[Use of hepatocytes in primary cultures to predict potential hepatocarcinogenicity of compounds]

Short-term tests for genotoxic activity will detect a variety of potential carcinogens. However, experience over the last few years has shown that many chemical carcinogens are not detected in these tests. A large proportion of these non-mutagenic (non-genotoxic) carcinogens induce tumors in the rodent liver after life-long feeding. One class of such carcinogens are the hypolipidemic drugs many of which induce a characteristic hepatomegaly upon subchronic treatment. Typically this liver enlargement is accompanied by increased mitotic activity and a proliferation of the hepatic peroxisome compartment. Results also suggest a correlation between the degree and the nature of the hepatomegalic response to a compound, and its hepatocarcinogenic potency, but it remains unclear whether the growth stimulation and/or the peroxisome proliferation is correlated with the carcinogenicity. Both, the induction of peroxisomal enzyme and of replicative DMA synthesis may be measured in primary cultures of adult rat hepatocytes following in vitro exposition. Moreover, the ability of the compounds tested to induce in vitro replicative DNA synthesis in primary cultures of adult rat hepatocytes correlated well with the potency of the hepatomegalic response induced in vivo in treated rodents. Consequently, studies using such cultures might be useful to characterize and possibly predict in vitro the hepatocarcinogenic potency of some new compounds. The early recognition of the possible carcinogenic property of a new substance might accordingly contribute to the reduction of a number of life-long studies.