BRCA1 and breast carcinoma: Interestingly, a significant proportion of TNBC show high expression of miR-155 (moreover, it was shown to be epigenetically regulated by BRCA1 and up-regulated in BRCA1-deficient or BRCA-mutant breast cancer [137]) and stimulated by pro-oncogenic stimuli such as hypoxia, both risk factors for TNBC.