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Breast cancer research and treatment

DNA damage response markers are differentially expressed in BRCA-mutated breast cancers.


PMID 25690937

Abstract

Cells have stringent DNA repair pathways that are specific for each different set of DNA lesions which is accomplished through the integration of complex array of proteins. However, BRCA-mutated breast cancer (BC) has defective DNA repair mechanisms. This study aims to investigate differential expression of a large panel of DNA repair markers to characterise DNA repair mechanisms in BRCA-associated tumours compared to sporadic tumours in an attempt to characterise these tumours in routine practice. Immunohistochemistry and tissue microarray technology were applied to a cohort of clinically annotated series of sporadic (nxa0=xa01849), BRCA1-mutated (nxa0=xa048), and BRCA2-mutated (nxa0=xa027) BC. The following DNA damage response (DDR) markers are used; BRCA1, BRCA2, RAD51, Ku70/Ku80, BARD, PARP1 (cleaved), PARP1 (non-cleaved), and P53 in addition to basal cytokeratins, ER, PR, and HER2. A significant proportion of BRCA1 tumours were positive for PARP1 (non-cleaved), and negative for BARD1 and RAD51 compared with sporadic BC. BRCA2 tumours were significantly positive for PARP1 (non-cleaved) compared with sporadic tumours. RAD51 was significantly higher in BRCA1 compared with BRCA2 tumours (pxa0=xa00.005). When BRCA1/2 BCs were compared to triple-negative (TN) sporadic tumours of the studied DDR proteins, BARD1 (pxa0