The Complex Relationship between BRCA1and ERA in Hereditary Breast Cancer

Breast cancer1 (BRCA1) was initially identified as one of the genes conferring genetic predisposition to both breast and ovarian cancer. One of the interesting aspects of BRCA1-linked cancers is the observed specificity for estrogen-responsive tissues such as breast and ovary. Recent advances in our understanding of BRCA1-linked breast cancers have revealed a complex relationship between BRCA1and estrogen receptor a (ERa) signaling. Estrogen stimulation increases expression of BRCA1 at the mRNA and protein level and conversely BRCA1functions to both induce ERamRNA expression and act as a negative regulator of ERa signaling. Here, we review the relationship between BRCA1and ERa and discuss the use of antiestrogen therapies such as tamoxifen and aromatase inhibitors in the treatment of BRCA1mutation carriers.