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Abstract
Cysteine residues on proteins play key roles in catalysis and regulation. These functional cysteines serve as active sites for nucleophilic and redox catalysis, sites of allosteric regulation, and metal-binding ligands on proteins from diverse classes including proteases, kinases, metabolic enzymes, and transcription factors. In this review, we focus on a few select examples that serve to highlight the multiple functions performed by cysteines, with an emphasis on cysteine-mediated protein activities implicated in cancer. The enhanced reactivity of functional cysteines renders them susceptible to modification by electrophilic species. Toward this end, we discuss recent advancements and future prospects for utilizing cysteine-reactive small molecules as drugs and imaging agents for the treatment and diagnosis of cancer.
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Affiliation(s)
- Nicholas J. Pace
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Eranthie Weerapana
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
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102
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Dinkova-Kostova AT. The Role of Sulfhydryl Reactivity of Small Molecules for the Activation of the KEAP1/NRF2 Pathway and the Heat Shock Response. SCIENTIFICA 2012; 2012:606104. [PMID: 24278719 PMCID: PMC3820647 DOI: 10.6064/2012/606104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/07/2012] [Indexed: 05/28/2023]
Abstract
The KEAP1/NRF2 pathway and the heat shock response are two essential cytoprotective mechanisms that allow adaptation and survival under conditions of oxidative, electrophilic, and thermal stress by regulating the expression of elaborate networks of genes with versatile protective functions. The two pathways are independently regulated by the transcription factor nuclear factor-erythroid 2 p45-related factor 2 (NRF2) and heat shock factor 1 (HSF1), respectively. The activity of these transcriptional master regulators increases during conditions of stress and also upon encounter of small molecules (inducers), both naturally occurring as well as synthetically produced. Inducers have a common chemical property: the ability to react with sulfhydryl groups. The protein targets of such sulfhydryl-reactive compounds are equipped with highly reactive cysteine residues, which serve as sensors for inducers. The initial cysteine-sensed signal is further relayed to affect the expression of large networks of genes, which in turn can ultimately influence complex cell fate decisions such as life and death. The paper summarizes the multiple lines of experimental evidence demonstrating that the reactivity with sulfhydryl groups is a major determinant of the mechanism of action of small molecule dual activators of the KEAP1/NRF2 pathway and the heat shock response.
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Affiliation(s)
- Albena T. Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cancer Research, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, James Arrott Drive, Dundee DD1 9SY, UK
- Department of Pharmacology and Molecular Sciences and Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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103
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Yuan Y, Ji L, Luo L, Lu J, Ma X, Ma Z, Chen Z. Quinone reductase (QR) inducers from Andrographis paniculata and identification of molecular target of andrographolide. Fitoterapia 2012; 83:1506-13. [DOI: 10.1016/j.fitote.2012.08.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 08/24/2012] [Accepted: 08/24/2012] [Indexed: 10/27/2022]
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104
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Melega S, Canistro D, Pagnotta E, Iori R, Sapone A, Paolini M. Effect of sprout extract from Tuscan black cabbage on xenobiotic-metabolizing and antioxidant enzymes in rat liver. Mutat Res 2012. [PMID: 23183052 DOI: 10.1016/j.mrgentox.2012.10.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In recent years, health protection by natural products has received considerable attention, and a multitude of nutraceuticals have been characterized and their use promoted. Dietary consumption of Cruciferous vegetables, rich in glucosinolates (GLs), and their myrosinase-mediated hydrolysis products isothiocyanates (ITCs), were associated with reductions in cancer risk. In this study, the chemo-preventive potential of sprout extract of Tuscan black cabbage (Brassica oleracea L. var. acephala subvar. Laciniata L.) (TBCSE), through modulation of the xenobiotic-metabolizing apparatus and antioxidant defenses, was investigated in Sprague-Dawley rat liver. TBCSE was administered either orally or intraperitoneally, at a dose of 15mg/kg b.w., daily for twenty-one consecutive days, in the absence or presence of exogenous myrosinase, β-thioglucoside glucohydrolase (MYR), to distinguish the effects of intact GLs and ITCs, in the context of the extract. A complex, mild modulation pattern of P450-related monooxygenases was observed, mainly regarding CYP content (up to 36% loss), NADPH cytochrome (P450) c-reductase (up to 26% loss), CYP1A1 (up to 23% loss), but no evident distinctions among the effects of the extracts containing GLs or ITCs, were noted. In contrast, significant inductions of phase-II enzymes (up to 107% for UDP-glucuronosyl-transferase, and up to 36% for glutathione S-transferase) were recorded only where the GLs to ITCs conversion had occurred. A boosting effect on catalase (up to 38%), NAD(P)H:quinone reductase (up to 70%), glutathione reductase and glutathione peroxidase (up to 10%) was also recorded, suggesting an indirect antioxidant capacity of the extracts. Overall, the general phase-I inhibition, together with the up-regulation of detoxifying phase-II and antioxidant enzymes, exerted by the TBCSE supplementation, seem to be in line with the classical chemopreventive theory, but whether the addition of exogenous MYR is relevant, still remains to be clarified. These results are in support of the potential health-promoting application of TBCSE, as a nutraceutical.
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Affiliation(s)
- Simone Melega
- Department of Pharmacy and Biotechnology, Molecular Toxicology Unit, Alma Mater Studiorum-University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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105
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Melchini A, Needs PW, Mithen RF, Traka MH. Enhanced in vitro biological activity of synthetic 2-(2-pyridyl) ethyl isothiocyanate compared to natural 4-(methylsulfinyl) butyl isothiocyanate. J Med Chem 2012; 55:9682-92. [PMID: 22998472 DOI: 10.1021/jm300929v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dietary isothiocyanates (ITC) derived from cruciferous vegetables have been shown to have numerous biological effects consistent with chemoprotective activity. In this study we synthesized a novel ITC, 2-(2-pyridyl) ethyl ITC (PY-ITC), and assessed its chemopreventive ability in comparison to sulforaphane (SF), the ITC derived from broccoli. PY-ITC suppressed cancerous cell growth and proliferation at lower concentrations than SF and was more potent at inducing p21 protein. Through the use of whole genome arrays we demonstrate that prostate cells exposed to PY-ITC or SF have similar biological response, albeit PY-ITC alters a greater number of genes, and to a greater extent. In the presence of a phosphatidylinositol-3-kinase (PI3K) inhibitor PY-ITC had a more pronounced effect on gene expression, emphasizing the important role of PI3K/AKT signaling in mediating the chemopreventive effects of ITCs. These results highlight the importance of the ITC side chain in bioactivity.
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Affiliation(s)
- Antonietta Melchini
- Food & Health Programme, Institute of Food Research , Norwich Research Park, NR4 7UA United Kingdom
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106
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Thompson AD, Dugan A, Gestwicki JE, Mapp AK. Fine-tuning multiprotein complexes using small molecules. ACS Chem Biol 2012; 7:1311-20. [PMID: 22725693 DOI: 10.1021/cb300255p] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Multiprotein complexes such as the transcriptional machinery, signaling hubs, and protein folding machines are typically composed of at least one enzyme combined with multiple non-enzymes. Often the components of these complexes are incorporated in a combinatorial manner, in which the ultimate composition of the system helps dictate the type, location, or duration of cellular activities. Although drugs and chemical probes have traditionally targeted the enzyme components, emerging strategies call for controlling the function of protein complexes by modulation of protein-protein interactions (PPIs). However, the challenges of targeting PPIs have been well documented, and the diversity of PPIs makes a "one-size-fits-all" solution highly unlikely. These hurdles are particularly daunting for PPIs that encompass large buried surface areas and those with weak affinities. In this Review, we discuss lessons from natural systems, in which allostery and other mechanisms are used to overcome the challenge of regulating the most difficult PPIs. These systems may provide a blueprint for identifying small molecules that target challenging PPIs and affecting molecular decision-making within multiprotein systems.
