title: Novel mechanism of action for hydralazine: induction of hypoxia-inducible factor-1alpha, vascular endothelial growth factor, and angiogenesis by inhibition of prolyl hydroxylases.
abstract: The vasodilator hydralazine, used clinically in cardiovascular therapy, relaxes arterial smooth muscle by inhibiting accumulation of intracellular free Ca2+ via an unidentified primary target. Collagen prolyl hydroxylase is a known target of hydralazine. We therefore investigated whether inhibition of other members of this enzyme family, namely the hypoxia-inducible factor (HIF)-regulating O2-dependent prolyl hydroxylase domain (PHD) enzymes, could represent a novel mechanism of action. Hydralazine induced rapid and transient expression of HIF-1alpha and downstream targets of HIF (endothelin-1, adrenomedullin, haem oxygenase 1, and vascular endothelial growth factor [VEGF]) in endothelial and smooth muscle cells and induced endothelial cell-specific proliferation. Hydralazine dose-dependently inhibited PHD activity and induced nonhydroxylated HIF-1alpha, evidence for HIF stabilization specifically by inhibition of PHD enzyme activity. In vivo, hydralazine induced HIF-1alpha and VEGF protein in tissue extracts and elevated plasma VEGF levels. In sponge angiogenesis assays, hydralazine increased stromal cell infiltration and blood vessel density versus control animals. Thus, hydralazine activates the HIF pathway through inhibition of PHD activity and initiates a pro-angiogenic phenotype. This represents a novel mechanism of action for hydralazine and presents HIF as a potential target for treatment of ischemic disease.
authors.affiliation: Cancer Research UK Molecular Oncology Laboratory, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Knowles
authors.forename: Ya-Min
authors.initials: YM
authors.lastname: Tian
authors.forename: David R
authors.initials: DR
authors.lastname: Mole
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Harris
mesh_terms: D053607:Adrenomedullin; D043925:Angiogenesis Inducing Agents / Q000494:pharmacology*; D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D002277:Carcinoma / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000473:pathology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D019332:Endothelin-1 / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000235:genetics; D051547:Heme Oxygenase-1; D006801:Humans; D006830:Hydralazine / Q000494:pharmacology*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020007:Implants, Experimental; D007680:Kidney Neoplasms / Q000473:pathology; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D043925:Angiogenesis Inducing Agents; D004268:DNA-Binding Proteins; D019332:Endothelin-1; D004791:Enzyme Inhibitors; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D009687:Nuclear Proteins; D010455:Peptides; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D014665:Vasodilator Agents; D053607:Adrenomedullin; D006830:Hydralazine; D011393:Procollagen-Proline Dioxygenase; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse