The Nrf2 - NF-kappaB interest thread

Hi!

I'm suffering from a hyper-allergy to cigarette smoke. The doctors I have visited thusfar "have never heard of" such a thing and have referred me to a psychiatrist. Thanks to PubMed, Eurekalert, ScienceDaily and Wikipedia, I now know my problem is Nrf2 - NF-kappaB -related. Since the related pathways also seem important to aging and cancer, I hope Imminst will tolerate this Nrf2 - NF-kappaB interest thread. Anyone with an interest in these topics can post abstracts/references to interesting research on these topics. Anyone who wants to join the discussion to point out errors in logic or ommissions, etc. is also welcome.

Since my problem is cigarette smoke-related, the abstracts I post will be skewed towards cigarette smoke-induced oxidative stress and inflammation.

(This post will be updated with a short overview of Nrf2 - NF-kappaB and their relation to oxidative stress and inflammation in a while, such as to provide an overview for people not familiar with these pathways. To put it in one sentence: activation of Nrf2 induces protection against oxidative stress, inhibition of NF-kappaB inhibits inflammation.)


I'm color-coding stuff below (don't know if I can keep this up, but I will try). Legend:

• General background knowledge
• Important information on the current study/article
• Very important information/conclusions
• Abbreviation
  

• Resveratrol
• Nrf2
  

Edited by Shinigami, 25 December 2008 - 05:24 AM.

Activating the lung's antioxidant defense by targeting Nrf2 inhibits the development of emphysema

Using a molecule similar to one found in an experimental cancer drug, researchers at the Johns Hopkins Bloomberg School of Public Health demonstrated that activation of a key component of the lung's antioxidant defense system, Nrf2, can prevent emphysema in mice. The researchers believe that activation of Nrf2 could be a novel target for therapies to prevent chronic obstructive pulmonary disease (COPD), which comprises emphysema and chronic bronchitis. COPD is a major public health problem and it is the fourth leading cause of death in the U.S. The study is published in the online Early Edition of PNAS: Proceeding of the National Academy of Sciences.

"There are no effective therapies for COPD and there is an urgent need to develop novel intervention strategies. Targeting the Nrf2 pathway presents a novel strategy which needs to be tested for their efficacy in intervening COPD in patients," said Shyam Biswal, PhD, senior author of the study and an associate professor in the Bloomberg School of Public Health's Department of Environmental Health Sciences and the Division of Pulmonary and Critical Care Medicine at the Johns Hopkins School of Medicine.

Nrf2 (nuclear factor erythroid-derived 2-related factor 2) works as a "master gene" that turns on numerous antioxidant and pollutant-detoxifying genes to protect the lungs from environmental pollutants, such as cigarette smoke. Biswal previously identified that disruption of Nrf2 expression in mice caused early onset and severe emphysema. More recently, his team demonstrated for the first time a close correlation between the Nrf2 decline and the progression of COPD in humans.

For the current study, Biswal, along with postdoctoral fellows, Thomas Sussan, PhD, Tirumalai Rangasamy, PhD, and David J. Blake, PhD, observed mice exposed to cigarette smoke to determine if activation of Nrf2 could prevent emphysema. Exposed mice—fed a diet containing CDDO-Im, which is known to activate Nrf2—were significantly less likely to have oxidative stress and lung cell damage associated with emphysema. The researchers also noted substantially improved function in the portion of the heart responsible circulating oxygenated blood through the body—a function that is typically diminished with emphysema. CDDO-Im is closely related to CDDO-Me, an experimental cancer drug approved for phase II clinical trials.

"Nrf2 is an important regulator of the body's antioxidant defense system, and activation of Nrf2 is a promising therapeutic strategy for attenuating COPD progression in patients," said Thomas Sussan, PhD, lead author of the study.

According to the researchers, COPD affects more than 16 million Americans and it is the only disease among the top 10 causes of death with a rising mortality rate in the United States. It is predicted to be the third largest cause of death by 2020 and has already reached worldwide epidemic proportions.

Is there anyone who knows more about the mentioned clinical trials?

The mentioned study (full text):

Targeting Nrf2 with the triterpenoid CDDO- imidazolide attenuates cigarette smoke-induced emphysema and cardiac dysfunction in mice.

Sussan TE,Rangasamy T,Blake DJ,Malhotra D,El-Haddad H,Bedja D,Yates MS,Kombairaju P,Yamamoto M,Liby KT,Sporn MB,Gabrielson KL,Champion HC,Tuder RM,Kensler TW,Biswal S.

Department of Environmental Health Sciences, Bloomberg School of Public Health.

Chronic obstructive pulmonary disease (COPD), which comprises emphysema and chronic bronchitis resulting from prolonged exposure to cigarette smoke (CS), is a major public health burden with no effective treatment. Emphysema is also associated with pulmonary hypertension, which can progress to right ventricular failure, an important cause of morbidity and mortality among patients with COPD. Nuclear erythroid 2 p45 related factor-2 (Nrf2) is a redox-sensitive transcription factor that up-regulates a battery of antioxidative genes and cytoprotective enzymes that constitute the defense against oxidative stress. Recently, it has been shown that patients with advanced COPD have a decline in expression of the Nrf2 pathway in lungs, suggesting that loss of this antioxidative protective response is a key factor in the pathophysiological progression of emphysema. Furthermore, genetic disruption of Nrf2 in mice causes early-onset and severe emphysema. The present study evaluated whether the strategy of activation of Nrf2 and its downstream network of cytoprotective genes with a small molecule would attenuate CS-induced oxidative stress and emphysema. Nrf2(+/+) and Nrf2(-/-) mice were fed a diet containing the potent Nrf2 activator, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), while being exposed to CS for 6 months. CDDO-Im significantly reduced lung oxidative stress, alveolar cell apoptosis, alveolar destruction, and pulmonary hypertension in Nrf2(+/+) mice caused by chronic exposure to CS. This protection from CS-induced emphysema depended on Nrf2, as Nrf2(-/-) mice failed to show significant reduction in alveolar cell apoptosis and alveolar destruction after treatment with CDDO-Im. These results suggest that targeting the Nrf2 pathway during the etiopathogenesis of emphysema may represent an important approach for prophylaxis against COPD.

Also strongly related:

Nrf2-dependent sulfiredoxin-1 expression protects against cigarette smoke-induced oxidative stress in lungs.
Singh A, Ling G, Suhasini AN, Zhang P, Yamamoto M, Navas-Acien A, Cosgrove G, Tuder RM, Kensler TW, Watson WH, Biswal S. Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 212045, USA.

