Estrogen receptor α attenuates transforming growth factor-β signaling in breast cancer cells independent from agonistic and antagonistic ligands

Matthias B. Stope (1) , Simone L. Popp (1) , Cornelius Knabbe (2) , Miriam B. Buck (1)

1 Dr. Margarete Fischer-Bosch Institute for Clinical Pharmacology [Stuttgart]
2 Department of Clinical Chemistry

To investigate a presumed crosstalk between estrogen receptor α (ERα) and the TGF-β signaling pathway in breast cancer, we analyzed the TGF-β-induced expression of the plasminogen activator inhibitor 1 (PAI-1) gene in ER-positive MCF-7 cells. After siRNA-mediated knock-down of endogenous ERα, the transcription level of PAI-1 was upregulated, pointing to an attenuation of TGF-β signaling by the presence of ERα. We verified these findings by a vice versa approach using a primary ER-negative cell model transiently overexpressing either ERα or ERβ. We found that ERα, but not ERβ, led to a strong inhibition of the TGF-β1 signal, monitored by TGF-β reporter assays. This attenuation was completely independent of receptor stimulation by β-estradiol (E2) or inhibition by the pure antagonist ICI 182.780 (ICI). Our results indicate a permanent repression of PAI-1 by ERα and suggest a ligand-independent crosstalk between ERα and TGF-β signaling in breast cancer cells.

Mots clés: Transforming growth factor β; Estrogen receptor; Crosstalk

Matthias B. Stope, Simone L. Popp, Cornelius Knabbe, Miriam B. Buck. Estrogen receptor α attenuates transforming growth factor-β signaling in breast cancer cells independent from agonistic and antagonistic ligands. Breast Cancer Research and Treatment, 2009, 120 (2), pp.357-367. ⟨10.1007/s10549-009-0393-2⟩. ⟨hal-00535358⟩