Poly(ADP-ribose)polymerase-1 (PARP-1) in carcinogenesis:: Potential role of PARP inhibitors in cancer treatment

Poly(ADP-ribose)polymerase-1 (PARP-1) is a nuclear, zinc-finger, deoxyribonucleic acid (DNA)-binding protein that detects specifically DNA strand breaks generated by different genotoxic agents. Whereas activation of PARP-1 by mild genotoxic stimuli facilitates DNA repair and cell survival, severe DNA damage triggers different pathways of cell death, including PARP-mediated cell death through the translocation of apoptosis inducing factor (AIF) from the mitochondria to the nucleus. Pharmacological inhibition or genetic ablation of PARP-1 results in a clear benefit in cancer treatment by different mechanisms, including selective killing of homologous recombination-deficient tumor cells, downregulation of tumor-related gene expression, and decrease in the apoptotic threshold in the cotreatment with chemo- and radiotherapy. We summarize in this review the findings and concepts for the role of PARP-1 and poly (ADP-ribosylation) in the regulation of carcinogenesis and some of the preclinical and clinical data available for these agents, together with the challenges facing the clinical development of these agents.