microRNA-188 over-expression inhibited cellular proliferation and invasion of gastric cancer by targeting SOX4

Previous studies reported that microRNA-188 (miR-188) was down-regulated and acted as a tumor suppressor in oral squamous cell carcinoma, hepatocellular carcinoma and prostate cancer. However, the expression, biological roles and molecular mechanism of miR-188 in gastric cancer remain unclear. In this study, we measured the expression levels of miR-188 in gastric cancer tissues and cell lines. The results showed that miR-188 was significantly down-regulated in gastric cancer tissues and cell lines. Then following functional studies revealed that miR-188 over-expression inhibited proliferation and invasion of gastric cancer cells. Using bioinformatic analysis, luciferase report assay, qRT-PCR and western blot, SOX4 was identified as a novel direct target gene of miR-188 in gastric cancer. Moreover, SOX4 under-expression had the similar functions with miR-188 over-expression in gastric cancer, further suggesting that miR-188 inhibited proliferation and invasion of GC cells though directly targeting SOX4. These findings indicated that miR-188 was down-regulated and acted as a tumor suppressor in gastric cancer through directly targeting SOX4. miR-188/SOX4 based targeted therapy could be a novel therapeutic application to treat patients with gastric cancer.