[Chemical cancerization of hamster embryo cells in mass culture]

For periods between 24 and 72 hours mass cultures of hamster embryo cells were put in contact with the following carcinogens: 7,10-dimethylbenz (c) acridine (2 mug/ml), benzo (a) pyrene (0,1 mug/ml), 7-methyl benz (a) anthracene (5 and 10 mug/ml), 3-methyl-cholanthrene (0,1 mum/ml), and 7,12-dimethyl benz (a) anthracene (0,05 mug/ml). The cancerisation of cells thus treated was demonstrated by hamster grafting as soon as 4 1/2 months post-treatment. By contrast neither the cells treated by benzo (e) pyrene (non-carcinogenic in animals) nor those of the two control lines resulted in tumours when grafted into hamsters even after culture for 8 and 15 months. These transformed and malignant cultures differ from the controls by their rapid uncontrolled growth and in their morphology. Moreover the morphological characteristics of transformation are evident as soon as 2 months after treatment and for the majority of the compounds studied well before cancerization is demonstrable by hamster grafts. During the course of the first 2 months toxic effects of the compounds are evident in the partial destruction of the cultures and by the appearance of colonies composed in part of cells in disorderly growth. The cells of these colonies when isolated and returned to culture do not survive beyond 4 or 5 passages. Moreover grafts of cultures at 30 days after exposure to carcinogens has never resulted in tumour in the hamster host.