Enterolactone induces heme oxygenase-1 expression through nuclear factor-E2-related factor 2 activation in endothelial cells

Ischemic Stroke Shifts the Protein and Metabolite Profiles of Colon in Mice

Over half of all stroke patients present gastrointestinal complications. It has been speculated that there is an intriguing brain-gut connection. However, molecular mechanisms of the connection remain poorly illuminated. Thus, this study is aimed to investigate molecular alternations regarding proteins and metabolites in the colon upon ischemic stroke using multi-omics analyses. Here, stroke mouse model was induced by means of transient middle cerebral artery occlusion. After the confirmation of successful model evaluated as evidenced by neurological deficit and cerebral blood flow decrease, the proteins and metabolites of colon and brain were respectively measured using multiple omics. Functional analysis of differentially expressed proteins (DEPs) and differential metabolites was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation. There were 434 common DEPs in the colon and brain after stroke. The DEPs in the two tissues displayed common enrichment in several pathways upon GO/KEGG analyses. The common KEGG pathways of DEPs were mainly linked to the inflammation and immune network. Although there was no common differential metabolite and its corresponding pathway in the two tissues, several metabolism pathways in the colon were also changed after stroke. In conclusion, we have demonstrated that the proteins and metabolites in the colon are significantly changed after ischemic stroke, which provides molecular-level evidence regarding the brain-gut connection. In this light, several common enriched pathways of DEPs may become potential therapeutic targets for stroke upon the brain-gut axis. Notably, we have discovered a promising colon-derived metabolite enterolactone possibly beneficial for tackling stroke.

Anticancer potential of flaxseed lignans, their metabolites and synthetic counterparts in relation with molecular targets: current challenges and future perspectives

Lignans are known dietary polyphenols found in cereals, plants and seeds. Flaxseed is one of the major sources of lignans mainly existing in the form of secoisolariciresinol diglucoside (SDG) which can be metabolised by the gut microbes into secoisolariciresinol (SECO) and mammalian lignan (enterodiol and enterolactone) that are easily absorbed through the intestines. Numerous studies reveal that flaxseed lignans (FLs) can be promising chemotherapeutics/chemopreventive agents. Their anticancer activity can occur through the induction of apoptosis, inhibition of cell proliferation, and the hindering of metastasis and angiogenesis. The anti-carcinogenesis of flaxseed lignans is achieved through multiple molecular mechanisms involving biochemical entities such as cellular kinases, cell cycle mediators, transcription factors, inflammatory cytokines, reactive oxygen species, and drug transporters. This review summarizes the bioavailability of FLs, their anticancer mechanisms in relevance to molecular targets, safety, and the scope of future research. Overall, FLs can be utilized in functional foods, dietary supplements, and pharmaceuticals for the management and prevention of cancers.

Bacteria in human lumbar discs - subclinical infection or contamination? Metabolomic evidence for colonization, multiplication, and cell-cell cross-talk of bacteria

BACKGROUND CONTEXT

The accumulating evidence associating sub-clinical infection with disc degeneration (DD) and the controversy of contamination versus infection mandates a further understanding of the microbial activity in the disc and host-microbiome interaction.

PURPOSE

To utilize a novel approach of metabolomics to probe the presence of bacterial metabolites involved in colonization, survival, and replication in human lumbar intervertebral discs (LIVD).

STUDY DESIGN

An observational case-control study.

PATIENT SAMPLE

Nucleus pulposus from the LIVD of three brain-dead voluntary organ donors (MRI normal and classified as controls) and of three patients undergoing surgery for disc degeneration (DD) (cases) were utilized.

METHODS

Untargeted metabolite profiling was carried out in six discs (3-controls and 3-cases) after extraction using methanol: acetonitrile: water (2:2:1) solvent system and acquired through HPLC-MS/MS platform using C18 reversed-phase column. From the total IVD metabolome, microbial metabolites were filtered by mapping against HMDB, ChEBI, SigMol, Siderophore database, ecdmb database, and PaMet databases. The biological functions of the metabolites were then studied by MSEA pipeline from Metaboanalyst, and the enrichment ratio, p-value, and Variably Importance Projection scores of the metabolites were calculated. Degeneration responsive changes in the abundance of the microbial metabolites were calculated based on the peak intensities between the control and cases.

RESULTS

Mass spectrometry identified a total of 17601 and 15003 metabolites, respectively, in the control and degenerated discs. Preliminary mapping of the above metabolites against HMDB indicated the multiple sources, and of these, 64 metabolites were of microbial origin, accounting for 1.6% of the total IVD metabolome. Principle Component Analysis and Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA) showed distinct clustered patterns between control and disc degene`ration, indicating a strong variation in concentration, peak, and spectral values of the 64 metabolites between controls and cases. After the exclusion of metabolites that were also associated with humans, drugs, and food, 39 metabolites specific to bacteria were isolated. Nine were primary metabolites related to bacterial growth and survival, and the remaining 30 were secondary metabolites related to different environmental stress response activities. The three significant pathways (p<.001) which were predominant in the bacterial metabolites were autoinducer-2 biosynthesis, peptidoglycan biosynthesis, and chorismate pathway. In addition, a significant fold change of >1.0 was found for nine metabolites which included (S)-14-Methyilhexadecanoic acid related to P. acnes, 9-OxoODE, and 13-OxoODE related to gut flora, vibriobactin - a siderophore, tuberculosinol and iso-tuberculosinol, virulence factors of M. tuberculosis. There was also upregulation of Autoinducer- 2, an important "Quorum sensing molecule" involved in bacterial cross-talk.

