p68/DdX5 supports β-catenin & RNAP II during androgen receptor mediated transcription in prostate cancer

PLoS One. 2013;8(1):e54150. doi: 10.1371/journal.pone.0054150. Epub 2013 Jan 17.

Abstract

The DEAD box RNA helicase p68 (Ddx5) is an important androgen receptor (AR) transcriptional co-activator in prostate cancer (PCa) and is over-expressed in late stage disease. β-Catenin is a multifunctional protein with important structural and signalling functions which is up-regulated in PCa and similar to p68, interacts with the AR to co-activate expression of AR target genes. Importantly, p68 forms complexes with nuclear β-Catenin and promotes gene transcription in colon cancer indicating a functional interplay between these two proteins in cancer progression. In this study, we explore the relationship of p68 and β-Catenin in PCa to assess their potential co-operation in AR-dependent gene expression, which may be of importance in the development of castrate resistant prostate cancer (CRPCa). We use immunoprecipitation to demonstrate a novel interaction between p68 and β-Catenin in the nucleus of PCa cells, which is androgen dependent in LNCaP cells but androgen independent in a hormone refractory derivative of the same cell line (representative of the CRPCa disease type). Enhanced AR activity is seen in androgen-dependent luciferase reporter assays upon transient co-transfection of p68 and β-Catenin as an additive effect, and p68-depleted Chromatin-Immunoprecipitation (ChIP) showed a decrease in the recruitment of the AR and β-Catenin to androgen responsive promoter regions. In addition, we found p68 immunoprecipitated with the processive and non-processive form of RNA polymerase II (RNAP II) and show p68 recruited to elongating regions of the AR mediated PSA gene, suggesting a role for p68 in facilitating RNAP II transcription of AR mediated genes. These results suggest p68 is important in facilitating β-Catenin and AR transcriptional activity in PCa cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cell Nucleus / metabolism
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Immunoblotting
  • Immunoprecipitation
  • Male
  • Prostate-Specific Antigen / genetics
  • Prostate-Specific Antigen / metabolism
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology
  • Protein Binding
  • RNA Interference
  • RNA Polymerase II / metabolism*
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic*
  • beta Catenin / genetics
  • beta Catenin / metabolism*

Substances

  • Receptors, Androgen
  • beta Catenin
  • RNA Polymerase II
  • Prostate-Specific Antigen
  • Ddx5 protein, human
  • DEAD-box RNA Helicases