Oxidative stress results in protein oxidation and is involved in the pathogenesis of lung diseases such as chronic obstructive pulmonary disorder (COPD). Sulfiredoxin-1 (Srx1) catalyzes the reduction of cysteine sulfinic acid to sulfenic acid in oxidized proteins and protects them from inactivation. This study examined the mechanism of transcriptional regulation of Srx1 and its possible protective role during oxidative stress associated with COPD. Nrf2, a transcription factor known to influence susceptibility to pulmonary diseases, upregulates Srx1 expression during oxidative stress caused by cigarette smoke exposure in the lungs of mice. Disruption of Nrf2 signaling by genetic knockout in mice or RNAi in cells downregulated the expression of Srx1. In silico analysis of the 5'-promoter-flanking region of Srx1 identified multiple antioxidant-response elements (AREs) that are highly conserved. Reporter and chromatin-immunoprecipitation assays demonstrated that ARE1 at -228 is critical for the Nrf2-mediated response. Attenuation of Srx1 expression with RNAi potentiated the toxicity of hydrogen peroxide (H(2)O(2)), whereas overexpression of Srx1 protected against H(2)O(2)-mediated cell death in vitro. Immunoblot analysis revealed dramatic decreases in Srx1 expression in lungs from patients with COPD relative to nonemphysematous lungs together with a decline in Nrf2 protein. Thus, Srx1, a key Nrf2-regulated gene, contributes to protection against oxidative injury in the lung.

Edited by Shinigami, 25 December 2008 - 05:16 AM.

Glutathione peroxidase 2, the major cigarette smoke-inducible isoform of GPX in lungs, is regulated by Nrf2.
Singh A, Rangasamy T, Thimmulappa RK, Lee H, Osburn WO, Brigelius-Flohé R, Kensler TW, Yamamoto M, Biswal S. Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.

Disruption of NF-E2-related factor (Nrf2), a redox-sensitive basic leucine zipper transcription factor, causes early-onset and more severe emphysema due to chronic cigarette smoke. Nrf2 determines the susceptibility of lungs to cigarette smoke-induced emphysema in mice through the transcriptional induction of numerous antioxidant genes. The lungs of Nrf2-/- mice have higher oxidative stress as evident from the increased levels of lipid peroxidation (4-hydroxy-2-nonenal) and oxidative DNA damage (7,8-dihydro-8-Oxo-2'deoxyguanosine) in response to cigarette smoke. Glutathione peroxidases (GPX) are the primary antioxidant enzymes that scavenge hydrogen peroxide and organic hydroperoxides. Among the five GPX isoforms, expression of GPX2 was significantly induced at both mRNA and protein levels in the lungs of Nrf2+/+ mice, in response to cigarette smoke. Activation of Nrf2 by specific knock down of the cytosolic inhibitor of Nrf2, Keap1, by small inhibitory RNA (siRNA) upregulated the expression of GPx2, whereas Nrf2 siRNA down-regulated the expression of GPX2 in lung epithelial cells. An ARE sequence located in the 5' promoter-flanking region of exon 1 that is highly conserved between mouse, rat, and human was identified. Mutation of this ARE core sequence completely abolished the activity of promoter-reporter gene construct. The binding of Nrf2 to the GPX2 antioxidant response element was confirmed by chromatin immunoprecipation, electrophoretic mobility shift assays, and site-directed mutagenesis. This study shows that GPX2 is the major oxidative stress-inducible cellular GPX isoform in the lungs, and that its basal as well as inducible expression is dependent on Nrf2.

Edited by Shinigami, 25 December 2008 - 04:54 AM.

Genetic ablation of Nrf2 enhances susceptibility to cigarette smoke-induced emphysema in mice.
Rangasamy T, Cho CY, Thimmulappa RK, Zhen L, Srisuma SS, Kensler TW, Yamamoto M, Petrache I, Tuder RM, Biswal S. Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.

Although inflammation and protease/antiprotease imbalance have been postulated to be critical in cigarette smoke-induced (CS-induced) emphysema, oxidative stress has been suspected to play an important role in chronic obstructive pulmonary diseases. Susceptibility of the lung to oxidative injury, such as that originating from inhalation of CS, depends largely on its upregulation of antioxidant systems. Nuclear factor, erythroid-derived 2, like 2 (Nrf2) is a redox-sensitive basic leucine zipper protein transcription factor that is involved in the regulation of many detoxification and antioxidant genes. Disruption of the Nrf2 gene in mice led to earlier-onset and more extensive CS-induced emphysema than was found in wild-type littermates. Emphysema in Nrf2-deficient mice exposed to CS for 6 months was associated with more pronounced bronchoalveolar inflammation; with enhanced alveolar expression of 8-oxo-7,8-dihydro-2'-deoxyguanosine, a marker of oxidative stress; and with an increased number of apoptotic alveolar septal cells--predominantly endothelial and type II epithelial cells--as compared with wild-type mice. Microarray analysis identified the expression of nearly 50 Nrf2-dependent antioxidant and cytoprotective genes in the lung that may work in concert to counteract CS-induced oxidative stress and inflammation. The responsiveness of the Nrf2 pathway may act as a major determinant of susceptibility to tobacco smoke-induced emphysema by upregulating antioxidant defenses and decreasing lung inflammation and alveolar cell apoptosis.

Edited by Shinigami, 25 December 2008 - 05:10 AM.

Resveratrol induces glutathione synthesis by activation of Nrf2 and protects against cigarette smoke-mediated oxidative stress in human lung epithelial cells.
Kode A, Rajendrasozhan S, Caito S, Yang SR, Megson IL, Rahman I. Department of Environmental Medicine, Lung Biology and Disease Program, University of Rochester Medical Center, Box 850,601 Elmwood Ave., Rochester, NY 14642, USA.

Nuclear erythroid-related factor 2 (Nrf2), a redox-sensitive transcription factor, is involved in transcriptional regulation of many antioxidant genes, including glutamate-cysteine ligase (GCL). Cigarette smoke (CS) is known to cause oxidative stress and deplete glutathione (GSH) levels in alveolar epithelial cells. We hypothesized that resveratrol, a polyphenolic phytoalexin, has antioxidant signaling properties by inducing GSH biosynthesis via the activation of Nrf2 and protects lung epithelial cells against CS-mediated oxidative stress. Treatment of human primary small airway epithelial and human alveolar epithelial (A549) cells with CS extract (CSE) dose dependently decreased GSH levels and GCL activity, effects that were associated with enhanced production of reactive oxygen species. Resveratrol restored CSE-depleted GSH levels by upregulation of GCL via activation of Nrf2 and also quenched CSE-induced release of reactive oxygen species. Interestingly, CSE failed to induce nuclear translocation of Nrf2 in A549 and small airway epithelial cells. On the contrary, Nrf2 was localized in the cytosol of alveolar and airway epithelial cells due to CSE-mediated posttranslational modifications such as aldehyde/carbonyl adduct formation and nitration. On the other hand, resveratrol attenuated CSE-mediated Nrf2 modifications, thereby inducing its nuclear translocation associated with GCL gene transcription, as demonstrated by GCL-promoter reporter and Nrf2 small interfering RNA approaches. Thus resveratrol attenuates CSE-mediated GSH depletion by inducing GSH synthesis and protects epithelial cells by reversing CSE-induced posttranslational modifications of Nrf2. These data may have implications in dietary modulation of antioxidants in treatment of chronic obstructive pulmonary disease.

