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Updated: Jun 16, 2025

Method for Measuring the Activity of Deubiquitinating Enzymes in Cell Lines and Tissue Samples
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The deubiquitinase USP9X regulates RIT1 protein abundance and oncogenic phenotypes

Amanda K Riley1,2, Michael Grant3, Aidan Snell3

  • 1Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA, USA.

Iscience
|August 20, 2024
PubMed

Insights

The deubiquitinase USP9X regulates RIT1 protein levels in lung cancer. Inhibiting USP9X decreases RIT1 abundance, resensitizing cancer cells to EGFR tyrosine kinase inhibitors.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • RIT1 is an understudied oncogene in lung cancer, structurally similar to RAS GTPases.
  • RIT1 activity regulation is not fully understood, but protein abundance is crucial.
  • USP9X was previously identified as a dependency in RIT1-mutant lung cancer cells.

Purpose of the Study:

  • To investigate the regulatory relationship between USP9X and RIT1.
  • To determine if USP9X deubiquitinase activity impacts RIT1 protein stability and abundance.
  • To assess the therapeutic potential of targeting USP9X in RIT1-driven lung cancer.

Main Methods:

  • Demonstrated RIT1 as a substrate of USP9X for both wild-type and mutant forms.
  • Utilized USP9X depletion to assess effects on RIT1 protein stability and abundance.
  • Evaluated the impact of USP9X depletion on sensitivity to EGFR tyrosine kinase inhibitors in vitro and in vivo.

Main Results:

  • USP9X deubiquitinase activity is essential for maintaining RIT1 protein stability and abundance.
  • Depletion of USP9X significantly reduces RIT1 protein levels.
  • USP9X inhibition resensitizes RIT1-driven lung cancer cells to EGFR tyrosine kinase inhibitors.

Conclusions:

  • USP9X is a key regulator of RIT1 protein abundance and stability.
  • Targeting USP9X represents a potential therapeutic strategy for RIT1-driven lung cancers.
  • This study expands the understanding of RIT1 oncogene regulation in lung cancer.
Keywords:
CancerMolecular biologyProteomics

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