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Affiliation(s)
- Andrea D. Thompson
- Program
in Chemical Biology, ‡Departments of Pathology and Biological Chemistry and the Life Sciences
Institute, and §Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Amanda Dugan
- Program
in Chemical Biology, ‡Departments of Pathology and Biological Chemistry and the Life Sciences
Institute, and §Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jason E. Gestwicki
- Program
in Chemical Biology, ‡Departments of Pathology and Biological Chemistry and the Life Sciences
Institute, and §Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Anna K. Mapp
- Program
in Chemical Biology, ‡Departments of Pathology and Biological Chemistry and the Life Sciences
Institute, and §Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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107
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Kalo E, Kogan-Sakin I, Solomon H, Bar-Nathan E, Shay M, Shetzer Y, Dekel E, Goldfinger N, Buganim Y, Stambolsky P, Goldstein I, Madar S, Rotter V. Mutant p53R273H attenuates the expression of phase 2 detoxifying enzymes and promotes the survival of cells with high levels of reactive oxygen species. J Cell Sci 2012; 125:5578-86. [PMID: 22899716 DOI: 10.1242/jcs.106815] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Uncontrolled accumulation of reactive oxygen species (ROS) causes oxidative stress and induces harmful effects. Both high ROS levels and p53 mutations are frequent in human cancer. Mutant p53 forms are known to actively promote malignant growth. However, no mechanistic details are known about the contribution of mutant p53 to excessive ROS accumulation in cancer cells. Herein, we examine the effect of p53(R273H), a commonly occurring mutated p53 form, on the expression of phase 2 ROS-detoxifying enzymes and on the ability of cells to readopt a reducing environment after exposure to oxidative stress. Our data suggest that p53(R273H) mutant interferes with the normal response of human cells to oxidative stress. We show here that, upon oxidative stress, mutant p53(R273H) attenuates the activation and function of NF-E2-related factor 2 (NRF2), a transcription factor that induces the antioxidant response. This effect of mutant p53 is manifested by decreased expression of phase 2 detoxifying enzymes NQO1 and HO-1 and high ROS levels. These findings were observed in several human cancer cell lines, highlighting the general nature of this phenomenon. The failure of p53(R273H) mutant-expressing cells to restore a reducing oxidative environment was accompanied by increased survival, a known consequence of mutant p53 expression. These activities are attributable to mutant p53(R273H) gain of function and might underlie its well-documented oncogenic nature in human cancer.
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Affiliation(s)
- Eyal Kalo
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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108
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Makia NL, Amunom I, Falkner KC, Conklin DJ, Surapureddi S, Goldstein JA, Prough RA. Activator protein-1 regulation of murine aldehyde dehydrogenase 1a1. Mol Pharmacol 2012; 82:601-13. [PMID: 22740640 DOI: 10.1124/mol.112.078147] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Previously we demonstrated that aldehyde dehydrogenase (ALDH) 1a1 is the major ALDH expressed in mouse liver and is an effective catalyst in metabolism of lipid aldehydes. Quantitative real-time polymerase chain reaction analysis revealed a ≈2.5- to 3-fold induction of the hepatic ALDH1A1 mRNA in mice administered either acrolein (5 mg/kg acrolein p.o.) or butylated hydroxylanisole (BHA) (0.45% in the diet) and of cytosolic NAD⁺-dependent ALDH activity. We observed ≈2-fold increases in ALDH1A1 mRNA levels in both Nrf2⁺/⁺ and Nrf2⁻/⁻ mice treated with BHA compared with controls, suggesting that BHA-induced expression is independent of nuclear factor E2-related factor 2 (Nrf2). The levels of activator protein-1 (AP-1) mRNA and protein, as well as the amount of phosphorylated c-Jun were significantly increased in mouse liver or Hepa1c1c7 cells treated with either BHA or acrolein. With use of luciferase reporters containing the 5'-flanking sequence of Aldh1a1 (-1963/+27), overexpression of c-Jun resulted in an ≈4-fold induction in luciferase activity, suggesting that c-Jun transactivates the Aldh1a1 promoter as a homodimer and not as a c-Jun/c-Fos heterodimer. Promoter deletion and mutagenesis analyses demonstrated that the AP-1 site at position -758 and possibly -1069 relative to the transcription start site was responsible for c-Jun-mediated transactivation. Electrophoretic mobility shift assay analysis with antibodies against c-Jun and c-Fos showed that c-Jun binds to the proximal AP-1 site at position -758 but not at -1069. Recruitment of c-Jun to this proximal AP-1 site by BHA was confirmed by chromatin immunoprecipitation analysis, indicating that recruitment of c-Jun to the mouse Aldh1a1 gene promoter results in increased transcription. This mode of regulation of an ALDH has not been described before.
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Affiliation(s)
- N L Makia
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky, USA
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109
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La Marca M, Beffy P, Della Croce C, Gervasi PG, Iori R, Puccinelli E, Longo V. Structural influence of isothiocyanates on expression of cytochrome P450, phase II enzymes, and activation of Nrf2 in primary rat hepatocytes. Food Chem Toxicol 2012; 50:2822-30. [PMID: 22664424 DOI: 10.1016/j.fct.2012.05.044] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 05/18/2012] [Accepted: 05/19/2012] [Indexed: 11/25/2022]
Abstract
Primary cultures of rat hepatocytes were used to investigate whether and how eight isothiocynates (ITCs) with different chemical structures (the aromatic benzyl, 4-hydroxybenzyl, phenethyl isothiocyanates and the aliphatic allyl, napin, iberin, raphasatin isothiocyanates and sulforaphane) derived from hydrolyzed glucosinolates, were able to modulate cytochrome P450 (CYP) and antioxidant/detoxifying enzymes and to activate the Nrf2 transcription factor. The aromatic ITCs at 40 μM markedly increased the transcription of CYP1A1 and 1A2 mRNA and increased the associated ethoxyresorufin O-deethylase (EROD) activity after 24 h of treatment. By contrast, the aliphatic ITCs (40 μM) decreased CYP1A1 and 1A2 transcription, together with the corresponding EROD activity. The same treatment also caused a striking and similar transcriptional repression of CYP3A2, and the corresponding benzyloxyquinoline debenzylase activity in response to all the ITCs tested. In the same culture conditions, most of the antioxidant/detoxifying enzymes were significantly up-regulated by 40μM ITCs. In particular, NAD(P)H:quinone oxidoreductase and heme oxygenase-1 were induced, although to different levels, at transcriptional, protein and/or activity levels by all the ITCs. However, glutathione S-transferase activity was not induced by the allyl, benzyl, and 4-hydroxybenzyl ITCs, glutathione reductase activity was not induced by benzyl, and 4-hydroxybenzyl ITCs and catalase activity was not induced by allyl ITC. As for the Nrf2 transcription factor, a partial translocation of its protein from the cytosol to the nucleus was revealed by immunoblotting after 1h of treatment for all the ITCs tested. The ability of ITCs to induce the antioxidant and phase II enzymes did not appear to be affected by their hydrophilicity or other structural factors. Taken together, these results show that these ITCs are effective inducers of ARE/Nrf2-regulated antioxidant/detoxifying genes and have the potential to inhibit, at least in rat liver, the bioactivation of carcinogens dependent on CYP3A2 catalysis.
