The PARP-1 inhibitor Olaparib suppresses BRCA1 protein levels, increases apoptosis and causes radiation hypersensitivity in BRCA1 lymphoblastoid cells.

The use of polyADPribose polymerase inhibitors in cancer treatment provides a unique opportunity to target DNA repair processes in cancer cells while leaving normal tissue intact. The PARP-1 enzyme repairs DNA single strand breaks (SSB). Therefore PARP-1 inhibition in negative cancers results in the formation of cytotoxic DNA double strand breaks (DSB) causing synthetic lethality.