Korean J Gastroenterol.  2012 Aug;60(2):79-85. 10.4166/kjg.2012.60.2.79.

DNA Double Strand Breaks in Gastric Epithelium with Helicobacter pylori Infection

• Chang YJ
• Byun SW
• Kim HK
• Cho YS
• Kim SS
• Kim JI
• Kim JK
• Jung ES

• KMID: 1387335
• DOI: http://doi.org/10.4166/kjg.2012.60.2.79

Abstract

BACKGROUND/AIMS
DNA double strand breaks (DSB) is one of the critical types of DNA damage. If unrepaired, DSB is accumulated in the nucleus of cells, the cells become apoptotic or transform to tumor by way of genomic instability. Some of malignant cancers and its premalignant lesions were proven to have DSB in their nuclei. There was no report that Helicobacter pylori (H. pylori), the gastric carcinogen, induce DNA DSB in gastric epithelium in vivo. The aim of this study was to investigate whether H. pylori induce DSB in the gastric epithelial cells of chronic gastritis.
METHODS
Immunohistochemical stains were performed for the DSB markers, phospho-53BP1 and gammaH2AX, in the gastric epithelium derived from 44 peptic ulcer disease patients before and after H. pylori eradication. DNA fragmentation assay was performed in the cell line to investigate the DNA damage by H. pylori infection.
RESULTS
The mean expression score of gammaH2AX was significantly higher in the H. pylori infected gastric epithelium as compared to the H. pylori eradicated gastric epithelium (8.8+/-5.5 vs. 6.2+/-5.3 respectively; p=0.008). The expression score of phospho-53BP1 between before and after eradication of H. pylori was not statistically different, but tended to be higher in H. pylori infection. DNA fragmentation was developed significantly more in the cell lines after infection with H. pylori.
CONCLUSIONS
DSB of DNA damage was typical feature of H. pylori infection in the gastric epithelium.

Keyword

Gastric mucosa; Helicobacter pylori; DNA breaks, double stranded; Gamma-H2AX protein, human; 53BP1 protein, human

MeSH Terms

Adult
Aged
Aged, 80 and over
Anti-Bacterial Agents/therapeutic use
Cell Line, Tumor
DNA/metabolism
*DNA Breaks, Double-Stranded
Female
Gastric Mucosa/*metabolism
Helicobacter Infections/drug therapy/*metabolism
Helicobacter pylori/*drug effects/pathogenicity
Histones/genetics/metabolism
Humans
Immunohistochemistry
Intracellular Signaling Peptides and Proteins/genetics/metabolism
Male
Middle Aged
Peptic Ulcer/genetics/pathology

Figure

• 

  Fig. 1 Immunohistochemistry for γH2AX and phospho-53BP1 proteins were detected in the nuclei of epithelial and interstitial inflammatory cells of the gastric mucosa (×200). (A) γH2AX before Helicobacter pylori (H. pylori) eradication. (B) γH2AX after eradication. (C) Phospho-53BP1 before eradication. (D) Phospho-53BP1 after eradication. Expression of γH2AX reduced in gastric epithelial cells after the eradication of H. pylori and phospho-53BP1 tended to be decreased after H. pylori eradication.

• 

  Fig. 2 Change of γH2AX and phospho-53BP1 expressions in the gastric epithelial cells of 44 patients following eradication of Helicobacter pylori (H. pylori). (A) The percentage of epithelial cells expressing γH2AX reduced significantly after eradication of H. pylori. (B) Gastric epithelial cells expressing phospho-53BP1 tended to be decreased after H. pylori eradication. The thick black bars indicate the mean values (**p<0.01). Hp, H. pylori.

• 

  Fig. 3 The induction of DNA fragmentation in Helicobacter pylori (H. pylori) infected AGS cells. Lane 2 and lane 3 in which H. pylori were infected induced DNA fragmentation in cells. Lane 1 indicated AGS, lane 2 was HS3C, lane 3 was AGS infected by H. pylori, and lane 4 was H. pylori only. M indicates molecular marker.

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