H pylori stimulates proliferation of gastric cancer cells through activating mitogen-activated protein kinase cascade.

AIM

To explore the mechanism by which H pylori causes activation of gastric epithelial cells.

METHODS

A VacA (+) and CagA (+) standard H pylori line NCTC 11637 and a human gastric adenocarcinoma derived gastric epithelial cell line BGC-823 were applied in the study. MTT assay and (3)H-TdR incorporation test were used to detect the proliferation of BGC-823 cells and Western blotting was used to detect the activity and existence of related proteins.

RESULTS

Incubation with H pylori extract increased the proliferation of gastric epithelial cells, reflected by both live cell number and DNA synthesis rate. The activity of extracellular signal-regulated protein kinase (ERK) signal transduction cascade increased within 20 min after incubation with H pylori extract and appeared to be a sustained event. MAPK/ERK kinase (MEK) inhibitor PD98059 abolished the action of H pylori extract on both ERK activity and cell proliferation. Incubation with H pylori extract increased c-Fos expression and SRE-dependent gene expression. H pylori extract caused phosphorylation of several proteins including a protein with molecular size of 97.4 kDa and tyrosine kinase inhibitor genistein inhibited the activation of ERK and the proliferation of cells caused by H pylori extract.

CONCLUSION

Biologically active elements in H pylori extract cause proliferation of gastric epithelial cells through activating tyrosine kinase and ERK signal transduction cascade.