Expression of bcl-2 Protein in Gastric Adenoma and Adenocarcinoma

Kim, Young Sill; Kim, Byung Kee; Shim, Sang In

Abstract

The bcl-2 oncoprotein confers a survival advantage to cells by blocking programmed cell death. Overexpression of bcl-2 probably plays a role in tumorigenesis, and the expression of the bcl-2 protein has been investigated in many kinds of tumors. However, there have been only a few reports on expression of bcl-2 in human gastric adenocarcinoma. The aim of this study was to investigate the relationship between the expression of bcl-2 protein and several clinical and pathological parameters such as age, tumor site, size, histological type, depth of invasion, Lauren's classification, and grade. Immunohistochemical staining using monoclonal bcl-2 protein antibody, clone 124, was performed on paraffin embedded specimens from 23 gastric adenomas and from 45 gastric adenocarcinomas. The results are as follows. 1. Variable intensity of epithelial staining was noted from case to case, although the lymphocytic component showed similar intensity in all examples. The staining was located at the gland and mucous neck region of non-neoplastic epithelium. 2. The more differentiated type of gastric adenocarcinoma showed the higher expression rate and intensity. 3. The relationship between the expression rates of bcl-2 protein and tumor grade (adenoma early gastric adenocarcinoma advanced gastric adenocarcinoma) was statistically significant. The reactivity in adenoma was somewhat stronger with a uniform pattern, while in adenocarcinoma it was much weaker with a heterogenous pattern. 4. Intestinal type carcinomas by Lauren's criteria showed a higher expression rate and intensity than diffuse type. These results suggest that the bcl-2 expression would be found in the early phase of gastric tumorigenesis, and the expression rate and intensity would decrease according to the tumor progression.