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Specificity and heregulin regulation of Ebp1 (ErbB3 binding protein 1) mediated repression of androgen receptor

Y Zhang1, A W Hamburger

  • 1Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA.

British Journal of Cancer
|December 8, 2004
PubMed

Insights

Ebp1 acts as a corepressor for the androgen receptor (AR) in prostate cancer cells. Its interaction with AR and repressive activity are modulated by heregulin (HRG), a ligand for ErbB3/4 receptors.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Signaling

Background:

  • ErbB receptors are involved in prostate cancer progression.
  • The interaction between ErbB receptors and the androgen receptor (AR) is not well understood.
  • Ebp1 protein, identified through its association with ErbB3, interacts with AR.

Purpose of the Study:

  • To investigate the effect of Ebp1 on AR function in prostate cancer cell lines.
  • To examine the regulation of Ebp1 by heregulin (HRG), an ErbB3/4 ligand.
  • To elucidate the role of Ebp1 as a potential AR coregulator.

Main Methods:

  • Utilized natural AR-regulated promoters to assess transcriptional activation.
  • Employed siRNA to downregulate Ebp1 expression in LNCaP cells.
  • Investigated protein-protein interactions using co-immunoprecipitation assays.
  • Analyzed the impact of HRG treatment on Ebp1-ErbB3 and Ebp1-AR associations.

Main Results:

  • Ebp1 repressed the transcriptional activation of wild-type AR in prostate cancer cell lines.
  • Downregulation of Ebp1 led to AR activation in the absence of androgen.
  • Ebp1 associated with ErbB3 in LNCaP cells, and HRG induced their dissociation.
  • HRG treatment enhanced Ebp1's association with AR and its repressive activity.

Conclusions:

  • Ebp1 functions as an AR corepressor in prostate cancer.
  • Ebp1's corepressor activity is regulated by the ErbB3/4 ligand, HRG.
  • These findings highlight a novel regulatory mechanism involving Ebp1, AR, and ErbB signaling in prostate cancer.

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