title: Evidence for functional platelet-derived growth factor receptors on MG-63 human osteosarcoma cells.
abstract: The specific interaction of platelet-derived growth factor (PDGF) with the human osteosarcoma cell line MG-63 was studied. Scatchard analysis of 125I-PDGF binding to MG-63 cells indicated there were 32,000 specific PDGF-binding sites per cell with a Kd of 2.4 X 10(-11) M. Unlabeled PDGF blocked the specific binding of labeled PDGF to MG-63 cells at concentrations greater than 1 ng/ml. When assayed for phosphorylation of MG-63 membrane vesicles, PDGF was shown to stimulate a dose-dependent phosphorylation of a protein (phosphoprotein with a molecular weight of 185,000) which was stable in 1 M NaOH. In the absence of PDGF, a prominent alkali-stable phosphoprotein with a molecular weight of 116,000 was noted. PDGF also stimulated a dose-dependent increase in [3H]aminoisobutyric acid uptake, [3H]thymidine incorporation, and cell proliferation. When tested for secretion of PDGF-like factors, the mitogenic activity of MG-63-conditioned serum-free medium was not blocked by anti-PDGF antiserum. Concentrated MG-63-conditioned medium did not compete with 125I-PDGF for specific receptor sites on diploid fibroblasts. Therefore, MG-63 osteosarcoma cells have functional PDGF receptors and do not secrete PDGF-like mitogens.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004261:DNA Replication; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D012516:Osteosarcoma / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor
chemical_list: D000596:Amino Acids; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D017479:Receptors, Platelet-Derived Growth Factor