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Affiliation(s)
- M La Marca
- Istituto di Biologia e Biotecnologia Agraria, CNR, via Moruzzi 1, 56100 Pisa, Italy
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110
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Canistro D, Barillari J, Melega S, Sapone A, Iori R, Speroni E, Paolini M. Black cabbage seed extract affects rat Cyp-mediated biotransformation: organ and sex related differences. Food Chem Toxicol 2012; 50:2612-21. [PMID: 22634264 DOI: 10.1016/j.fct.2012.05.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/13/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
Abstract
Brassicaceae are widely consumed in many parts of the world and their dietary intake has been associated with cancer risk reduction. Extracts and metabolites derived from cruciferous vegetables have thus gained popularity as potential cancer chemopreventive agents. We have previously found, unexpectly, that glucoraphanin, the most extensively present glucosinolate in these vegetables, is a potent mutagen bioactivating Phase-I enzyme inducer. In the present study, the influence of black cabbage seed extract, rich in glucoraphanin, was investigated on Phase-I enzymes in different organs of male or female rats. Oral seed extract injection at 120 or 240 mg/kg b.w. for one or four consecutive days, significantly affected various cytochrome P450 (CYP) -linked monooxygenases in a complex way being the lung the most responsive organ (in males, up to ∼2600% increase for CYP2B1/2 isoform and ∼96% loss for CYP1A1, CYP3A1/2). These findings indicate that the extract may strongly enhance and/or suppress rat xenobiotic biotransformation pathways and that caution should be paid to the possible influence on human metabolism. These data suggest an overall evaluation of the balance between beneficial vs. possible adverse effects for each agent, even if of natural origin, prior to routinely, preventive mass use.
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Affiliation(s)
- Donatella Canistro
- Department of Pharmacology, Molecular Toxicology Unit, Alma Mater Studiorum-University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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111
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Magesh S, Chen Y, Hu L. Small molecule modulators of Keap1-Nrf2-ARE pathway as potential preventive and therapeutic agents. Med Res Rev 2012; 32:687-726. [PMID: 22549716 DOI: 10.1002/med.21257] [Citation(s) in RCA: 586] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elements (ARE) pathway represents one of the most important cellular defense mechanisms against oxidative stress and xenobiotic damage. Activation of Nrf2 signaling induces the transcriptional regulation of ARE-dependent expression of various detoxifying and antioxidant defense enzymes and proteins. Keap1-Nrf2-ARE signaling has become an attractive target for the prevention and treatment of oxidative stress-related diseases and conditions including cancer, neurodegenerative, cardiovascular, metabolic, and inflammatory diseases. Over the last few decades, numerous Nrf2 inducers have been developed and some of them are currently undergoing clinical trials. Recently, overactivation of Nrf2 has been implicated in cancer progression as well as in drug resistance to cancer chemotherapy. Thus, Nrf2 inhibitors could potentially be used to improve the effectiveness of cancer therapy. Herein, we review the signaling mechanism of Keap1-Nrf2-ARE pathway, its disease relevance, and currently known classes of small molecule modulators. We also discuss several aspects of Keap1-Nrf2 interaction, Nrf2-based peptide inhibitor design, and the screening assays currently used for the discovery of direct inhibitors of Keap1-Nrf2 interaction.
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Affiliation(s)
- Sadagopan Magesh
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA
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112
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Chen H, Lv L, Soroka D, Warin RF, Parks TA, Hu Y, Zhu Y, Chen X, Sang S. Metabolism of [6]-shogaol in mice and in cancer cells. Drug Metab Dispos 2012; 40:742-53. [PMID: 22246389 PMCID: PMC3310425 DOI: 10.1124/dmd.111.043331] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 01/13/2012] [Indexed: 11/22/2022] Open
Abstract
Ginger has received extensive attention because of its antioxidant, anti-inflammatory, and antitumor activities. However, the metabolic fate of its major components is still unclear. In the present study, the metabolism of [6]-shogaol, one of the major active components in ginger, was examined for the first time in mice and in cancer cells. Thirteen metabolites were detected and identified, seven of which were purified from fecal samples collected from [6]-shogaol-treated mice. Their structures were elucidated as 1-(4'-hydroxy-3'-methoxyphenyl)-4-decen-3-ol (M6), 5-methoxy-1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-one (M7), 3',4'-dihydroxyphenyl-decan-3-one (M8), 1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-ol (M9), 5-methylthio-1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-one (M10), 1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-one (M11), and 5-methylthio-1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-ol (M12) on the basis of detailed analysis of their (1)H, (13)C, and two-dimensional NMR data. The rest of the metabolites were identified as 5-cysteinyl-M6 (M1), 5-cysteinyl-[6]-shogaol (M2), 5-cysteinylglycinyl-M6 (M3), 5-N-acetylcysteinyl-M6 (M4), 5-N-acetylcysteinyl-[6]-shogaol (M5), and 5-glutathiol-[6]-shogaol (M13) by analysis of the MS(n) (n = 1-3) spectra and comparison to authentic standards. Among the metabolites, M1 through M5, M10, M12, and M13 were identified as the thiol conjugates of [6]-shogaol and its metabolite M6. M9 and M11 were identified as the major metabolites in four different cancer cell lines (HCT-116, HT-29, H-1299, and CL-13), and M13 was detected as a major metabolite in HCT-116 human colon cancer cells. We further showed that M9 and M11 are bioactive compounds that can inhibit cancer cell growth and induce apoptosis in human cancer cells. Our results suggest that 1) [6]-shogaol is extensively metabolized in these two models, 2) its metabolites are bioactive compounds, and 3) the mercapturic acid pathway is one of the major biotransformation pathways of [6]-shogaol.
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Affiliation(s)
- Huadong Chen
- Center for Excellence in Post-Harvest Technologies, North Carolina Agricultural and Technical State University, North Carolina Research Campus, 500 Laureate Way, Kannapolis, NC 28081, USA
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113
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Zanichelli F, Capasso S, Cipollaro M, Pagnotta E, Cartenì M, Casale F, Iori R, Galderisi U. Dose-dependent effects of R-sulforaphane isothiocyanate on the biology of human mesenchymal stem cells, at dietary amounts, it promotes cell proliferation and reduces senescence and apoptosis, while at anti-cancer drug doses, it has a cytotoxic effect. AGE (DORDRECHT, NETHERLANDS) 2012; 34:281-93. [PMID: 21465338 PMCID: PMC3312628 DOI: 10.1007/s11357-011-9231-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 03/02/2011] [Indexed: 04/16/2023]
Abstract
Brassica vegetables are attracting a great deal of attention as healthy foods because of the fact that they contain substantial amounts of secondary metabolite glucosinolates that are converted into isothiocyanates, such as sulforaphane [(-)1-isothiocyanato-4R-(methylsulfinyl)-butane] (R-SFN), through the actions of chopping or chewing the vegetables. Several studies have analyzed the biological and molecular mechanisms of the anti-cancer activity of synthetic R,S-sulforaphane, which is thought to be a result of its antioxidant properties and its ability to inhibit histone deacetylase enzymes (HDAC). Few studies have addressed the possible antioxidant effects of R-SFN, which could protect cells from the free radical damage that strongly contribute to aging. Moreover, little is known about the effect of R-SFN on stem cells whose longevity is implicated in human aging. We evaluated the effects of R-SFN on the biology on human mesenchymal stem cells (MSCs), which, in addition to their ability to differentiate into mesenchymal tissues, support hematopoiesis, and contribute to the homeostatic maintenance of many organs and tissues. Our investigation found evidence that low doses of R-SFN promote MSCs proliferation and protect them from apoptosis and senescence, while higher doses have a cytotoxic effect, leading to the induction of cell cycle arrest, programmed cell death and senescence. The beneficial effects of R-SFN may be ascribed to its antioxidant properties, which were observed when MSC cultures were incubated with low doses of R-SFN. Its cytotoxic effects, which were observed after treating MSCs with high doses of R-SFN, could be attributed to its HDAC inhibitory activity. In summary, we found that R-SFN, like many other dietary supplements, exhibits a hormetic behavior; it is able to induce biologically opposite effects at different doses.
