Inverse Relation between Expression of Gastric Tumor Suppressor RUNX3 and Helicobacter pylori Cag A status in Gastric Epithelial Dysplasia: 2011 ACG Presidential Poster

Abstract

Purpose: RUNX3 is a novel tumor suppressor gene and necessary for the suppression of cell proliferation of the gastric epithelium. Immunohistochemically, RUNX3 protein is expressed in normal mucosa, but not in cancer cells. The aim of this study was to evaluate the expression of RUNX3 in the category 3 and 4 gastric epithelial dysplasia (GED) according to the revised Vienna classification. We explored the role of RUNX3 in early gastric carcinogenesis. Methods: All tissue samples were excised by endoscopic mucosal resection. Fifty-one category 3 tissue samples and 56 category 4 samples were evaluated by RUNX3 staining and subclassifed by immunophenotype (CD10, MUC5A and MUC6). In GED and its normal surrounding tissue, infection of Helicobacter pylori (H. pylori) was examined by silver stain. Also, Cag A status was assessed by polymerase chain reaction. Results: Positive expression of RUNX3 was observed in 27 (52.9%) cases of the 51 category 3 lesions, whereas in the 56 category 4 lesions, 18 (32.1%) cases had positive immunoreactivity for RUNX3 (P = 0.02). Between immunophenotype and positive RUNX3 expression, there were no significant differences. In category 3 lesions, RUNX3-positive, Cag A-positive rate was 50% (5/10), and RUNX3-negative, Cag A-positive rate was 50% (12/16) (P = 0.19). In category 4 lesions, RUNX3-positive, Cag A-positive rate was 28.5% (2/7), whereas RUNX3-negative, Cag A-positive rate was 71.4% (15/21) (P = 0.04). Conclusion: The expression of RUNX3 is negative correlation with H. pylori Cag A status in GED. The loss of expression of RUNX3 might be a very early event in the progression of gastric carcinogenesis.