Abstract: Objective The present study was aimed to investigate the role of miR-211/TFAM in the regulation of proliferation of breast cancer cells. Methods In the present study, we choose miR-211 and TFAM as the research object. First we transfected breast cancer cells with miR-211 mimics or miR-211 inhibitor to achieve miR-211 overexpression or miR-211 silencing, and detected the expression of miR-211 and the expression level of TFAM proteins in response to miR-211 overexpression or miR-211 silencing; secondly luciferase reporter gene plasmid with or without a six base pairs mutation in the 3’UTR of TFAM (mut-TFAM/wt-TFAM) were conducted and co-transfected with miR-211 mimics or miR-211 inhibitor, then the changes of the luciferase activity were detected; then pcDNA3.1/TFAM plasmid was constructed and co-transfected with miR-211 mimics or miR-211 inhibitor, TFAM protein expression level changes were determined in response to miR-211 overexpression or miR-211 silencing; lastly the cell proliferation was determined in response to mimics NC/miR-211 mimics and pcDNA3.1/TFAM co-transfection. Results Overexpression of miR-211 inhibits the expression of TFAM protein, miR-211 silencing promote TFAM protein expression; miR-211 can regulate the expression of TFAM by direct targeting; TFAM overexpression was achieved by pcDNA3.1/TFAM transfection, and TFAM overexpression can restore the inhibitory effect of miR-211 on TFAM; miR-211 can inhibit the growth and proliferation of breast cancer cells, TFAM can promote the growth and proliferation of breast cancer cells; TFAM can restore the inhibitory effect of miR-211 on growth and proliferation of breast cancer cells. Conclusion miR-211 regulates the growth of breast cancer cell through targeting HMGB.

Key words: miR-211, TFAM, growth, proliferation, human breast cancer