HIGH PREVALENCE OF BCL-2 ONCOPROTEIN EXPRESSION IN SMALL-CELL LUNG-CANCER

Bcl-2 oncoprotein, a member of a new category of oncogenes associated with the regulation of programmed cell death (apoptosis), has been con sidered to be involved in biological processes such as tumorigenesis a nd tumor development. To determine the role of bcl-2 oncoprotein in lu ng cancer, we preliminarily examined the expression of this protein in various histological types. Immunohistochemical staining using monocl onal bcl-2 oncoprotein antibody was performed in surgically resected f rozen specimens. Bcl-2 staining was seen in nine of 13 small cell lung cancers (69%), while only 18 out of 69 non-small cell lung cancers (2 6%) expressed bcl-2 oncoprotein, showing a significantly increased inc idence of bcl-2 oncoprotein expression in the former histological type . Considering the greater aggressiveness of small cell lung cancer com pared to non-small cell lung cancer, the possibility exists that the h igh prevalence of bcl-2 oncoprotein expression in small cell lung lung cancer is closely associated with tumorigenesis and tumor development .