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Ubiquitination by TOPORS regulates the prostate tumor suppressor NKX3.1.


The NKX3.1 gene located at 8p21.2 encodes a homeodomain-containing transcription factor that acts as a haploinsufficient tumor suppressor in prostate cancer. Diminished protein expression of NKX3.1 has been observed in prostate cancer precursors and carcinomas. TOPORS is a ubiquitously expressed E3 ubiquitin ligase that can ubiquitinate tumor suppressor p53. Here we report interaction between NKX3.1 and TOPORS. NKX3.1 can be ubiquitinated by TOPORS in vitro and in vivo, and overexpression of TOPORS leads to NKX3.1 proteasomal degradation in prostate cancer cells. Conversely, small interfering RNA-mediated knockdown of TOPORS leads to an increased steady-state level and prolonged half-life of NKX3.1. These data establish TOPORS as a negative regulator of NKX3.1 and implicate TOPORS in prostate cancer progression.

Pubmed ID: 18077445


  • Guan B
  • Pungaliya P
  • Li X
  • Uquillas C
  • Mutton LN
  • Rubin EH
  • Bieberich CJ


The Journal of biological chemistry

Publication Data

February 22, 2008

Associated Grants

  • Agency: NCI NIH HHS, Id: CA99951

Mesh Terms

  • Animals
  • Homeodomain Proteins
  • Humans
  • Male
  • Mice
  • NIH 3T3 Cells
  • Neoplasm Proteins
  • Nuclear Proteins
  • Prostatic Neoplasms
  • Proteasome Endopeptidase Complex
  • Protein Binding
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Ubiquitin-Protein Ligases
  • Ubiquitination