Graves D T, Antoniades H N, Williams S R, Owen A J
Cancer Res. 1984 Jul;44(7):2966-70.
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.
研究了血小板衍生生长因子（PDGF）与人骨肉瘤细胞系MG-63的特异性相互作用。对125I-PDGF与MG-63细胞的结合进行Scatchard分析表明，每个细胞有32,000个特异性PDGF结合位点，解离常数（Kd）为2.4×10（-11）M。未标记的PDGF在浓度大于1 ng/ml时可阻断标记的PDGF与MG-63细胞的特异性结合。在检测MG-63膜囊泡的磷酸化时，PDGF可刺激一种蛋白（分子量为185,000的磷蛋白）的剂量依赖性磷酸化，该蛋白在1 M NaOH中稳定。在无PDGF的情况下，可观察到一种分子量为116,000的显著的碱稳定磷蛋白。PDGF还可刺激[3H]氨基异丁酸摄取、[3H]胸腺嘧啶核苷掺入和细胞增殖的剂量依赖性增加。在检测PDGF样因子的分泌时，MG-63条件性无血清培养基的促有丝分裂活性未被抗PDGF抗血清阻断。浓缩的MG-63条件培养基不能与125I-PDGF竞争二倍体成纤维细胞上的特异性受体位点。因此，MG-63骨肉瘤细胞具有功能性PDGF受体，且不分泌PDGF样有丝分裂原。
