeted aptamers are also discussed.

Aptamer and its therapeutic applications for age-related macular degeneration / 中华眼底病杂志

Vascular endothelial growth factor (VEGF),platelet derived growth factor (PDGF) and complements play key roles in the pathogenesis of age-related macular degeneration (AMD).Pegaptanib,the first therapeutic aptamer against VEGF165,has been approved by the Food and Drug Administration (FDA) of US for the treatment of exudative AMD.Another two aptamers El0030 and ARC1905,each target PDGF-B and complement C5 respectively,are undergoing clinical trials.Recent trends to treat AMD are combined therapies targeting multiple key molecules in the pathogenesis of AMD;aptamers against multiple targets may become the preferred drug for AMD.

Screening and identification of aptamers against the recombinant transpeptidase domain of PBP 2a / 重庆医学

Objective To screen and identify the aptamers of the recombinant transpeptidase domain of PBP2a(penicillin binding protein 2a ,PBP2a) .Methods By using the recombinant transpeptidase domain of PBP2a as the screening target ,oligonucle-otides which were capable of specifically binding to the protein were screened by a random oligonucleotide library through the stem -atic evolution of ligand by exponential enrichment (SELEX )technique .The ssDNA was cloned and sequenced ,and the secondary structure of aptamer clones was predicted with mfold program .Results After 11 cycles of the selection ,the aptamers which were capable of binding to PBP2a with high affinity have been selected .40 clones from the 8 and 10 cycles were selected randomly and se-quenced .The aptamers obtained had no obvious homology according to their sequences by the sequence alignments ,and the 40 aptamers were classified to three groups according to their secondary structures .The aptamer 13 was found to be specific for the target protein with the highest affinity .Conclusion Aptamers for the recombinant transpeptidase domain of PBP2a with high affili-ty and specificity were successfully screened by SELEX ,which lays a foundation for exploring new ways of diagnosis and treatment of MRSA infection .

Nucleic acid aptamer for caner therapeutics and diagnostics / 国际肿瘤学杂志

Nucleic acid aptamer is the systematic evolution of ligands by exponential enrichment syn-thesized in vitro screening technology resulting single-stranded oligonucleotides (DNA or RNA),by folding into unique spatial structure specific recognition binding target molecules.Aptamers function is similar to the anti-bodies but more specifically,as novel molecular probes for the field of cancer therapeutics and diagnostics.

Aptamers as molecular probes in tumor molecular imaging / 国际肿瘤学杂志

The ideal molecular imaging probe should have characteristics of specificity,sensitivity and safety.Aptamers are sing-strand DNA or RNA oligonucleotides which can bind their targets with high specificity and high affinity.Aptamers are new types of molecular imaging probe because they have many advantages,such as their large sum of possible targets,small molecule weights,easily production and modification,low immuno-genicity,high tissue penetration and so on.Now more and more aptamers research on tumor molecular imaging provides a new technology and tool for tumor diagnosis and therapy.

Recent progress of aptamer inhibitors targeting c-Met / 中国生化药物杂志

c-Met is one member of the receptor tyrosine kinases (RTKs).It is closely related between the over-expression of c-Met and a wide variety of tumor occurrence, development, invasion, metastasis, prognosis and drug resistance.Therefore, c-Met is a potential target for oncotherapy, and researches on its inhibitors have become a hot spot in the field of tumor treatment.Aptamers targeting c-Met are gained from systematic evolution of ligands by exponential enrichment (SELEX).They can bind to c-Met with high specificity and affinity, resulting in the activation or inhibition of c-Met.We envision that anti-c-Met aptamers would be ideal new c-Met inhibitors after optimization, and could be developed into potential targeted drugs for cancers.