The Expression of bcl-2 Oncoprotein in Colorectal Polyps and Cancers

Chang, Sae Kyung; Moon, Cheol; Kim, Jeong Wook; Heo, Cheol Heang; Kim, Hyung Jun; Do, Jae Hyuk; Joe, Jun Hyung

Abstract

Background/Aims,, The bcl-2 gene is an oncogene that inhibits programmed cell death or apoptosis. Overexpression of bcl-2 probably plays a role in colorectal carcinogenesis. The aim of our study was to assess the possible role of bcl-2 in colorectal tumorigenesis and to evaluate its clinical significance.
METHODS
We investigated bcl-2 expression in adenomas and carcinomas of the large bowel by immunohistochemistry. The cases included 20 adenomas and 24 colorectal carcinomas.
RESULTS
In normal mucosa bcl-2 immunoreactivity was detected only in the proliferative cells of the colonic crypts. Conversely, bcl-2 immunoreactivity was noted in 60% of adenomas and the potency of immunoreactivity was noted to be one positive in 10 cases of adenomas and two positive in 2 cases of adenomas. In colorectal carcinomas, bcl-2 expression was noted in 70.8% of carcinomas and was undetectable in 29.2% and focal staining (less than 50% immunostained neoplastic cells) in 54.2% of carcinomas. The remaining 16.6% of the carcinomas displayed diffuse (more than 50% immunostained neoplastic cells) bcl-2 immunoreactivity. In colorectal adenornas bcl-2 expression was not correlated with the pathologic type of adenomas, but correlated with adenoma size. In colorectal carcinomas, bcl-2 expression was not correlated with relevant clinicopathologic parameters, including disease stage and tumor differen.iation.
CONCLUSIONS
Our data suggest that the bcl-2 oncoprotein may play a role in colorectal tumorigenesis and be correlated with tumor size. In the case of carcinomas, the expression of the bcl-2 oncoprotein did not show statistical significance compared with adenomas. But, the potency of bcl-2 expression was more stronger in carcinomas than in adenomas and showed statistical significance.