title: Selection of DNA aptamers against epithelial cell adhesion molecule for cancer cell imaging and circulating tumor cell capture.
abstract: Epithelial cell adhesion molecule (EpCAM) is overexpressed in most solid cancers and is an ideal antigen for clinical applications in cancer diagnosis, prognosis, imaging, and therapy. Currently, most of the EpCAM-based diagnostic, prognostic, and therapeutic strategies rely on the anti-EpCAM antibody. However, the use of EpCAM antibody is restricted due to its large size and instability. In this study, we have successfully identified DNA aptamers that selectively bind human recombinant EpCAM protein. The aptamers can specifically recognize a number of live human cancer cells derived from breast, colorectal, and gastric cancers that express EpCAM but not bind to EpCAM-negative cells. Among the aptamer sequences identified, a hairpin-structured sequence SYL3 was optimized in length, resulting in aptamer sequence SYL3C. The Kd values of the SYL3C aptamer against breast cancer cell line MDA-MB-231 and gastric cancer cell line Kato III were found to be 38 ± 9 and 67 ± 8 nM, respectively, which are better than that of the full-length SYL3 aptamer. Flow cytometry analysis results indicated that the SYL3C aptamer was able to recognize target cancer cells from mixed cells in cell media. When used to capture cancer cells, up to 63% cancer cell capture efficiency was achieved with about 80% purity. With the advantages of small size, easy synthesis, good stability, high binding affinity, and selectivity, the DNA aptamers reported here against cancer biomarker EpCAM will facilitate the development of novel targeted cancer therapy, cancer cell imaging, and circulating tumor cell detection.
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, People's Republic of China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Song
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhu
authors.forename: Yuan
authors.initials: Y
authors.lastname: An
authors.forename: Weiting
authors.initials: W
authors.lastname: Zhang
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhang
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Chundong
authors.initials: C
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Duan
authors.forename: Chaoyong James
authors.initials: CJ
authors.lastname: Yang
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis* / Q000235:genetics; D052157:Aptamers, Nucleotide / Q000138:chemical synthesis / Q000737:chemistry*; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000235:genetics; D045744:Cell Line, Tumor; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D015870:Gene Expression; D006801:Humans; D055029:Inverted Repeat Sequences; D014411:Neoplastic Stem Cells / Q000737:chemistry* / Q000473:pathology; D061848:Optical Imaging; D011485:Protein Binding; D052156:SELEX Aptamer Technique
chemical_list: D000951:Antigens, Neoplasm; D052157:Aptamers, Nucleotide; D014408:Biomarkers, Tumor; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D005456:Fluorescent Dyes; D016650:Fluorescein-5-isothiocyanate