Progesterone receptor is involved in 2,3,7,8-tetrachlorodibenzo-p-dioxin-stimulated breast cancer cells proliferation.

Sex hormones are pivotal for both normal and neoplastic development of breast tissues. TCDD, with sex hormonal activity, executes multiple biological activities primarily through AhR. However, the detailed mechanisms how TCDD affects human breast cell are mostly unexplored. We analyzed the biological effects and underlying mechanisms of TCDD on MCF-7 cells. PR, other than AhR, was involved in TCDD-stimulated MCF-7 cell proliferation. TCDD inactivated Akt-FoxO3a pathway, increased cdc25C/cdc2 activity, decreased P21/P27 activity, and enriched G2/M phase, in a PR- and AhR-dependent manner. In conclusion, our study demonstrated for the first time that PR was involved in TCDD-stimulated breast cell proliferation.