title: Activity of the estrogen-metabolizing enzyme cytochrome P450 1B1 influences the development of pulmonary arterial hypertension.
abstract: BACKGROUND
  Pulmonary arterial hypertension (PAH) is a hyperproliferative vascular disorder observed predominantly in women. Estrogen is a potent mitogen in human pulmonary artery smooth muscle cells and contributes to PAH in vivo; however, the mechanisms attributed to this causation remain obscure. Curiously, heightened expression of the estrogen-metabolizing enzyme cytochrome P450 1B1 (CYP1B1) is reported in idiopathic PAH and murine models of PAH.
  
  
  RESULTS
  Here, we investigated the putative pathogenic role of CYP1B1 in PAH. Quantitative reverse transcription-polymerase chain reaction, immunoblotting, and in situ analysis revealed that pulmonary CYP1B1 is increased in hypoxic PAH, hypoxic+SU5416 PAH, and human PAH and is highly expressed within the pulmonary vascular wall. PAH was assessed in mice via measurement of right ventricular hypertrophy, pulmonary vascular remodeling, and right ventricular systolic pressure. Hypoxic PAH was attenuated in CYP1B1(-/-) mice, and the potent CYP1B1 inhibitor 2,3',4,5'-tetramethoxystilbene (TMS; 3 mg · kg(-1) · d(-1) IP) significantly attenuated hypoxic PAH and hypoxic+SU5416 PAH in vivo. TMS also abolished estrogen-induced proliferation in human pulmonary artery smooth muscle cells and PAH-pulmonary artery smooth muscle cells. The estrogen metabolite 16α-hydroxyestrone provoked human pulmonary artery smooth muscle cell proliferation, and this mitogenic effect was greatly pronounced in PAH-pulmonary artery smooth muscle cells. ELISA analysis revealed that 16α-hydroxyestrone concentration was elevated in PAH, consistent with CYP1B1 overexpression and activity. Finally, administration of the CYP1B1 metabolite 16α-hydroxyestrone (1.5 mg · kg(-1) · d(-1) IP) caused the development of PAH in mice.
  
  
  CONCLUSIONS
  Increased CYP1B1-mediated estrogen metabolism promotes the development of PAH, likely via the formation of mitogens, including 16α-hydroxyestrone. Collectively, this study reveals a possible novel therapeutic target in clinical PAH.
authors.affiliation: Professor of Pulmonary Pharmacology, Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK. Mandy.maclean@glasgow.ac.uk
authors.forename: Kevin
authors.initials: K
authors.lastname: White
authors.forename: Anne Katrine
authors.initials: AK
authors.lastname: Johansen
authors.forename: Margaret
authors.initials: M
authors.lastname: Nilsen
authors.forename: Loredana
authors.initials: L
authors.lastname: Ciuclan
authors.forename: Emma
authors.initials: E
authors.lastname: Wallace
authors.forename: Leigh
authors.initials: L
authors.lastname: Paton
authors.forename: Annabel
authors.initials: A
authors.lastname: Campbell
authors.forename: Ian
authors.initials: I
authors.lastname: Morecroft
authors.forename: Lynn
authors.initials: L
authors.lastname: Loughlin
authors.forename: John D
authors.initials: JD
authors.lastname: McClure
authors.forename: Matthew
authors.initials: M
authors.lastname: Thomas
authors.forename: Kirsty M
authors.initials: KM
authors.lastname: Mair
authors.forename: Margaret R
authors.initials: MR
authors.lastname: MacLean
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015687:Cell Hypoxia; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D002908:Chronic Disease; D065633:Cytochrome P-450 CYP1B1; D004790:Enzyme Induction; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D006801:Humans; D006894:Hydroxyestrones / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000201:enzymology* / Q000209:etiology / Q000473:pathology; D017380:Hypertrophy, Right Ventricular / Q000201:enzymology; D000860:Hypoxia / Q000150:complications; D008168:Lung / Q000201:enzymology / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000473:pathology; D011651:Pulmonary Artery / Q000201:enzymology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013267:Stilbenes / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C440850:2,4,3',5'-tetramethoxystilbene; D004967:Estrogens; D006894:Hydroxyestrones; D013267:Stilbenes; C026702:16-hydroxyestrone; D004958:Estradiol; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; C585498:Cyp1b1 protein, mouse; D065633:Cytochrome P-450 CYP1B1