Dataset Information

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): Q Exactive

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Fernando Garcia

LAB HEAD: Fernando Garcia

PROVIDER: PXD040496 | Pride | 2023-06-14

REPOSITORIES: Pride

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			Action	DRS
	20180313_FG_8plex_USP9_F1.raw	Raw
	20180313_FG_8plex_USP9_F10.raw	Raw
	20180313_FG_8plex_USP9_F11.raw	Raw
	20180313_FG_8plex_USP9_F12.raw	Raw
	20180313_FG_8plex_USP9_F13.raw	Raw

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Deubiquitinase USP9X loss sensitizes renal cancer cells to mTOR inhibition.

Roldán-Romero Juan M JM Valdivia Carlos C Santos Maria M Lanillos Javier J Maroto Pablo P Anguera Georgia G Calsina Bruna B Martinez-Montes Angel A Monteagudo María M Mellid Sara S Leandro-García Luis J LJ Montero-Conde Cristina C Cascón Alberto A Roncador Giovanna G Coloma Javier J Robledo Mercedes M Rodriguez-Antona Cristina C

International journal of cancer 20230601 6

Mammalian target of rapamycin (mTOR) is a central regulator of mammalian metabolism and physiology. Aberrant hyperactivation of the mTOR pathway promotes tumor growth and metastasis, and can also promote tumor resistance to chemotherapy and cancer drugs; this makes mTOR an attractive cancer therapeutic target. mTOR inhibitors have been approved to treat cancer; however, the mechanisms underlying drug sensitivity remain poorly understood. Here, whole exome sequencing of three chromophobe renal ce ...[more]

PMID: 37260183

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Project description:Background There is much discussion in the cancer drug development community about how to incorporate molecular tools into early-stage clinical trials to assess target modulation, measure anti-tumor activity, and enrich the clinical trial population for patients who are more likely to benefit. Small, molecularly focused clinical studies offer the promise of the early definition of optimal biologic dose and patient population. Methods and Findings Based on preclinical evidence that phosphatase and tensin homolog deleted on Chromosome 10 (PTEN) loss sensitizes tumors to the inhibition of mammalian target of rapamycin (mTOR), we conducted a proof-of-concept Phase I neoadjuvant trial of rapamycin in patients with recurrent glioblastoma, whose tumors lacked expression of the tumor suppressor PTEN. We aimed to assess the safety profile of daily rapamycin in patients with glioma, define the dose of rapamycin required for mTOR inhibition in tumor tissue, and evaluate the antiproliferative activity of rapamycin in PTEN-deficient glioblastoma. Although intratumoral rapamycin concentrations that were sufficient to inhibit mTOR in vitro were achieved in all patients, the magnitude of mTOR inhibition in tumor cells (measured by reduced ribosomal S6 protein phosphorylation) varied substantially. Tumor cell proliferation (measured by Ki-67 staining) was dramatically reduced in seven of 14 patients after 1 wk of rapamycin treatment and was associated with the magnitude of mTOR inhibition (p = 0.0047, Fisher exact test) but not the intratumoral rapamycin concentration. Tumor cells harvested from the Ki-67 nonresponders retained sensitivity to rapamycin ex vivo, indicating that clinical resistance to biochemical mTOR inhibition was not cell-intrinsic. Rapamycin treatment led to Akt activation in seven patients, presumably due to loss of negative feedback, and this activation was associated with shorter time-to-progression during post-surgical maintenance rapamycin therapy (p < 0.05, Logrank test). Conclusions Rapamycin has anticancer activity in PTEN-deficient glioblastoma and warrants further clinical study alone or in combination with PI3K pathway inhibitors. The short-term treatment endpoints used in this neoadjuvant trial design identified the importance of monitoring target inhibition and negative feedback to guide future clinical development. Keywords: Comparative Genomic Hybridization