APOPTOSIS AND CANCER RISK ASSESSMENT

Apoptosis is one form of physiological or active cell death. The balan ce between cell proliferation and cell death or apoptosis not only eff ects organ growth but also has a profound impact on the net increase a nd growth of initiated cells and preneoplastic and tumor cell populati ons. With respect to cancer development apoptosis is becoming widely r ecognized as being an innate tissue defense against carcinogens by inh ibiting survival and controlling growth of precancerous cell populatio ns and tumors at different stages of carcinogenesis, Experimental data on cell birth and cell. death rates help identify the mode of action of a chemical and can be incorporated into biologically based cancer m odels. This article describes the quantitation and regulation of apopt osis in rodent liver and how loss of regulation can have a role in hep atocarcinogenesis. A biologically-based mouse liver cancer model is pr esented and utilized to describe how treatment related growth effects affect the process of carcinogenesis, Advantages acid limitations of b iologically based cancer models in cancer research and risk assessment are discussed.