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PDGF induces c‐myc mRNA expression in MG‐63 human osteosarcoma cells but does not stimulate cell replication
Author(s) -
Womer Richard B.,
Frick Kevin,
Mitchell Christopher D.,
Ross Alonzo H.,
Bishayee Subal,
Scher Charles D.
Publication year - 1987
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041320109
Subject(s) - platelet derived growth factor receptor , autophosphorylation , microbiology and biotechnology , cell culture , dna synthesis , receptor , biology , platelet derived growth factor , growth factor , cell growth , tyrosine phosphorylation , phosphorylation , biochemistry , dna , protein kinase a , genetics
The platelet‐derived growth factor (PDGF) modulated growth response of the MG‐63 human osteosarcoma cell line, which neither expresses c‐ sis mRNA nor secretes a PDGF analogue, was characterized. Scatchard analysis demonstrated that the MG‐63 cells have 23,000 receptors per cell with a kd of 5 × 10 −11 M. The receptor became phosphorylated, in a PDGF concentration‐dependent manner, when 32 P‐orthophosphate‐labeled cells were treated with PDGF for 3 h at 4°C. The phosphorylated receptor was identified by autora‐diography and gel electrophoresis after isolation of the 32 P‐labeled receptor using a solid‐phase monoclonal antibody directed against phosphotyrosine. Binding of the receptor to the antibody was inhibited by 5 mM phenyl phosphate, further suggesting that PDGF stimulated tyrosine‐specific receptor autophosphorylation. In addition, treatment of MG‐63 cells with PDGF for 3 h at 37°C induced a 7.5‐fold increase in c‐ myc mRNA accumulation as analyzed on Northern gels. However, MG‐63 cells grew equally well in either serum‐(which contains PDGF) or plasma‐(which does not) supplemented medium. Furthermore, PDGF did not stimulate DNA synthesis in growth arrested MG‐63 cells, nor did it potentiate DNA synthesis modulated by somatomedin C. Thus MG‐63 cells are a naturally occurring cell variant in which PDGF stimulates c‐ myc expression but does not modulate mitogenesis.