Influences of Helicobacter pylori on cyclooxygenase-2 expression and prostaglandinE2 synthesis in rat gastric epithelial cells in vitro

Background and Aim: It is known that cyclooxygenase (COX)‐2 is over expressed in gastrointestinal neoplasia and Helicobacter pylori (H. pylori) infection is causally linked to gastric cancer. The present study aimed to elucidate the effects of H. pylori on COX‐2 expression and prostaglandinE2 (PGE2) production in a gastric epithelial cell line derived from normal rat gastric mucosa (RGM1). Method: H. pylori water extracts were prepared from a supernatant of the H. pylori suspension in distilled water. RGM1 cells were cultured with H. pylori water extracts at the final concentration of 2.5, 5, 10 µg/mL for 24 h. For the time sequence study, RGM1 cells were cultured with 10 µg/mL H. pylori water extracts for 0, 6, 12, 24 and 48 h. COX‐1 and COX‐2 expression in the RGM1 cells was analyzed by western blotting. The levels of PGE2 in the cultured media were measured by enzyme immunoassay. Results: H. pylori did not affect COX‐1 expression; whereas COX‐2 expression increased by six‐fold at 24 h after incubation of RGM1 cells with 10 µg/mL H. pylori water extracts. The increase in COX‐2 expression was evident after 12 h of incubation; reached a peak at 24 h and declined at 48 h. H. pylori dose dependently increased COX‐2 expression and PGE2 synthesis in RGM1 cells. Conclusion: H. pylori induces COX‐2 expression and increases PGE2 synthesis in RGM1 cells in vitro. These results indicate that H. pylori‐associated gastric carcinogenesis may depend on COX‐2 expression.