Quantitative Studies of In Vitro Transformation by Chemical Carcinogens

Abstract

The addition of carcinogenic polycyclic hydrocarbons to cells of Syrian hamster embryos resulted in the formation of altered clones not seen with control conditions. The presence of altered clones was not due to the X-irradiated feeder cells or the antibiotics. The addition of carcinogens produced a crisscross pattern of both light and dense clones. Altered clones were obtained with both randombred and inbred hamsters. The frequency of appearance of altered clones was related to the known carcinogenic potency of the compounds tested. Toxicity increased with the amount of the compound and was related to its potency as a carcinogen. At constant carcinogen concentration the number of altered clones increased with the number of cells exposed. Positive results were obtained with carcinogen concentrations yielding about a 50% decrease in cloning efficiency, which suggests that the alteration was due to induction rather than to selection.