Inhibition of PARP-1 in vivo: (1) depletes both PARP-1 and AR at target genes, (2) significantly reduces expression of target genes, including pro-tumorigenic ets genes referenced previously, (3) sensitizes both castration-resistant and castration-sensitive prostate cancer cells to genotoxic insult and androgen depletion, (4) enhances the anti-tumor effects of anti-androgen therapy, and (5) delays onset of resistance to anti-androgen therapy. This evidence concerns the gene PARP1 and prostate cancer.