Expression of BRCA1 and BRCA2 proteins and their correlation with clinical staging in breast cancer

The purpose of this study was to evaluate the level of expression of the BRCA1 and BRCA2 proteins in sporadic breast cancer cases to determine the functional role of these genes in breast carcinogenesis.

Paraffin embedded histologically proven invasive breast tissue sections that were obtained from 40 patients and the adjacent normal breast tissue sections used as controls to determine breast carcinoma specific changes in the expression of BRCA1 and BRCA2 by immunohistochemistry (IHC).

Majority of the cases express either low or no detectable level of BRCA1 expression in tumor tissues in comparison with control; the decline in BRCA1 expression was found to be more prominent in advanced grade 3 disease. On the other hand, the expression of BRCA2 protein was moderate or low in breast cancer cases and its overall distribution did not show significant difference when compared with controls. Interestingly, those breast cancer cases, which were found to express low or no BRCA1 expression, demonstrated a higher protein level of BRCA2. The inverse correlation of BRCA1 and BRCA2 expression was more prominent in post-menopausal patients.

Our results demonstrate in a subset of cases that decline in BRCA1 expression that may be associated with potentially compensatory increase in BRCA2 protein, which may depend on tumor grade as well as menopausal status.