miR-200c has been shown to regulate the epithelial-mesenchymal transition(EMT) by inhibiting ZEB1 and ZEB2 expression in breast cancer cells. This study further examined the role of miR-200c in the invasion and metastasis of breast cancer that goes beyond the regulation on ZEB1 and ZEB2 expression. In this study, the bioinformatics software(miRanda) was used to predict the target gene of miR-200c and Renilla luciferase assay to verify the result. The metastatic breast cancer cells MDA-MB-231 were cultured and transfected with the miR-200c mimic or inhibitor. The expressions of miR-200c and HMGB1 were detected by RT-PCR and Western blotting, respectively. Transwell assay and wound healing assay were employed to examine the invasive and migrating ability of transfected cells. Target prediction and Renilla luciferase analysis revealed that HMGB1 was a putative target gene of miR-200c. After transfection of MDA-MB-231 cells with the miR-200c mimic or inhibitor, the expression of miR-200c was significantly increased or decreased when compared with cells transfected with the miR-200c mimic NC or inhibitor NC. Moreover, the expression of HMGB1 was reversely correlated with that of miR-200c in transfected cells. Tranwell assay showed that the number of invasive cells was significantly reduced in miR-200c mimic group when compared with miR-200c inhibitor group. It was also found that the migrating ability of cells transfected with miR-200c mimics was much lower than that of cells transfected with miR-200c inhibitors. It was suggested that miR-200c can suppress the invasion and migration of breast cancer cells by regulating the expression of HMGB1. miR-200c and HMGB1 may become useful biomarkers for progression of breast cancer and targets of gene therapy.
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