Edited by Shinigami, 25 December 2008 - 05:01 AM.

Decline in NRF2-regulated antioxidants in chronic obstructive pulmonary disease lungs due to loss of its positive regulator, DJ-1.
Malhotra D, Thimmulappa R, Navas-Acien A, Sandford A, Elliott M, Singh A, Chen L, Zhuang X, Hogg J, Pare P, Tuder RM, Biswal S. Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Room E7624, 615 North Wolfe St., Baltimore, MD 21205, USA.

RATIONALE: Oxidative stress is a key contributor in chronic obstructive pulmonary disease (COPD) pathogenesis caused by cigarette smoking. NRF2, a redox-sensitive transcription factor, dissociates from its inhibitor, KEAP1, to induce antioxidant expression that inhibits oxidative stress. OBJECTIVES: To determine the link between severity of COPD, oxidative stress, and NRF2-dependent antioxidant levels in the peripheral lung tissue of patients with COPD. METHODS: We assessed the expression of NRF2, NRF2-dependent antioxidants, regulators of NRF2 activity, and oxidative damage in non-COPD (smokers and former smokers) and smoker COPD lungs (mild and advanced). Cigarette smoke-exposed human lung epithelial cells (Beas2B) and mice were used to understand the mechanisms. MEASUREMENTS AND MAIN RESULTS: When compared with non-COPD lungs, the COPD patient lungs showed (1) marked decline in NRF2-dependent antioxidants and glutathione levels, (2) increased oxidative stress markers, (3) significant decrease in NRF2 protein with no change in NRF2 mRNA levels, and (4) similar KEAP1 but significantly decreased DJ-1 levels (a protein that stabilizes NRF2 protein by impairing KEAP1-dependent proteasomal degradation of NRF2). Exposure of Bea2B cells to cigarette smoke caused oxidative modification and enhanced proteasomal degradation of DJ-1 protein. Disruption of DJ-1 in mouse lungs, mouse embryonic fibroblasts, and Beas2B cells lowered NRF2 protein stability and impaired antioxidant induction in response to cigarette smoke. Interestingly, targeting KEAP1 by siRNA or the small-molecule activator sulforaphane restored induction of NRF2-dependent antioxidants in DJ-1-disrupted cells in response to cigarette smoke. CONCLUSIONS: NRF2-dependent antioxidants and DJ-1 expression was negatively associated with severity of COPD. Therapy directed toward enhancing NRF2-regulated antioxidants may be a novel strategy for attenuating the effects of oxidative stress in the pathogenesis of COPD.

Edited by Shinigami, 25 December 2008 - 05:06 AM.

(much more still to come, but I'll be pauzing once in a while )

Since activation of Nrf2 is clearly important (cfr. supra) to induce protection from oxidative stress, anything that activates Nrf2 is relevant to this thread.

[Effect of Spearmint oil on inflammation, oxidative alteration and Nrf2 expression in lung tissue of COPD rats] [Article in Chinese]
Zhao CZ, Wang Y, Tang FD, Zhao XJ, Xu QP, Xia JF, Zhu YF. Zhejiang Respiratory Drugs Research Laboratory of State Food and Drugs Administration, College of Medicine, Zhejiang University, Hangzhou 310058,China.

OBJECTIVE: To investigate the effect of Spearmint oil on inflammation, oxidative alteration and Nrf2 expression in rats with chronic obstructive pulmonary disease(COPD). METHODS: COPD model was induced by intratracheal instillation of Klebsiella pneumonia and lipopolysaccharide (LPS) for 12 weeks in rats, and COPD rats were treated with Spearmint oil for 3 weeks. After COPD was induced, the pathological changes, changes in leucocyte number in blood and bronchoalveolar lavage fluid (BALF), MDA in lung homogenate and Nrf2 expression were observed. The effects of Spearmint oil on these changes were determined. RESULT: Spearmint oil 100 mg*kg(-1)significantly reduced leucocyte numbers in BALF, and attenuated bronchiolitis, pulmonary interstitial inflammation and inflammation cell infiltration. Spearmint oil 30-300 mg*kg(-1)decreased the destruction of pulmonary alveolus and the thickness of bronchioles walls, and inhibited goblet cell proliferation. Spearmint oil significantly reduced MDA in lung homogenate, and decreased the expression of Nrf2 protein in lung tissues. CONCLUSION: Spearmint oil has protective effect on lung injury in COPD rats, since it improves pulmonary inflammation,oxidative alteration, and enhances Nrf2 protein expression.

I don't really understand this abstract, it seems to contradict the research posted previously.

Edited by Shinigami, 25 December 2008 - 05:34 AM.

The synthetic oleanane triterpenoid, CDDO-methyl ester, is a potent antiangiogenic agent.
Vannini N, Lorusso G, Cammarota R, Barberis M, Noonan DM, Sporn MB, Albini A. Multimedica IRCCS, Milan, Italy.

We show that the synthetic oleanane triterpenoid, CDDO-methyl ester (CDDO-Me; methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate) is an effective agent for suppressing angiogenesis, both in cell culture and in vivo. The potency of CDDO-Me is particularly striking when dosed in vivo to inhibit the angiogenic effects of vascular endothelial growth factor and tumor necrosis factor-alpha in Matrigel sponge assays; activity is seen at i.p. doses of CDDO-Me as low as 0.003 mg/kg of body weight. If the Matrigel sponges are impregnated with CDDO-Me just before implantation in the mice, picomolar doses of CDDO-Me will suppress angiogenesis. CDDO-Me also inhibits growth of endothelial cells in monolayer cultures and suppresses neovascular morphogenesis in three-dimensional cultures, but significantly higher doses (50-200 nmol/L) are required. We also show antiangiogenic effects of CDDO-Me on xenografts of Kaposi's sarcoma cells in immunocompromised mice, using CD31 as a marker. Several known individual molecular targets of CDDO-Me and related triterpenoids that are relevant to all of these findings include nuclear factor-kappaB signaling, signal transducers and activators of transcription signaling, and transforming growth factor-beta signaling, as well as Keap1, the endogenous inhibitor of the transcription factor Nrf2. However, the particularly potent antiangiogenic activity seen in vivo in the present experiments suggest that CDDO-Me, as an angioprevention agent, may be interacting with an entire network of molecular and cellular targets, rather than at a single molecular locus or in a single-cell type.

Edited by Shinigami, 25 December 2008 - 05:42 AM.

(It seems the time before you can no longer edit posts is limited to one hour, which -- in this context -- is a pitty.)

