Expression of apoptosis, proliferating cell nuclear antigen, and apoptosis-related antigens (bcl-2, c-myc, Fas, Lewis(y) and p53) in human cholangiocarcinomas and hepatocellular carcinomas

In site expression of apoptosis and its related antigens has rarely been evaluated in human liver tumors. Therefore, investigation using in situ nick end-labeling and immunohistochemical methods of the in situ expression of apoptosis, proliferating cells, and apoptosis-related antigens in 7 normal livers, 20 cholangiocarcinomas (CC) and 17 hepatocellular carcinomas (HCC) was done. Apoptotic cells as determined by the nick end-labeling method and proliferating cell nuclear antigen-positive cells were present in all specimens, and the percentage of them was significantly higher in CC than in HCC. Bcl-2 protein was present only in one CC and one HCC, but was occasionally noted in bile ducts in non-cancerous livers. C-myc and Fas antigens were not found in any of the cases. Lewis(y) antigen was expressed in 8 CC, but was absent in the other cases although bile ducts in non-cancerous livers frequently expressed Lewis(y). p53 protein was present in 8 CC, but was absent in the other cases. Serial section observations showed that apoptotic cancer cells were consistently negative for proliferating cell nuclear antigen; bcl-2-positive cells did not show apoptosis; p53-positive cancer cells showed apoptosis. Some Lewis(y)-positive cancer cells showed apoptosis, while others did not. These data suggest that apoptosis and cell proliferation are involved in CC and HCC, and their degree is more severe in CC than in HCC. p53 protein (stimulative) may regulate apoptosis in some cases, whereas c-myc, Fas and Lewis(y) are not related to apoptosis in CC and HCC in vivo. Many other factors may regulate apoptosis in CC and HCC in vivo.