The deubiquitinase USP9X regulates RIT1 protein abundance and oncogenic phenotypes

Amanda K Riley; Michael Grant; Aidan Snell; Elizabeth Cromwell; Athea Vichas; Sitapriya Moorthi; Callie Rominger; Shrikar P Modukuri; Anatoly Urisman; Pau Castel; Lixin Wan; Alice H Berger

doi:10.1016/j.isci.2024.110499

The deubiquitinase USP9X regulates RIT1 protein abundance and oncogenic phenotypes

iScience. 2024 Jul 14;27(8):110499. doi: 10.1016/j.isci.2024.110499. eCollection 2024 Aug 16.

Authors

Amanda K Riley^{1

2}, Michael Grant³, Aidan Snell³, Elizabeth Cromwell⁴, Athea Vichas¹, Sitapriya Moorthi¹, Callie Rominger¹, Shrikar P Modukuri^{3

5}, Anatoly Urisman⁶, Pau Castel⁷, Lixin Wan³, Alice H Berger^{1

8

9}

Affiliations

¹ Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA, USA.
² Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA.
³ Department of Molecular Oncology, Molecular Medicine Program, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA.
⁴ Preclinical Modeling Shared Resource, Fred Hutch Cancer Center, Seattle, WA, USA.
⁵ Department of Chemistry, University of South Florida, Tampa, FL, USA.
⁶ Department of Pathology, University of California, San Francisco, San Francisco, CA, USA.
⁷ Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA.
⁸ Herbold Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA.
⁹ Department of Genome Sciences, University of Washington, Seattle, WA, USA.

Abstract

RIT1 is a rare and understudied oncogene in lung cancer. Despite structural similarity to other RAS GTPase proteins such as KRAS, oncogenic RIT1 activity does not appear to be tightly regulated by nucleotide exchange or hydrolysis. Instead, there is a growing understanding that the protein abundance of RIT1 is important for its regulation and function. We previously identified the deubiquitinase USP9X as a RIT1 dependency in RIT1-mutant cells. Here, we demonstrate that both wild-type and mutant forms of RIT1 are substrates of USP9X. Depletion of USP9X leads to decreased RIT1 protein stability and abundance and resensitizes cells to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in vitro and in vivo. Our work expands upon the current understanding of RIT1 protein regulation and presents USP9X as a key regulator of RIT1-driven oncogenic phenotypes.

Keywords: Cancer; Molecular biology; Proteomics.

Abstract

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