title: Everolimus induces Met inactivation by disrupting the FKBP12/Met complex.
abstract: Inhibition of the mechanistic target of rapamycin (mTOR) is a promising treatment strategy for several cancer types. Rapamycin derivatives such as everolimus are allosteric mTOR inhibitors acting through interaction with the intracellular immunophilin FKBP12, a prolyl isomerase with different cellular functions. Although mTOR inhibitors have significantly improved survival of different cancer patients, resistance and lack of predictive factors of response remain unsolved issues. To elucidate the mechanisms of resistance to everolimus, we evaluated Met activation in everolimus-sensitive/resistant human cancer cells, in vitro and in vivo. Biochemical and computational analyses were performed. Everolimus-resistant cells were xenografted into mice (10/group) and studied for their response to everolimus and Met inhibitors. The statistical significance of the in vitro results was evaluated by Student's t test.Everolimus reduced Met phosphorylation in everolimus-sensitive cells. This event was mediated by the formation of a Met-FKBP12 complex, which in turn is disrupted by everolimus. Aberrant Met activation in everolimus-resistant cells and overexpression of wild-type/mutant Met caused everolimus resistance. Pharmacological inhibition and RNA silencing of Met are effective in condition of everolimus resistance (P<0.01). In mice xenografted with everolimus-resistant cells, the combination of everolimus with the Met inhibitor PHA665752 reduced tumor growth and induced a statistically significant survival advantage (combination vs control P=0.0005).FKBP12 binding is required for full Met activation and everolimus can inhibit Met. Persistent Met activation might sustain everolimus resistance. These results identify a novel everolimus mechanism of action and suggest the development of clinical strategies based on Met inhibitors in everolimus-resistant cancers.
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Raimondo
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: D'Amato
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Servetto
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Rosa
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Marciano
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Formisano
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Concetta
authors.initials: C
authors.lastname: Di Mauro
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Roberta Clara
authors.initials: RC
authors.lastname: Orsini
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Cascetta
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Ciciola
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: De Maio
authors.affiliation: Department of Oncology, University of Turin, Candiolo Cancer Institute - FPO IRCCS, Turin, Italy.
authors.forename: Maria Flavia
authors.initials: MF
authors.lastname: Di Renzo
authors.affiliation: DiSTABiF, Second University of Naples, Caserta, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Cosconati
authors.affiliation: Department of Pharmacy, University of Naples "Federico II", Naples, Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Bruno
authors.affiliation: Department of Pharmacy, University of Naples "Federico II", Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Randazzo
authors.affiliation: Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy.
authors.forename: Filomena
authors.initials: F
authors.lastname: Napolitano
authors.affiliation: Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy.
authors.forename: Nunzia
authors.initials: N
authors.lastname: Montuori
authors.affiliation: Department of Molecular Medicine and Medical Biotechnologies, University of Naples "Federico II", Naples, Italy.
authors.forename: Bianca Maria
authors.initials: BM
authors.lastname: Veneziani
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Sabino
authors.initials: S
authors.lastname: De Placido
authors.affiliation: Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bianco
mesh_terms: D000495:Allosteric Site; D000818:Animals; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D000068338:Everolimus / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010766:Phosphorylation; D034622:RNA Interference; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D000068338:Everolimus; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases; D058570:TOR Serine-Threonine Kinases
keywords: FKBP12; Met; everolimus; everolimus resistance