miR-338-3p inhibits epithelial-mesenchymal transition and metastasis in hepatocellular carcinoma cells

// Jing-Song Chen 1 , Li-Li Liang 2 , Hong-Xu Xu 3 , Fan Chen 4 , Shun-Li Shen 5 , Wei Chen 5 , Lian-Zhou Chen 4 , Qiao Su 6 , Long-Juan Zhang 4 , Jiong Bi 4 , Wen-Tao Zeng 4 , Wen Li 4 , Ning Ma 7 and Xiao-Hui Huang 4 1 Department of Gastrointestinal Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China 2 Departments of Pediatrics, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China 3 Departments of Laboratory, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China 4 Departments of General Surgical Laboratory, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China 5 Departments of Hepatobiliary Surgery, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China 6 Animal Center, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China 7 Department of Gastrointestinal, Hernia and Abdominal Surgery, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China Correspondence to: Ning Ma, email: maning85322@163.com Xiao-Hui Huang, email: hxiaohui2006@126.com Keywords: miR-338-3p, epithelial-mesenchymal transition, Snail1, N-cadherin, sonic hedgehog Received: November 25, 2015 Accepted: June 04, 2016 Published: June 17, 2016 ABSTRACT Down-regulation of the miRNA miR-338-3p correlates with the invasive ability of hepatocellular carcinoma (HCC) cells. However, it is currently unclear whether down-regulation of miR-338-3p induces epithelial-mesenchymal transition (EMT), which may be the underlying mechanism governing HCC invasion. Here, we demonstrate that restoration of miR-338-3p expression via transfection of a miR-338-3p mimic reversed EMT and inhibited the motility and invasiveness of HCC cells. Conversely, silencing of endogenous miR-338-3p expression with a miR-338-3p-specific inhibitor induced EMT and enhanced HCC cell motility. Additionally, Snail1 (an upstream regulatory protein of EMT) and Gli1 (a key transcription factor in the sonic hedgehog (SHH) signaling pathway) expression was up-regulated in cells treated with the miR-338-3p inhibitor and down-regulated by the miR-338-3p mimic. Further analyses demonstrated that miR-338-3p inhibitor-induced EMT in HCC cells was blocked by treatment with a small interfering RNA (siRNA) targeting Snail1, that the SHH signaling pathway was required for both miR-338-3p inhibitor-induced EMT and up-regulation of Snail1, and that miR-338-3p targeted a sequence within the 3´-untranslated region of N-cadherin mRNA. Notably, miR-338-3p expression was significantly down-regulated in HCC samples from patients with metastases and was associated with poor metastasis-free survival rates. Lastly, correlations between the expression levels of miR-338-3p and E-cadherin, Smoothened (SMO), Gli1, Snail1, N-cadherin, and vimentin were confirmed in HCC xenograft tumors and HCC patient specimens. Our findings suggest that miR-338-3p suppresses EMT and metastasis via both inhibition of the SHH/Gli1 pathway and direct binding of N-cadherin. miR-338-3p is a potential therapeutic target for metastatic HCC.