Carcinogenesis Advance Access published online on September 10, 2008
Carcinogenesis, doi:10.1093/carcin/bgn218
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Outer Membrane Vesicles Enhance the Carcinogenic Potential of Helicobacter Pylori
1 Departments of Surgery, University of Otago Christchurch, New Zealand
2 Departments of Pathology, University of Otago Christchurch, New Zealand
* Corresponding Author: Dr Jacqueline Keenan, University of Otago Christchurch, PO Box 4345, Christchurch, New Zealand. Phone: 64 3 3640 570; Fax: 64 3 3641 427; E-mail: jacqui.keenan{at}otago.ac.nz
Chronic Helicobacter pylori infection is associated with an increased risk of gastric carcinogenesis. These non-invasive bacteria colonise the gastric mucosa and constitutively shed small outer membrane vesicles (OMV). In this study we investigated the direct effect of H. pylori OMV on cellular events associated with carcinogenesis. We observed increased micronuclei formation in AGS human gastric epithelial cells treated with OMV isolated from a toxigenic H. pylori strain (60190). This effect was absent in OMV from strain 60190v:1 that has a mutant vacA, indicating VacA-dependent micronuclei formation. VacA induces intracellular vacuolation, and reduced acridine orange staining indicated disruption in the integrity of these vacuoles. This was accompanied by an alteration in iron metabolism and glutathione loss, suggesting a role for oxidative stress in genomic damage. Increasing intracellular glutathione levels with a glutathione ester abrogated the VacA-mediated increase in micronuclei formation. In conclusion, OMV-mediated delivery of VacA to the gastric epithelium may constitute a new mechanism for H. pylori-induced gastric carcinogenesis.
Received June 26, 2008; revised September 3, 2008; accepted September 6, 2008.