title: Simvastatin-induced heme oxygenase-1 increases apoptosis of Neuro 2A cells in response to glucose deprivation.
abstract: Heme oxygenase-1 (HO-1) has been suggested as an important mediator of the cholesterol-independent cytoprotection actions of statins, which may be of benefit for the treatment of degenerative neurological diseases and for reduction of infarct volume after cerebral ischemia. Overexpression of HO-1, however, has dual effects under oxidative stress, and the release of ferric iron from heme under these conditions may result in detrimental rather than cytoprotective effects. This study was designed to investigate the effect of simvastatin-induced HO-1 on Neuro 2A cells in response to glucose deprivation. We demonstrated that simvastatin induced a dose- and time-dependent upregulation of HO-1 protein expression in Neuro 2A cells. The induction of HO-1 after simvastatin treatment was mediated by nuclear factor erythroid 2-related factor 2 (Nrf2), which was expressed by Western blots of nuclear fractions and retarded complex formation in the electrophoretic mobility shift assay reaction. In addition, simvastatin activated the extracellular signal-regulated kinase and p38, but not the phosphorylation of c-Jun N-terminal kinase and Akt. Glucose deprivation in the cells pretreated with simvastatin induced more HO-1 expression, and the transcript could be decreased by small interfering RNA for Nrf2. This upregulation of HO-1 was significantly associated with increased apoptosis, manifested as expression at the protein level of 17-kDa cleaved caspase-3 and increased percentage of apoptotic cells shown by flow cytometry. The increased cleaved caspase-3 expression and percentage of apoptotic cells was significantly reduced by the HO inhibitor zinc protoporphyrin. Addition of the iron chelator desferrioxamine also resulted in blockade of the aggravated apoptosis, which implies that iron production from HO-1 activity may play an important role in the increased apoptosis in response to glucose deprivation in neuronal cells pretreated with simvastatin.
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung Memorial Hospital-Koahsiung Medical Center, Chang Gung Unversity College of Medicine, Taiwan. m93chinghua@gmail.com
authors.forename: Ching-Hua
authors.initials: CH
authors.lastname: Hsieh
authors.forename: Cheng-Shyuan
authors.initials: CS
authors.lastname: Rau
authors.forename: Min-Wei
authors.initials: MW
authors.lastname: Hsieh
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Seng-Feng
authors.initials: SF
authors.lastname: Jeng
authors.forename: Tsu-Hsiang
authors.initials: TH
authors.lastname: Lu
authors.forename: Shun-Sheng
authors.initials: SS
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000096:biosynthesis; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003676:Deferoxamine / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005947:Glucose / Q000172:deficiency*; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000633:toxicity*; D007150:Immunohistochemistry; D007502:Iron Chelating Agents / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D019821:Simvastatin / Q000633:toxicity*; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000096:biosynthesis
chemical_list: D004791:Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007502:Iron Chelating Agents; D011524:Protoporphyrins; D012333:RNA, Messenger; C017803:zinc protoporphyrin; D019821:Simvastatin; D051547:Heme Oxygenase-1; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3; D005947:Glucose; D003676:Deferoxamine