Here we illustrate the unique role of miRNAsin their dramatic participation in breast cancer cells and our data demonstrates that the levels of PRC group of proteins in breast cancer cell lines MDAMB-231 and BT-549 can be altered by using the miRNAs i.e. miR-200a, miR-200b, miR-15a, miR-429and miR-203 which have possible binding sites at the 3’UTR sequences of BMI1. The gene discussed is BMI1; the disease is breast carcinoma.