Effects of estrogen antagonists on estradiol-enhanced radiation transformation in vitro

We have previously reported that radiation and 17 beta-estradiol can induce transformation in vitro in C3H 10T1/2 cells. In the present series of experiments, we have observed that antagonists of estrogen action, such as c-AMP activating agents (theophylline and dibutyryl c-AMP) and the anti-estrogen, tamoxifen, suppress radiation/17 beta-estradiol enhanced transformation in vitro. None of these known estrogen antagonists had a significant effect on transformation induced by radiation alone. Our results with added dibutyryl c-AMP, theophylline and tamoxifen suggest that estrogen receptor complex formation may play a role in estrogen-enhanced radiation transformation in vitro.