DNA synthesis in U‐2 OS human osteosarcoma cells is independent of PDGF binding to functional cell surface receptors

Abstract

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.

Characterization of a high‐molecular‐weight protein immunoprecipitated by platelet‐derived growth factor antisera

“…It has been demonstrated that U-2 0s human osteosarcoma cells possess PDGF receptors and that approximately one-third of these receptors are available for binding exogenous PDGF (Betsholtz et al, 1984;Graves et al, 1985;Richter and Graves, 1988). Experiments presented here indicate that the high-molecular-weight protein immunoprecipitated by PDGF antisera is the PDGF receptor and is based on the following observations.…”

Mesenchymal Cell Growth Factors

“…Richter and Graves have suggested that in some cases PDGF Oral Biology and Medicine expression may be a result of malignant development rather than the cause of it. 57 The production of PDGF by nontransformed cells emphasizes that PDGF production is not necessarily associated with malignancy. Endothelial cells, which are the first vascular cell type to appear during angiogenesis, produce PDGF.…”