title: Involvement of Nrf2, p38, B-Raf, and nuclear factor-kappaB, but not phosphatidylinositol 3-kinase, in induction of hemeoxygenase-1 by dietary polyphenols.
abstract: The highly inducible enzyme, hemeoxygenase-1 (HO-1), metabolizes heme, thereby protecting a variety of cells against oxidative stress and apoptosis. Up-regulation by cancer chemopreventive agents has been reported, but its regulation and function in transformed cells are unclear. We compared induction by two dietary polyphenols, curcumin and epigallocatechin-3-gallate (EGCG), with that by the endogenous substrate hemin in epithelial and endothelial cells and examined the relevance to apoptosis. Curcumin or hemin (20 microM) induced HO-1 in breast cells from 5 to 24 h. Curcumin (5-40 microM) or hemin (5-100 microM) induced HO-1 and nuclear levels of nuclear factor (erythroid-derived 2)-related factor (Nrf2) in a dose-dependent manner. EGCG had no effect in breast cells, but at 30 microM, it induced nuclear translocation of Nrf2 and HO-1 expression in B-lymphoblasts. In all cases, induction was inhibited by pretreatment with the phosphatidylinositol 3-kinase (PI3K) inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) or the p38 inhibitor 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580). The nuclear factor-kappaB (NF-kappaB)-DNA binding inhibitor helenalin (20 microM) also prevented induction. However, wortmannin had no effect, suggesting that PI3K was not involved. Curcumin and hemin also induced nuclear Nrf2 and HO-1 effectively in wild-type mouse embryo fibroblasts (wt MEFs) and in B-Raf(-/-) MEFs but not in Nrf2(-/-) MEFs. However, EGCG (5-20 microM) induced HO-1 only in wt MEFs. Results suggest that signaling through p38 mitogen-activated protein kinase, NF-kappaB, and Nrf2 as well as other unidentified molecules is involved in HO-1 induction by hemin and both polyphenols, but cell-specific factors also play a role, particularly with respect to EGCG. Induction of HO-1 by curcumin, EGCG, or low concentrations (5-10 microM) of helenalin did not protect MDA-MB468 breast cells or B-lymphoblasts from apoptosis.
authors.affiliation: Cancer Biomarkers and Prevention Group, Department of Cancer Studies, Biocenter, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: Catherine K
authors.initials: CK
authors.lastname: Andreadi
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Howells
authors.forename: Paul A
authors.initials: PA
authors.lastname: Atherfold
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Manson
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D001940:Breast / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D003474:Curcumin / Q000494:pharmacology*; D004032:Diet; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D016328:NF-kappa B / Q000032:analysis / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D059808:Polyphenols; D012717:Sesquiterpenes / Q000494:pharmacology; D045789:Sesquiterpenes, Guaiane; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D002392:Catechin; D003474:Curcumin; D005419:Flavonoids; D051547:Heme Oxygenase-1; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; D010636:Phenols; D019869:Phosphatidylinositol 3-Kinases; D059808:Polyphenols; D012717:Sesquiterpenes; D045789:Sesquiterpenes, Guaiane; D048051:p38 Mitogen-Activated Protein Kinases; C495636:Nfe2l2 protein, mouse; C001329:helenalin; C045651:epigallocatechin gallate