Poly(ADP-ribose) polymerase is involved in base excision repair of DNA single-strand breaks. If PARP is inhibited, these breaks can accumulate, potentially leading to double-strand breaks. These double-strand breaks are normally repaired by error-free homologous recombination, of which BRCA1 and BRCA2 proteins are involved. If these proteins are affected by somatic mutation or epigenetic silencing, eventual chromosomal instability and cell death can be seen.