Nrf2 defends the lung from oxidative stress.
Cho HY, Reddy SP, Kleeberger SR. Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. cho2@niehs.nih.gov

Nuclear factor, erythroid 2 related factor 2 (Nrf2) belongs to the Cap'n'collar/basic region leucine zipper (CNC-bZIP) transcription factor family, and is activated by diverse oxidants, pro-oxidants, antioxidants, and chemopreventive agents. After phosphorylation and dissociation from the cytoplasmic inhibitor, Kelch-like ECH-associated protein 1 (Keap1), Nrf2 translocates to the nucleus and binds to an antioxidant response element (ARE). Through transcriptional induction of ARE-bearing genes that encode antioxidant-detoxifying proteins, Nrf2 activates cellular rescue pathways against oxidative injury, inflammation/immunity, apoptosis, and carcinogenesis. ARE-driven genes include direct antioxidants (e.g., GPx), thiol metabolism-associated detoxifying enzymes (e.g., GSTs), stress-response genes (e.g., HO-1), and others (e.g., PSMB5). Application of nrf2 germ-line mutant mice elucidated protective roles for Nrf2 in various models of human disorders in the liver, lung, kidney, brain, and circulation. In the lung, deficiency of nrf2 augmented injury caused by bleomycin and environmental oxidants including hyperoxia, diesel exhaust particles, and cigarette smoke. Microarray analyses of lungs from nrf2-deficient and -sufficient mice identified Nrf2-dependent genes that might be critical in pulmonary protection. Observations from these studies highlight the importance of the Nrf2-antioxidant pathway and may provide new therapeutic strategies for acute respiratory distress syndrome, idiopathic pulmonary fibrosis, cancer, and emphysema in which oxidative stress is implicated.

(I will try to indicate reviews with exclamation mark icons.)

Edited by Shinigami, 25 December 2008 - 06:02 AM.

Nrf2: a potential molecular target for cancer chemoprevention by natural compounds.
Jeong WS, Jun M, Kong AN. Food Science Institute, School of Food & Life Science, College of Biomedical Science & Engineering, Inje University, South Korea.

One of the most prominent strategies of cancer chemoprevention might be protecting cells or tissues against various carcinogens and carcinogenic metabolites derived from exogenous or endogenous sources. This protection could be achieved through the induction of phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase, NAD(P)H quinone oxidoreductase 1, and heme oxygenase-1, a process that is mediated mainly by the antioxidant response elements (ARE) within the promoter regions of these genes. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a member of the Cap 'n' collar (CNC) family of basic region-leucine zipper transcription factors, plays a key role in ARE-mediated gene expression. Under normal condition, Nrf2 is sequestered in the cytoplasm by an actin-binding protein, Kelch-like ECH associating protein 1 (Keap1), and upon exposure of cells to inducers such as oxidative stress and certain chemopreventive agents, Nrf2 dissociates from Keap1, translocates to the nucleus, binds to AREs, and transactivates phase 2 detoxifying and antioxidant genes. Several upstream signaling pathways including mitogen-activated protein kinases, protein kinase C, phosphatidylinositol 3-kinase, and transmembrane kinase are implicated in the regulation of Nrf2/ARE activity. Furthermore, many natural chemopreventive agents are known to induce Nrf2/ARE-dependent gene expression, also in part by regulating the turnover of the Nrf2 protein itself. This review discusses our current understanding of the Nrf2/ARE pathway as a potential molecular target for cancer chemoprevention, as well as the feasibility of screening natural compounds for activation of this pathway and as potential cancer preventive agents for human use.

Edited by Shinigami, 25 December 2008 - 06:03 AM.

(did I say "discussion"? These abstracts and the color-coding pretty much speak for themselves )

Nrf2 as a novel molecular target for chemoprevention.

Lee JS, Surh YJ. National Research Laboratory of Molecular Carcinogenesis and Chemoprevention, College of Pharmacy, Seoul National University, Shinlim-dong, Kwanak-ku, Seoul 151-742, South Korea.

One of the rational and effective strategies for chemoprevention is the blockade of DNA damage caused by carcinogenic insult. This can be achieved either by reducing the formation of reactive carcinogenic species or stimulating their detoxification. A wide spectrum of xenobiotic metabolizing enzymes catalyze both phase I (oxidation and reduction) and phase II biotransformation (conjugation) reactions involved in carcinogen activation and/or deactivation. Several antioxidant-response element (ARE)-regulated gene products such as glutathione S-transferase, NAD(P)H:quinone oxidoreductase 1, UDP-glucuronosyltransferase, gamma-glutamate cysteine ligase, and hemeoxygenase-1 are known to mediate detoxification and/or to exert antioxidant functions thereby protecting cells from genotoxic damage. The transcription of ARE-driven genes is regulated, at least in part, by nuclear transcription factor erythroid 2p45 (NF-E2)-related factor 2 (Nrf2), which is sequestered in cytoplasm by Kelch-like ECH-associated protein 1 (Keap1). Exposure of cells to ARE inducers results in the dissociation of Nrf2 from Keap1 and facilitates translocation of Nrf2 to the nucleus, where it heterodimerizes with small Maf protein, and binds to ARE, eventually resulting in the transcriptional regulation of target genes. The Nrf2-Keap1-ARE signaling pathway can be modulated by several upstream kinases including phosphatidylinositol 3-kinase, protein kinase C, and mitogen-activated protein kinases. Selected Nrf2-Keap1-ARE activators, such as oltipraz, anethole dithiolethione, sulforaphane, 6-methylsulphinylhexyl isothiocyanate, curcumin, caffeic acid phenethyl ester, 4'-bromoflavone, etc. are potential chemopreventive agents. This mini-review will focus on a chemopreventive strategy directed towards protection of DNA and other important cellular molecules by inducing de novo synthesis of phase II detoxifying or antioxidant genes via the Nrf2-ARE core signaling pathway.

Edited by Shinigami, 25 December 2008 - 06:03 AM.

Nrf2 as a master redox switch in turning on the cellular signaling involved in the induction of cytoprotective genes by some chemopreventive phytochemicals.
Surh YJ, Kundu JK, Na HK. National Research Laboratory of Molecular Carcinogenesis and Chemoprevention, College of Pharmacy, Seoul National University, Seoul, South Korea. surh@plaza.snu.ac.kr

