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Mol Oncol. 2014 Mar;8(2):323-36. doi: 10.1016/j.molonc.2013.12.005. Epub 2013 Dec 15.

Pre-clinical efficacy of PU-H71, a novel HSP90 inhibitor, alone and in combination with bortezomib in Ewing sarcoma.

Author information

  • 1Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA. Electronic address: ambatis@mskcc.org.
  • 2Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
  • 3Department of Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
  • 4Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
  • 5Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA.
  • 6Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. Electronic address: m-moore@ski.mskcc.org.

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.

Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

KEYWORDS:

Bortezomib; Ewing sarcoma; HSP90 inhibitor; PU-H71

PMID:
24388362
[PubMed - indexed for MEDLINE]
PMCID:
PMC3982393
Free PMC Article
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