Helicobacter pylori Infection and a P53 Codon 72 Single Nucleotide Polymorphism: a Reason for an Unexplained Asian Enigma

摘要

Aim: P53, the most commonly mutated tumor suppressor gene in all types of human cancer, is involvedin cell cycle arrest and control of apoptosis. Although p53 contains several polymorphic sites, the codon 72polymorphism is by far more common. There are divergent reports but many studies suggest p53 pro/pro SNPmay be associated with susceptibility to developing various cancers in different regions of the world. The presentstudy aimed to find any correlation between H. pylori infection and progression of carcinogenesis, by studyingapoptosis and the p53 gene in gastric biopsies from north Indian population. Materials and Methods: A total of921 biopsies were collected and tested for prevalence of H. pylori by rapid urease test (RUT), imprint cytologyand histology. Apoptosis was studied by the TUNEL method. Analysis of p53 gene polymorphism at codon 72was accomplished by PCR using restriction enzyme BstU1. Observation: Out of 921 samples tested 56.7% (543)were H. pylori positive by the three techniques. The mean apoptotic index (AI) in the normal group was 2.12,while gastritis had the maximum 4.24 followed by gastric ulcer 2.28, gastropathy 2.22 and duodenal ulcer 2.08.Mean AI in cases with gastric cancer (1.72) was less than the normal group. The analysis of p53 72 SNP revealedthat p53 (Arg/Arg), (Pro /Arg) variant are higher (40.59% & 33.66%) as compared to p53 pro/pro variant(25.74%) inthe healthy population. Conclusions: The North Indian population harbors Arg or Pro/Arg SNP thatis capable of withstanding stress conditions; this may be the reason of low incidence of gastric disease in spiteof high infection with H. pylori. There was no significant association with H. pylori infection and AI. However,there is increased apoptosis in gastritis which may occur independent of H. pylori or p53 polymorphism.