Antiandrogen Effects of Mifepristone on Coactivator and Corepressor Interactions with the Androgen Receptor

Liang Nian Song, Meghan Coghlan, Edward P. Gelmann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Scopus citations

Abstract

Mifepristone is a potent antagonist of steroid hormone receptors such as glucocorticoid and progesterone receptors. We investigated the potential for mifepristone to act as an antiandrogen and compared it with partial androgen receptor (AR) agonists and antagonists, in particular bicalutamide. Mifepristone was an effective antiandrogen in vitro that inhibited transcription from three androgen-responsive promoters and blocked the agonist R1881 in a dose-dependent manner. Like bicalutamide, mifepristone also antagonized the action of androgen receptor with a (T877A) mutation. Mifepristone competed effectively with R1881 with a relative binding affinity comparable to that of cyproterone acetate, and much higher than that of hydroxyflirtamide and bicalutamide in a binding assay. Mifepristone could effectively Induce the binding of the herpes simplex viral protein 16/AR fusion protein to the hormone response elements in the murine mammary tumor virus-luciferase reporter. With either wild-type or T877A mutant AR, mifepristone alone was unable to induce any detectable interaction with coactivators transcriptional intermediary factor-2 or β-catenin but could inhibit the R1881-induced binding of AR to transcriptional intermediary factor-2 and β-catenin. Similarly, mifepristone could inhibit the R1881-induced N/C-terminal interaction in a dose-dependent manner even though mifepristone alone has no effect on the N/C-terminal interaction of AR. We found that mifepristone could induce a strong interaction between AR and corepressors nuclear receptor corepressor and silencing mediator for retinoid and thyroid hormone receptors in both transactivation and two-hybrid assays to a greater degree than hydroxyflutamide, cyproterone acetate, and bicalutamide. The AR-corepressor interaction was also seen in coimmunoprecipitation assays. Finally, mifepristone at high concentrations induced a low level of prostate-specific antigen expression in LNCaP and antagonized prostate-specific antigen expression induced by R1881. Mifepristone also antagonized R1881 action on the growth of LNCaP prostate cancer cells.

Original languageEnglish (US)
Pages (from-to)70-85
Number of pages16
JournalMolecular Endocrinology
Volume18
Issue number1
DOIs
StatePublished - Jan 2004

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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