Involvement of tumor necrosis factor-α in the upregulation of CXCR4 expression in gastric cancer induced by Helicobacter pylori

Chenghai Zhao,Ning Zhang,Xianmin Bu,Xiaomei Lu,Wei Wang

doi:10.1186/1471-2407-10-419

Abstract

BackgroundH. pylori, whose infection increases tumor invasiveness and metastasis, is generally labelled as the strongest risk factor for the development of gastric cancer. It appears not to be a coincidence that there is also an overexpression of CXCR4 and an obvious involvement in gastric cancer metastasis. The aim of this study attempts to investigate and further to establish a link between them. With H. pylori being a potent inducer of TNF-α, whether TNF-α, a tumor promoter, is involved in the induction of CXCR4 expression by H. pylori was also under research in this study.MethodsExpression of CXCR4, TNF-α, IL-6 and IL-1β mRNA was determined by real-time PCR. CXCR4 protein expression was detected by Western blotting. Concentrations of TNF-α, IL-6 and IL-1β in cell culture supernatants were measured using the Quantikine Elisa kit. To abrogate TNF-α expression in HGC27 cells, TNF-α RNAi plasmid was used to transfect them.ResultsLevels of CXCR4 and TNF-α mRNA were significantly higher in H. pylori-positive gastric cancers (n = 19) compared to H. pylori-negative ones (n = 15). A subsequently Spearman's rank correlation test showed there was a positive correlation between the level of CXCR4 mRNA and that of TNF-α in 34 primary gastric cancers. Other results followed: Expression of CXCR4 and TNF-α was upregulated in gastric cancer cell MKN45 and HGC27 after infection with H. pylori 26695 (cag PAI+ ) or Tx30a (cag PAI- ); The induction of CXCR4 expression by H. pylori was inhibited significantly by a neutralizing TNF-α antibody, infliximab; CXCR4 expression was upregulated in MKN45 cells after treatment with exogenous TNF-α or co-culture with macrophage, and was downregulated in HGC27 cells after transfection with TNF-α RNAi plasmid. There was a significant increase in the migration of MKN45 cells treated with H. pylori 26695, and a strong inhibition when AMD 3100, a CXCR4 antagonist, or infliximab, was added.ConclusionsOur findings demonstrated that H. pylori upregulates CXCR4 expression in gastric cancer through TNF-α.

Highlights

H. pylori, whose infection increases tumor invasiveness and metastasis, is generally labelled as the strongest risk factor for the development of gastric cancer
It is well accepted that Helicobacter pylori (H. pylori) is a strong risk factor for the development of various gastric diseases, namely chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer, and it is acknowledged that the interaction between H. pylori and epithelial cells contributes to such development
Expression of CXCR4 and tumor necrosis factor-a (TNF-a) mRNA in primary gastric cancers CXCR4 mRNA was determined by real-time reversetranscription PCR in 34 gastric cancers, and its expression in each specimen was standardized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression

Summary

Introduction

H. pylori, whose infection increases tumor invasiveness and metastasis, is generally labelled as the strongest risk factor for the development of gastric cancer. It appears not to be a coincidence that there is an overexpression of CXCR4 and an obvious involvement in gastric cancer metastasis. Tumor cell migration is critically regulated by chemokine/chemokine receptor system. Another focus of our attention is shed on CXCR4, the most common chemokine receptor overexpressed in a series of cancers (gastric cancer included) by far [7,8]. It arouses great interests to find a link between H. pylori infection and CXCR4 overexpression in gastric cancer

Methods

Results

Conclusion