Immunohistochemical Detection of BRCA-1 and BRCA-2 Expression in Human Breast and Ovarian Tumors

Breast cancer susceptibility proteins 1 and 2 (BRCA-1 and BRCA-2) are two key tumor suppressor genes that play important roles in tumorigenesis. Functional loss or reduction of BRCA-1 and/or BRCA-2 protein expression often leads to poor clinical outcomes in breast and ovarian cancer patients. To explore the utility of BRCA-1 and -2 as potential predictive biomarkers for targeted therapeutic approaches, we optimized and used an immunohistochemistry procedure to determine the expression profiles of BRCA-1 and BRCA-2 proteins on a large number of human breast and ovarian tumors and corresponding normal tissues. We found the expression of BRCA-1 and BRCA-2 proteins was down-regulated in breast and ovarian tumors when compared with corresponding normal tissues. BRCA-1 expression was detected in 100% of normal breast tissues whereas it was expressed in 91% and 71% of primary and metastatic tumors, respectively. Furthermore, the expression levels of BRCA-1 were lower in the majority of primary and metas...