(584as) Screening of Functional Aptamers Against Alpha-Methylacyl-CoA Racemase

Alpha-methylacyl-CoA racemase(AMACR) is an emerging prostate cancer marker, which is known as P504S in cancer research literature. Campared to prostate-specific antigen (PSA)that is a traditional prostate cancer marker, AMACR is more specific and senstive in diagnosis of prostate cancer¹. Moreover, it is already known that over production of AMACR has been highly associated with not only prostate cancer but also breast, colon, renal and other cancers. Recently, it is proven that inhibition of the AMACR expression can diminish the growth of prostate cancer cell lines². This means that AMACR is a viable chemotherapeutic target in prostate cancer therapy. An aptamer is a manmade protein-binding nucleic acid ligand, and its affinity and specificity can rival an antibody. Moreover, compared to an antibody, an aptamer has many advantages such as high affinity and specificity, easy synthesis and modification, high chemical stability (for DNA and modified RNA), small size, low immunogenicity, and so on. Therefore, this work aims at selection of a panel of functional DNA aptamers that target the catalytic site of AMACR and can thus potentially regulate the catalytic activity of AMACR. To this end, we covalently immobilize AMACR on the surface of micro-epoxy beads and use a DNA library with a centered 35-mer randomized region  to interact with the bead-bound AMACR in an in vitro selection process called SELEX. After a few rounds of selection, we further use the 2(R)-pristanoyl CoA, a AMACR substrate³, to compete the binding ligands  from the substrate-binding epitope on AMACR, which is considered the catalytic site and collect and amplify the eluted DNA molecules  as a new ligand pool for the following selection round. Finally, the functionl aptamer candidates  targeting AMACR’s catalytic site are evolved. To the best of our knowledge, it is the first time that AMACR’s aptamers are selected. Moreover, the AMACR aptamers obtained by an epitope-targeting selection approach can be applied in both affinity-based detection of AMACR and regulation of AMACR’s activity.

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