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Updated: Apr 9, 2026
Testing Targeted Therapies in Cancer using Structural DNA Alteration Analysis and Patient-Derived Xenografts
Published on: July 25, 2020
Global analysis of cancer cell responses to USP9X inhibition
Philipp Schenk1,2, Shane M Devine1,2, Simon A Cobbold1,2
1The Walter and Eliza Hall Institute for Medical Research, Parkville, VIC, Australia.
Abstract:
The ubiquitin-specific protease (USP) USP9X is a human deubiquitinase (DUB) with a large number of described targets and cellular roles. In cancer, USP9X is found as an oncogene or as a tumour suppressor depending on context, and its utility as a target for cancer therapy remains unclear. We here describe WEHI-092, a piperazine-based USP9X-specific small-molecule inhibitor, which binds to a unique region in the USP9X Fingers-subdomain, distinct from known DUB-inhibitor binding sites. Using proteomics and ubiquitinomics, we show that USP9X targets distinct substrates compared to USP7, yet the substrate profile of USP9X varies significantly across cancer cell lines. We reveal a core set of 17 proteins commonly regulated by USP9X in most cell lines, which we consider as proximal biomarkers for USP9X inhibition. Consistent with proteomics, we show in unrelated cell lines that WEHI-092 treatment arrests the cell cycle in metaphase without inducing cell death. This explains growth suppression in long-term clonogenic assays in most cancer cell lines, and positions USP9X inhibitors as a new class of selective mitotic poisons.
Insights
Researchers developed WEHI-092, a novel USP9X inhibitor, revealing its potential as a mitotic poison. This targeted therapy arrests the cell cycle, offering a new strategy for cancer treatment by inhibiting USP9X (ubiquitin-specific protease 9, X-linked).
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- USP9X (ubiquitin-specific protease 9, X-linked) is a deubiquitinase with context-dependent roles in cancer, acting as either an oncogene or tumor suppressor.
- Its therapeutic utility in cancer remains incompletely understood, necessitating further investigation into targeted inhibition strategies.
Purpose of the Study:
- To characterize WEHI-092, a novel small-molecule inhibitor targeting USP9X.
- To elucidate the substrate specificity of USP9X and its role in cell cycle regulation across different cancer types.
Main Methods:
- Development and characterization of WEHI-092, a USP9X-specific inhibitor.
- Proteomics and ubiquitinomics to identify USP9X targets and compare them with USP7.
- Cell cycle analysis and clonogenic assays to assess the functional impact of WEHI-092 treatment.
Main Results:
- WEHI-092 binds to a unique site on USP9X, distinct from other deubiquitinase inhibitor binding pockets.
- USP9X regulates a core set of 17 proteins across various cancer cell lines, serving as potential biomarkers for inhibition.
- WEHI-092 treatment induces metaphase cell cycle arrest without causing cell death, leading to growth suppression.
Conclusions:
- USP9X inhibitors, like WEHI-092, represent a new class of selective mitotic poisons with potential applications in cancer therapy.
- Understanding USP9X substrate specificity and its role in cell cycle regulation is crucial for developing targeted cancer treatments.
