title: Pre-clinical efficacy of PU-H71, a novel HSP90 inhibitor, alone and in combination with bortezomib in Ewing sarcoma.
abstract: Ewing sarcoma is characterized by multiple deregulated pathways that mediate cell survival and proliferation. Heat shock protein 90 (HSP90) is a critical component of the multi-chaperone complexes that regulate the disposition and activity of a large number of proteins involved in cell-signaling systems. We tested the efficacy of PU-H71, a novel HSP90 inhibitor in Ewing sarcoma cell lines, primary samples, benign mesenchymal stromal cells and hematopoietic stem cells. We performed cell cycle analysis, clonogenic assay, immunoblot analysis and reverse phase protein array in Ewing cell lines and in vivo experiments in NSG and nude mice using the A673 cell line. We noted a significant therapeutic window in the activity of PU-H71 against Ewing cell lines and benign cells. PU-H71 treatment resulted in G2/M phase arrest. Exposure to PU-H71 resulted in depletion of critical proteins including AKT, pERK, RAF-1, c-MYC, c-KIT, IGF1R, hTERT and EWS-FLI1 in Ewing cell lines. Our results indicated that Ewing sarcoma tumor growth and the metastatic burden were significantly reduced in the mice injected with PU-H71 compared to the control mice. We also investigated the effects of bortezomib, a proteasome inhibitor, alone and in combination with PU-H71 in Ewing sarcoma. Combination index (CI)-Fa plots and normalized isobolograms indicated synergism between PU-H71 and bortezomib. Ewing sarcoma xenografts were significantly inhibited when mice were treated with the combination compared to vehicle or either drug alone. This provides a strong rationale for clinical evaluation of PU-H71 alone and in combination with bortezomib in Ewing sarcoma.
authors.affiliation: Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA. Electronic address: ambatis@mskcc.org.
authors.forename: Srikanth R
authors.initials: SR
authors.lastname: Ambati
authors.affiliation: Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Eloisi Caldas
authors.initials: EC
authors.lastname: Lopes
authors.affiliation: Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Kohji
authors.initials: K
authors.lastname: Kosugi
authors.affiliation: Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Ullas
authors.initials: U
authors.lastname: Mony
authors.affiliation: Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Zehir
authors.affiliation: Department of Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Smit K
authors.initials: SK
authors.lastname: Shah
authors.affiliation: Department of Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Tony
authors.initials: T
authors.lastname: Taldone
authors.affiliation: Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Andre L
authors.initials: AL
authors.lastname: Moreira
authors.affiliation: Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Meyers
authors.affiliation: Department of Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Chiosis
authors.affiliation: Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. Electronic address: m-moore@ski.mskcc.org.
authors.forename: Malcolm A S
authors.initials: MA
authors.lastname: Moore
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000493:pharmacokinetics*; D052117:Benzodioxoles / Q000819:agonists / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D001897:Boronic Acids / Q000819:agonists / Q000494:pharmacology*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011687:Purines / Q000819:agonists / Q000494:pharmacology*; D011719:Pyrazines / Q000819:agonists / Q000494:pharmacology*; D012512:Sarcoma, Ewing / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
chemical_list: D052117:Benzodioxoles; D001897:Boronic Acids; D018841:HSP90 Heat-Shock Proteins; D011687:Purines; D011719:Pyrazines; C526550:9H-purine-9-propanamine, 6-amino-8-((6-iodo-1,3-benzodioxol-5-yl)thio)-N-(1-methylethyl)-; D000069286:Bortezomib
keywords: Bortezomib; Ewing sarcoma; HSP90 inhibitor; PU-H71