title: Vascular endothelial growth factor receptor-2-mediated mitogenesis is negatively regulated by vascular endothelial growth factor receptor-1 in tumor epithelial cells.
abstract: Vascular endothelial growth factor (VEGF) receptors are present on nonendothelial cells suggesting that VEGF may mediate nonendothelial effects during organogenesis and tumorigenesis. Here we show that VEGF receptor-1 (VEGFR-1) negatively regulates VEGFR-2-mediated proliferation via nitric oxide (NO) in an epithelial cancer cell line ECV304. Cell proliferation was assessed by [(3)H]thymidine incorporation, fluorescent-activated cell-sorting analysis, and cell number using a Coulter Counter. Total NO generated by the action of nitric oxide synthase was measured by Seivers NOA 280 Nitric Oxide Chemiluminescence Analyser. VEGF (1 ng/ml) stimulated DNA synthesis and increased ECV304 cell number in a manner that was inhibited by a neutralizing anti-VEGFR-2 antibody. In contrast, VEGF (50 ng/ml) stimulated NO release in a manner that was inhibited by functionally neutralizing anti-VEGFR-1 antibody. Blockage of the VEGFR-1 receptor signal with anti-VEGFR-1 stimulated DNA synthesis and increased cell number. Cell-cycle analysis showed that inhibition of VEGFR-1 increased the transition from G(1) to S phase whereas inhibition of VEGFR-2 blocked the VEGF-mediated transition from G(1) to S phase. Finally, the addition of NO donors suppressed both VEGF-mediated proliferation and the increase in growth after blockade of VEGFR-1. Conversely, inhibition of VEGF mediated NO release by nitric oxide synthase inhibitor, L-monomethyl-L-arginine, restored the mitogenic effect of VEGF. These findings identify a dose-dependent reciprocal regulatory mechanism for VEGF via its two receptors. It shows that VEGFR-1 induces cell cytostasis via NO and as such is a suitable target for molecular strategies suppressing tumorigenesis.
authors.affiliation: Department of Reproductive and Vascular Biology, Division of Reproductive and Child Health, The Medical School, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Dunk
authors.forename: A
authors.initials: A
authors.lastname: Ahmed
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology; D008934:Mitogens / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000276:immunology / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology / Q000502:physiology*; D017978:Receptors, Growth Factor / Q000276:immunology / Q000502:physiology*; D040262:Receptors, Vascular Endothelial Growth Factor; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D008222:Lymphokines; D008934:Mitogens; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; C110881:S-nitro-N-acetylpenicillamine; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D004247:DNA; D019001:Nitric Oxide Synthase; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D040281:Vascular Endothelial Growth Factor Receptor-1; D010396:Penicillamine