title: Baicalein inhibition of hydrogen peroxide-induced apoptosis via ROS-dependent heme oxygenase 1 gene expression.
abstract: In the present study, baicalein (BE) but not its glycoside, baicalin (BI), induced heme oxygenase-1 (HO-1) gene expression at both the mRNA and protein levels, and the BE-induced HO-1 protein was blocked by adding cycloheximide (CHX) or actinomycin D (Act D). Activation of ERK, but not JNK or p38, proteins via induction of phosphorylation in accordance with increasing intracellular peroxide levels was detected in BE-treated RAW264.7 macrophages. The addition of the ERK inhibitor, PD98059, (but not the p38 inhibitor, SB203580, or the JNK inhibitor, SP600125) and the chemical antioxidant, N-acetyl cysteine (NAC), significantly reduced BE-induced HO-1 protein expression by respectively blocking ERK protein phosphorylation and intracellular peroxide production. Additionally, BE but not BI effectively protected RAW264.7 cells from hydrogen peroxide (H(2)O(2))-induced cytotoxicity, and the preventive effect was attenuated by the addition of the HO inhibitor, SnPP, and the ERK inhibitor, PD98059. H(2)O(2)-induced apoptotic events including hypodiploid cells, DNA fragmentation, activation of caspase 3 enzyme activity, and a loss in the mitochondrial membrane potential with the concomitant release of cytochrome c from mitochondria to the cytosol were suppressed by the addition of BE but not BI. Blocking HO-1 protein expression by the HO-1 antisense oligonucleotide attenuated the protective effect of BE against H(2)O(2)-induced apoptosis by suppressing HO-1 gene expression in macrophages. Overexpression of the HO-1 protein inhibited H(2)O(2)-induced apoptotic events such as DNA fragmentation and hypodiploid cells by reducing intracellular peroxide production induced by H(2)O(2), compared with those events in neo-control (neo-RAW264.7) cells. In addition, CO, but not bilirubin and biliverdin, addition inhibits H(2)O(2)-induced cytotoxicity in macrophages. It suggests that CO can be responsible for the protective effect associated with HO-1 overexpression. The notion of induction of HO-1 gene expression through a ROS-dependent manner suppressing H(2)O(2)-induced cell death is identified in the present study.
authors.affiliation: Graduate Institute of Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Hui-Yi
authors.initials: HY
authors.lastname: Lin
authors.forename: Shing-Chuan
authors.initials: SC
authors.lastname: Shen
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Lin
authors.forename: Liang-Yo
authors.initials: LY
authors.lastname: Yang
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology*; D002248:Carbon Monoxide / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D044950:Flavanones / Q000737:chemistry / Q000378:metabolism*; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008665:Metalloporphyrins / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D015394:Molecular Structure; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D011524:Protoporphyrins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D044950:Flavanones; D005419:Flavonoids; D008665:Metalloporphyrins; D016376:Oligonucleotides, Antisense; D016877:Oxidants; D011524:Protoporphyrins; D017382:Reactive Oxygen Species; C038044:baicalin; C006680:baicalein; D002248:Carbon Monoxide; D006861:Hydrogen Peroxide; C032628:tin protoporphyrin IX; D051547:Heme Oxygenase-1; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one