Inappropriate activation of androgen receptor by relaxin via beta-catenin pathway

Oncogene. 2008 Jan 17;27(4):499-505. doi: 10.1038/sj.onc.1210671. Epub 2007 Jul 23.

Abstract

We have previously demonstrated that human H2-relaxin can mediate androgen-independent growth of LNCaP through a mechanism that involves the activation of the androgen receptor (AR) signaling pathway. The goal of the current study is to elucidate the mechanism(s) by which H2-relaxin causes activation of the AR pathway. Our data indicate that there is cross-talk between AR and components of the Wnt signaling pathway. Addition of H2-relaxin to LNCaP cells resulted in increased phosphorylation of protein kinase B (Akt) and inhibitory phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) with subsequent cytoplasmic accumulation of beta-catenin. Immunoprecipitation and immunocytochemical studies demonstrated that the stabilized beta-catenin formed a complex with AR, which was then translocated into the nucleus. Chromatin immunoprecipitation analysis determined that the AR/beta-catenin complex binds to the proximal region of the prostate-specific antigen promoter. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, using LY294002, prevented both H2-relaxin-mediated phosphorylation of Akt and GSK-3beta and translocation of beta-catenin/AR into the nucleus. Knockdown of beta-catenin levels using a beta-catenin-specific small interfering RNA inhibited H2-relaxin-induced AR activity. The combined data demonstrate that PI3K/Akt and components of the Wnt pathway can facilitate H2-relaxin-mediated activation of the AR pathway.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cell Nucleus / drug effects
  • Chromones / pharmacology
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation, Neoplastic
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Humans
  • Male
  • Models, Biological
  • Morpholines / pharmacology
  • Phosphorylation
  • Promoter Regions, Genetic
  • Prostate-Specific Antigen / genetics
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / pathology
  • Protein Binding
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Androgen / metabolism*
  • Relaxin / physiology*
  • Signal Transduction / physiology
  • Tumor Cells, Cultured
  • beta Catenin / metabolism
  • beta Catenin / physiology*

Substances

  • Chromones
  • Enzyme Inhibitors
  • Morpholines
  • RLN2 protein, human
  • Receptors, Androgen
  • beta Catenin
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Relaxin
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3
  • Prostate-Specific Antigen