The tumor suppressor ING3 is degraded by SCF(Skp2)-mediated ubiquitin-proteasome system

Oncogene. 2010 Mar 11;29(10):1498-508. doi: 10.1038/onc.2009.424. Epub 2009 Nov 23.

Abstract

The inhibitor of growth family member 3 (ING3) has been shown to modulate transcription, cell cycle control and apoptosis. We previously reported that nuclear ING3 expression was remarkably reduced in melanomas, which correlated with a poorer patient survival, suggesting that decreased ING3 expression may be associated with melanoma progression. However, the mechanism of diminished ING3 expression in melanoma is not clear. Here we show that ING3 level was decreased in metastatic melanoma cells because of a rapid degradation. Furthermore, we showed that ING3 undergoes degradation through the ubiquitin-proteasome pathway. ING3 physically interacts with subunits of E3 ligase Skp1-Cullin-F-box protein complex (SCF complex). Knockdown of F-box protein S-phase kinase-associated protein 2 (Skp2) reduces the ubiquitination of ING3 and significantly stabilizes ING3 in melanoma cells. In addition, lysine 96 residue is essential for ING3 ubiquitination as its mutation to arginine dramatically abrogated ING3 degradation. Disruption of ING3 degradation stimulated ING3-induced G1 cell-cycle arrest and enhanced ultraviolet-induced apoptosis. Taken together, our data show that ING3 is degraded by the ubiquitin-proteasome pathway through the SCF(Skp2) complex and interruption of ING3 degradation enhances the tumor-suppressive function of ING3, which provides a potential cancer therapeutic approach by interfering ING3 degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / radiation effects
  • Blotting, Western
  • Cell Cycle
  • Cell Line
  • Cell Line, Tumor
  • Gene Expression
  • Genes, Tumor Suppressor
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Lysine / genetics
  • Lysine / metabolism
  • Melanoma / genetics
  • Melanoma / metabolism
  • Melanoma / pathology
  • Mutation
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Binding
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • S-Phase Kinase-Associated Proteins / genetics
  • S-Phase Kinase-Associated Proteins / metabolism*
  • SKP Cullin F-Box Protein Ligases / metabolism
  • Signal Transduction
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Tumor Suppressor Proteins
  • Ubiquitin / metabolism*
  • Ubiquitination
  • Ultraviolet Rays

Substances

  • Homeodomain Proteins
  • ING3 protein, human
  • S-Phase Kinase-Associated Proteins
  • Trans-Activators
  • Tumor Suppressor Proteins
  • Ubiquitin
  • SKP Cullin F-Box Protein Ligases
  • Proteasome Endopeptidase Complex
  • Lysine