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Affiliation(s)
- Fulvia Zanichelli
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
| | - Stefania Capasso
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
| | - Marilena Cipollaro
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
| | - Eleonora Pagnotta
- Consiglio per la Ricerca e la Sperimentazione in Agricoltura (C.R.A.), Industrial Crop Research Centre, Bologna, Italy
| | - Maria Cartenì
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
| | - Fiorina Casale
- Department of Pediatrics “F. Fede”, Second University of Naples, Naples, Italy
| | - Renato Iori
- Consiglio per la Ricerca e la Sperimentazione in Agricoltura (C.R.A.), Industrial Crop Research Centre, Bologna, Italy
| | - Umberto Galderisi
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA USA
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
- Human Health Foundation, Spoleto, Italy
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114
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Zhang Y, Ahn YH, Benjamin IJ, Honda T, Hicks RJ, Calabrese V, Cole PA, Dinkova-Kostova AT. HSF1-dependent upregulation of Hsp70 by sulfhydryl-reactive inducers of the KEAP1/NRF2/ARE pathway. ACTA ACUST UNITED AC 2012; 18:1355-61. [PMID: 22118669 DOI: 10.1016/j.chembiol.2011.09.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 12/14/2022]
Abstract
The KEAP1/NRF2/ARE pathway and the heat shock response are inducible cytoprotective systems regulated by transcription factors NRF2 and HSF1, respectively. We report that structurally distinct small molecule NRF2 activators, all of which react with sulfhydryl groups but differ in potency by 15,000-fold, upregulate Hsp70, a prototypic HSF1-dependent gene. Hsp70 upregulation requires HSF1 but is NRF2 independent. We further demonstrate that a sulfoxythiocarbamate inducer conjugates to the negative regulator of HSF1, Hsp90. The differential concentration dependence of the two responses suggests that activation of NRF2 precedes that of HSF1: the KEAP1/NRF2/ARE pathway is at the forefront of cellular defense, protecting against instant danger; the heat shock response closely follows to resolve subsequent potentially devastating damage, saving the proteome. This uncovered duality undoubtedly contributes to the cytoprotective effects of such molecules in models of carcinogenesis, cardiovascular disease, and neurodegeneration.
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Affiliation(s)
- Ying Zhang
- Divison of Cancer Research, Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, UK
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115
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Jacob JK, Tiwari K, Correa-Betanzo J, Misran A, Chandrasekaran R, Paliyath G. Biochemical basis for functional ingredient design from fruits. Annu Rev Food Sci Technol 2012; 3:79-104. [PMID: 22224553 DOI: 10.1146/annurev-food-022811-101127] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Functional food ingredients (nutraceuticals) in fruits range from small molecular components, such as the secondary plant products, to macromolecular entities, e.g., pectin and cellulose, that provide several health benefits. In fruits, the most visible functional ingredients are the color components anthocyanins and carotenoids. In addition, several other secondary plant products, including terpenes, show health beneficial activities. A common feature of several functional ingredients is their antioxidant function. For example, reactive oxygen species (ROS) can be oxidized and stabilized by flavonoid components, and the flavonoid radical can undergo electron rearrangement stabilizing the flavonoid radical. Compounds that possess an orthodihydroxy or quinone structure can interact with cellular proteins in the Keap1/Nrf2/ARE pathway to activate the gene transcription of antioxidant enzymes. Carotenoids and flavonoids can also exert their action by modulating the signal transduction and gene expression within the cell. Recent results suggest that these activities are primarily responsible for the health benefits associated with the consumption of fruits and vegetables.
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Affiliation(s)
- Jissy K Jacob
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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116
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Copple IM. The Keap1-Nrf2 cell defense pathway--a promising therapeutic target? ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2012; 63:43-79. [PMID: 22776639 DOI: 10.1016/b978-0-12-398339-8.00002-1] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
By regulating the basal and inducible expression of an abundance of detoxification enzymes, antioxidant proteins, xenobiotic transporters and other stress response proteins, the Keap1-Nrf2 pathway plays a crucial role in determining the sensitivity of mammalian cells to chemical and oxidative insults that have the capacity to provoke cellular harm. This review highlights historical and recent advances in our understanding of the molecular mechanisms that regulate the activity of the Keap1-Nrf2 pathway. The important role of Nrf2 in protecting against the onset of specific diseases and drug-induced toxicities is also examined, alongside the emerging role of Nrf2 in promoting oncogenesis and chemotherapeutic drug resistance. A particular emphasis is placed on the potential for translation of this mechanistic understanding into clinical strategies that can improve human health, with consideration of the potential applications of targeting Nrf2 therapeutically.
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Affiliation(s)
- Ian M Copple
- The University of Liverpool, MRC Centre for Drug Safety Science, Department of Molecular & Clinical Pharmacology, Liverpool, United Kingdom
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117
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Jacob C, Battaglia E, Burkholz T, Peng D, Bagrel D, Montenarh M. Control of oxidative posttranslational cysteine modifications: from intricate chemistry to widespread biological and medical applications. Chem Res Toxicol 2011; 25:588-604. [PMID: 22106817 DOI: 10.1021/tx200342b] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cysteine residues in proteins and enzymes often fulfill rather important roles, particularly in the context of cellular signaling, protein-protein interactions, substrate and metal binding, and catalysis. At the same time, some of the most active cysteine residues are also quite sensitive toward (oxidative) modification. S-Thiolation, S-nitrosation, and disulfide bond and sulfenic acid formation are processes which occur frequently inside the cell and regulate the function and activity of many proteins and enzymes. During oxidative stress, such modifications trigger, among others, antioxidant responses and cell death. The unique combination of nonredox function on the one hand and participation in redox signaling and control on the other has placed many cysteine proteins at the center of drug design and pesticide development. Research during the past decade has identified a range of chemically rather interesting, biologically very active substances that are able to modify cysteine residues in such proteins with huge efficiency, yet also considerable selectivity. These agents are often based on natural products and range from simple disulfides to complex polysulfanes, tetrahydrothienopyridines, α,β -unsaturated disulfides, thiuramdisulfides, and 1,2-dithiole-3-thiones. At the same time, inhibition of enzymes responsible for posttranslational cysteine modifications (and their removal) has become an important area of innovative drug research. Such investigations into the control of the cellular thiolstat by thiol-selective agents cross many disciplines and are often far from trivial.
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Affiliation(s)
- Claus Jacob
- Division of Bioorganic Chemistry, School of Pharmacy, Saarland University, D-66123 Saarbruecken, Germany.
