DNA synthesis in U-2 OS human osteosarcoma cells is independent of PDGF binding to functional cell surface receptors.
Previous studies have shown that suramin reveals specific PDGF binding sites on U-2 OS human osteosarcoma cells. Studies presented here indicate that U-2 OS cells pretreated with suramin internalize and degrade 125I-PDGF and respond to PDGF by increased tyrosine kinase activity and amino acid transport. However, DNA synthesis in these cells is not reduced by incubation with the PDGF blocking agent suramin and is not stimulated by exogenous PDGF. These data indicate that U-2 OS cells possess functional PDGF receptors but that high levels of DNA synthesis in these cells is unrelated to the binding of secreted PDGF to these cell surface receptors. Thus, it is unlikely that the PDGF mitogen produced by U-2 OS cells stimulates proliferation through an autocrine mechanism involving secretion and subsequent binding to PDGF receptors.
Richter
M R
MR
Department of Periodontics, University of Texas Health Science Center, San Antonio 78284.
Graves
D T
DT
D000596:Amino Acids / Q000378:metabolism; D002460:Cell Line; D004261:DNA Replication; D006801:Humans; D008970:Molecular Weight; D012516:Osteosarcoma / Q000235:genetics* / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor; D013498:Suramin / Q000494:pharmacology
D000596:Amino Acids; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D013498:Suramin; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor