Glycogen synthase kinase-3beta activity is required for androgen-stimulated gene expression in prostate cancer.
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.
Department of Urology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA.
Xinbo
X
Liao
J Brantley
JB
Thrasher
Jeffery
J
Holzbeierlein
Scott
S
Stanley
Benyi
B
Li
D000728:Androgens / Q000502:physiology*; D001692:Biological Transport / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D008297:Male; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D051176:beta Catenin
D000728:Androgens; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D015534:Trans-Activators; D051176:beta Catenin; D014443:Tyrosine; C494918:AKT1 protein, human; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3