Effects of Helicobacter pylori γ-Glutamyltranspeptidase on Apoptosis and Inflammation in Human Biliary Cells

Several studies have reported the presence of H. pylori in individuals with hepatobiliary diseases, but in vitro and in vivo studies are still needed. Here, we determined the effects of H. pylori gamma-glutamyltranspeptidase (GGT) on the induction of apoptosis and IL-8 production in a human cholangiocarcinoma cell line (KKU-100 cells). Cell viability and DNA synthesis were examined by MTT and BrdU assays, respectively. RT-PCR and western blot analysis were performed to assess gene and protein expression, respectively. IL-8 secretion in KKU-100 cells was measured by ELISA. Exposure to the H. pylori ggt (+) strain decreased KKU-100 cell survival and DNA synthesis when compared with cells exposed to the H. pylori ggt mutant strain. Treatment with recombinant H. pylori GGT (rHP-GGT) dramatically decreased cell survival and DNA synthesis, and stimulated apoptosis; these features corresponded to an increased level of iNOS gene expression in KKU-100 cells treated with rHP-GGT. RT-PCR and western blot analyses revealed that rHP-GGT treatment enhanced the expression of pro-apoptotic molecules (Bax, Caspase-9, and Caspase-3) and down-regulated the expression of anti-apoptotic molecules (Bcl-2 and Bcl-xL). The extrinsic-mediated apoptosis molecules, including Fas and activated Caspase-8, were not expressed after treatment with rHP-GGT. Furthermore, rHP-GGT significantly stimulated IL-8 secretion in KKU-100 cells. Our data indicate that H. pylori GGT might be involved in the development of cancer in hepatobiliary cells by altering cell kinetics and promoting inflammation.