Specific receptors for platelet-derived growth factor on cells derived from connective tissue and glia.

Abstract

A cellular receptor for [human] platelet-derived growth factor (PDGF) was demonstrated by incubation of 125I-labeled PDGF with human foreskin fibroblast cultures followed by liberation of cell-bound radioactivity with Triton X-100. The cellular binding of labeled PDGF in the presence of increasing amounts of unlabeled PDGF showed saturation; scatchard analysis of binding data indicated a single class of receptors having Kd = 1 .times. 10-9 M. The number of PDGF binding sites was .apprxeq. 3 .times. 105/cell. Labeled PDGF binding reached an apparent equilibrium after 3 h at 4.degree. C. At 37.degree. C, it passed maximum after 30 min and then decreased with time due to degradation of the tracer. A large excess of unlabeled PDGF reduced labeled PDGF binding by more than 90% whereas similar doses of epidermal growth factor, fibroblast growth factor, or insulin had no effect. Apparently PDGF did not share receptors with these factors. PDGF receptors were found on [human] skin fibroblasts, normal and malignant glial cells, [porcine] smooth muscle cells, and [mouse] 3T3 cells but not on epithelial-derived cells, [human] neuroblastoma cells, endothelial cells, or peripheral lymphocytes. As only the receptor-positive cells, i.e., the connective tissue- and glia-derived cells, are responsive to stimulation with PDGF, these findings imply a functional significance of the PDGF receptor. The cells used in this study included: human foreskin AG1523 cell; skin 911S cell; brain U-1508C6 cell; glioblastoma U-251 MG cell; osteosarcoma U-2 OS cell; osteosarcoma U-393 OS cell; thyroid cancer SW 1736 cell; squamous lung carcinoma U-1752 cell; epidermal cancer A-431 cell; neuroblastoma SH cell; umbilical vein HEC cell; blood lymphocytes; porcine renal artery cell; thyroid gland PTh 33 cell; and mouse embryo fibroblast 3T3 cell.