RESUMO
Background: Nowadays, highly specific aptamers generated by cell SELEX technology[systematic evolution of ligands by exponential enrichment] are being applied forearly detection of cancer cells. Prostate Specific Membrane Antigen [PSMA], over expressedin prostate cancer, is a highly specific marker and therefore can be used fordiagnosis of the prostate cancer cells. The aim of the present study was to select singlestrandedDNA aptamers against LNCap cells highly expressing PSMA, using cell-SELEX method which can be used as a diagnostic tool for the detection of prostatecancer cells
Methods: After 10 rounds of cell-SELEX, DNA aptamers were isolated against PSMAusing LNCaP cells as a target and PC-3 cell lines for counter SELEX. Five DNA aptamerswith more than 70% affinity were selected up on flow cytometry analysis of positiveclones
Results: Dissociation constants of two selected sequences [A12-B1] were estimated inthe range of 33.78-3.77 and 57.49-2.214 pmol, respectively. Conserved secondary structuresof A12 and B1 sequences suggest the necessity of these structures for binding withhigh affinity to native PSMA. Comparison of the secondary structures of our isolatedaptamers and aptamer A10 obtained by protein SELEX showed similar stem-loopstructures which could be responsible for the recognition of PSMA on LNCap cell surface
Conclusion: Our results indicated that selected aptamers may turn out to be idealcandidates for the development of a detection tool and also can be used in targeteddrug delivery for future smart drugs