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118
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Fimognari C, Turrini E, Ferruzzi L, Lenzi M, Hrelia P. Natural isothiocyanates: genotoxic potential versus chemoprevention. Mutat Res 2011; 750:107-131. [PMID: 22178957 DOI: 10.1016/j.mrrev.2011.12.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 12/01/2011] [Accepted: 12/02/2011] [Indexed: 12/12/2022]
Abstract
Isothiocyanates, occurring in many dietary cruciferous vegetables, show interesting chemopreventive activities against several chronic-degenerative diseases, including cancer, cardiovascular diseases, neurodegeneration, diabetes. The electrophilic carbon residue in the isothiocyanate moiety reacts with biological nucleophiles and modification of proteins is recognized as a key mechanism underlying the biological activity of isothiocyanates. The nuclear factor-erythroid-2-related factor 2 system, which orchestrates the expression of a wide array of antioxidant genes, plays a role in the protective effect of isothiocyanates against almost all the pathological conditions reported above. Recent emerging findings suggest a further common mechanism. Chronic inflammation plays a central role in many human diseases and isothiocyanates inhibit the activity of many inflammation components, suppress cyclooxygenase 2, and irreversibly inactivate the macrophage migration inhibitory factor. Due to their electrophilic reactivity, some isothiocyanates are able to form adducts with DNA and induce gene mutations and chromosomal aberrations. DNA damage has been demonstrated to be involved in the pathogenesis of various chronic-degenerative diseases of epidemiological relevance. Thus, the genotoxicity of the isothiocyanates should be carefully considered. In addition, the dose-response relationship for genotoxic compounds does not suggest evidence of a threshold. Thus, chemicals that are genotoxic pose a greater potential risk to humans than non-genotoxic compounds. Dietary consumption levels of isothiocyanates appear to be several orders of magnitude lower than the doses used in the genotoxicity studies and thus it is highly unlikely that such toxicities would occur in humans. However, the beneficial properties of isothiocyanates stimulated an increase of dietary supplements and functional foods with highly enriched isothiocyanate concentrations on the market. Whether such concentrations may exert a potential health risk cannot be excluded with certainty and an accurate evaluation of the toxicological profile of isothiocyanates should be prompted before any major increase in their consumption be recommended or their clinical use suggested.
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Affiliation(s)
- Carmela Fimognari
- Department of Pharmacology, University of Bologna, via Irnerio 48, 40126 Bologna, Italy.
| | - Eleonora Turrini
- Department of Pharmacology, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Lorenzo Ferruzzi
- Department of Pharmacology, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Monia Lenzi
- Department of Pharmacology, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Patrizia Hrelia
- Department of Pharmacology, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
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119
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Development of Neh2-luciferase reporter and its application for high throughput screening and real-time monitoring of Nrf2 activators. ACTA ACUST UNITED AC 2011; 18:752-65. [PMID: 21700211 DOI: 10.1016/j.chembiol.2011.03.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 03/11/2011] [Accepted: 03/25/2011] [Indexed: 12/30/2022]
Abstract
The NF-E2-related factor 2 (Nrf2) is a key transcriptional regulator of antioxidant defense and detoxification. To directly monitor stabilization of Nrf2, we fused its Neh2 domain, responsible for the interaction with its nucleocytoplasmic regulator, Keap1, to firefly luciferase (Neh2-luciferase). We show that Neh2 domain is sufficient for recognition, ubiquitination, and proteasomal degradation of Neh2-luciferase fusion protein. The Neh2-luc reporter system allows direct monitoring of the adaptive response to redox stress and classification of drugs based on the time course of reporter activation. The reporter was used to screen the Spectrum library of 2000 biologically active compounds to identify activators of Nrf2. The most robust and yet nontoxic Nrf2 activators found--nordihydroguaiaretic acid, fisetin, and gedunin--induced astrocyte-dependent neuroprotection from oxidative stress via an Nrf2-dependent mechanism.
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120
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Lee BC, Fomenko DE, Gladyshev VN. Selective reduction of methylsulfinyl-containing compounds by mammalian MsrA suggests a strategy for improved drug efficacy. ACS Chem Biol 2011; 6:1029-35. [PMID: 21823615 DOI: 10.1021/cb2001395] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Identification of pathways of drug metabolism provides critical information regarding efficacy and safety of these compounds. Particularly challenging cases involve stereospecific processes. We found that broad classes of compounds containing methylsulfinyl groups are reduced to methylsulfides specifically by methionine sulfoxide reductase A, which acts on the S-stereomers of methionine sulfoxides, whereas the R-stereomers of these compounds could not be efficiently reduced by any methionine sulfoxide reductase in mammals. The findings of efficient reduction of S-methylsulfinyls and deficiency in the reduction of R-methylsulfinyls by methionine sulfoxide reductases suggest strategies for improved efficacy and decreased toxicity of drugs and natural compounds containing methylsulfinyls through targeted use of their enantiomers.
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Affiliation(s)
- Byung Cheon Lee
- Center for Redox Medicine, Division of Genetics, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Dmitri E. Fomenko
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Vadim N. Gladyshev
- Center for Redox Medicine, Division of Genetics, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, United States
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121
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Shibata T, Kimura Y, Mukai A, Mori H, Ito S, Asaka Y, Oe S, Tanaka H, Takahashi T, Uchida K. Transthiocarbamoylation of proteins by thiolated isothiocyanates. J Biol Chem 2011; 286:42150-42161. [PMID: 21998322 DOI: 10.1074/jbc.m111.308049] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Isothiocyanates, membrane-permeable electrophiles that form adducts with thiols, have been suggested to have important medical benefits. Here we shed light on isothiocyanate-thiol conjugates and studied their electrophilic potential transferring an isothiocyanate moiety to cellular proteins. When we examined the effect of sulfhydryl molecules on cellular response induced by 6-methylsulfinylhexyl isothiocyanate (6-HITC), an analog of sulforaphane isolated from broccoli, we observed significant induction of heme oxygenase-1 by 6-HITC even in the presence of N-acetyl-L-cysteine or glutathione (GSH). In addition, the authentic 6-HITC-β-mercaptoethanol (6-HITC-ME) conjugate markedly up-regulated the enzyme expression, suggesting the electrophilic potential of thiolated isothiocyanates. To gain a chemical insight into the cellular response induced by thiolated isothiocyanates, we studied the occurrence of transthiocarbamoylation of sulfhydryl molecules by 6-HITC-ME and observed that, upon incubation of 6-HITC-ME with GSH, a single product corresponding to the GSH conjugate of 6-HITC was generated. To test the functional ability of thiolated isothiocyanates to thiocarbamoylate proteins in living cells, we designed a novel probe, combining an isothiocyanate-reactive group and an alkyne functionality, and revealed that the transthiocarbamoylation of proteins occurred in the cells upon exposure to 6-HITC-ME. The target of thiocarbamoylation included heat shock protein 90 β (Hsp90β), a chaperone ATPase of the Hsp90 family implicated in protein maturation and targeting. To identify the sites of the Hsp90β modification, we utilized nano-LC/MALDI-TOF MS/MS and suggested that a thiol group on the peptide containing Cys-521 reacted with 6-HITC, resulting in a covalent adduct in a 6-HITC-treated recombinant Hsp90β in vitro. The site-selective binding to Cys-521 was supported by in silico modeling. Further study on the thiocarbamoylation of Hsp90β suggested that the formation of 6-HITC-Hsp90β conjugate might cause activation of heat shock factor-1, rapidly signaling a potential heat shock response. These data suggest that thiolated isothiocyanates are an active metabolite that could contribute to cellular responses through transthiocarbamoylation of cellular proteins.
