Abstract
Phosphorylation of the phosphatase and tensin homolog (PTEN) tumor suppressor at Ser380/Thr382/Thr383 residues is a novel mechanism underlying PTEN inactivation in gastric carcinogenesis, which may be triggered by Helicobacter pylori infection. To investigate this further, the effect of H. pylori infection on PTEN phosphorylation and the subsequent activation of focal adhesion kinase (FAK), were evaluated in gastric tissue samples from Mongolian gerbils and in the human gastric epithelial mucosa cell line GES-1 using immunohistochemistry, western blotting and Transwell assays. The in vivo and in vitro results of the present study demonstrated that H. pylori infection induced the phosphorylation and inactivation of PTEN at Ser380/Thr382/383, and the subsequent phosphorylation and activation of FAK at Tyr397. Gastric epithelial cell invasion was also increased. Furthermore, stable expression of a dominant-negative PTEN mutant inhibited the enhanced FAK activation and cell invasion induced by H. pylori infection. These results suggest that the mechanism underlying H. pylori-induced carcinogenesis may involve promoting cell invasion through the phosphorylation of PTEN and the activation of FAK.