TRAF6 promotes the invasion and metastasis and predicts a poor prognosis in gastric cancer

Purpose: This study investigated the relationships of TRAF6 expression with clinical pathologic parameters and the prognosis of patients with gastric cancer. This study also explored the roles of TRAF6 in cell apoptosis and invasiveness, as well as underlying molecular mechanism of gastric cancer cell line in vitro. Methods: A total of 90 cases of tissue microarrays were immunohistochemically analyzed for TRAF6 expression. Cell proliferation was measured by MIT assay. Flow cytometry was used for analyzing cell apoptosis and cell invasion ability was detected by a Transwell invasion assay. Protein expression was assessed by Western blotting. Results: TRAF6 was expressed in 53 of 90 (58.9%) cases of gastric cancer. TRAF6 expression was significantly positively correlated with advanced N stage, pathological stage and a poor prognosis, but not an independent predictor of a poor prognosis in gastric cancer (p = 0.083). The knockdown of TRAF6 increased cell apoptosis and reduced invasive ability of BGC-823 cell. Moreover, TRAF6 down-regulation decreased protein levels of phosphor-Akt, Bcl-2 and MMP9 and up-regulation of Bax in BGC-823 cell. Inversely, overexpression of TRAF6 in SGC-7901 cells increased protein levels of phosphor-Akt, Bcl-2 and MMP9 and down-regulation of Bax. Conclusions: The expression of TRAF6 was positively correlated with an advanced N stage and acted as a predictor of a poor prognosis in patients with gastric cancer. Moreover, TRAF6 regulating cell apoptosis and invasive ability of gastric cancer cells might be associated with Akt activation and alterations of protein expression of Bc12, Bax and MMP9. (C) 2015 Elsevier GmbH. All rights reserved.