Beta-platelet-derived Growth Factor Receptor Mediates Motility and Growth of Ewing's Sarcoma Cells

Oncogene. 2003 Apr 17;22(15):2334-42. doi: 10.1038/sj.onc.1206330.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Becaplermin
  • Bone Neoplasms / metabolism
  • Bone Neoplasms / pathology*
  • Cell Division / drug effects
  • Chemotaxis / drug effects
  • Class Ib Phosphatidylinositol 3-Kinase
  • Disease Progression
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Isoenzymes / metabolism
  • Mice
  • Mice, SCID
  • Neoplasm Proteins / biosynthesis
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / physiology*
  • Neoplasm Transplantation
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phospholipase C gamma
  • Phosphorylation / drug effects
  • Platelet-Derived Growth Factor / pharmacology*
  • Protein Processing, Post-Translational / drug effects
  • Proto-Oncogene Proteins c-sis
  • Receptor, Platelet-Derived Growth Factor beta / biosynthesis
  • Receptor, Platelet-Derived Growth Factor beta / drug effects
  • Receptor, Platelet-Derived Growth Factor beta / genetics
  • Receptor, Platelet-Derived Growth Factor beta / physiology*
  • Recombinant Proteins / pharmacology
  • Sarcoma, Ewing / metabolism
  • Sarcoma, Ewing / pathology*
  • Signal Transduction / drug effects
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / metabolism
  • Type C Phospholipases / metabolism
  • Tyrphostins / pharmacology

Substances

  • 6,7-dimethoxy-2-phenylquinoxaline
  • Enzyme Inhibitors
  • Isoenzymes
  • Neoplasm Proteins
  • Platelet-Derived Growth Factor
  • Proto-Oncogene Proteins c-sis
  • Recombinant Proteins
  • Tyrphostins
  • platelet-derived growth factor A
  • Becaplermin
  • Phosphatidylinositol 3-Kinases
  • Class Ib Phosphatidylinositol 3-Kinase
  • PIK3CG protein, human
  • Pik3cg protein, mouse
  • Receptor, Platelet-Derived Growth Factor beta
  • Type C Phospholipases
  • Phospholipase C gamma