Androgen receptor activity at the prostate specific antigen locus: steroidal and non-steroidal mechanisms

Mol Cancer Res. 2003 Mar;1(5):385-92.

Abstract

Ligand-activated androgen receptors (ARs) occupy target genes and recruit histone modifiers that influence transcriptional competency. In LNCaP prostate cancer cells, the natural ligand 5alpha-dihydrotestosterone (DHT) activates transiently transfected AR-responsive promoter constructs; concurrent treatment with the protein kinase A activator forskolin enhanced AR stimulation induced by DHT. Additional treatment with the cytokine IL-6, purportedly an AR activator, markedly inhibited receptor activity. To assess AR activity on natural chromatin-integrated promoters/enhancers, we determined AR occupancy of the endogenous prostate specific antigen (PSA) promoter/enhancer as well as PSA expression in LNCaP cells treated with DHT; AR occupancy of the PSA enhancer was rapid (within 1 h of stimulation), robust (10-fold over background), and sustained (8-16 h). In contrast, AR occupancy of the PSA promoter was only increased by 2-fold. Histone H3 acetylation at both the enhancer and promoter was evident 1-2 h after DHT treatment. Detectable pre- and mature PSA mRNA levels appeared after 1 and 6 h treatment, respectively. Substantial qualitative and quantitative differences in PSA expression and AR occupancy of the PSA enhancer were observed when DHT-induced and ligand-independent activations of the AR were compared; forskolin stimulated PSA mRNA and protein expression, whereas IL-6 inhibited both DHT- and forskolin-stimulated expression. IL-6 did not diminish DHT-dependent AR occupancy of the PSA enhancer but inhibited CBP/p300 recruitment, histone H3 acetylation, and cell proliferation. These findings provide a contextual framework for interpreting the contribution of non-steroidal activation of the AR to signaling in vivo, and have implications for prostate cancer cell growth.

Publication types

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

MeSH terms

  • Acetylation
  • Adenylyl Cyclases / metabolism
  • Cell Division / physiology
  • Colforsin / pharmacology
  • Dihydrotestosterone / metabolism
  • Dihydrotestosterone / pharmacology*
  • Genes, Reporter
  • Histones / metabolism
  • Humans
  • Interleukin-6 / metabolism
  • Interleukin-6 / pharmacology
  • Ligands
  • Luciferases / genetics
  • Male
  • Promoter Regions, Genetic
  • Prostate-Specific Antigen / genetics
  • Prostate-Specific Antigen / metabolism*
  • Prostatic Neoplasms*
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism*
  • Tumor Cells, Cultured

Substances

  • Histones
  • Interleukin-6
  • Ligands
  • Receptors, Androgen
  • Dihydrotestosterone
  • Colforsin
  • Luciferases
  • Prostate-Specific Antigen
  • Adenylyl Cyclases