Cyclic AMP potentiates down regulation of epidermal growth factor receptors by platelet-derived growth factor |
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Authors: | E B Leof N E Olashaw W J Pledger E J O'Keefe |
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Affiliation: | 1. Department of Bacteriology and Immunology, University of North Carolina School of Medicine Chapel Hill, North Carolina 27514 USA;2. Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, North Carolina 27514 USA;3. Department of Dermatology, University of North Carolina School of Medicine Chapel Hill, North Carolina 27514 USA;4. Cancer Cell Biology Program, Cancer Research Center University of North Carolina School of Medicine Chapel Hill, North Carolina 27514 USA |
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Abstract: | Pretreatment of cells with platelet-derived growth factor (PDGF) has been shown to decrease binding sites for 125I-labelled epidermal growth factor (EGF) (1,2,3). Agents which elevate cellular cyclic AMP concentrations enhance this ability, and the change in EGF binding is inversely proportional to the elevation of cyclic AMP. In quiescent density arrested cells, the sensitivity of cells to down regulation of EGF receptors by PDGF is proportional to the cyclic AMP content of the cultures in three different cell lines. Agents which elevate cyclic AMP and which potentiate PDGF mediated heterologous down regulation of EGF receptors are able, like cholera toxin (3), to stimulate cells to synthesize DNA in defined medium in the absence of EGF. Down regulation of EGF receptors by PDGF in combination with agents elevating cyclic AMP effectively mimics the action of EGF. |
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Keywords: | Address Correspondence to: Edward J. O'Keefe Department of Dermatology 5016 Old Clinic Building University of North Carolina Chapel Hill North Carolina 27514. |
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