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

Endocrinology. 2004 Jun;145(6):2941-9. doi: 10.1210/en.2003-1519. Epub 2004 Feb 26.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androgens / physiology*
  • Biological Transport / drug effects
  • Cell Line, Tumor
  • Cell Nucleus / metabolism
  • Cytoskeletal Proteins / metabolism
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation* / drug effects
  • Gene Silencing
  • Glycogen Synthase Kinase 3 / antagonists & inhibitors
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Humans
  • Male
  • Phosphorylation
  • Prostatic Neoplasms / enzymology*
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism*
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • RNA, Small Interfering / metabolism
  • Receptors, Androgen / metabolism
  • Trans-Activators / metabolism
  • Tyrosine / metabolism
  • beta Catenin

Substances

  • Androgens
  • CTNNB1 protein, human
  • Cytoskeletal Proteins
  • Enzyme Inhibitors
  • Proto-Oncogene Proteins
  • RNA, Small Interfering
  • Receptors, Androgen
  • Trans-Activators
  • beta Catenin
  • Tyrosine
  • AKT1 protein, human
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3