MicroRNA-372-3p promotes the epithelial-mesenchymal transition in breast carcinoma by activating the Wnt pathway.

PURPOSE: To explore the role of microRNA (miR)-372-3p in the epithelial-mesenchymal transition (EMT) of breast carcinoma and its potential mechanism. METHODS: The expression of miR-372-3p was detected by real-time PCR (RT-PCR) in 48 samples of breast carcinoma tissues, 30 samples of normal breast tissues, normal breast cells (MCF-10A) and breast carcinoma cells (MCF-7, MDA-MB-231 and HCC38). Transfection efficacy of miR-372-3p mimic and miR-372-3p inhibitor was determined by RT-PCR. Cell viability and invasion were determined by CCK-8 assay and wound healing assay, respectively. The interaction between miR-372-3p and DDK1 was verified by the luciferase reporter assay. Expression levels of DDK1, Wnt3a, E-cadherin and N-cadherin in breast carcinoma cells transfected with miR-372-3p mimic, miR-372-3p inhibitor and DKK1 were detected by Western blot. RESULTS: The expression of miR-372-3p in breast carcinoma tissues was higher than that of normal breast tissues. Correlation analysis revealed that the miR-372-3p expression was negatively correlated with the postoperative survival, but positively correlated with the tumor size and stage of patients with breast carcinoma. No significant correlation was observed between the miR-372-3p expression and age, gender or lymph node metastasis. The receiver operating characteristics (ROC) curve indicated a high diagnostic sensitivity and specificity for miR-372-3p. CCK-8 assay and wound healing assay illustrated that miR-372-3p increased the viability and invasion of MDA-MB-231 and HCC38 cells, respectively. Luciferase activity assay suggested that miR-372-3p was specifically bound to the 3'UTR of DKK1. Overexpressed miR-372-3p markedly increased the expressions of Wnt3a and N-cadherin, but decreased the expressions of DKK1 and E-cadherin, which were reversed by miR-372-3p knockdown. The protein expressions of E-cadherin and N-cadherin were remarkably increased in cells co-transfected with miR-372-3p mimic and DKK1 in comparison with those transfected with miR-372-3p mimic only. CONCLUSIONS: MiR-372-3p is upregulated in breast carcinoma tissues, which promotes the viability and invasion of breast carcinoma cells through the Wnt pathway.