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Endocrinology. 2004 Jun;145(6):2941-9. Epub 2004 Feb 26.

Glycogen synthase kinase-3beta activity is required for androgen-stimulated gene expression in prostate cancer.

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1
Department of Urology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA.

Abstract

Despite the specificity inferred by its name, glycogen synthase kinase (GSK)-3beta is an important kinase with a plethora of significant cellular targets, including cytoskeletal proteins and transcription factors, and its activity is regulated by phosphorylation on tyrosine/serine residues. As part of our efforts to dissect the molecular basis responsible for androgen-independent progression of prostate cancer, we investigated the role of GSK-3beta in androgen-stimulated gene expression in human prostate cancer cells. Pretreatment of prostate cancer cells harboring wild-type or mutant androgen receptor with the GSK-3beta inhibitors, lithium chloride (LiCl), RO318220, or GF109203X, inhibited R1881-stimulated androgen-responsive reporter activity in a dose- and time-dependent manner. In addition, the expression of two endogenous androgen-stimulated gene products, prostate-specific antigen and matrix metalloproteinase-2, was suppressed by the GSK-3beta inhibitors in those cells. Most importantly, knocking down GSK-3beta expression via a small interference RNA-mediated gene silencing approach also reduced R1881-stimulated gene expression, demonstrating the specificity of GSK-3beta involvement. Moreover, R1881 treatment of the cells increased phosphorylation status of GSK-3beta on tyrosine residue Y(216) but not on serine residue S(9). Pretreatment of the cells with phosphatidylinositol 3-kinase inhibitor LY294002 or wortmannin, which blocks androgen action in cells, abolished R1881-induced GSK-3beta Y(216) phosphorylation. However, the phosphatidylinositol 3kinase or GSK-3beta inhibitors did not block R1881-induced nuclear translocation of androgen receptor. Finally, knocking down the expression of Akt or beta-catenin, the two GSK-3beta-related signaling molecules, via siRNA-mediated gene silencing did not significant affect R1881-stimulated gene expression. These findings suggest that GSK-3beta activity is required for androgen-stimulated gene expression in prostate cancer cells.

PMID:
14988390
DOI:
10.1210/en.2003-1519
[Indexed for MEDLINE]
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