Failure of Chloro-s-triazine-Derived Compounds to Induce Estrogenic Responses in Vivo and in Vitro

The estrogenic activity of simazine and atrazine was investigated in the immature female Sprague-Dawley rat uterus, the estrogen-responsive MCF-7 human breast cancer cell line and PL3 yeast strain. Atrazine and simazine (50 - 300 mg/kg × 3) did not induce rat uterine wet weight, cytosolic progesterone receptor (PR) levels, or uterine peroxidase activity. In rats cotreated with 17β-estradiol (E2) plus atrazine or simazine, there was some inhibition of E2-induced uterine PR binding and peroxidase activity. In MCF-7 cells, simazine and atrazine did not affect E2-induced cell proliferation, nuclear PR levels or luciferase activity in cells transiently transfected with the Gal4-estrogen receptor chimera and a Gal4-regulated luciferase reporter gene, and no antiestrogenic activity was observed in cotreated cells, while growth was observed on similar media supplemented with 1 nM E2. These results indicate that atrazine and simazine are not estrogenic.