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Helicobacter pylori induces promoter methylation of E-cadherin via interleukin-1β activation of nitric oxide production in gastric cancer cells
Article first published online: 13 MAR 2012
Copyright © 2012 American Cancer Society
Volume 118, Issue 20, pages 4969–4980, 15 October 2012
How to Cite
Huang, F.-Y., Chan, A. O.-O., Rashid, A., Wong, D. K.-H., Cho, C.-H. and Yuen, M.-F. (2012), Helicobacter pylori induces promoter methylation of E-cadherin via interleukin-1β activation of nitric oxide production in gastric cancer cells. Cancer, 118: 4969–4980. doi: 10.1002/cncr.27519
- Issue published online: 5 OCT 2012
- Article first published online: 13 MAR 2012
- Manuscript Accepted: 6 FEB 2012
- Manuscript Revised: 29 DEC 2011
- Manuscript Received: 24 JUN 2011
- gastric cancer;
- Helicobacter pylori;
Helicobacter pylori infection causes gastric mucosal inflammatory responses, resulting in up-regulation of interleukin-1β (IL-1β) and overproduction of mutagenic nitric oxide (NO). The authors previously demonstrated that IL-1β plays an important role in H. pylori-induced E-cadherin (E-cad) methylation. Here, they extend the study to investigate the downstream effect of IL-1β on H. pylori-induced gastric inflammation and aberrant DNA methylation.
Human gastric cancer cell lines (MKN7, MKN74, and TMK-1) with and without pretreatment of IL-1 receptor antagonist (IL-1ra) were treated with IL-1β or infected with H. pylori. Promoter methylation status of E-cad was examined by methylation-specific polymerase chain reaction (PCR). Expression of E-cad, inducible nitric oxide synthase (iNOS), and nuclear factor κB (NFκB) was assessed by quantitative reverse transcriptase PCR, Western blotting, or immunofluorescence. NO production and total DNA methyltransferase (DNMT) activity were assayed fluorometrically.
Both IL-1β treatment and H. pylori infection-induced E-cad methylation led to a decrease in E-cad expression at both mRNA and protein levels. Total DNMT enzymatic activity was significantly elevated in treated cells, accounting for the observed E-cad methylation induction. Increased expression of NFκB was accompanied by up-regulation of iNOS and production of NO in treated cells. Reversal of all these phenomena in cells pretreated with IL-1ra suggested H. pylori-induced E-cad methylation via IL-1β stimulation of the NFκB transcriptional system, leading to activation of DNMT activity by NO production.
These findings reveal a previously unknown effect of IL-1β and NO on H. pylori-induced aberrant DNA methylation. This possible pathway indicates the role of NO in epigenetic modification that links inflammation to carcinogenesis. Cancer 2012. © 2012 American Cancer Society.