Sister-chromatid exchange induction by carcinogens in HTC cells: an in vitro system which does not require addition of activating factors.

The hepatic tumor cell line (HTC) was tested for the ability to produce sister chromatid exchanges (SCEs) in response to chemical carcinogens which require activation. Without the addition of exogenous microsomal enzyme preparations, cyclophosphamide, N-nitrosodiethylamine (DEN) and aflatoxin B1 (AFB1) induced significant levels of SCEs in these cells. Mitomycin C (MMC) and ultraviolet light, which do not require activation, also produced significant levels of SCEs. The induction of SCEs in HTC cells by AFB1 was shown to be inhibited by estradiol, a known inhibitor of microsomal activating enzymes. For the carcinogens tested, the HTC cell SCE assay was quite sensitive and comparable to other mammalian test systems. Exceptional sensitivity was found in the case of AFB1. SCE analysis of HTC cells offers a simplified system of detecting carcinogens requiring activation. This system also has the potential of investigating interactions between agents such as steroid hormones and carcinogens.