Relationship between Helicobacter pylori infection and expression of ras p21 and p53 in gastric carcinoma and precancerosis

Objective To investigate the relationship between Helicobacter pylori (HP) infection and expression of p21 (ras proto-oncogene product p21 protein) and p53 (p53 cancer suppressive gene product mutant p53 protein). Methods The biopsy samples from 42 cases of gastric cancer (GC), 23 dysplasia (Dys), 26 intestinal metaplasia (IM), 14 chronic atrophic gastritis (CAG), 24 chronic superficial gastritis (CSG) and 20 normal gastric mucosa, were examined for the expression of p21 and p53 by immunohistochemical method and for the presence of HP after toluidine blue staining. Results The HP positive rates in Dys, IM, CAG and CSG groups were significantly higher than that in normal gastric mucosa group (P0.05). In GC patients, the HP positive rate in non-cardiac cancer cases was obviously higher than in cardiac cancer cases (61.9% vs 28.6%, P0.01). The expressions of p21 and p53 were zero in CSG and normal gastric mucosa groups, significantly higher in GC and Dys groups than in other groups. Besides, the rates of p21 and p53 expression were higher among the HP positive patients than among the HP negative ones in the GC, Dys and IM groups (P0.05). Conclusion HP infection is significantly related to the expreessions of p21 and p53 , suggesting that HP infection be involved in the activation of ras oncogene and mutation of p53 tumor suppresser gene.