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SUMOylation of the lysine-less tumor suppressor p14ARF counters ubiquitylation-dependent degradation

Ahmed El Motiam1,2,3, Yanis H Bouzaher4, Haifen Chen5

  • 1Centro de Investigación en Medicina Molecular (CIMUS), Universidade de Santiago de Compostela, Instituto de Investigaciones Sanitarias (IDIS), Santiago de Compostela, Spain. elmotiam@lunenfeld.ca.

Cell Death & Disease
|July 12, 2025
PubMed

Insights

The tumor suppressor p14ARF is SUMOylated at its N-terminus, which stabilizes it against degradation. Inhibiting NEDDylation boosts SUMOylation and p14ARF levels, impacting prostate cancer cell cytotoxicity.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Post-translational Modifications

Background:

  • The tumor suppressor p14ARF interacts with UBC9, an enzyme involved in SUMOylation, but the precise relationship and effect of SUMOylation on p14ARF remain unclear.
  • p14ARF lacks lysine residues, making its potential for post-translational modification by SUMOylation an area of investigation.

Purpose of the Study:

  • To investigate the SUMOylation of p14ARF and its functional consequences.
  • To explore the interplay between p14ARF, SUMOylation, ubiquitination, and NEDDylation pathways.
  • To determine the role of p14ARF in the context of NEDDylation inhibition and prostate cancer cell death.

Main Methods:

  • Investigated SUMO2 conjugation to p14ARF using biochemical assays.
  • Utilized UBC9 depletion and pharmacological inhibitors (MLN4924/Pevonedistat, TAK-243) to modulate SUMOylation, ubiquitination, and NEDDylation.
  • Assessed p14ARF protein levels and mRNA expression of SUMOylation components.
  • Evaluated the impact of MLN4924 on prostate cancer cell cytotoxicity in a p14ARF-dependent manner.

Main Results:

  • SUMO2 conjugates to the N-terminus of p14ARF, enhancing its stability.
  • Depletion of UBC9 or inhibition of SUMOylation leads to p14ARF degradation.
  • Inhibition of ubiquitination or NEDDylation increases p14ARF SUMOylation and levels.
  • MLN4924 treatment upregulates SUMO1, SUMO2, and UBC9 mRNA, globally increasing SUMOylation.
  • p14ARF is crucial for MLN4924-induced cytotoxicity in prostate cancer cells.

Conclusions:

  • p14ARF undergoes SUMOylation, critical for preventing ubiquitin-mediated degradation, despite lacking lysine residues.
  • A novel link is established between NEDDylation inhibition and enhanced SUMOylation.
  • p14ARF plays a significant role in the anti-cancer effects of NEDDylation inhibitors like MLN4924 in prostate cancer.

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