title: Up-regulation of hypoxia inducible factor 1alpha by isoflurane in Hep3B cells.
abstract: BACKGROUND
  The volatile anesthetic isoflurane induces hypoxia inducible factor (HIF)-1-responsive genes heme oxygenase 1, inducible nitric oxide synthase, and vascular endothelial growth factor (VEGF) expression. Little is known about the extent to which induction of HIF-1alpha is affected by isoflurane.
  
  
  METHODS
  Hep3B cells were exposed to isoflurane at various concentrations (0.5-4%) or for different time periods (2-8 h) at 37 degrees C. HIF-1alpha gene expression and transcriptional activity, heme oxygenase 1, inducible nitric oxide synthase, and VEGF gene expression were quantified.
  
  
  RESULTS
  Isoflurane induced a time- and concentration-dependent increase in HIF-1alpha protein but not for HIF-1alpha messenger RNA (mRNA) in Hep3B cells. The maximal increase was induced by 2% isoflurane, and the cells incubated with 2% isoflurane for 4-8 h expressed the highest protein. Similarly, HIF-1alpha transcriptional activity was higher in Hep3B cells exposed to 2% isoflurane for 16 h than that in control cells. The combination of 2% isoflurane and desferrioxamine, a hypoxia mimetic, caused a higher level of HIF-1alpha protein than that induced by 2% isoflurane alone. Reoxygenation and inhibitor of proteasome pathway MG132 did not affect the isoflurane-induced HIF-1alpha protein accumulation. Cycloheximide, an inhibitor for protein synthesis, completely abrogated the induction of HIF-1alpha protein by isoflurane. Isoflurane stimulated heme oxygenase 1, inducible nitric oxide synthase, and VEGF mRNA expression in a concentration-dependent manner, and inactivation of HIF-1alpha attenuated the induction of VEGF mRNA by isoflurane.
  
  
  CONCLUSIONS
  Isoflurane can up-regulate HIF-1alpha and enhance HIF-1-responsive genes heme oxygenase 1, inducible nitric oxide synthase, and VEGF mRNA expression in Hep3B cells. The induction of HIF-1alpha by isoflurane does not involve protein degradation but depends on translation pathway.
authors.affiliation: Department of Anesthesiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, 1630 Dongfang Road, Shanghai 200127, China.
authors.forename: Qi Fang
authors.initials: QF
authors.lastname: Li
authors.forename: Xiang Rui
authors.initials: XR
authors.lastname: Wang
authors.forename: Yue Wu
authors.initials: YW
authors.lastname: Yang
authors.forename: Dian San
authors.initials: DS
authors.lastname: Su
mesh_terms: D000199:Actins / Q000096:biosynthesis; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis*; D007530:Isoflurane / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D000199:Actins; D018685:Anesthetics, Inhalation; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D007530:Isoflurane; D052247:Nitric Oxide Synthase Type II