The Effect On The Expression And Activation Of RhoA In The Gastric Cancer Cells Stimulated By Helicobacter Pylori

Helicobacter pylori is a Gram-negative, microaerophilic bacterium which is located in human gastric mucosa. The epidemiological data suggests that about 50 percent of people are infected with Hp. Infection with this bacterium is a worldwide phenomenon. Pathological and clinical studies have convincingly proved the etiological role of Hp in the development of chronic gastritis, peptic ulcer and gastric adenocarcinoma. However, the mechanism through which Hp infection leads to gastroduodenal diseases remains unclear. The abnormal expression of RhoA is closely associated with the occurrence and development of cancer. RhoA can activate different signal transduction and play role in cell cycle regulation, though the mechanism still needs to be elucidated. In this study, Hp was isolated from human gastric mucosa and cultivated on solid culture medium. The extract of the bacteria was obtained by sonication. Human gastric cancer cell line SGC-7901 was starved for 24 h in cultrue medium without serum. After stimulating the starved cells for 10 min by the extract of Hp, the active RhoA was isolated by pull-down assay and detected by western boltting. The mRNA level of RhoA gene was examined by semi-quantitative RT-PCR. In the gastric cancer cells stimulated by the Hp extract for ten minutes, the level of RhoA mRNA did not change. In gastric cancer cells stimulated by extract of different kinds of Hp, the level of RhoA mRNA had no obvious difference. However, the level of active RhoA was increased dose-dependently in cells stimulated with Hp extract. The results suggest that Hp has no obvious effect on the expression of RhoA protein but can stimulate the activity of RhoA. This is helpful for us to elucidate the mechanism of the occurrence and the development of Hp associated gastric deseases.