A wide array of dietary phytochemicals have been reported to induce the expression of enzymes involved in both cellular antioxidant defenses and elimination/inactivation of electrophilic carcinogens. Induction of such cytoprotective enzymes by edible phytochemicals largely accounts for their cancer chemopreventive and chemoprotective activities. Nuclear factor-erythroid-2-related factor 2 (Nrf2) plays a crucial role in the coordinated induction of those genes encoding many stress-responsive and cytoptotective enzymes and related proteins. These include NAD(P)H:quinone oxidoreductase-1, heme oxygenase-1, glutamate cysteine ligase, glutathione S-transferase, glutathione peroxidase, thioredoxin, etc. In resting cells, Nrf2 is sequestered in the cytoplasm as an inactive complex with the repressor Kelch-like ECH-associated protein 1 (Keap1). The release of Nrf2 from its repressor is most likely to be achieved by alterations in the structure of Keap1. Keap1 contains several reactive cysteine residues that function as sensors of cellular redox changes. Oxidation or covalent modification of some of these critical cysteine thiols would stabilize Nrf2, thereby facilitating nuclear accumulation of Nrf2. After translocation into nucleus, Nrf2 forms a heterodimer with other transcription factors, such as small Maf, which in turn binds to the 5'-upstream CIS-acting regulatory sequence, termed antioxidant response elements (ARE) or electrophile response elements (EpRE), located in the promoter region of genes encoding various antioxidant and phase 2 detoxifying enzymes. Certain dietary chemopreventive agents target Keap1 by oxidizing or chemically modifying one or more of its specific cysteine thiols, thereby stabilizing Nrf2. In addition, phosphorylation of specific serine or threonine residues present in Nrf2 by upstream kinases may also facilitate the nuclear localization of Nrf2. Multiple mechanisms of Nrf2 activation by signals mediated by one or more of the upstream kinases, such as mitogen-activated protein kinases, phosphatidylionositol-3-kinase/Akt, protein kinase C, and casein kinase-2 have recently been proposed. This review highlights the cytoprotective gene expression induced by some representative dietary chemopreventive phytochemicals with the Nrf2-Keap1 system as a prime molecular target.

Chemoprevention through the Keap1-Nrf2 signaling pathway by phase 2 enzyme inducers.
Kwak MK, Wakabayashi N, Kensler TW. Department of Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.

One successful strategy for cancer chemoprevention is modulation of drug metabolizing enzymes, leading to a facilitated elimination of endogenous and environmental carcinogens. Inducers of phase 2 enzymes such as dithiolethiones inhibit tumorigenesis of environmental carcinogens in various animal models and modulate the metabolism of the carcinogen aflatoxin B1 in human clinical trials. Increasing lines of evidence show that the Keap1-Nrf2 complex is a key molecular target of chemopreventive phase 2 enzyme inducers. The transcription factor Nrf2 is a member of the basic leucine-zipper NF-E2 family and interacts with the antioxidant response element (ARE) in the promoter region of phase 2 detoxifying enzymes. A cytoplasmic actin-binding protein, Keap1, is an inhibitor of Nrf2 that sequesters it in the cytoplasm. Inducers dissociate this complex, allowing Nrf2 to translocate to the nucleus. Disruption of the nrf2 gene in mice leads to the loss of chemopreventive efficacy by inducers. This review focuses on (1) the role of Nrf2 in the regulation of phase 2 and antioxidative genes, (2) the molecular actions of dithiolethiones on the Keap1-Nrf2 pathway, and (3) the contribution of Nrf2-regulated gene families to the cytoprotective actions of dithiolethiones and other inducers. Rapidly accumulating data on this pathway is providing insight into the coordinated mammalian defense systems against electrophiles and oxidative stresses and the means by which it may be targeted by small molecules.

Edited by Shinigami, 25 December 2008 - 06:26 AM.

Nrf2-deficient mice are highly susceptible to cigarette smoke-induced emphysema.
Iizuka T, Ishii Y, Itoh K, Kiwamoto T, Kimura T, Matsuno Y, Morishima Y, Hegab AE, Homma S, Nomura A, Sakamoto T, Shimura M, Yoshida A, Yamamoto M, Sekizawa K. Department of Respiratory Medicine, University of Tsukuba, Japan.

Inflammation, protease/anti-protease imbalance and oxidative stress play important roles in the pathogenesis of emphysema. Nrf2 counteracts oxidative tissue damage and inflammation through transcriptional activation via the anti-oxidant responsive element (ARE). To clarify the protective role of Nrf2 in the development of emphysema, the susceptibility of Nrf2-knockout mice to cigarette smoke (CS)-induced emphysema was examined. In Nrf2-knockout mice, emphysema was first observed at 8 weeks and exacerbated by 16 weeks following CS-exposure, whereas no pathological abnormalities were observed in wild-type mice. Neutrophilic lung inflammation and permeability lung damage were significantly enhanced in Nrf2-knockout mice 8 weeks after CS-exposure. Importantly, neutrophil elastase activity in bronchoalveolar lavage fluids was markedly higher in Nrf2-knockout mice preceding the pronounced neutrophil accumulation. The expression of secretory leukoprotease inhibitor, a potent inhibitor of neutrophil elastase, was inducible in wild-type, but not in Nrf2-knockout mice. This protease/anti-protease imbalance, together with the lack of inducible expression of ARE-regulated anti-oxidant/anti-inflammatory genes, may explain the predisposition of Nrf2-knockout mice to neutrophilic inflammation. Indeed, specific activators of Nrf2 induced the expression of the SLPI gene in macrophages. These results indicate that Nrf2 protects against the development of emphysema by regulating not only the oxidant/anti-oxidant balance, but also inflammation and the protease/anti-protease balance.

Induction of drug-metabolizing enzymes by garlic and allyl sulfide compounds via activation of constitutive androstane receptor and nuclear factor E2-related factor 2.
Fisher CD, Augustine LM, Maher JM, Nelson DM, Slitt AL, Klaassen CD, Lehman-McKeeman LD, Cherrington NJ. Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA.

Garlic oil (GO) contains several linear sulfur compounds, including diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), that induce drug-metabolizing enzymes such as CYP2B and NAD(P)H quinone oxidoreductase 1 (NQO1). CYP2B and NQO1 are primarily regulated by constitutive androstane receptor (CAR) and nuclear factor E2-related factor 2 (Nrf2) transcription factors, respectively. The purpose of this study was to determine whether GO and its specific constituents induce these two enzymes via CAR and Nrf2 activation. Female Wistar-Kyoto (WKY) rats express little CAR protein and exhibit less induction of CYP2B1/2 than males. GO, DAS, and DADS, but not DATS, induced CYP2B1/2 mRNA levels to a greater extent in WKY males than in females, suggesting CAR activation. Conversely, DAS induced NQO1 levels equally in WKY males and females, indicating CAR-independent induction in rats. DAS, but not GO, DADS, or DATS, induced CYP2B10 mRNA levels 530-fold in wild-type (WT) mice, whereas this induction was attenuated in CAR(-/-) mice. DAS induced NQO1 in WT and CAR(-/-) mice equally, suggesting CAR-independent induction in mice. DAS induced NQO1 5-fold in WT mice, whereas induction was completely absent in Nrf2(-/-) mice, indicating DAS also activates Nrf2. DAS induction of CYP2B10 mRNA was independent of Nrf2 presence or absence. In in vivo transcription assays, DAS activated the human CYP2B6 promoter, and the antioxidant response element of the human NQO1 promoter, respectively. These studies indicate that GO constituents, particularly DAS, activate CAR and Nrf2 to induce drug-metabolizing enzymes.

