title: The novel HSP90 inhibitor STA-1474 exhibits biologic activity against osteosarcoma cell lines.
abstract: Osteosarcoma (OSA), the most common malignant bone tumor in dogs and children, exhibits a similar clinical presentation and molecular biology in both species. Unfortunately, 30-40% of children and 90% of dogs still die of disease despite aggressive therapy. The purpose of this study was to test the biologic activity of a novel heat shock protein 90 (HSP90) inhibitor, STA-1474, against OSA. Canine and human OSA cell lines and normal canine osteoblasts were treated with STA-1474 and evaluated for effects on proliferation (CyQuant), apoptosis (Annexin V, PARP cleavage, caspase 3/7 activation) and known HSP90 client proteins. HSP90 was immunoprecipitated from normal and malignant osteoblasts and Western blotting for co-chaperones was performed. Mice bearing canine OSA xenografts were treated with STA-1474, and tumors samples were evaluated for caspase-3 activation and loss of p-Akt/Akt. Treatment with STA-1474 promoted loss of cell viability, inhibition of cell proliferation and induction of apoptosis in OSA cell lines. STA-1474 and its active metabolite STA-9090 also demonstrated increased potency compared to 17-AAG. STA-1474 exhibited selectivity for OSA cells versus normal canine osteoblasts, and HSP90 co-precipitated with co-chaperones p23 and Hop in canine OSA cells but not in normal canine osteoblasts. Furthermore, STA-1474 downregulated the expression of p-Met/Met, p-Akt/Akt and p-STAT3. Finally, STA-1474 induced tumor regression, caspase-3 activation and downregulation of p-Met/Met and p-Akt/Akt in OSA xenografts. Together, these data suggest that HSP90 represents a relevant target for therapeutic intervention in OSA.
authors: Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors: Jennifer K
authors: JK
authors: McCleese
authors: Misty D
authors: MD
authors: Bear
authors: Stacey L
authors: SL
authors: Fossey
authors: Robert M
authors: RM
authors: Mihalek
authors: Kevin P
authors: KP
authors: Foley
authors: Weiwen
authors: W
authors: Ying
authors: James
authors: J
authors: Barsoum
authors: Cheryl A
authors: CA
authors: London
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D004285:Dogs; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D007211:Indoles; D051379:Mice; D016513:Mice, SCID; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D018841:HSP90 Heat-Shock Proteins; D007211:Indoles; D050796:STAT3 Transcription Factor; D014230:Triazoles; C545221:STA-1474; D011065:Poly(ADP-ribose) Polymerases; D019009:Proto-Oncogene Proteins c-kit; D053148:Caspase 3