title: Resistance to sunitinib in renal clear cell carcinoma results from sequestration in lysosomes and inhibition of the autophagic flux.
abstract: Metastatic renal cell carcinomas (mRCC) are highly vascularized tumors that are a paradigm for the treatment with antiangiogenesis drugs targeting the vascular endothelial growth factor (VEGF) pathway. The available drugs increase the time to progression but are not curative and the patients eventually relapse. In this study we have focused our attention on the molecular mechanisms leading to resistance to sunitinib, the first line treatment of mRCC. Because of the anarchic vascularization of tumors the core of mRCC tumors receives only suboptimal concentrations of the drug. To mimic this in vivo situation, which is encountered in a neoadjuvant setting, we exposed sunitinib-sensitive mRCC cells to concentrations of sunitinib below the concentration of the drug that gives 50% inhibition of cell proliferation (IC50). At these concentrations, sunitinib accumulated in lysosomes, which downregulated the activity of the lysosomal protease CTSB (cathepsin B) and led to incomplete autophagic flux. Amino acid deprivation initiates autophagy enhanced sunitinib resistance through the amplification of autolysosome formation. Sunitinib stimulated the expression of ABCB1 (ATP-binding cassette, sub-family B [MDR/TAP], member 1), which participates in the accumulation of the drug in autolysosomes and favor its cellular efflux. Inhibition of this transporter by elacridar or the permeabilization of lysosome membranes with Leu-Leu-O-methyl (LLOM) resensitized mRCC cells that were resistant to concentrations of sunitinib superior to the IC50. Proteasome inhibitors also induced the death of resistant cells suggesting that the ubiquitin-proteasome system compensates inhibition of autophagy to maintain a cellular homeostasis. Based on our results we propose a new therapeutic approach combining sunitinib with molecules that prevent lysosomal accumulation or inhibit the proteasome.
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Sandy
authors: S
authors: Giuliano
authors: b Centre Scientifique de Monaco Biomedical Department, Monaco, Principality of Monaco.
authors: Yann
authors: Y
authors: Cormerais
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Maeva
authors: M
authors: Dufies
authors: b Centre Scientifique de Monaco Biomedical Department, Monaco, Principality of Monaco.
authors: Renaud
authors: R
authors: Grépin
authors: c University of Nice Sophia Antipolis; Center Méditerranéen de Médecine Moléculaire; INSERM ; Nice , France.
authors: Pascal
authors: P
authors: Colosetti
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Amine
authors: A
authors: Belaid
authors: d Centre Antoine Lacassagne ; Nice , France.
authors: Julien
authors: J
authors: Parola
authors: e University of Nice Sophia Antipolis; Institut de Chimie de Nice; UMR CNRS 7272 ; Nice , France.
authors: Anthony
authors: A
authors: Martin
authors: f University of Nice Sophia Antipolis; Center de Microscopie Appliquée ; Nice , France.
authors: Sandra
authors: S
authors: Lacas-Gervais
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Nathalie M
authors: NM
authors: Mazure
authors: e University of Nice Sophia Antipolis; Institut de Chimie de Nice; UMR CNRS 7272 ; Nice , France.
authors: Rachid
authors: R
authors: Benhida
authors: c University of Nice Sophia Antipolis; Center Méditerranéen de Médecine Moléculaire; INSERM ; Nice , France.
authors: Patrick
authors: P
authors: Auberger
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Baharia
authors: B
authors: Mograbi
authors: a University of Nice Sophia Antipolis, Institute for Research on Cancer and Aging of Nice; UMR CNRS 7284; INSERM ; Nice , France.
authors: Gilles
authors: G
authors: Pagès
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008247:Lysosomes / Q000187:drug effects*; D009364:Neoplasm Recurrence, Local / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D011758:Pyrroles / Q000494:pharmacology*; D000077210:Sunitinib; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D007211:Indoles; D011758:Pyrroles; D042461:Vascular Endothelial Growth Factor A; D000077210:Sunitinib
keywords: Leu-Leu-O-Methyl; angiogenesis; elacridar; lysosome; proteasome inhibitors; renal cell carcinoma; resistance; sunitinib