Inhibitory Effect of Carcinogenic Aromatic Hydrocarbons on Transformation of 3T3 Cells by SV 40 1

Abstract

Summary

The carcinogenic polycyclic aromatic hydrocarbons 7,12-dimethylbenz[α] anthracene (0.0005 μg/ml) and 3-methylcholanthrene (0.005 μg/ml) did not have a toxic effect on the plating efficiency of 3T3 cells. The number of SV 40-transformed clones of 3T3 cells was decreased when these carcinogens were added 24 hr after virus inoculation and were in contact with the cells for 7 days. However, there was no effect when the carcinogens were in contact with the cells for 48 hr before or for 3 hr immediately after virus inoculation. No direct effect of the carcinogens on the infectivity of SV 40 was observed when the virus was incubated with from 0.002 to 200 μg/ml of the carcinogens and subsequently titered in the BSC-1 cell line. These findings confirm in vitro for another oncogenic virus the previously described inhibitory effect of these carcinogens on Friend and Rauscher virus leukemias. The most likely explanation seems to be an effect of the carcinogens on the synthesis of cellular DNA during the period when the virus directs the events leading to transformation.