Proteasomal degradation unleashes the pro-death activity of androgen receptor

Cell Res. 2010 Oct;20(10):1138-47. doi: 10.1038/cr.2010.65. Epub 2010 May 18.

Abstract

Androgen receptor (AR) is able to promote stress-induced cell death independently of its transcription activity in androgen-independent prostate cancer cells. Yet, the underlying mechanism is incompletely understood. Here, we report that stress-induced proteasomal degradation of AR contributes to its pro-death activity. Upon exposure to ultraviolet light and staurosporine, AR underwent proteasomal degradation. Blockade of AR degradation significantly suppressed stress-induced apoptosis in androgen-independent prostate cancer cells. Ectopic expression of the AR N-terminal (AR-N) domain, which lacks DNA- and ligand-binding abilities, led to cell death without any additional death stimuli. Truncation analysis revealed that AR-N domain contains several sub-domains that regulate the pro-death activity of AR, specifically the first 105 amino acids, which function as a minimal pro-death domain acting upstream of caspases. The pro-apoptotic activity of AR N-terminal fragments was suppressed by ectopic expression of Bcl-2 or selected caspase inhibitors. Thus, our results reveal a novel mechanism by which AR promotes stress-induced cell death in androgen-independent prostate cancer cells.

Publication types

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

MeSH terms

  • Apoptosis*
  • Caspase Inhibitors
  • Caspases / metabolism
  • Cell Line, Tumor
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism*
  • Staurosporine / pharmacology
  • Stress, Physiological
  • Ultraviolet Rays

Substances

  • Caspase Inhibitors
  • Enzyme Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • Receptors, Androgen
  • Caspases
  • Proteasome Endopeptidase Complex
  • Staurosporine