Signaling pathway and pepsinogen secretion in Helicobacter pylori-infectedhuman gastric adenocarcinoma

Although in vitro studies have suggested that Helicobacter pylori not only attaches to cultured cells but also induces signal transduction events in h ost cells, the underlying mechanism of H. pylori action has yet to be fully investigated. In the present study, a cytotoxin-positive H. pylori was use d to infect and examined for its effect on the stimulation of second messen gers in human gastric adenocarcinoma (AGS). Results showed that H, pylori i ncreased cytosolic free calcium concentration [Ca2+](i) in host cells in a dose-dependent manner. The increase of [Ca2+](i) was due to release from th e intracellular Ca2+ store as well as entry to the extracellular Ca2+ H. py lori infection on host cells was also found to induce the generations of in ositol phosphates, adenosine 3',5'-cyclic monophosphate, and guanosine 3',5 '-cyclic monophosphate, and to stimulate the secretion of pepsinogen.