Phosphorylation of H2AX at Ser 139 (γH2AX) is a biomarker of DNA double-strand breaks (DSBs). The present study aimed to explore the association between γH2AX levels and gastric pathology and Helicobacter pylori (H. pylori) infection. Gastric biopsies were obtained from 302 H. pylori-negative and -positive patients, including those with chronic gastritis (CG), intestinal metaplasia (IM), dysplasia (Dys) and gastric cancer (GC). Proteins were extracted from five gastric epithelial cell lines and from 10 specimens of matched GC and adjacent normal tissues. The expression of γH2AX, a biomarker for the detection of DNA DSBs, in gastric tissues was detected by immunohistochemistry and western blotting. The expression of γH2AX progressively increased in tissues according to pathological stage from CG to Dys, but was slightly decreased in GC. H. pylori infection was associated with increased γH2AX expression, IM and Dys. Overexpression of γH2AX in GC was found to correlate with tumor location, gross appearance, differentiation, depth of invasion, TNM stage and lymph node metastasis. The results indicated that DSBs appear to be an early molecular event in gastric carcinogenesis, which may be associated with H. pylori infection. Moreover, immunohistochemical staining of γH2AX was found to correlate with a number of clinicopathological characteristics. The expression of γH2AX may serve as a valuable biomarker for the diagnosis and progression of GC.
Keywords: DNA double-strand breaks; Helicobacter pylori; gastric carcinogenesis; γH2AX.