Downregulated microRNA-200a promotes EMT and tumor growth through the Wnt/β-catenin pathway by targeting the E-cadherin repressors ZEB1/ZEB2 in gastric adenocarcinoma

In a previous study, we found that microRNA (miRNA)-200a suppresses Wnt/beta-catenin signaling by interacting with beta-catenin, thereby inhibiting migration, invasion and proliferation. However, the mechanism involved in this suppression remains unclear. In the present study, we investigated the underlying mechanism of miR-200a regulation of epithelial-mesenchymal transition (EMT) in gastric carcinoma cells, and confirmed the tumor suppressor role of miR-200a in vivo. The expressions of miRNA-200a, -200b and -200c, identified by fluorescent in situ hybridization, were downregulated and inversely correlated with WHO grades of gastric adenocarcinoma (GA). The expression of the potential miR-200a target genes ZEB1 and ZEB2 was detected immunohistochemically. These examinations used the same tissue microarrays to analyze the relationships between miR-200a and potential target genes. The expression of miR-200a and ZEB1/ZEB2 in the same GA tissue microarrays was inversely related. Restored miR-200a expression inhibited tumor growth in nude mice harboring subcutaneous SGC7901 xenografts. The expression of N-cadherin, beta-catenin, Twistl and Snail2 decreased, and E-cadherin levels increased, when miR-200a was elevated, as tested by fluorescence microscopy and immunohistochemistry. Similar results were observed in vivo. We found upregulated miR-200a expression to increase E-cadherin and suppress the Wnt/beta-catenin pathway by targeting ZEB1 and ZEB2 in GA, thus delaying tumor growth in vivo. The effect of miR-200a on Wnt/beta-catenin signaling may provide a therapeutic target against EMT.