Over-expression of wild-type Rad51 correlates with histological grading of invasive ductal breast cancer.

Breast cancer is a major cause of cancer-related death in women. BRCA1 tumour-suppressor function is abolished in sporadic breast cancer by down-regulation of the protein level. This down-regulation inversely correlates with tumour grading. BRCA1 is part of a multiprotein complex, which also contains the recombination factor Rad51. Here we describe that in contrast to BRCA1, histological grading of sporadic invasive ductal breast cancer significantly correlates with over-expression of wild-type Rad51. These data suggest that in addition to the absence of the tumour-suppressor protein BRCA1, over-expression of wild-type Rad51 also contributes to the pathogenesis of a significant percentage of sporadic breast cancers and that other mechanisms than mutations must be responsible for this altered expression.