Synergistic effects of endothelin-1 (ET-1) and transforming growth factor alpha (TGF-alpha) or epidermal growth factor (EGF) on DNA replication and G1 to S phase transition.
The cooperative cell kinetic actions of ET-1 with TGF-alpha or EGF in normal rat kidney fibroblasts (NRK-49F) and KNRK cells (Kirsten MSV transformed) were analyzed by [3H]-thymidine incorporation assay and flow cytometry. A marked synergistic effect of TGF-alpha and ET-1 (or EGF and ET-1) on DNA synthesis and G1 to S transition was observed in NRK cells; 15-20% S for TGF-alpha and 12% S for ET-1 alone but 45-50% S in combination. There was no detectable effect on cell cycle kinetics by TGF-alpha (1 ng/ml) or EGF (1 ng/ml) plus ET-1 (1 ng/ml) in KNRK cells treated for 22 hours. Insulin, insulin-like growth factor I (IGF-I), fibroblast growth factor (FGF), platelet derived growth factor (PDGF), and transforming growth factor beta (TGF-beta) were also tested and found to have no significant synergistic effects on ET-1 actions. Our findings suggest that the combination of TGF-alpha (EGF) and ET-1 is an important part of an intricate network which coordinates progression of G1 to S phase in normal cells.
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Department of Biochemistry and Molecular Biology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock 72205.
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D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002461:Cell Line, Transformed; D004261:DNA Replication; D016232:Endothelins / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D051381:Rats; D016196:S Phase / Q000187:drug effects; D016211:Transforming Growth Factor alpha / Q000494:pharmacology*
D016232:Endothelins; D007328:Insulin; D016211:Transforming Growth Factor alpha; D004815:Epidermal Growth Factor