miR-146a and miR-638 in BRCA1-deficient triple negative breast cancer tumors, as potential biomarkers for improved overall survival

Mechanisms that lead to the reduced expression of BRCA1 in triple-negative breast cancer (TNBC) tumors are not fully understood. A possible cause is overexpression of miR-146a and miR-638, which regulate BRCA1 expression in other cancers. To evaluate the expression of these microRNAs in relation to BRCA1 expression in TNBC tumors. Expression of both microRNAs was assessed by real time qPCR using Taqman microRNA assays in TNBC tumors. Results were related to protein expression of BRCA1 and patient's survival. miR-146a and miR-638 were overexpressed in 36% and 59% of TNBC tumors, respectively. Overexpression was preeminent in BRCA1-deficient tumors and significantly associated to a better overall survival. Both miRNAs are potential biomarkers for improved overall survival in patients with BRCA1-deficient TNBC tumors.