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Affiliation(s)
- Takahiro Shibata
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yuuki Kimura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Akihiro Mukai
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hitoshi Mori
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Sohei Ito
- School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Yukio Asaka
- Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Sho Oe
- Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Hiroshi Tanaka
- Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Takashi Takahashi
- Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Koji Uchida
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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122
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Liang H, Yuan Q. Natural sulforaphane as a functional chemopreventive agent: including a review of isolation, purification and analysis methods. Crit Rev Biotechnol 2011; 32:218-34. [DOI: 10.3109/07388551.2011.604838] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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123
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Tkachev VO, Menshchikova EB, Zenkov NK. Mechanism of the Nrf2/Keap1/ARE signaling system. BIOCHEMISTRY (MOSCOW) 2011; 76:407-22. [PMID: 21585316 DOI: 10.1134/s0006297911040031] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nrf2 regulates expression of genes containing antioxidant-respons(iv)e element (ARE) in their promoters and plays a pivotal role among all redox-sensitive transcription factors. Nrf2 is constitutively controlled by repressor protein Keap1, which acts as a molecular sensor of disturbances in cellular homeostasis. These molecular patterns are in close interconnection and function as parts of the integrated redox-sensitive signaling system Nrf2/Keap1/ARE. Depending on cellular redox balance, activity of this signaling system changes at the levels of transcription, translation, posttranslational modification, nuclear translocation of transcription factor, and its binding to ARE-driven gene promoters. This review summarizes current conceptions of Nrf2/Keap1/ARE induction and inactivation.
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Affiliation(s)
- V O Tkachev
- Scientific Center of Clinical and Experimental Medicine, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia.
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124
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Hormetics: dietary triggers of an adaptive stress response. Pharm Res 2011; 28:2680-94. [PMID: 21818712 DOI: 10.1007/s11095-011-0551-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 07/27/2011] [Indexed: 12/31/2022]
Abstract
A series of dietary ingredients and metabolites are able to induce an adaptive stress response either by generation of reactive oxygen species (ROS) and/or via activation of the Nrf2/Keap1 stress response network. Most of the molecules belong to activated Michael acceptors, electrophiles capable to S-alkylate redox sensitive cysteine thiols. This review summarizes recent advances in the (re)search of these compounds and classifies them into distinct groups. More than 60 molecules are described that induce the Nrf2 network, most of them found in our daily diet. Although known as typical antioxidants, a closer look reveals that these molecules induce an initial mitochondrial or cytosolic ROS formation and thereby trigger an adaptive stress response and hormesis, respectively. This, however, leads to higher levels of intracellular glutathione and increased expression levels of antioxidant enzymes such as glutathione peroxidase, thioredoxin reductase, and superoxide dismutase. According to this principle, the author suggests the term hormetics to describe these indirect antioxidants.
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125
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Brown KK, Hampton MB. Biological targets of isothiocyanates. Biochim Biophys Acta Gen Subj 2011; 1810:888-94. [PMID: 21704127 DOI: 10.1016/j.bbagen.2011.06.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 05/13/2011] [Accepted: 06/07/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND Isothiocyanates are phytochemicals with a broad array of effects in biological systems. Bioactivity includes the stimulation of cellular antioxidant systems, induction of apoptosis and interference with cytokine production and activity. Epidemiological evidence and experimental studies indicate that naturally occurring isothiocyanates and synthetic derivatives have anti-cancer and anti-inflammatory properties. SCOPE OF REVIEW This review focuses on the molecular targets of isothiocyanates, and how target modification translates into a biological response. MAJOR CONCLUSIONS Isothiocyanates may mediate their effects via direct protein modification or indirectly by disruption of redox homeostasis and increased thiol oxidation. Some target proteins have been identified, but in-depth searches with new techniques are needed to reveal novel targets. Site-directed mutagenesis and isothiocyanate structure-activity relationships will assist in determining the biological significance of specific modifications. GENERAL SIGNIFICANCE Target identification is important for rational drug design and exploiting the therapeutic potential of isothiocyanates. It also provides insight into the diverse pathways that these compounds regulate.
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Affiliation(s)
- Kristin K Brown
- Free Radical Research Group, Department of Pathology, University of Otago, Christchurch, New Zealand
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126
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Ernst IMA, Schuemann C, Wagner AE, Rimbach G. 3,3'-Diindolylmethane but not indole-3-carbinol activates Nrf2 and induces Nrf2 target gene expression in cultured murine fibroblasts. Free Radic Res 2011; 45:941-9. [PMID: 21615272 DOI: 10.3109/10715762.2011.571683] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
There is increasing interest in the gene-regulatory activity of Brassica vegetable derived phytochemicals such as 3,3'-diindolylmethane (DIM) and indole-3-carbinol (I3C). DIM is formed under acidic conditions by dimerization of I3C. This study compared the Nrf2 activating potential of DIM and I3C in murine fibroblasts (NIH3T3). In contrast to its precursor I3C, DIM induces the transactivation of Nrf2. Furthermore, Nrf2 targets such as HO-1, γGCS and NQO1 were increased on the mRNA and protein levels following DIM treatment. DIM was less potent than sulforaphane (used as positive control) in inducing Nrf2-dependent gene expression. The present data suggest that the dimerization of I3C to DIM increases its Nrf2 inducing activity.
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Affiliation(s)
- I M A Ernst
- Institute of Human Nutrition and Food Science, Christian-Albrechts-University Kiel , Hermann-Rodewald-Strasse 6, 24118 Kiel, Germany
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127
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Zhang X, Luo L, Ma Z. A deuterium-labelling mass spectrometry-tandem diode-array detector screening method for rapid discovery of naturally occurring electrophiles. Anal Bioanal Chem 2011; 400:3463-71. [PMID: 21544543 DOI: 10.1007/s00216-011-4983-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 04/02/2011] [Indexed: 01/31/2023]
Abstract
Because electrophiles regulate many signalling pathways in cells, by modifying cysteine residues in proteins, they have a wide range of biological activity. In this study, a deuterium-labelling mass spectrometry-tandem diode-array detector (MS-DAD) screening method was established for rapid discovery of naturally occurring electrophiles. Glutathione (GSH) was used as a probe and incubated with natural product extracts. To distinguish different types of electrophile, incubation was performed in two reaction solvents, H(2)O and D(2)O. Ten types of naturally occurring electrophile were chosen, on the basis of their properties, to undergo the screening assay. By using this screening method, we successfully discovered the bioactive electrophile 4-hydroxyderricin in an ethanol extract of Angelica keiskei. This electrophile had potent NAD(P)H:quinone oxidoreductase 1 (NQO1)-inducing activity at a concentration of 20 μmol L(-1).
