Helicobacter pylori induces gastric mucosal intestinal metaplasia through the inhibition of interleukin-4-mediated HMG box protein Sox2 expression.
ABSTRACT Helicobacter pylori is a major cause of the transdifferentiation into intestinal metaplasia that may develop gastric cancer. However, the molecular pathogenesis of this transdifferentiation is poorly understood. A SRY-related HMG box protein Sox2 is an essential transcription factor of organ development in brain, lung, and stomach. Our aim of this study was to investigate the mechanism responsible for regulation of Sox2 in host Th1-dominant response to H. pylori. Sox2 protein was immunohistochemically expressed in both human oxyntic and pyloric glands with H. pylori infection, but not in intestinal metaplasia. Western immunoblotting of gastric epithelial cell lines showed that IL-4, a Th2-related cytokine, dose dependently enhanced Sox2 expression among H. pylori infection-mediated cytokines. Small changes of Sox2 expression were observed after each treatment with IFN-gamma, IL-1beta, or TNF-alpha. IL-4-mediated Sox2 induction was suppressed by the inhibition of STAT6 activation with STAT6 RNA interference, and electrophoretic mobility shift assay indicated that activation of the Sox2 promoter by IL-4 occurred through the action of STAT6. Furthermore, H. pylori and IFN-gamma inhibited the phosphorylation of STAT6, resulting in the suppression of IL-4-mediated Sox2 expression. Immunohistochemical analyses showed significantly the suppressed STAT6 activity in H. pylori-infected human gastric mucosa. Additionally, downregulation of Sox2 by knockdown experiments led to intestinal phenotype with expressions of Cdx2 and MUC2. These results suggest that H. pylori and IFN-gamma interfere with the differentiation into oxyntic and pyloric glands by the downregulation of Sox2 on IL-4/STAT6 signaling, which may contribute to the transdifferentiation into intestinal metaplasia.
- SourceAvailable from: Dolores Ortiz-masia[Show abstract] [Hide abstract]
ABSTRACT: Macrophages, which exhibit great plasticity, are important components of the inflamed tissue and constitute an essential element of regenerative responses. Epithelial Wnt signalling is involved in mechanisms of proliferation and differentiation and expression of Wnt ligands by macrophages has been reported. We aim to determine whether the macrophage phenotype determines the expression of Wnt ligands, the influence of the macrophage phenotype in epithelial activation of Wnt signalling and the relevance of this pathway in ulcerative colitis. Human monocyte-derived macrophages and U937-derived macrophages were polarized towards M1 or M2 phenotypes and the expression of Wnt1 and Wnt3a was analyzed by qPCR. The effects of macrophages and the role of Wnt1 were analyzed on the expression of β-catenin, Tcf-4, c-Myc and markers of cell differentiation in a co-culture system with Caco-2 cells. Immunohistochemical staining of CD68, CD206, CD86, Wnt1, β-catenin and c-Myc were evaluated in the damaged and non-damaged mucosa of patients with UC. We also determined the mRNA expression of Lgr5 and c-Myc by qPCR and protein levels of β-catenin by western blot. Results show that M2, and no M1, activated the Wnt signaling pathway in co-culture epithelial cells through Wnt1 which impaired enterocyte differentiation. A significant increase in the number of CD206+ macrophages was observed in the damaged mucosa of chronic vs newly diagnosed patients. CD206 immunostaining co-localized with Wnt1 in the mucosa and these cells were associated with activation of canonical Wnt signalling pathway in epithelial cells and diminution of alkaline phosphatase activity. Our results show that M2 macrophages, and not M1, activate Wnt signalling pathways and decrease enterocyte differentiation in co-cultured epithelial cells. In the mucosa of UC patients, M2 macrophages increase with chronicity and are associated with activation of epithelial Wnt signalling and diminution in enterocyte differentiation.PLoS ONE 01/2013; 8(10):e78128. · 3.53 Impact Factor
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ABSTRACT: Gastric cancer remains a serious health concern worldwide. Patients would greatly benefit from the discovery of new biomarkers that predict outcome more accurately and allow better treatment and follow-up decisions. Here, we used a retrospective, observational study to assess the expression and prognostic value of the transcription factors SOX2 and CDX2 in gastric cancer.BMC Cancer 10/2014; 14(1):753. · 3.33 Impact Factor
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ABSTRACT: The inflammatory infiltrate of the gastric mucosa associated with Helicobacter pylori infection increases the presence of the pro-inflammatory cytokine IL-6 that activates both the SHP-2/ERK/MAPK and the JAK/STAT signalling pathways. Furthermore, the ectopic expression of CDX2 is detected in pre-neoplasic lesions associated with decreased levels of SOX2, and we found that in gastric adenocarcinomas their expression is inversely correlated. To determine the role of IL-6 in the regulation of CDX2, MKN45, that constitutively express p-STAT3, and NUGC-4 gastric cancer cell lines were treated with IL-6, which induced the CDX2 up-regulation and SOX2 down-regulation. ChIP assays determined that in IL-6-treated cells, c-JUN and p-STAT3 bound to CDX2 promoter in MKN45 cells whereas in NUGC-4 cells, p-STAT3 binds to and c-JUN releases from the CDX2 promoter. Specific inhibition of STAT3 and ERK1/2 phosphorylation through AG490 and U0126, respectively, and STAT3 down-regulation using shRNA verified that the SHP-2/ERK/MAPK pathway regulates the expression of CDX2 in basal conditions, and the CDX2 up-regulation by IL-6 is through the JAK/STAT pathway in NUGC-4 cells whereas in MKN45 cells both pathways contribute to the CDX2 up-regulation. In conclusion, the signalling pathways activated by IL-6 have a crucial role in the regulation of CDX2 that is a key factor in the process of gastric carcinogenesis, suggesting that the inflammatory infiltrate in the gastric mucosa is relevant in this process and a potential target for new therapeutic approaches.Biochimica et biophysica acta. 06/2014;