Abstract: Objective To investigate the expression and the clinical significance of Alpha-Catenin(α-Cat) in carcinogenesis of gastric mucosa and its relationship with Helicobacter pylori(Hp) infection.Methods SP immunohistochemical technique was used to detect the expression of α-Cat in 96 cases of gastric carcinoma tissue and their adjacent tissues,and 15 control tissues.Rapid urease test and histological staining Warthin-Starry were used to determine the status of Hp infection.Results The positive rates of α-Cat expression in gastric cancer tissues,cancer-adjacent tissues and control tissues were 34.4%,56.2% and 100% respective1y(P<0.05).The expression of α-Cat in the Hp-positive cancer tissues was markedly lower than that in Hp-negative ones(36.2% vs.51.8%,P<0.05).The positive rate of α-Cat in cancer tissue was positively paralleled with the increase of differentiation grade,but there was no significant difference between the positive rate of α-Cat and the depth of tumor invasion or lymph node metastasis(P>0.05).Conclusions The expression of α-Cat was gradually down-regulated during the course of gastric carcinogenesis.Hp infection is closely related to the expression of α-Cat in gastric cancer.Hp infection might be an initiating factor,and the activation of α-Cat might be one of the key events in the pathogenesis of gastric cancer.Hp infection and α-Cat expression play synergic roles in occurrence and development of gastric cancer.

Key words: Helicobacter pylori, Gastric cancer