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Affiliation(s)
- Xiaoyu Zhang
- School of Pharmaceutical Sciences, Zhejiang University, Zijingang Campus, Hangzhou, China
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128
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Bongard RD, Krenz GS, Gastonguay AJ, Williams CL, Lindemer BJ, Merker MP. Characterization of the threshold for NAD(P)H:quinone oxidoreductase activity in intact sulforaphane-treated pulmonary arterial endothelial cells. Free Radic Biol Med 2011; 50:953-62. [PMID: 21238579 PMCID: PMC3851029 DOI: 10.1016/j.freeradbiomed.2011.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 01/03/2011] [Accepted: 01/06/2011] [Indexed: 12/22/2022]
Abstract
Treatment of bovine pulmonary arterial endothelial cells in culture with the phase II enzyme inducer sulforaphane (5μM, 24h; sulf-treated) increased cell-lysate NAD(P)H:quinone oxidoreductase (NQO1) activity by 5.7 ± 0.6 (mean ± SEM)-fold, but intact-cell NQO1 activity by only 2.8 ± 0.1-fold compared to control cells. To evaluate the hypothesis that the threshold for sulforaphane-induced intact-cell NQO1 activity reflects a limitation in the capacity to supply NADPH at a sufficient rate to drive all the induced NQO1 to its maximum activity, total KOH-extractable pyridine nucleotides were measured in cells treated with duroquinone to stimulate maximal NQO1 activity. NQO1 activation increased NADP(+) in control and sulf-treated cells, with the effect more pronounced in the sulf-treated cells, in which the NADPH was also decreased. Glucose-6-phosphate dehydrogenase (G-6-PDH) inhibition partially blocked NQO1 activity in control and sulf-treated cells, but G-6-PDH overexpression via transient transfection with the human cDNA alleviated neither the restriction on intact sulf-treated cell NQO1 activity nor the impact on the NADPH/NADP(+) ratios. Intracellular ATP levels were not affected by NQO1 activation in control or sulf-treated cells. An increased dependence on extracellular glucose and a rightward shift in the K(m) for extracellular glucose were observed in NQO1-stimulated sulf-treated vs control cells. The data suggest that glucose transport in the sulf-treated cells may be insufficient to support the increased metabolic demand for pentose phosphate pathway-generated NADPH as an explanation for the NQO1 threshold.
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Affiliation(s)
- Robert D Bongard
- Department of Pulmonary Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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129
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Baird L, Dinkova-Kostova AT. The cytoprotective role of the Keap1-Nrf2 pathway. Arch Toxicol 2011; 85:241-72. [PMID: 21365312 DOI: 10.1007/s00204-011-0674-5] [Citation(s) in RCA: 734] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 02/08/2011] [Indexed: 12/11/2022]
Abstract
An elaborate network of highly inducible proteins protects aerobic cells against the cumulative damaging effects of reactive oxygen intermediates and toxic electrophiles, which are the major causes of neoplastic and chronic degenerative diseases. These cytoprotective proteins share common transcriptional regulation, through the Keap1-Nrf2 pathway, which can be activated by various exogenous and endogenous small molecules (inducers). Inducers chemically react with critical cysteine residues of the sensor protein Keap1, leading to stabilisation and nuclear translocation of transcription factor Nrf2, and ultimately to coordinate enhanced expression of genes coding for cytoprotective proteins. In addition, inducers inhibit pro-inflammatory responses, and there is a linear correlation spanning more than six orders of magnitude of concentrations between inducer and anti-inflammatory activity. Genetic deletion of transcription factor Nrf2 renders cells and animals much more sensitive to the damaging effects of electrophiles, oxidants and inflammatory agents in comparison with their wild-type counterparts. Conversely, activation of the Keap1-Nrf2 pathway allows survival and adaptation under various conditions of stress and has protective effects in many animal models. Cross-talks with other signalling pathways broadens the role of the Keap1-Nrf2 pathway in determining the fate of the cell, impacting fundamental biological processes such as proliferation, apoptosis, angiogenesis and metastasis.
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Affiliation(s)
- Liam Baird
- Biomedical Research Institute, University of Dundee, Dundee, Scotland, UK
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130
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Hu C, Eggler AL, Mesecar AD, van Breemen RB. Modification of keap1 cysteine residues by sulforaphane. Chem Res Toxicol 2011; 24:515-21. [PMID: 21391649 DOI: 10.1021/tx100389r] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Activation of the transcription factor NF-E2-related factor-2 (Nrf2) through modification of Kelch-like ECH-associated protein 1 (Keap1) cysteines, leading to up-regulation of the antioxidant response element (ARE), is an important mechanism of cellular defense against reactive oxygen species and xenobiotic electrophiles. Sulforaphane, occurring in cruciferous vegetables such as broccoli, is a potent natural ARE activator that functions by modifying Keap1 cysteine residues, but there are conflicting in vitro and in vivo data regarding which of these cysteine residues react. Although most biological data indicate that modification of C151 is essential for sulforaphane action, some recent studies using mass spectrometry have failed to identify C151 as a site of Keap1 sulforaphane reaction. We have reconciled these conflicting data using mass spectrometry with a revised sample preparation protocol and confirmed that C151 is indeed among the most readily modified cysteines of Keap1 by sulforaphane. Previous mass spectrometry-based studies used iodoacetamide during sample preparation to derivatize free cysteine sulfhydryl groups causing the loss of sulforaphane from highly reactive and reversible cysteine residues on Keap1 including C151. By omitting iodoacetamide from the protocol and reducing sample preparation time, our mass spectrometry-based studies now confirm previous cell-based studies which showed that sulforaphane reacts with at least four cysteine residues of Keap1 including C151.
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Affiliation(s)
- Chenqi Hu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois College of Pharmacy, 833 S. Wood Street, Chicago, IL 60612, United States
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131
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Kansanen E, Bonacci G, Schopfer FJ, Kuosmanen SM, Tong KI, Leinonen H, Woodcock SR, Yamamoto M, Carlberg C, Ylä-Herttuala S, Freeman BA, Levonen AL. Electrophilic nitro-fatty acids activate NRF2 by a KEAP1 cysteine 151-independent mechanism. J Biol Chem 2011; 286:14019-27. [PMID: 21357422 DOI: 10.1074/jbc.m110.190710] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitro-fatty acids (NO(2)-FAs) are electrophilic signaling mediators formed in vivo via nitric oxide (NO)- and nitrite (NO(2)(-))-dependent reactions. Nitro-fatty acids modulate signaling cascades via reversible covalent post-translational modification of nucleophilic amino acids in regulatory proteins and enzymes, thus altering downstream signaling events, such as Keap1-Nrf2-antioxidant response element (ARE)-regulated gene expression. In this study, we investigate the molecular mechanisms by which 9- and 10-nitro-octadec-9-enoic acid (OA-NO(2)) activate the transcription factor Nrf2, focusing on the post-translational modifications of cysteines in the Nrf2 inhibitor Keap1 by nitroalkylation and its downstream responses. Of the two regioisomers, 9-nitro-octadec-9-enoic acid was a more potent ARE inducer than 10-nitro-octadec-9-enoic acid. The most OA-NO(2)-reactive Cys residues in Keap1 were Cys(38), Cys(226), Cys(257), Cys(273), Cys(288), and Cys(489). Of these, Cys(273) and Cys(288) accounted for ∼50% of OA-NO(2) reactions in a cellular milieu. Notably, Cys(151) was among the least OA-NO(2)-reactive of the Keap1 Cys residues, with mutation of Cys(151) having no effect on net OA-NO(2) reaction with Keap1 or on ARE activation. Unlike many other Nrf2-activating electrophiles, OA-NO(2) enhanced rather than diminished the binding between Keap1 and the Cul3 subunit of the E3 ligase for Nrf2. OA-NO(2) can therefore be categorized as a Cys(151)-independent Nrf2 activator, which in turn can influence the pattern of gene expression and therapeutic actions of nitroalkenes.
