Expression of miR-451 and its correlation with drug resistance in breast cancer cells

Objective: To investigate the expression of miR-451 in breast cancer cells and its correlation with drug resistance to ADM (adriamycin). Methods: Stem-loop real-time PCR was used to detect the expression of miR-451 (microRNA-451) in breast cancer MCF-7 cells and their ADM-resistant cells (MCF-7/ADM). The mimics of miR-451 and the negative control RNA (NC) were transfected into MCF-7/ADM cells by LipofectAMINE 2000. The expression levels of MDR1 (multi-drug resistance gene 1) mRNA and P-gp (P-glycoprotein) protein were examined using real-time fluorescence quantitative PCR and Western blotting, respectively. MTT was used to analyze the proliferation of MCF-7/ADM cells transfected with miR-451 mimics and treated with ADM at different concentrations. Results: The expression level of miR-451 was lower in MCF-7/ADM cells than in MCF-7 cells (P < 0.05). The expressions of MDR1 mRNA and P-gp protein were decreased in MCF-7/ADM cells after transfection with miR-451 mimics as compared with those in the NC group (P < 0.05). The sensitivity of MCF-7/ADM cells transfected with miR-451 mimics and treated with ADM was enhanced and the IC50 (half inhibition concentration) value of ADM in miR-451 mimics transfection group was less than that of the NC group (P < 0.05). Conclusion: The expression of miR-451 is down-regulated in breast cancer ADM-resistant cells, which may play a vital role in drug resistance by regulating the expression of MDR1/P-gp. DOI:10.3781/j.issn.1000-7431.2012.12.006