Abstract: Objective: To study the effect of miR-200c on the migration and proliferation abilities of breast cancer MDA-MB-231 and BT-549 cells,and to clarify the mechanism of miR-200c in inhibiting the epithelial-mesenchymal transiton (EMT) of triple negative breast cancer. Methods: The human triple negative breast cancer cell lines (MDA-MB-231 and BT-549) were chosen in this study.The cells were transiently transfected with miR-200c mimics and Lipo2000(experimental group),miR-200c negative control and Lipo2000(negative control group),and Lipo2000 alone (reagent control group); at the same time, blank control group was set up.The expression levels of vimentin and β-catenin mRNA and protein were detected by RT-PCR and Western blotting method.The proliferation rates and migration abilities of MDA-MB-231 cells and BT-549 cells after transfection of miR-200c were analyzed by CCK8 assay and wound healing assay. Results: The RT-PCR and Western blotting showed that the expression levels of vimentin and β-catenin mRNA and proteins in experimental group were decreased,and the differences were statistically significant compared with blank control group, negative control group and reagent control group(P<0.05).The CCK8 results showed that the proliferation rates of the cells in experimental group were lower than those in negative control group and reagent control group(P<0.05).The wound healing assay results showed that the recovery rate of scratch width in experimental group was lower than those in negative control group and reagent control group (P<0.05). Conclusion: miR-200c might inhibit EMT in triple negative breast cancer by regulating the expressions of β-catenin and vimentin mRNA and proteins in MDA-MB-231 and BT-549 cells and decreasing the abilities of migration and proliferation of triple negative breast cancer cells.

Key words: β-catenin, epithelial-mesenchymal transiton, triple negative breast cancer, vimentin, breast neoplasms, miR-200c