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Affiliation(s)
- Emilia Kansanen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FIN-70211 Kuopio, Finland
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132
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Lee BC, Gladyshev VN. The biological significance of methionine sulfoxide stereochemistry. Free Radic Biol Med 2011; 50:221-7. [PMID: 21075204 PMCID: PMC3311537 DOI: 10.1016/j.freeradbiomed.2010.11.008] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 11/04/2010] [Accepted: 11/05/2010] [Indexed: 12/22/2022]
Abstract
Methionine can be oxidized by reactive oxygen species to a mixture of two diastereomers, methionine-S-sulfoxide and methionine-R-sulfoxide. Both free amino acid and protein-based forms of methionine-S-sulfoxide are stereospecifically reduced by MsrA, whereas the reduction of methionine-R-sulfoxide requires two enzymes, MsrB and fRMsr, which act on its protein-based and free amino acid forms, respectively. However, mammals lack fRMsr and are characterized by deficiency in the reduction of free methionine-R-sulfoxide. The biological significance of such biased reduction of methionine sulfoxide has not been fully explored. MsrA and MsrB activities decrease during aging, leading to accumulation of protein-based and free amino acid forms of methionine sulfoxide. Since methionine is an indispensible amino acid in human nutrition and a key metabolite in sulfur, methylation, and transsulfuration pathways, the consequences of accumulation of its oxidized forms require further studies. Finally, in addition to methionine, methylsulfinyl groups are present in various drugs and natural compounds, and their differential reduction by Msrs may have important therapeutic implications.
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Affiliation(s)
- Byung Cheon Lee
- Division of Genetics, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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133
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Majkova Z, Layne J, Sunkara M, Morris AJ, Toborek M, Hennig B. Omega-3 fatty acid oxidation products prevent vascular endothelial cell activation by coplanar polychlorinated biphenyls. Toxicol Appl Pharmacol 2010; 251:41-9. [PMID: 21130106 DOI: 10.1016/j.taap.2010.11.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 11/22/2010] [Accepted: 11/22/2010] [Indexed: 11/15/2022]
Abstract
Coplanar polychlorinated biphenyls (PCBs) may facilitate development of atherosclerosis by stimulating pro-inflammatory pathways in the vascular endothelium. Nutrition, including fish oil-derived long-chain omega-3 fatty acids, such as docosahexaenoic acid (DHA, 22:6ω-3), can reduce inflammation and thus the risk of atherosclerosis. We tested the hypothesis that cyclopentenone metabolites produced by oxidation of DHA can protect against PCB-induced endothelial cell dysfunction. Oxidized DHA (oxDHA) was prepared by incubation of the fatty acid with the free radical generator 2,2-azo-bis(2-amidinopropane) dihydrochloride (AAPH). Cellular pretreatment with oxDHA prevented production of superoxide induced by PCB77, and subsequent activation of nuclear factor-κB (NF-κB). A₄/J₄-neuroprostanes (NPs) were identified and quantitated using HPLC ESI tandem mass spectrometry. Levels of these NPs were markedly increased after DHA oxidation with AAPH. The protective actions of oxDHA were reversed by treatment with sodium borohydride (NaBH₄), which concurrently abrogated A₄/J₄-NP formation. Up-regulation of monocyte chemoattractant protein-1 (MCP-1) by PCB77 was markedly reduced by oxDHA, but not by un-oxidized DHA. These protective effects were proportional to the abundance of A₄/J₄ NPs in the oxidized DHA sample. Treatment of cells with oxidized eicosapentaenoic acid (EPA, 20:5ω-3) also reduced MCP-1 expression, but less than oxDHA. Treatment with DHA-derived cyclopentenones also increased DNA binding of NF-E2-related factor-2 (Nrf2) and downstream expression of NAD(P)H:quinone oxidoreductase (NQO1), similarly to the Nrf-2 activator sulforaphane. Furthermore, sulforaphane prevented PCB77-induced MCP-1 expression, suggesting that activation of Nrf-2 mediates the observed protection against PCB77 toxicity. Our data implicate A₄/J₄-NPs as mediators of omega-3 fatty acid-mediated protection against the endothelial toxicity of coplanar PCBs.
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Affiliation(s)
- Zuzana Majkova
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536-0200, USA
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134
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Dinkova-Kostova AT, Talalay P, Sharkey J, Zhang Y, Holtzclaw WD, Wang XJ, David E, Schiavoni KH, Finlayson S, Mierke DF, Honda T. An exceptionally potent inducer of cytoprotective enzymes: elucidation of the structural features that determine inducer potency and reactivity with Keap1. J Biol Chem 2010; 285:33747-55. [PMID: 20801881 PMCID: PMC2962473 DOI: 10.1074/jbc.m110.163485] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 08/20/2010] [Indexed: 12/15/2022] Open
Abstract
The Keap1/Nrf2/ARE pathway controls a network of cytoprotective genes that defend against the damaging effects of oxidative and electrophilic stress, and inflammation. Induction of this pathway is a highly effective strategy in combating the risk of cancer and chronic degenerative diseases, including atherosclerosis and neurodegeneration. An acetylenic tricyclic bis(cyano enone) bearing two highly electrophilic Michael acceptors is an extremely potent inducer in cells and in vivo. We demonstrate spectroscopically that both cyano enone functions of the tricyclic molecule react with cysteine residues of Keap1 and activate transcription of cytoprotective genes. Novel monocyclic cyano enones, representing fragments of rings A and C of the tricyclic compound, reveal that the contribution to inducer potency of the ring C Michael acceptor is much greater than that of ring A, and that potency is further enhanced by spatial proximity of an acetylenic function. Critically, the simultaneous presence of two cyano enone functions in rings A and C within a rigid three-ring system results in exceptionally high inducer potency. Detailed understanding of the structural elements that contribute to the reactivity with the protein sensor Keap1 and to high potency of induction is essential for the development of specific and selective lead compounds as clinically relevant chemoprotective agents.
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Affiliation(s)
- Albena T. Dinkova-Kostova
- From the Biomedical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
- the Lewis B. and Dorothy Cullman Chemoprotection Center and the Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and
| | - Paul Talalay
- the Lewis B. and Dorothy Cullman Chemoprotection Center and the Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and
| | - John Sharkey
- From the Biomedical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Ying Zhang
- From the Biomedical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - W. David Holtzclaw
- the Lewis B. and Dorothy Cullman Chemoprotection Center and the Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and
| | - Xiu Jun Wang
- From the Biomedical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Emilie David
- the Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755
| | | | - Stewart Finlayson
- From the Biomedical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Dale F. Mierke
- the Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755
| | - Tadashi Honda
- the Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755
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135
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Saw CLL, Wu Q, Kong ANT. Anti-cancer and potential chemopreventive actions of ginseng by activating Nrf2 (NFE2L2) anti-oxidative stress/anti-inflammatory pathways. Chin Med 2010; 5:37. [PMID: 20979613 PMCID: PMC2990743 DOI: 10.1186/1749-8546-5-37] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 10/27/2010] [Indexed: 12/13/2022] Open
Abstract
This article reviews recent basic and clinical studies of ginseng, particularly the anti-cancer effects and the potential chemopreventive actions by activating the transcriptional factor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2 or NFE2L2)-mediated anti-oxidative stress or anti-inflammatory pathways. Nrf2 is a novel target for cancer prevention as it regulates the antioxidant responsive element (ARE), a critical regulatory element in the promoter region of genes encoding cellular phase II detoxifying and anti-oxidative stress enzymes. The studies on the chemopreventive effects of ginseng or its components/products showed that Nrf2 could also be a target for ginseng's actions. A number of papers also demonstrated the anti-inflammatory effects of ginseng. Targeting Nrf2 pathway is a novel approach to the investigation of ginseng's cancer chemopreventive actions, including some oxidative stress and inflammatory conditions responsible for the initiation, promotion and progression of carcinogenesis.
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Affiliation(s)
- Constance Lay-Lay Saw
- Center for Cancer Prevention Research, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, USA.
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