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Targeting Protein Neddylation to Inactivate Cullin-RING Ligases by Gossypol: A Lucky Hit or a New Start?

Qing Yu1,2,3, Yi Sun3

  • 1Department of Head and Neck Surgery, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Science, Hangzhou, Zhejiang, People's Republic of China.

Drug Design, Development and Therapy
|January 14, 2021
PubMed

Insights

Gossypol inhibits cullin neddylation, a key step for cancer-driving E3 ligases (CRLs). This natural product, combined with an MCL-1 inhibitor, shows synergistic anti-cancer effects, offering new therapeutic strategies.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cancer Research

Background:

  • Cullin-RING E3 ligases (CRLs) are crucial for protein degradation via the ubiquitin-proteasome system (UPS), accounting for ~20% of cellular protein turnover.
  • Overactive CRLs are implicated in numerous human cancers, making them significant therapeutic targets.
  • CRL activation depends on cullin neddylation, catalyzed by specific enzymes.

Purpose of the Study:

  • To identify small-molecule inhibitors of cullin neddylation using a high-throughput screening assay.
  • To investigate the anti-cancer potential of gossypol, a natural product, as a CRL inhibitor.
  • To evaluate the synergistic anti-proliferative effects of combining gossypol with existing cancer therapies.

Main Methods:

  • Development of an AlphaScreen-based in vitro assay for cullin neddylation.
  • High-throughput screening to identify neddylation inhibitors.
  • Biochemical assays to determine gossypol's mechanism of action on CRL1 and CRL5.
  • Cell-based assays to assess the anti-proliferative effects of gossypol and combination therapies.

Main Results:

  • Gossypol was identified as a potent inhibitor of cullin-1 and cullin-5 neddylation.
  • Gossypol directly binds to cullin-1/-5, inhibiting CRL1/5 ligase activity.
  • Inhibition of CRL1/5 leads to the accumulation of substrates MCL-1 and NOXA.
  • Combination of gossypol and an MCL-1 inhibitor demonstrated synergistic anti-proliferative activity in cancer cell lines.

Conclusions:

  • Gossypol exhibits novel activity as an inhibitor of Cullin-RING E3 ligases (CRL1 and CRL5).
  • Gossypol's ability to block cullin neddylation and induce substrate accumulation offers a new therapeutic avenue.
  • The combination of gossypol with MCL-1 inhibitors presents a promising strategy for enhanced anti-cancer efficacy.
Keywords:
anti-cancer drugcullin-RING E3 ligaseshigh-throughput screennatural productneddylationsmall-molecule inhibitors

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