The different expression patterns of miRNAs in ERα + and ERα- human breast cancer cells and tumors have been frequently reported [13–15], including downregulation of miR-17/20, miR-145 and let-7 in ERα + breast cancer [16–18] and upregulation of miR-221/222 in ERα- breast cancer [19]. This evidence concerns the gene ESR1 and breast carcinoma.