Helicobacter pylori Infection Targets Adherens Junction Regulatory Proteins and Results in Increased Rates of Migration in Human Gastric Epithelial Cells

Abstract

The human gastric pathogen Helicobacter pylori attaches to antral epithelial cells in vivo. Cultured human antral epithelial cells, AGS and NCI-N87 cell lines, were grown in the absence or presence of H. pylori and compared with respect to gene transcript levels, protein expression, organization of the actin cytoskeleton, and the regulation of cell migration. The Clontech Neurobiology array detected differentially expressed transcripts, while Western blots were used to investigate related changes in protein levels. Infection with H. pylori consistently upregulated annexin II, S100 A7, Rho-GTP, and IQGAP-1, whereas SSTR-1 was downregulated upon H. pylori infection. In the adherens junction, E-cadherin and IQGAP-1 were translocated from the plasma membrane to intracellular vesicles. The primary and NCI-N87 cells were similar with respect to cell-cell and cell-matrix adhesion and cell migratory behavior; in contrast the AGS cells were significantly different from the primary gastric epithelial cell preparations, and thus caution must be used when using this cell line for studies of gastric disease. These studies demonstrate a correlation between H. pylori infection and alterations to epithelial cell adhesion molecules, including increased levels of Rho-GTP and cell migration. These data indicate that destabilizing epithelial cell adherence is one of the factors increasing the risk of H. pylori-infected individuals developing gastric cancer.Helicobacter pylori is a spiral, gram-negative rod that attaches specifically to the gastric epithelial cells lining the antrum of the stomach (2). H. pylori is able to withstand the hostile environment of the stomach by secretion of urease buffers, which neutralize the pH of its immediate surroundings. Flagella allow these highly motile bacteria to cross the mucous lining of the stomach and to attach to the apical surface of the mucosal epithelial cells. These antral epithelial cells are linked together at the apical surface by a system of interacting proteins that comprise the tight and adherens junctions (12, 31). These junctions effectively seal off the lumen of the stomach, preventing access of gastric acid and pathogens to the interstitial space and, hence, to the general circulation.Individuals infected by H. pylori have increased gastrin levels and decreased levels of somatostatin (SST) hormones that regulate gastric acid secretion. As a result, infected individuals develop mucosal gastritis, increasing their risk of ulceration and, in the longer term, gastric cancer (10, 11). Gastric adenocarcinomas show characteristic changes in the expression of E-cadherin, a transmembrane protein forming the core of the adherens junction. Loss of the E-cadherin complex at the apical pole is thought to induce loss of cell-cell adhesion (34). Direct evidence of E-cadherin mutations triggering tumorigenesis has come from recent studies linking inactivating germ line mutations of the E-cadherin gene (CDH1) in hereditary diffuse gastric cancer (33). Furthermore, it has been shown that the ...

Helicobacter pylori Activates Calpain via Toll-Like Receptor 2 To Disrupt Adherens Junctions in Human Gastric Epithelial Cells

“…However, it is becoming clear that H. pylori can also have more-direct effects on the AJ. Indeed, in vitro H. pylori can rapidly disrupt the integrity of the AJ without affecting E-cadherin and ␤-catenin expression (10,45). Our results also indicate that H. pylori disrupts AJs at an intracellular level via activation of the host cell protease calpain.…”

“…␤-Catenin is aberrantly activated in gastric cancer precursor lesions (40), suggesting that AJ modifications precede adenocarcinoma development. Studies using a gerbil-adapted strain of H. pylori in an in vivo model of disease have shown that ␤-catenin activation plays a role in gastric tumorigenesis (14), and AJ disruption has been linked to increased cell migration (10,45) and cellular transdifferentiation from a gastric to an intestinal phenotype in vitro (29). However, despite advances in this area, the mechanisms whereby persistent H. pylori infection alters gastric epithelial AJs remain incompletely understood.…”

Role of Annexin-II in GI cancers: Interaction with gastrins/progastrins

“…In a recent study, normal and gastric cancer cells were infected with H. pylori and differential expression of genes and proteins measured (133). H. pylori infection consistently up-regulated Annexin II, S100A7 and the Rho-GTP protein and significantly altered the location of E-cadherin from plasma membrane to intra-cellular vesicles (133).. Based on the results, the authors suggested that H. pylori infection results in destabilizing epithelial cell adherence via the up-regulation of specific membrane associated proteins such as Annexin II and S100A7, which may play a role in increasing the risk of gastric carcinogenesis (133).…”

Helicobacter pyloriChemotaxis Modulates Inflammation and Bacterium-Gastric Epithelium Interactions in Infected Mice

“…AGS (ATCC CRL-1739 [56]) or NCI-N87 (CRL-5822 [13]) human gastric epithelial cells were cultured according to the ATCC guidelines in Dulbecco's modified Eagle's medium (DMEM). To assay cytokine and chemokine production, cells were seeded at 2 ϫ 10 5 cells/well in 24-well tissue culture plates and incubated for 24 h. After this time, H. pylori, cultured for 24 h on CHBA, was scraped from a plate and resuspended in sterile DMEM or phosphate-buffered saline.…”