PLK1 and prostate carcinoma: The aptamer-siRNA chimera was constructed to target the cell surface receptor prostate specific membrane antigen (PSMA) overexpressed in prostate cancer cells via the A10 RNA aptamer [53], while the delivered siRNA targeted the polo-like kinase 1 (PLK1) and B-cell lymphoma 2 (BCL2) genes, which are overexpressed in numerous human tumors [225].