[In vitro transformation induced by carcinogens in rat tracheal epithelial cells].

An in vitro transformation system was established using primary rat tracheal epithelial (RTE) cells cultured in medium with or without feeder layer cells. About 24-48 hours after plating, RTE cells were exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0-0.6 microgram/ml), benzo (a) pyrene (BaP, 0-20 micrograms/ml), or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK,0-2.0mg/ml). One or two weeks after exposure, enhanced growth variants (EGV) among the RTE cells were selected in serum containing medium by removing either the feeder layer or bovine pituitary extract (BPE) and epidermal growth factor (EGF). The results showed that EGV transformation was induced by MNNG, BaP and NNK, and a dose dependent EGV transformation was observed in the MNNG and NNK experiments. Our experimental results suggest that for the selection of EGV's from among RTE cells exposed to chemical carcinogens, the use of BPE- and EGF-free medium is more sensitive and convenient than is removing the feeder layers.