MicroRNA-200a affects malignant biological behaviors of breast cancer cells by inhibiting epithelial-mesenchymal transition

AIM: To investigate the effect of microRNA-200a (miR-200a) on the malignant biological beha-viors of breast cancer cells and its regulatory mechanism. METHODS: The expression of miR-200a in human breast can-cer cell lines MDA-MB-231, MDA-MB-468 and MCF-7, and normal human mammary epithelial cell line MCF-10A was detected by RT-qPCR. CCK-8 assay was used to detect the viability of MDA-MB-231 cells after transfection with miR-200a mimic or miR-200a inhibitor. Flow cytometry method and Transwell assay were used to detect the apoptosis and invasive ability of MDA-MB-231 cells after transfection with miR-200a mimic or miR-200a inhibitor. The expression of SIP1, E-cadherin, N-cadherin, Snail, Twist, ZEB1 and ZEB2 at mRNA and protein levels was determined by RT-qPCR and Western blot. RESULTS: Compared with MCF-10A cells, the lowest expression of miR-200a was observed in the MDA-MB-231 cells (P<0.05). Over-expression of miR-200a attenuated the viability of MDA-MB-231 cells (P<0.05), increased apoptosis (P<0.05) and decreased the invasion ability (P<0.05). The expression of SIP1, N-cadherin, Snail, Twist, ZEB1 and ZEB2 at mRNA and protein levels was also significantly down-regulated, while the mRNA and protein expression of E-cadherin was significantly increased (P<0.05). Transfection with miR-200a inhibitor reversed the above results. CONCLUSION: Up-regulation of miR-200a inhibits the viability and invasion ability of MDA-MB-231 cells and promotes the apoptosis of MDA-MB-231 cells. miR-200a may regulate the biological behaviors of breast cancer by inhibiting epithelial-mesenchymal transition.