MiR-638 acts as a tumor suppressor gene in gastric cancer

// Yu Shen 1, * , Haiqun Chen 2, * , Ling Gao 1 , Weigang Zhang 1 , Jun He 1 , Xiaohua Yang 1 , Lei Qin 1 , Xiaofeng Xue 1 and Zhaoji Guo 1 1 Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, P.R. China 2 Department of General Surgery, Xinhua Hospital Affiliated to Jiaotong University Chongming Branch, Shanghai 200000, P.R. China * These authors have contributed equally to this work Correspondence to: Lei Qin, email: qinlei@suda.edu.cn Xiaofeng Xue, email: xfxue@suda.edu.cn Zhaoji Guo, email: guozhaoji600@126.com Keywords: miR-638; SOX2; gastric cancer; cell proliferation; invasion Received: January 25, 2017      Accepted: September 05, 2017      Published: November 20, 2017 ABSTRACT Gastric cancer is one of the major causes of cancer mortality. Several microRNAs play a role in the tumor growth and invasion. However, the underlying molecular mechanism remains poorly understood. We detected the miR-638 expression levels in tumor samples and adjacent noncancerous tissues from 68 patients with gastric cancer as well as in the gastric cancer cell line SGC-7901 and SC-M1. The cell cycle was analyzed by flow cytometry, cell proliferation was observed by CCK-8 assay and cell invasion was detected using Transwell assay. MiR-638 was down-regulated in human GC tissues and its expression level was negatively correlated to TNM stage and lymph metastasis. In the cell lines, aberrant expression of miR-638 was related to the cell proliferation, cell cycle and invasion. We also found that SOX2 had a negative correlation with miR-638 in GC tissues, and miR-638 overexpression could decrease SOX2 expression level by directly binding the 3’-UTR of SOX2. in vitro , down-regulating SOX2 by siRNA could counteract the effect of miR-638 inhibitor on GC cells proliferation and invasion. Our results demonstrate that miR-638 may play a pivotal role in the growth and invasion of GC.