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This Article Accepted manuscript (PDF) All Versions of this Article: JME-08-0084v1 42/5/429    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Eisold, M. Articles by Baniahmad, A. Search for Related Content PubMed PubMed Citation Articles by Eisold, M. Articles by Baniahmad, A.

M Eisold, Human Genetics, University Jena, Jena, Germany
M Asim, Human Genetics, University Jena, Jena, Germany
H Eskelinen, Biosciences, University Kuopio, Kuopio, Finland
T Linke, Human Genetics, University Jena, Jena, Germany
A Baniahmad, Human Genetics, University Jena, Jena, 07745, Germany

Correspondence: Aria Baniahmad, Email: aban{at}mti.uni-jena.de

Abstract

Prostate cancer is one of the most prominent malignancies of elderly males. The growth of normal prostate and prostate cancer (PCa) cells depends on functional androgen receptor (AR). Binding of agonistic ligand enhances the transactivation function of AR and hence promotes the growth of prostate epithelial cells. We have earlier shown that AR antagonistic ligands such as cyproterone acetate (CPA) promote the recruitment of transcriptional corepressors such as SMRT leading to repression of AR transactivation in non-PCa cells. Unfortunately however, in LNCaP PCa cells, CPA functions as a agonist and thereby increases AR transactivation function. Here, we show that activated MEK signaling cascade inhibits functional recruitment of corepressor SMRT to CPA-bound AR in PCa cells. Chemical blockade of MEK kinase using a specific inhibitor U0126 increases the interaction and hence repression of AR by the corepressor SMRT in LNCaP PCa cells. This inhibition also results in enhanced antagonistic behavior of CPA as assessed by reporter and cell growth assays. Moreover, the growth of LNCaP cells stably overexpressing SMRT was more robustly inhibited in presence of CPA and U1026. In line with this, the growth rate of LNCaP cells was decelerated in the presence of both CPA and U0126. This suggests that activated MEK signaling pathway attenuates the functional recruitment of corepressor SMRT to AR induced by antagonists and thus indicates the important role of corepressors in mediating repression of both AR transactivation and prostate cancer cell growth by antagonists. Further, these findings suggest that combining receptor antagonists with signaling inhibitors could be a beneficial approach for PCa treatment.