LOSS OF PS2 PROTEIN EXPRESSION IS AN EARLY EVENT OF INTESTINAL-TYPE GASTRIC-CANCER

To investigate the prevalence of pS2 expression in gastric cancer with respect to tumor histopathology intestinal metaplasia and Helicobacte r pylori (H. pylori) infection, pathologic specimens of 91 patients wi th gastric cancer were immunostained for pS2, Such immunoreactivity wa s correlated with the status of H. pylori infection, tumor staging, hi stology, subtyping, and associated intestinal metaplasia, Positive pS2 staining was seen throughout all non-neoplastic epithelia, and in all 9 patients with the complete type of intestinal metaplasia. In contra st, 21 of 45 incomplete type of intestinal metaplasia had negative pS2 staining (P<0.001), and 54 out of 91 tumors (59.3%) showed loss of pS 2 expression in the cancer tissues proper, There mas no correlation of pS2 expression with age, gender, depth of invasion, duodenal involvem ent, lymph node metastasis, venous invasion or H. pylori infection Neg ative pS2 staining was significantly higher in the intestinal (74.5%) and Borrmann type I, II, III (64.2%) tumors than the diffuse (43.2%, P <0.005) and Borrmann type IV (20%, P<0.05) tumors. Our results indicat e that loss of pS2 expression may occur as an early event in the malig nant transformation process of intestinal-type tumors.