Andreadi Catherine K, Howells Lynne M, Atherfold Paul A, Manson Margaret M
Cancer Biomarkers and Prevention Group, Department of Cancer Studies, Biocenter, University of Leicester, Leicester LE1 7RH, UK.
Mol Pharmacol. 2006 Mar;69(3):1033-40. doi: 10.1124/mol.105.018374. Epub 2005 Dec 14.
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.
高诱导性酶血红素加氧酶-1（HO-1）可代谢血红素，从而保护多种细胞免受氧化应激和凋亡的影响。已有报道称癌症化学预防剂可使其上调，但其在转化细胞中的调节和功能尚不清楚。我们比较了两种膳食多酚姜黄素和表没食子儿茶素-3-没食子酸酯（EGCG）与内源性底物血红素对上皮细胞和内皮细胞中HO-1的诱导作用，并研究了其与凋亡的相关性。姜黄素或血红素（20μM）在5至24小时内诱导乳腺癌细胞中的HO-1。姜黄素（5 - 40μM）或血红素（5 - 100μM）以剂量依赖性方式诱导HO-1和核因子（红细胞衍生2）相关因子（Nrf2）的核水平。EGCG对乳腺癌细胞无作用，但在30μM时，它可诱导B淋巴细胞母细胞中Nrf2的核转位和HO-1表达。在所有情况下，用磷脂酰肌醇3-激酶（PI3K）抑制剂2-（4-吗啉基）-8-苯基-4H-1-苯并吡喃-4-酮（LY294002）或p38抑制剂4-（4-氟苯基）-2-（4-甲基亚磺酰基苯基）-5-（4-吡啶基）-1H-咪唑（SB203580）预处理可抑制诱导作用。核因子κB（NF-κB）-DNA结合抑制剂海伦内酯（20μM）也可阻止诱导作用。然而，渥曼青霉素无作用，表明PI3K未参与其中。姜黄素和血红素在野生型小鼠胚胎成纤维细胞（wt MEFs）和B-Raf（-/-）MEFs中也可有效诱导核Nrf2和HO-1，但在Nrf2（-/-）MEFs中则不能。然而，EGCG（5 - 20μM）仅在wt MEFs中诱导HO-1。结果表明，通过p38丝裂原活化蛋白激酶、NF-κB和Nrf2以及其他未鉴定分子的信号传导参与了血红素和两种多酚对HO-1的诱导作用，但细胞特异性因子也发挥作用，尤其是对于EGCG而言。姜黄素、EGCG或低浓度（5 - 10μM）的海伦内酯对HO-1的诱导并不能保护MDA-MB468乳腺癌细胞或B淋巴细胞母细胞免受凋亡。
