title: Essential role of calcium in vascular endothelial growth factor A-induced signaling: mechanism of the antiangiogenic effect of carboxyamidotriazole.
abstract: Vascular endothelial growth factor-A (VEGF-A) plays a major role in tumor angiogenesis and raises the concentration of intracellular free calcium ([Ca2+]i). Carboxyamidotriazole (CAI), an inhibitor of calcium influx and of angiogenesis, is under investigation as a tumoristatic agent. We studied the effect of CAI and the role of [Ca2+]i in VEGF-A signaling in human endothelial cells. VEGF-A induced a biphasic [Ca2+]i signal. VEGF-A increased the level of intracellular inositol 1,4,5-trisphosphate (IP3), which suggests that VEGF-A releases Ca2+ from IP3-sensitive stores and induces store-operated calcium influx. Reduction of either extracellular or intracellular free Ca2+ inhibited VEGF-A-induced proliferation. CAI inhibited IP3 formation, both phases of the calcium signal, nitric oxide (NO) release, and proliferation induced by VEGF-A. CAI prevented neither activation of VEGF receptor-2 (VEGFR-2) (KDR/Flk-1), phospholipase C-g, or mitogen-activated protein kinase (MAP kinase) nor translocation of nuclear factor of activated T cells (NFAT). We conclude that calcium signaling is necessary for VEGF-A-induced proliferation. MAP kinase activation occurs independently of [Ca2+]i but is not sufficient to induce proliferation in the absence of calcium signaling. Inhibition of the VEGF-A-induced [Ca2+]i signal and proliferation by CAI can be explained by inhibition of IP3 formation and may contribute to the antiangiogenic action of CAI. Calcium-dependent NO formation may represent a link between calcium signaling and proliferation.
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D050778:NFATC Transcription Factors; D009569:Nitric Oxide / Q000378:metabolism; D009687:Nuclear Proteins; D051966:Phospholipase C gamma; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; D007527:Isoenzymes; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D014230:Triazoles; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D014443:Tyrosine; C062058:carboxyamido-triazole; D015544:Inositol 1,4,5-Trisphosphate; D040301:Vascular Endothelial Growth Factor Receptor-2; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D002118:Calcium