Helicobacter pylorigamma-glutamyltranspeptidase upregulates COX-2 and EGF-related peptide expression in human gastric cells

Abstract

SummaryGastric mucosa responds to Helicobacter pyloriinduced cell damage by increasing the expression of COX-2 and EGF-related peptides. We sought to investigate the bacterial virulence factor/s and the host cellular pathways involved in the upregulation of COX-2, HB-EGF and amphiregulin in MKN 28 and AGS gastric mucosal cells. H. pylori strain CCUG 17874 was grown in Brucella broth supplemented with 0.2% (2,6-dimethyl)-b b b b -cyclodextrins. The soluble proteins released in the culture medium by the bacterium were fractionated by exclusion size and anion exchange chromatography. A single peak retaining the ability to upregulate COX-2 and HB-EGF mRNA and protein expression was obtained. SDS-PAGE analysis of the peak showed two peptides with an apparent molecular weight of 38 and 22 kDa, which were identified by automated Edman degradation analysis as the N-terminal and C-terminal peptides of H. pylori g g g g -glutamyltranspeptidase respectively. Acivicin, a selective g g g g -glutamyltranspeptidase inhibitor, counteracted H. pylori -induced upregulation of COX-2 and EGF-related peptide mRNA expression. An H. pylori isogenic mutant g g g g -glutamyltranspeptidase-deficient strain did not exert any effect on COX-2, HB-EGF and amphiregulin mRNA expression. Blockade of phosphatidylinositol-3 kinase and p38 kinase, but not MAP kinase kinase, inhibited H. pylori g g g g -glutamyltranspeptidase-induced upregulation of COX-2 and EGFrelated peptide mRNA expression.

Induction of COX-2 expression by Helicobacter pylori is mediated by activation of epidermal growth factor receptor in gastric epithelial cells

“…In support of this, a previous study using bacterial culture supernatants from H. pylori to stimulate MKN28 cells showed that ␥-glutamyltranspeptidase present in the supernatant upregulates COX-2 expression (1). Conversely, other reports have indicated that the cag pathogenicity island is not involved in cox-2 gene expression induced by H. pylori (1,11). The discrepancy with our data could be explained by differences in the H. pylori strains used as well as the use of transformed cell lines in prior studies, which is in contrast to the conditionally immortalized cell model system employed in the current study.…”

Helicobacter pylori Can Induce Heparin-Binding Epidermal Growth Factor Expression via Gastrin and Its Receptor

“…It has been previously reported that H. pylori can induce an up-regulation in both HB-EGF gene expression and ectodomain shedding in human gastric cells (35,36). In addition, it has been shown that gastrin stimulation results in the up-regulation of the HB-EGF gene in gastric cells transfected with CCK-2R (37).…”

“…It has been previously reported that H. pylori-induced HB-EGF gene expression is due to the action of g-glutamyltranspeptidase (GGT), a recently identified bacterial enzyme (35). It has been reported that there may be a direct interaction between the bacterial GGT and the HB-EGF promoter, possibly via an oxidative stress-mediated mechanism.…”

Heparin‐binding epidermal growth factor‐like growth factor as a novel targeting molecule for cancer therapy

“…(44) Helicobacter pylori, which has a major etiological role in human gastric carcinogenesis, induces the activation of EGFR signaling mediated by the cleavage of proHB-EGF to promote enhanced gastric epithelial proliferation and gastric neoplasia. (45)(46)(47) Furthermore, in vitro experiments have shown that addition of an anti-HB-EGF blocking antibody to human glioblastoma cells reduces proliferation by 30 -40% compared with the addition of normal goat IgG. (48) Inhibition of HB-EGF expression in myeloma cells with CRM197 or an anti-HB-EGF antibody results in the suppression of cell proliferation and induction of cell apoptosis.…”