SCE induction by indirect mutagens/carcinogens in metabolically active cultured mammalian cell lines.

Sister chromatid exchange (SCE) analysis in a total of 20 cultured mammalian cell lines of various types exposed to a variety of indirect mutagens/carcinogens suggested that, among these, several human and rat tumor cell lines are intrinsically capable of metabolizing a wide range of mutagens/carcinogens into genotoxic forms to induce SCEs. These cells may therefore serve as simple in vitro SCE test systems for screening of activation-dependent genotoxins without the use of an exogenous activating system. In addition, a comparison of the relevant metabolizing enzyme activity and inducibility of SCEs by mutagens/carcinogens in such cell systems appears to provide clues about the metabolic pathways related to SCE induction. Based on our own data and those in the literature, practical and theoretical advantages of the use of a direct-activating SCE test system in genetic toxicology are discussed.