Poly(ADP-ribose) polymerase-1 (PARP-1) plays a central role in numerous cellular 
processes including DNA repair, replication, and transcription. PARP interacts 
directly, indirectly or via PARylation with various oncogenic proteins and 
regulates several transcription factors thereby modulating carcinogenesis. 
Therapeutic inhibition of PARP is therefore perceived as a promising anticancer 
strategy and a number of PARP inhibitors (PARPi) are currently under development 
and clinical evaluation. PARPi inhibit the DNA repair pathway and thus form the 
concept of synthetic lethality in cancer therapeutics. Preclinical and clinical 
studies have shown the potential of PARPi as chemopotentiator, radiosensitizer, 
or as adjuvant therapeutic agents. Recent studies have shown that PARP-1 could 
be either oncogenic or tumor suppressive in different cancers. PARP inhibitor 
resistance is also a growing concern in the clinical setting. Recently, changes 
in the levels of PARP-1 activity or expression in cancer patients have provided 
the basis for consideration of PARP-1 regulatory proteins as potential 
biomarkers. This review focuses on the current developments related to the role 
of PARP in cancer progression, therapeutic strategies targeting PARP-associated 
oncogenic signaling, and future opportunities in use of PARPi in anticancer 
therapeutics.