Deubiquitinase USP9X loss sensitizes renal cancer cells to mTOR inhibition

ABSTRACT: mTOR is a central regulator of mammalian metabolism and physiology. Aberrant hyperactivation of this pathway promotes tumor growth and metastasis and drives tumor resistance to chemotherapy and cancer drugs, making mTOR an attractive cancer therapeutic target. mTOR inhibitors have been approved to treat cancer, however, the basis for drug sensitivity remains poorly understood. Here, whole exome sequencing of three chromophobe renal cell carcinoma (chRCC) patients with exceptional mTOR inhibitor sensitivity, uncovered USP9X deubiquitinase as the only mutated gene shared by the tumors. The clonal characteristics of the mutations, revealed by studying multiple patients’ primary and metastatic samples along the years, together with the low USP9X mutation rate in unselected chRCC series, reinforced a causal link between USP9X and mTOR inhibitor sensitivity. Rapamycin treatment of USP9X depleted HeLa and renal cancer 786-O cells and the pharmacological inhibition of USP9X, confirmed a crucial role of this protein in the patients’ sensitivity to mTOR inhibition. As no direct effect of USP9X in mTORC1 was detected, we performed ubiquitylome analyses that identified p62 as a direct USP9X target. Increased p62 ubiquitination and an augmented rapamycin effect upon bortezomib treatment, together with p62 and LC3 immunofluorescence assays, suggested that dysregulated autophagy in USP9X depleted cells can synergize with mTOR inhibitors. In summary, here we show that USP9X constitutes a potential novel marker of sensitivity to mTOR inhibitors in chRCC patients and represents a clinically exploitable strategy that could increase sensitivity to these drugs

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Fernando Garcia  

LAB HEAD: Fernando Garcia

PROVIDER: PXD040496 | Pride | 2023-06-14

REPOSITORIES: Pride