Dominant negative PDGF-C inhibits growth of Ewing family tumor cell lines.
Nearly all cases of Ewing Family Tumors (EFT) harbor chimeric EWS/ETS transcription factors which are thought to aberrantly regulate transcriptional targets of phenotypic consequence. We have recently demonstrated that EWS/ETS proteins up-regulate platelet derived growth factor-C (PDGF-C), a novel transforming growth factor. To determine if PDGF-C signaling contributes to the malignant phenotype of EFT cell lines, we attempted to disrupt this presumed autocrine loop. AG1296, a PDGF receptor selective tyrosine kinase inhibitor, markedly inhibits anchorage-independent growth in an EFT cell line. To effect specific disruption, we have developed a dominant negative form of PDGF-C which is appropriately secreted and processed. This mutant has greatly reduced activity as a PDGF receptor agonist. When co-expressed with PDGF-C in a fibroblast transformation model, this dominant negative dramatically inhibits anchorage-independent growth. When this mutant is expressed in EFT cell lines, there is a similar reduction in anchorage-independent growth. This demonstrates that specific inhibition of PDGF-C signaling in EFT cell lines partially reverts their phenotype. These data support a significant role of PDGF-C in the biology of EFT. They also suggest that PDGF-C driven signaling may be a possible therapeutic target of more clinically relevant tyrosine kinase inhibitors.
Zwerner
Jeffrey P
JP
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35242, USA.
May
William A
WA
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D002455:Cell Division; D002460:Cell Line; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008222:Lymphokines; D051379:Mice; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000235:genetics* / Q000502:physiology*; D011233:Precipitin Tests; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D012512:Sarcoma, Ewing / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D004791:Enzyme Inhibitors; D008164:Luminescent Proteins; D008222:Lymphokines; D010982:Platelet-Derived Growth Factor; C411423:platelet-derived growth factor C; D049452:Green Fluorescent Proteins; D017479:Receptors, Platelet-Derived Growth Factor