I believe chopped garlic strongly activates Nrf2.

Edited by Shinigami, 25 December 2008 - 06:35 AM.

I believe chopped garlic strongly activates Nrf2.

Note that a lot at once when under heavy oxidative/inflammatory attack makes me feel very sick (temporarily).

Edited by Shinigami, 25 December 2008 - 07:22 AM.

Sulforaphane protects against cytokine- and streptozotocin-induced beta-cell damage by suppressing the NF-kappaB pathway.
Song MY, Kim EK, Moon WS, Park JW, Kim HJ, So HS, Park R, Kwon KB, Park BH. Department of Biochemistry, Medical School and Diabetes Research Center, Chonbuk National University, Jeonju, Jeonbuk, 561-756, Republic of Korea.

Sulforaphane (SFN) is an indirect antioxidant that protects animal tissues from chemical or biological insults by stimulating the expression of several NF-E2-related factor-2 (Nrf2)-regulated phase 2 enzymes. Treatment of RINm5F insulinoma cells with SFN increases Nrf2 nuclear translocation and expression of phase 2 enzymes. In this study, we investigated whether the activation of Nrf2 by SFN treatment or ectopic overexpression of Nrf2 inhibited cytokine-induced beta-cell damage. Treatment of RIN cells with IL-1beta and IFN-gamma induced beta-cell damage through a NF-kappaB-dependent signaling pathway. Activation of Nrf2 by treatment with SFN and induction of Nrf2 overexpression by transfection with Nrf2 prevented cytokine toxicity. The mechanism by which Nrf2 activation inhibited NF-kappaB-dependent cell death signals appeared to involve the reduction of oxidative stress, as demonstrated by the inhibition of cytokine-induced H(2)O(2) production. The protective effect of SFN was further demonstrated by the restoration of normal insulin secreting responses to glucose in cytokine-treated rat pancreatic islets. Furthermore, pretreatment with SFN blocked the development of type 1 diabetes in streptozotocin-treated mice.

Potent protection against aflatoxin-induced tumorigenesis through induction of Nrf2-regulated pathways by the triterpenoid 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole.
Yates MS, Kwak MK, Egner PA, Groopman JD, Bodreddigari S, Sutter TR, Baumgartner KJ, Roebuck BD, Liby KT, Yore MM, Honda T, Gribble GW, Sporn MB, Kensler TW. Johns Hopkins University, Baltimore, Maryland, USA.

Synthetic triterpenoid analogues of oleanolic acid are potent inducers of the phase 2 response as well as inhibitors of inflammation. We show that the triterpenoid, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), is a highly potent chemopreventive agent that inhibits aflatoxin-induced tumorigenesis in rat liver. The chemopreventive potency of CDDO-Im was evaluated by measuring inhibition of formation of putative preneoplastic lesions (glutathione S-transferase P positive foci) in the liver of rats exposed to aflatoxin B1. CDDO-Im produces an 85% reduction in the hepatic focal burden of preneoplastic lesions at 1 micromol/kg body weight and a >99% reduction at 100 micromol/kg body weight. CDDO-Im treatment reduces levels of aflatoxin-DNA adducts by approximately 40% to 90% over the range of 1 to 100 micromol/kg body weight. Additionally, changes in mRNA levels of genes involved in aflatoxin metabolism were measured in rat liver following a single dose of CDDO-Im. GSTA2, GSTA5, AFAR, and EPHX1 transcripts are elevated 6 hours following a 1 micromol/kg body weight dose of CDDO-Im. Microarray analysis using wild-type and Nrf2 knockout mice confirms that many phase 2 and antioxidant genes are induced in an Nrf2-dependent manner in mouse liver following treatment with CDDO-Im. Thus, low-micromole doses of CDDO-Im induce cytoprotective genes, inhibit DNA adduct formation, and dramatically block hepatic tumorigenesis. As a point of reference, oltipraz, an established modulator of aflatoxin metabolism in humans, is 100-fold weaker than CDDO-Im in this rat antitumorigenesis model. The unparalleled potency of CDDO-Im in vivo highlights the chemopreventive promise of targeting Nrf2 pathways with triterpenoids.

Network inference algorithms elucidate Nrf2 regulation of mouse lung oxidative stress.
Taylor RC, Acquaah-Mensah G, Singhal M, Malhotra D, Biswal S. Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, U.S. Department of Energy, Richland, Washington, United States of America. ronald.taylor24@gmail.com

A variety of cardiovascular, neurological, and neoplastic conditions have been associated with oxidative stress, i.e., conditions under which levels of reactive oxygen species (ROS) are elevated over significant periods. Nuclear factor erythroid 2-related factor (Nrf2) regulates the transcription of several gene products involved in the protective response to oxidative stress. The transcriptional regulatory and signaling relationships linking gene products involved in the response to oxidative stress are, currently, only partially resolved. Microarray data constitute RNA abundance measures representing gene expression patterns. In some cases, these patterns can identify the molecular interactions of gene products. They can be, in effect, proxies for protein-protein and protein-DNA interactions. Traditional techniques used for clustering coregulated genes on high-throughput gene arrays are rarely capable of distinguishing between direct transcriptional regulatory interactions and indirect ones. In this study, newly developed information-theoretic algorithms that employ the concept of mutual information were used: the Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNE), and Context Likelihood of Relatedness (CLR). These algorithms captured dependencies in the gene expression profiles of the mouse lung, allowing the regulatory effect of Nrf2 in response to oxidative stress to be determined more precisely. In addition, a characterization of promoter sequences of Nrf2 regulatory targets was conducted using a Support Vector Machine classification algorithm to corroborate ARACNE and CLR predictions. Inferred networks were analyzed, compared, and integrated using the Collective Analysis of Biological Interaction Networks (CABIN) plug-in of Cytoscape. Using the two network inference algorithms and one machine learning algorithm, a number of both previously known and novel targets of Nrf2 transcriptional activation were identified. Genes predicted as novel Nrf2 targets include Atf1, Srxn1, Prnp, Sod2, Als2, Nfkbib, and Ppp1r15b. Furthermore, microarray and quantitative RT-PCR experiments following cigarette-smoke-induced oxidative stress in Nrf2(+/+) and Nrf2(-/-) mouse lung affirmed many of the predictions made. Several new potential feed-forward regulatory loops involving Nrf2, Nqo1, Srxn1, Prdx1, Als2, Atf1, Sod1, and Park7 were predicted. This work shows the promise of network inference algorithms operating on high-throughput gene expression data in identifying transcriptional regulatory and other signaling relationships implicated in mammalian disease.

Note that, if I got that right, Park7 (implicated in Parkinsons) == DJ-1.

Note also that this article provides evidence for a direct link between Nrf2 and NF-kappaB (through Nfkbib).

Edited by Shinigami, 25 December 2008 - 11:42 AM.

