Immunohistochemical Study of p53 Gene Protein and bcl-2 Gene Protein Expression in Gastric Adenocarcinoma

ABSTRACT

The p53 oncoprotein, a product of the tumor suppressor gene encoded on the short arm of chromosome 17, has been noted in a number of human tumors as a tumor suppressor and some what has been related with cellular apoptosis. Thus, mutant p53 inhibits apoptosis. Like the mutant p53 oncoprotein, the bcl-2 oncoprotein expressed in various epithelial and nonepithelial cells plays a major role in inhibiting cellular apoptosis. To elucidate the role of bcl-2 and mutant p53 oncoprotein expression in gastric adenocarcinomas, immunohistochemical stains were carried out in 60 cases of gastric adenocarcinomas including 10 cases of early gastric cancer. We studied the expression patterns of the bcl-2 and the mutant p53 protein according to age, sex, histologic differentiation, tumor location, tumor size, lymph-node involvement, and depth of tumor invasion. The results were as follows: 1) p53 protein expression was detected in 39 of 60 cases (65%), and bcl-2 protein expression was detected in 29 of 60 cases (48%). 2) The p53 and the bcl-2 expression rates for early gastric cancer were 60% and 50%, and those for advanced gastric cancer were 66% and 40%, respectively. 3) There was no significant correlation of p53 or bcl-2 expression with sex, age, histologic differentiation, tumor location, tumor size, and lymph-node involvement; however, the expression of p53 was correlated with the depth of tumor invasion (p=0.049). Based on the present study, the expression of p53 is thought to be correlated with tumor progression and may be a useful prognostic factor in gastric adenocarcinomas.