title: Statin-mediated cytoprotection of human vascular endothelial cells: a role for Kruppel-like factor 2-dependent induction of heme oxygenase-1.
abstract: BACKGROUND
  Heme oxygenase-1 (HO-1), by exerting anti-inflammatory, antiproliferative, antiapoptotic and antioxidant effects in the vasculature, protects against atherosclerosis and post-transplant vasculopathy. We noted the overlap between the effects of HO-1 and those attributed to 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). This led to an investigation of the role of HO-1 in statin-mediated cytoprotection in primary human endothelial cells (ECs), and the ability of Kruppel-like factor 2 (KLF2) to regulate HO-1 function.
  
  
  RESULTS
  Treatment of human umbilical vein and aortic ECs with atorvastatin significantly upregulated HO-1 promoter activity, mRNA expression and protein expression, increasing HO-1 enzymatic activity as shown by raised intracellular bilirubin IXalpha. This effect was indirect, dependent upon inhibition of HMG-CoA reductase and geranylgeranylation, and independent of nitric oxide or changes in mRNA stability. Atorvastatin protected ECs against the generation of reactive oxygen species and H(2)O(2)-induced injury. HO-1 inhibition, with small interfering RNA (siRNA) or zinc protoporphyrin IX, abrogated atorvastatin-mediated cytoprotection. Atorvastatin upregulated KLF2 expression, whereas KLF2 siRNA attenuated statin-induced HO-1 and its associated antioxidant cytoprotective effects. Iron chelation, adenoviral-mediated overexpression of ferritin or supplementation of culture media with biliverdin reversed the inhibitory effects of HO-1 and KLF2 siRNA, suggesting that bile pigments and ferritin mediate the antioxidant actions of statin-induced HO-1.
  
  
  CONCLUSIONS
  We have identified a novel link between KLF2 and HO-1 in human vascular ECs, demonstrating that atorvastatin-mediated HO-1 upregulation, and its associated antioxidant effect, is KLF2-dependent. The relationship between KLF2 and HO-1 is likely to represent an important component of the vasculoprotective profile of statins.
authors.affiliation: Bywaters Centre for Vascular Inflammation, Imperial College London, Hammersmith Hospital, Du Cane Road, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Ali
authors.forename: S S
authors.initials: SS
authors.lastname: Hamdulay
authors.forename: A R
authors.initials: AR
authors.lastname: Kinderlerer
authors.forename: J J
authors.initials: JJ
authors.lastname: Boyle
authors.forename: E A
authors.initials: EA
authors.lastname: Lidington
authors.forename: T
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: M P
authors.initials: MP
authors.lastname: Soares
authors.forename: D O
authors.initials: DO
authors.lastname: Haskard
authors.forename: A M
authors.initials: AM
authors.lastname: Randi
authors.forename: J C
authors.initials: JC
authors.lastname: Mason
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D000069059:Atorvastatin; D001663:Bilirubin / Q000378:metabolism; D001664:Biliverdine / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005293:Ferritins / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D006538:Heptanoic Acids / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007502:Iron Chelating Agents / Q000494:pharmacology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D008798:Mevalonic Acid / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D054876:Prenylation; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007502:Iron Chelating Agents; C096161:KLF2 protein, human; D051741:Kruppel-Like Transcription Factors; D016877:Oxidants; D011524:Protoporphyrins; D011758:Pyrroles; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D013729:Terpenes; C017803:zinc protoporphyrin; D005293:Ferritins; D000069059:Atorvastatin; D006861:Hydrogen Peroxide; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D001664:Biliverdine; D001663:Bilirubin; D008798:Mevalonic Acid