title: Beta-platelet-derived growth factor receptor mediates motility and growth of Ewing's sarcoma cells.
abstract: The Ewing's sarcoma family of tumors (ESFT) contain a translocation, t(11;22), which results in the novel oncogenic fusion protein EWS/FLI1. Platelet-derived growth factors (PDGF) and their receptors (PDGFR) are involved in the induction and proliferation of numerous solid tumors and are the potential candidates for novel targeted antitumor therapy. Since a relation was reported between PDGF-C and EWS/FLI1, we sought to characterize the PDGF signaling pathway in ESFT. Eight out of nine ESFT cell lines were found to express significant levels of beta-PDGFR. Interestingly, none of the tested cell lines expressed alpha-PDGFR, which is the receptor isotype required for PDGF-C binding. By immunohistochemical staining 47 of 52 (90.4%) archival tumor samples from patients with ESFT were positive for beta-PDGFR. ESFT cell lines were treated with PDGF-AA or PDGF-BB ligands to evaluate downstream signaling. Autophosphorylation of beta-PDGFR and tyrosine phosphorylation of PLC-gamma, PI3Kp85 and Shc were detected only in PDGF-BB-stimulated cells that express beta-PDGFR. Receptor function was further evaluated using chemotaxis assays that showed TC-32 cell migration towards PDGF-BB. A specific PDGFR kinase inhibitor AG1295 blocked beta-PDGFR activation, downstream signaling, growth in cell culture and chemotaxis of TC-32 cells. AG1295 also delayed tumor formation and prolonged survival in an ESFT animal model. We conclude that ESFT express beta-PDGFR and that this is a functional and potentially crucial signaling pathway. Therefore, beta-PDGFRs may provide a novel therapeutic target in ESFT that can be utilized to design better treatment modalities.
authors.affiliation: Lombardi Cancer Center, Georgetowm University Medical Center, Washington, DC 20057-1469, USA. au26@georgetown.edu
authors.forename: A
authors.initials: A
authors.lastname: Uren
authors.forename: M S
authors.initials: MS
authors.lastname: Merchant
authors.forename: C J
authors.initials: CJ
authors.lastname: Sun
authors.forename: M I
authors.initials: MI
authors.lastname: Vitolo
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Tsokos
authors.forename: P B
authors.initials: PB
authors.lastname: Illei
authors.forename: M
authors.initials: M
authors.lastname: Ladanyi
authors.forename: A
authors.initials: A
authors.lastname: Passaniti
authors.forename: C
authors.initials: C
authors.lastname: Mackall
authors.forename: J A
authors.initials: JA
authors.lastname: Toretsky
mesh_terms: D000818:Animals; D000077214:Becaplermin; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D058544:Class Ib Phosphatidylinositol 3-Kinase; D018450:Disease Progression; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009368:Neoplasm Transplantation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D020574:Proto-Oncogene Proteins c-sis; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D012512:Sarcoma, Ewing / Q000378:metabolism / Q000473:pathology*; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: C407689:6,7-dimethoxy-2-phenylquinoxaline; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009363:Neoplasm Proteins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D020032:Tyrphostins; C075278:platelet-derived growth factor A; D000077214:Becaplermin; D019869:Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; C546760:PIK3CG protein, human; C546764:Pik3cg protein, mouse; D020797:Receptor, Platelet-Derived Growth Factor beta; D010738:Type C Phospholipases; D051966:Phospholipase C gamma