PARP-1 expression in breast cancer including -associated, triple negative and basal-like tumors: possible implications for PARP-1 inhibitor therapy

International audienceDespite ongoing trials of PARP inhibitors in the treatment of breast cancer (BC), the extent of poly(ADP-ribose)polymerase-1 (PARP-1) protein expression in BCs, which may influence treatment results, is not known. The purpose of this report is to assess expression of PARP-1 in BC including -associated, triple negative (TN), and basal-like tumors. Immunohistochemistry with a PARP-1 antibody on tissue microarrays from 130 -associated and 594 -non-related BCs was used. The vast majority of breast carcinomas expressed high level of nuclear PARP-1 protein and a small percentage of tumors exhibited both nuclear and cytoplasmic PARP-1 expression. There was a significant difference between the mean nuclear PARP-1 quickscore in -associated versus -non-associated carcinomas in all tumors ( < 0.0001), in the basal-like group ( = 0.0086), TN ( = 0.0015), and non-basal-like groups ( = 0.016) but not in the non-TN group. Among -associated BCs, low PARP-1 expression was found in 18.5% of all cases, 18.9% of basal-like and 21% of TN cancers. Among -non-related tumors, low PARP-1 expression was found in 8.8% of all cases, 3.1% of basal-like, and 2.7% of TN cancers. PARP-1 expression is significantly associated with status in basal-like and TN BCs. The assessment of PARP-1 expression in tumor samples may improve the selection of BC patients for PARP inhibitor therapy