Helicobacter pylori initiates a mesenchymal transition through ZEB1 in gastric epithelial cells

PLoS One. 2013;8(4):e60315. doi: 10.1371/journal.pone.0060315. Epub 2013 Apr 2.

Abstract

Chronic Helicobacter pylori infection provokes an inflammation of the gastric mucosa, at high risk for ulcer and cancer development. The most virulent strains harbor the cag pathogenicity island (cagPAI) encoding a type 4 secretion system, which allows delivery of bacterial effectors into gastric epithelial cells, inducing pro-inflammatory responses and phenotypic alterations reminiscent of an epithelial-to-mesenchymal transition (EMT). This study characterizes EMT features in H. pylori-infected gastric epithelial cells, and investigates their relationship with NF-κB activation. Cultured human gastric epithelial cell lines were challenged with a cagPAI+ H. pylori strain or cag isogenic mutants. Morphological changes, epithelial and mesenchymal gene expression and EMT-related microRNAs were studied. H. pylori up-regulates mesenchymal markers, including ZEB1. This transcription factor is prominently involved in the mesenchymal transition of infected cells and its up-regulation depends on cagPAI and NF-κB activation. ZEB1 expression and NF-κB activation were confirmed by immunohistochemistry in gastric mucosa from cagPAI+ H. pylori-infected patients. Gastric epithelial cell lines express high miR-200 levels, which are linked to ZEB1 in a reciprocal negative feedback loop and maintain their epithelial phenotype in non-infected conditions. However, miR-200b/c were increased upon infection, despite ZEB1 up-regulation and mesenchymal morphology. In the miR-200b-200a-429 cluster promoter, we identified a functional NF-κB binding site, recruiting NF-κB upon infection and trans-activating the microRNA cluster transcription. In conclusion, in gastric epithelial cells, cagPAI+ H. pylori activates NF-κB, which transactivates ZEB1, subsequently promoting mesenchymal transition. The unexpected N-FκB-dependent increase of miR-200 levels likely thwarts the irreversible loss of epithelial identity in that critical situation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / metabolism
  • Cell Line
  • Epithelial Cells / metabolism
  • Epithelial Cells / microbiology
  • Epithelial-Mesenchymal Transition / genetics*
  • Gastric Mucosa / metabolism*
  • Gastric Mucosa / microbiology*
  • Gastritis / genetics
  • Gastritis / metabolism
  • Gastritis / microbiology
  • Gastritis / pathology
  • Gene Expression
  • Gene Expression Regulation
  • Helicobacter Infections / genetics*
  • Helicobacter pylori / physiology*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Humans
  • MicroRNAs / genetics
  • NF-kappa B / metabolism
  • Phenotype
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Zinc Finger E-box-Binding Homeobox 1

Substances

  • Biomarkers
  • Homeodomain Proteins
  • MIRN200 microRNA, human
  • MicroRNAs
  • NF-kappa B
  • Transcription Factors
  • ZEB1 protein, human
  • Zinc Finger E-box-Binding Homeobox 1

Grant support

This work was supported by grants from Association de la Recherche contre le Cancer and La Ligue contre le Cancer (Committee of Dordogne, France). JB was supported by the French Ministry of Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.