Quantitative analysis of changes in cell proliferation and apoptosis during preneoplastic and neoplastic stages of hepatocarcinogenesis in rat

In situ markers for quantitative analysis of cell proliferation and apoptotic cell death have been used to evaluate both the proliferation level and net growth potential of preneoplastic nodules and malignant tumor tissues from rats experimentally induced for hepatocarcinogenesis by the dietary administration of 2-acetylaminofluorene. The findings show that although tumors have a much higher level of cell proliferation than preneoplastic liver nodules, the nodules have a higher potential for net growth when apoptosis is taken into account. These results support a role for a decrease in apoptosis during the promotion stage of carcinogenesis.