RBFOX2 confers tumor growth by PI3K/AKT and MAPK signaling in gastric cancer

Abstract

RNA-binding Fox (RBFOX)2, a member of a family of RNA-binding proteins, is well known as a regulator of alternative pre-mRNA splicing. However, its possible role in gastric cancer is unknown. In this study, we investigated the biologic role and clinical significance of RBFOX2 in gastric cancer growth and elucidated its underlying molecular mechanisms. We found that RBFOX2 was highly expressed in gastric cancer cell lines and tumor tissue compared with the adjacent nontumor tissue. We also found that RBFOX2 overexpression was correlated with poor overall survival in patients with gastric cancers. Multivariate survival analyses revealed that higher RBFOX2 expression was an independent prognostic factor for the overall survival of patients with gastric cancers. Suppression of RBFOX2 by shRNA inhibited gastric cancer cell proliferation, colony formation and induced apoptosis. Mechanism studies revealed that these effects were achieved through the simultaneous modulation of multiple signaling pathways. Knockdown of RBFOX2 expression by shRNA markedly inhibited the phosphorylation of phosphatidylinositol 3-hydroxy kinase, threonine kinase and extracellular signal-regulated kinase and Jun N-terminal kinases proteins. In contrast, the ectopic expression of RBFOX2 had the opposite effects. Moreover, RBFOX2 knockdown also induced the cleavage of caspase-3 and caspase-9 proteins. Collectively, these results demonstrate that RBFOX2 plays a critical role in regulating gastric cancer cell proliferation and survival and may be a potential prognostic biomarker and therapeutic target for gastric cancer.