Preclinical evaluation of targeting the Nrf2 pathway by triterpenoids (CDDO-Im and CDDO-Me) for protection from LPS-induced inflammatory response and reactive oxygen species in human peripheral blood mononuclear cells and neutrophils.
Thimmulappa RK, Fuchs RJ, Malhotra D, Scollick C, Traore K, Bream JH, Trush MA, Liby KT, Sporn MB, Kensler TW, Biswal S. Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.

Sepsis is characterized by an inappropriate host immune-inflammatory response and sustained oxidative damage. Nrf2, a bZIP oxidant-responsive transcription factor, regulates a battery of cytoprotective genes including antioxidants and maintains cellular redox homeostasis. Mouse studies have demonstrated a critical role of Nrf2 in improving survival during sepsis. This preclinical ex vivo study using neutrophils and peripheral blood mononuclear cells (PBMCs) as a surrogate cells evaluates the efficacy of CDDO-Im and CDDO-Me [imidazole and methyl ester derivative of 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO)] to activate the Nrf2 pathway and protect from lipopolysaccharide (LPS)-induced inflammatory response in humans. CDDO-Im treatment significantly induced Nrf2-dependent antioxidative genes (HO-1, GCLC, GCLM, and NQO1) in PBMCs isolated from six normal subjects. CDDO-Im increased nuclear accumulation of Nrf2 protein. Pretreatment of PBMC by CDDO-Im significantly attenuated LPS-induced cytokine expression. Similar increases in levels of antioxidant genes and suppression of LPS-induced cytokine expression was observed after CDDO-Me pretreatment. CDDO-Im also greatly inhibited LPS, fMLP, TNF-alpha, and TPA-induced ROS generation in neutrophils. In conclusion, these results demonstrate that activation of the Nrf2-dependent antioxidative pathway by CDDO-Im or CDDO-Me protects against the LPS-induced inflammatory response and suggest that they can be potential therapeutic candidates for intervening sepsis syndrome.

(If I'm not mistaken:) As LPS induces NF-kappaB directly and via TNF-alpha, and NF-kappaB induces cytokine expression (cfr. infra), this may suggest the attenuating effect of CDDO-Im on LPS-induced cytokine expression results from inhibition of NF-kappaB (see also http://www.imminst.o...o...t&p=286491).

As we're now getting on the topic of NF-kappaB, people may want to check out the attached image provided by the Cell journal, and the attached images from wikipedia (from NF-kappaB and TNF-alpha).

(If I'm not mistaken:) Briefly (looking at the cell journal image) you can see:

• A Toll-like receptor (TLR) at the far left which is being activated by lipopolyssacharide (LPS), a sugar secreted by gram-negative bacteria. This in turns activates NF-kappaB through phosphorylation of its inhibtor Ikk-beta (inhibitor of NF-kappaB beta).
• A Tumor-necrosis factor receptor (second from left), which is activated by TNF-alpha (amongst others?).
  • This also activated NF-kappaB through phosphorylation of its inhibtor IkkB and IkkA (inhibitor of NF-kappaB alpha).
  • Is also related to the JNK-pathway (last image from wikipedia).
  • Is related to the cell death pathway (Cell journal and wikipedia image).
• Two antigen receptors (right), also activating NF-kappaB.

The NF-kappaB seems to be intended to respond to bacterial infections by increasing inflammation and induction of cytokines, thus countering the infection. There seems to be a positive feedback loop through TNF-alpha (TNF-alpha not only activates NF-kappaB, but is also induced by it). Furthermore, NF-kappaB is also designed to be actived by antigens and is thus related to allergies.

As you can see the NF-kappaB complex and its inhibitors come in several varieties. We're indeed talking about a complex: NF-kappaB consist of RelA and another thing called p50 (or related things like p65?). A pretty in-depth discussion can be found at: http://people.bu.edu/gilmore/nf-kb/

A better (succinct) explanation from someone who actually knows what he is talking about is welcome!

Edited by Shinigami, 25 December 2008 - 01:11 PM.

Inhibition of cell growth and induction of apoptosis via inactivation of NF-kappaB by a sulfurcompound isolated from garlic in human colon cancer cells.
Ban JO, Yuk DY, Woo KS, Kim TM, Lee US, Jeong HS, Kim DJ, Chung YB, Hwang BY, Oh KW, Hong JT. College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk, Korea.

Compounds such as S-allylmercaptocysteine, diallyl disulfide, and S-trityl-L-cysteine isolated from garlic have been known to be effective in chemoprevention. Nuclear transcription factor-kappaB (NF-kappaB) has been known to be an implicated factor in apoptotic cell death of several cancer cells. In this study, we investigated whether a sulfurcompound (named thiacremonone) isolated from garlic could modulate NF-kappaB activity and thereby induce apoptotic cell death of colon cancer cells. Treatment with different concentrations (30 - 150 microg/ml) of thiacremonone for various periods (0 - 48 h) inhibited colon cancer cell (SW620 and HCT116) growth followed by induction of apoptosis in a dose-dependent manner. We also found that thiacremonone modulated tumor necrosis factor-alpha (TNF-alpha) and tetradeanoyl phorbol acetate (TPA)-induced NF-kappaB transcriptional and DNA binding activity. Moreover, thiacremonone suppressed NF-kappaB target anti-apoptotic genes (Bcl-2, cIAP1/2, and XIAP) and inflammatory genes (iNOS and COX-2), whereas it induced apoptotic genes (Bax, cleaved caspse-3, and cleaved PARP) expression. These results suggest that a novel sulfurocompound from garlic inhibited colon cancer cell growth through induction of apoptotic cell death by modulating of NF-kappaB.

Inhibition of cyclooxygenase 2 expression by diallyl sulfide on joint inflammation induced by urate crystal and IL-1beta.
Lee HS, Lee CH, Tsai HC, Salter DM. Department of Pathology, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan, ROC. herngsheng131419@gmail.com

OBJECTIVE: Investigation of the effects of diallyl sulfide (DAS), a garlic sulfur compound, on joint tissue inflammatory responses induced by monosodium urate (MSU) crystals and interleukin-1beta (IL-1beta). DESIGN: The HIG-82 synovial cell line was used to establish the experimental model and DAS regime. Primary cultures of articular chondrocytes and synovial fibroblasts obtained from patients undergoing joint replacement for osteoarthritis were used in experimental studies. Cyclooxygenase (COX) expression following MSU crystal and IL-1beta stimulation with/without DAS co-incubation was assessed by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunocytochemistry and nuclear factor-kappa B (NF-kappaB) activation determined by electrophoretic mobility shift assay. Prostaglandin E2 (PGE(2)) production was measured by enzyme-linked immunosorbent assay (ELISA). DAS effects on COX gene expression in an MSU crystal-induced acute arthritis in rats were assessed by RT-PCR. RESULTS: MSU crystals upregulated COX-2 expression in HIG-82 cells and this was inhibited by co-incubation with DAS. DAS inhibited MSU crystal and IL-1beta induced elevation of COX-2 expression in primary synovial cells and chondrocytes. Production of PGE(2) induced by crystals was suppressed by DAS and celecoxib. MSU crystals had no effect on expression of COX-1 in synovial cells. NF-kappaB was activated by MSU crystals and this was blocked by DAS. Increased expression of COX-2 in synovium following intraarticular injection of MSU crystals in a rat model was inhibited by co-administration of DAS. CONCLUSIONS: DAS prevents IL-1beta and MSU crystal induced COX-2 upregulation in synovial cells and chondrocytes and ameliorates crystal induced synovitis potentially through a mechanism involving NF-kappaB. Anti-inflammatory actions of DAS may be of value in treatment of joint inflammation.

