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

G Chen1, Y Wang, M Garate

  • 1Department of Dermatology and Skin Science, Jack Bell Research Centre, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V6H 3Z6.

Oncogene
|November 26, 2009
PubMed

Insights

Melanoma cells rapidly degrade ING3 protein via the ubiquitin-proteasome pathway. Inhibiting this degradation enhances ING3

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Biology

Background:

  • Inhibitor of growth family member 3 (ING3) regulates transcription, cell cycle, and apoptosis.
  • Reduced nuclear ING3 expression in melanoma correlates with poor patient survival, suggesting a role in melanoma progression.
  • The mechanism behind diminished ING3 expression in melanoma remains unclear.

Purpose of the Study:

  • To elucidate the mechanism of ING3 downregulation in melanoma.
  • To investigate the role of protein degradation in ING3 reduction.
  • To explore therapeutic strategies targeting ING3 degradation.

Main Methods:

  • Investigated ING3 protein levels in metastatic melanoma cells.
  • Utilized ubiquitin-proteasome pathway assays to study ING3 degradation.
  • Performed co-immunoprecipitation to identify ING3 interacting proteins.
  • Conducted knockdown experiments of Skp2 and site-directed mutagenesis of ING3.
  • Assessed cell-cycle arrest and apoptosis induction.

Main Results:

  • ING3 levels are decreased in metastatic melanoma due to rapid degradation via the ubiquitin-proteasome pathway.
  • ING3 physically interacts with the SCF(Skp2) E3 ligase complex.
  • Knockdown of Skp2 stabilizes ING3 and reduces its ubiquitination.
  • Mutation of lysine 96 abrogates ING3 ubiquitination and degradation.
  • Inhibiting ING3 degradation enhances ING3-mediated G1 cell-cycle arrest and UV-induced apoptosis.

Conclusions:

  • ING3 is degraded by the ubiquitin-proteasome pathway mediated by the SCF(Skp2) complex.
  • Targeting ING3 degradation can enhance its tumor-suppressive functions.
  • Interfering with ING3 degradation presents a potential therapeutic strategy for melanoma.

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