LITTLE EXPRESSION OF PROTOONCOGENE BCL-2 IN TUMOROUS CELLS OF HEPATOCELLULAR-CARCINOMA WITH CHRONIC HEPATITIS-C VIRUS-INFECTION

The proto-oncogene bcl-2, which was first found overexpressed in human follicular lymphoma, is now considered to inhibit apoptotic cell deat h, resulting in greater cell susceptibility to genetic alteration. Thu s, this gene might cause hyperplasia or occasionally lead to a more ma lignant phase, i.e. carcinoma. Overexpression of this gene has been re ported in several tumors. However, little has been clarified about its contribution to hepatocarcinogenesis. In this study, using immunoblot ting, immunohistochemical and in situ hybridization techniques, we exa mined the expression of the bcl-2 protein and messenger RNA in patient s having hepatocellular carcinoma with chronic hepatitis C virus infec tion. Immunoblot analysis indicated no significant differences in the amounts of bcl-2 protein between tumorous and nontumorous lesions. Fur thermore, immunohistochemistry as well as in situ hybridization techni que demonstrated that only lymphocytes infiltrating the tissues and tu mors were bcl-2 positive. These findings suggest that the proto-oncoge ne bcl-2 may make no or little contribution, if any, to hepatocarcinog enesis.