Enhancement of 2- and 16α-estradiol in MCF-7 human breast cancer cells by 2,3,7,8-tetrachlorodibenzo-P-dioxin

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin exhibits antiestrogenic activity and induces cytochromes P-450 in estrogen-dependent MCF-7 human breast-cancer cells. To determine whether induction of 2- or 16α-hydroxylation of 17β-estradiol has a role in this antiestrogenic activity, MCF-7 cells which were exposed to this xenobiotic for 72 hrs were incubated with either [2- 3 H] or [16α- 3 H] 17β-estradiol and the extent of tritiated H 2 O formation, indicative of site-specific hydroxylation, was determined