QUANTITATIVE STUDIES ON MALIGNANT TRANSFORMATIION OF MOUSE PROSTATE CELLS BY CARCINOGENIC HYDROCARBONS IN VITRO

A quantitative system for producing malignant transformation of adult C3H mouse ventral prostate cells in culture with carcinogenic hydrocarbons has been developed. Aneuploid cell lines derived from mouse prostate are plated at a low density on a feeder layer and treated with various hydrocarbons for different lengths of time; other dishes are treated with 0.5% dimethyl sulfoxide (the solvent for the hydrocarbons) as controls. After 8 days some dishes are fixed and stained and the colonies are counted for total plating efficiency. Two weeks later other dishes are also fixed and stained. In the DMSO controls, the cells remain as a monolayer. In the carcinogen‐treated dishes, piled‐up multilayered colonies are seen and their frequency is scored. It has been shown that each of such piled‐up colonies gives rise to fibrosarcomas in mice, whereas the cells obtained from the monolayer areas of treated dishes do not cause tumors. Thus, these piled‐up colonies represent malignant transformation, under conditions where no spontaneous malignant transformation occurs. There is an excellent quantitative correlation between the carcinogenic activities of eight hydrocarbons and the transformation frequencies they produce in this system. Malignant transformation has been produced by treatment with methylcholanthrene for only one day. The acquisition of heat sensitivity is an early consequence of malignant transformation in this system. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company