Differences of mutation of helicobacter pylori cagA gene isolated from duodenal ulcer and gastric cancer.

Abstract

69 Background: H. pylori is the pathogen of both duodenal ulcer and gastric carcinoma. However, they are markedly different in terms of its physiologic and pathologic basis. CagA is 120-145-kDa protein of H. pylori and located one end of Cag PAI encoding components of type IV secretion system. H. pylori expressing CagA are associated with development of atrophic gastritis, peptic ulcer, and gastric carcinoma. This study was aimed to examine the differences of cagA mutations of H. pylori isolated from duodenal ulcer and gastric carcinoma. Methods: Isolated H. pylori from 29 patients with gastric carcinoma and 31 patients with duodenal ulcer were compared the frequency of mutations after cloning of cagA of H. pylori. Results: Even there were diverse mutations scattered on whole sequence of cagA, mutations were more frequent in amino acid sequence 200-400 and 850-1100. Amino acid loci G311, D371, M393, T899, and S1068 were mutated in more than half of patients regardless of diseases. The mutations of CagA in C-terminal area, especially Q889, T899, R952, A968, R997, K1034, Q1067, and S1068, were 20% or more frequent in H. pylorifrom duodenal ulcer than those from gastric carcinoma. EPIYA type was not different between the duodenal ulcer and gastric carcinoma. Conclusions: These results suggest that the mutations of cagA of H. pylori, especially in C-terminus are distinguishable between duodenal ulcer and gastric carcinoma.