Diallyl sulfide induces apoptosis in Colo 320 DM human colon cancer cells: involvement of caspase-3, NF-kappaB, and ERK-2.
Sriram N, Kalayarasan S, Ashokkumar P, Sureshkumar A, Sudhandiran G. Department of Biochemistry, University of Madras, Guindy Campus, Chennai, Tamil Nadu 600 025, India.

Chemoprevention is regarded as one of the most promising and realistic approaches in the prevention of human cancer. Diallyl sulfide (DAS), an organosulfur component of garlic has been known for its chemopreventive activities against various cancers and also in recent years, numerous investigations have shown that sulfur-containing compounds induce apoptosis in multiple cell lines and experimental animals. Thus the present study was focused to elucidate the anticancerous effect and the mode of action of DAS against Colo 320 DM colon cancer cells. DAS induced apoptosis in Colo 320 DM cells was revealed by flow cytometer analysis and phosphatidyl serine exposure. DAS also promoted cell cycle arrest substantially at G2/M phase in Colo 320 DM cells. The production of reactive oxygen intermediates, which were examined by 2,7-dichlorodihydrofluorescein diacetate (H2DCF-DA), increased with time, after treatment with DAS. The activities of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were decreased upon DAS treatment, which shows the antiproliferative and the cytotoxic effects, respectively. The expression of NF-kappaB was upregulated in DAS treated cells, compared to normal cells. Further, DAS promoted the expression of caspase-3 and suppression of Extracellular Regulatory Kinase-2 (ERK-2) activity in Colo 320 DM cells that was determined by Western blot analysis. In conclusion, DAS increased the production of ROS, caused cell cycle arrest, decreased cell proliferation and induced apoptosis in Colo 320 DM cells. Thus, this study put forward DAS as a drug that can possibly be used to treat cancers.

Allicin, a major component of garlic, inhibits apoptosis in vital organs in rats with trauma/hemorrhagic shock.
Zhang Y, Yao HP, Huang FF, Wu W, Gao Y, Chen ZB, Liang ZY, Liang TB. Department of Emergency Medicine, Key Laboratory of Multi-organ Transplantation of Ministry of Public Health, Institute of Infectious Diseases, the First Affiliated Hospital, College of Medicine Zhejiang University, Hangzhou, China.

OBJECTIVE: Allicin is believed to be the main component responsible for the biological activity of garlic. The regulation of cell apoptosis may have therapeutic potential for trauma/hemorrhagic shock, and previous studies have demonstrated that allicin exerts protective effects against tissue ischemia-reperfusion injury. Therefore, this study examined the effects of allicin on apoptosis-related organ damage, induced by trauma/hemorrhagic shock. METHODS: Studies were performed on an in vivo model of spontaneously breathing rats with induced trauma/hemorrhagic shock; the left lower lobe of the lungs, left kidney, and intestine were resected, and the rats were subjected to femur fracture, ischemia for 30 mins, and reperfusion for 20 mins. Allicin (30 microg/kg) was administered during reperfusion. RESULTS: Allicin administered during reperfusion markedly attenuated injury and apoptosis of the lungs, kidneys, and intestine and decreased the concentrations of lactic acid and creatinine, the number of in situ TdT-mediated dUTP nick-end labeling-positive cells, and the activity and expression of caspase-3 and -9 (as determined by Western blot). Furthermore, immunohistochemistry and Western blot performed 24 hrs after reperfusion revealed increases in the levels of nuclear factor kappaB, phosphorylated p38, and extracellular signal-regulated kinase 1 mitogen-activated protein kinase in the allicin-untreated group when compared with the sham rats. Allicin treatment downregulated the levels of nuclear factor kappaB and phosphorylated p38 mitogen-activated protein kinase but did not modify those of phosphorylated extracellular signal-regulated kinase 1 mitogen-activated protein kinase. CONCLUSION: Allicin attenuates tissue injury and inhibits trauma/hemorrhagic shock- and reperfusion-induced apoptosis in several important organs via the p38 mitogen-activated protein kinase signal transduction pathway that functions to stimulate the activation of nuclear factor-kappaB, caspase-3 and -9, but not of extracellular signal-regulated kinase 1 mitogen-activated protein kinase.

Sounds contradictory? It seems the activation of the cell-death pathway depends on the redox status of the cell, which seems to differ between healthy and cancer cells. Anyone that can verify this possibility?

Edited by Shinigami, 25 December 2008 - 01:04 PM.

Garlic (Allium sativum) extract inhibits lipopolysaccharide-induced Toll-like receptor 4 dimerization.

Youn HS, Lim HJ, Lee HJ, Hwang D, Yang M, Jeon R, Ryu JH. Department of Biomedical Laboratory Science, College of Medical Sciences, Soonchunhyang University, Asan-Si, Chungnam 336-745, Korea. Garlic has long been used as a folk medicine. Numerous studies have demonstrated that a garlic extract and its sulfur-containing compounds inhibited nuclear factor kappa B (NF-kappaB) activation induced by various receptor agonists including lipopolysaccharide (LPS). Toll-like receptors (TLRs) play a key role in sensing diverse microbial products and inducing innate immune responses. The dimerization of TLR4 is required for the activation of downstream signaling pathways, including NF-kappaB. Therefore, TLR4 dimerization may be one of the first lines of regulation in activating LPS-induced signaling pathways. We report here biochemical evidence that the ethyl acetate fraction of garlic inhibited the LPS-induced dimerization of TLR4, resulting in the inhibition of NF-kappaB activation and the expression of cyclooxygenase 2 and inducible nitric oxide synthase. Our results demonstrate for the first time that a garlic extract can directly inhibit the TLRs-mediated signaling pathway at the receptor level. These results shed a new insight into understanding how garlic modulates the immune responses that could modify the risk of many chronic diseases.

How can you help?

• Read this thread before you go to sleep
• Dream about it
• Connect the links
• Report any clear insights you have found by doing this

or

• Relate the given abstracts with your own knowledge of the related pathways and discuss

or

• Make a succinct but thorough synopsis of all the articles on a page of this thread so I can put it in the last post of the page.

Edited by Shinigami, 25 December 2008 - 01:28 PM.