CONCLUSION

We identified several bacterial-specific metabolites participating in bacterial growth, survival, and cross-talk pathways. These were found in both groups but up-regulated in degenerated discs. The presence of Quorum sensing molecules and cell-cell interactions provides firm proof of colonization and growth. These findings indicate that the bacterial presence may not be mere contamination but could be colonization with a possible role in infection-mediated inflammation in DD.

CLINICAL SIGNIFICANCE

Proof of subclinical infection as an initiator of DD and documentation of exact germ and drug sensitivity will change the way millions of patients with non-specific low back pain (NSLBP) are treated across the world.

Protective Role of Polyphenols in Heart Failure: Molecular Targets and Cellular Mechanisms Underlying Their Therapeutic Potential

Heart failure (HF) is a leading cause of death in the United States, with a 5-year mortality rate of 50% despite modern pharmacological therapies. Plant-based diets are comprised of a diverse polyphenol profile, which lends to their association with reduced cardiovascular disease risk. Whether a polyphenol-rich diet can slow the progression of or reverse HF in humans is not known. To date, in vitro and in vivo studies have reported on the protective role of polyphenols in HF. In this review, we will discuss the major mechanisms by which polyphenols mitigate HF in vitro and in vivo, including (1) reduced cardiac inflammation and oxidative stress, (2) reduced mitochondrial dysfunction, (3) improved Ca²⁺ homeostasis, (4) increased survival signaling, and (5) increased sirtuin 1 activity.

Regulation of the Expression of Heme Oxygenase-1: Signal Transduction, Gene Promoter Activation, and Beyond

Significance: Heme oxygenase-1 (HO-1) is a ubiquitous 32-kDa protein expressed in many tissues and highly inducible. They catalyze the degradation of the heme group and the release of free iron, carbon monoxide, and biliverdin; the latter converted to bilirubin by biliverdin reductase. Its role in the regulation of cellular homeostasis is widely documented. Studying regulation of HO-1 expression is important not only to understand the life of healthy cells but also the unbalances in cell metabolism that lead to disease. Recent Advances: The regulation of its enzymatic activity depends heavily upon changes in expression studied mainly at the transcriptional level. Current knowledge regarding HO-1 gene expression focuses primarily on transcription factors such as Nrf2 (nuclear factor erythroid 2-related factor 2), AP-1 (activator protein-1), and hypoxia-inducible factor, which collect signal transduction pathway information at the HO-1 gene promoter. Understanding of gene expression regulation is not limited to transcription factor activity but also involves an extended range of post- or cotranscriptional regulated events. Critical Issues: In addition to the regulation of gene promoter activity, alternative splicing, alternative polyadenylation, and regulation of messenger RNA stability play critical roles in changes in HO-1 gene expression levels, involving specific factors, proteins, and microRNAs. All potential targets for diagnosis or treatment of diseases are related to HO-1 dysregulation. Future Directions: Unbalances in the tightly regulated gene expression mechanisms lead to cell transformation and cancer development. Knowledge of these events and signal transduction cascades triggered by oncogenes in which HO-1 plays a critical role is of upmost importance for research in this field.

PML/RARa Interferes with NRF2 Transcriptional Activity Increasing the Sensitivity to Ascorbate of Acute Promyelocytic Leukemia Cells

NRF2 (NF-E2 p45-related factor 2) orchestrates cellular adaptive responses to stress. Its quantity and subcellular location is controlled through a complex network and its activity increases during redox perturbation, inflammation, growth factor stimulation, and energy fluxes. Even before all-trans retinoic acid (ATRA) treatment era it was a common experience that acute promyelocytic leukemia (APL) cells are highly sensitive to first line chemotherapy. Since we demonstrated how high doses of ascorbate (ASC) preferentially kill leukemic blast cells from APL patients, we aimed to define the underlying mechanism and found that promyelocytic leukemia/retinoic acid receptor α (PML/RARa) inhibits NRF2 function, impedes its transfer to the nucleus and enhances its degradation in the cytoplasm. Such loss of NRF2 function alters cell metabolism, demarcating APL tissue from both normal promyelocytes and other acute myeloide leukemia (AML) blast cells. Resistance to ATRA/arsenic trioxide (ATO) treatment is rare but grave and the metabolically-oriented treatment with high doses of ASC, which is highly effective on APL cells and harmless on normal hematopoietic stem cells (HSCs), could be of use in preventing clonal evolution and in rescuing APL-resistant patients.

Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry, Pharmacokinetics, and Molecular Targets

Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

Dietary Polyphenols Targeting Arterial Stiffness: Interplay of Contributing Mechanisms and Gut Microbiome-Related Metabolism

Increased arterial stiffness is a degenerative vascular process, progressing with age that leads to a reduced capability of arteries to expand and contract in response to pressure changes. This progressive degeneration mainly affects the extracellular matrix of elastic arteries and causes loss of vascular elasticity. Recent studies point to significant interference of dietary polyphenols with mechanisms involved in the pathophysiology and progression of arterial stiffness. This review summarizes data from epidemiological and interventional studies on the effect of polyphenols on vascular stiffness as an illustration of current research and addresses possible etiological factors targeted by polyphenols, including pathways of vascular functionality, oxidative status, inflammation, glycation, and autophagy. Effects can either be inflicted directly by the dietary polyphenols or indirectly by metabolites originated from the host or microbial metabolic processes. The composition of the gut microbiome, therefore, determines the resulting metabolome and, as a consequence, the observed activity. On the other hand, polyphenols also influence the intestinal microbial composition, and therefore the metabolites available for interaction with relevant targets. As such, targeting the gut microbiome is another potential treatment option for arterial stiffness.

Lignans From Forsythia x Intermedia Leaves and Flowers Attenuate the Pro-inflammatory Function of Leukocytes and Their Interaction With Endothelial Cells

Aim of the study: Taking into account that overactivated leukocytes are an important factor in the development of many chronic diseases, we investigated the activity of phytochemically characterized (HPLC-DAD-MSⁿ) extracts from forsythia leaves and flowers on the pro- and anti-inflammatory functions of leukocytes (effects on IL-1β, IL-8, TNF-α, and TGFβ release) and their adherence to endothelial cells. Using bio-guided fractionation, we isolated the active compounds and determined their biological activity, and we included the positive control quercetin. Methods: The effect on IL-1β, TNF-α, IL-8, and TGF-α production by leukocytes was measured by enzyme-linked immunosorbent assay (ELISA). The surface expression of adhesion molecules was analyzed with flow cytometry, and the neutrophil attachment to the endothelial cells was assessed fluorimetrically. The effects on p38MAPK, ERK1/2 and JNK phosphorylation were determined using western blots. Results: Leaf extracts had the effect of decreasing TNF-α production in neutrophils and monocyte/macrophage cells. The bio-guided fractionation led to the isolation of the following lignan aglycones: (+)-pinoresinol, (+)-epipinoresinol, (-)-matairesinol, (+)-phillygenin, and (-)-arctigenin. Only phillygenin was able to stimulate the anti-inflammatory function of macrophages by inducing TGF-β release and IL-10 receptor surface expression. Arctigenin, phillygenin, and a metabolite produced by the gut microbiota, enterolactone, decreased TNF-α and IL-1β production and neutrophil adhesion to endothelial cells, probably by attenuating the p38 and ERK kinase pathways. Conclusion:Forsythia x intermedia is a valuable source of active lignans, which may be potential candidates for treating inflammatory diseases that are associated with the excessive production of cytokines such as TNF-α and IL-1β.

Impact of weight loss diet associated with flaxseed on inflammatory markers in men with cardiovascular risk factors: a clinical study

Background

Flaxseed has received attention for its anti-inflammatory and antioxidant role. The present study hypothesizes if flaxseed added to a weight loss diet could improve the lipid and metabolic profiles and decrease risk factors related to cardiovascular disease.

Methods

In a prospective, single blinded 42 days protocol, subjects were allocated into two groups with low carbohydrates intake: G_riceLC (35% of carbohydrate and 60g of raw rice powder per day) and G_flaxLC (32% of carbohydrate and 60g of flaxseed powder per day). Blood pressure, anthropometric measures and serum levels of isoprostane, C-reactive protein, Tumor Necrosis Factor-alpha, glucose, lipidic profile, uric acid, adiponectin, leptin and insulin were measured at baseline and at the end of interventions. Serum and urinary enterodiol and enterolactione were also measured.

Results

A total of 27 men with cardiovascular risk factors were evaluated, with mean age of 33 ± 10 years to G_riceLC and 40 ± 9 years to G_flaxLC. Both groups experienced weight loss and systolic blood pressure reduction. A decrease in inflammatory markers (CRP and TNF-α) was observed after flaxseed intake (mean decrease of 25% and 46% for G_flaxLC respectively). All groups also showed improvement in levels of total cholesterol, LDL-c, uric acid and adiponectin. Only G_flaxLC group showed a decrease in triglyceride levels.

Conclusion

This study suggests that flaxseed added to a weight loss diet could be an important nutritional strategy to reduce inflammation markers such as CRP and TNF-α.

Trial registration

ClinicalTrials.gov NCT02132728.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2891-14-5) contains supplementary material, which is available to authorized users.

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.

Sauchinone from Saururus chinensis protects vascular inflammation by heme oxygenase-1 induction in human umbilical vein endothelial cells

Sauchinone, a diastereomeric lignan isolated from the roots of Saururus chinensis (LOUR.) BAILL. (Saururaceae), is reported to exert a variety of biological activities such as hepatoprotective, anti-inflammatory actions and inhibitory effects on bone resorption. In this study, we investigated the effect of sauchinone in suppressing cell adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) expression in high glucose stimulated human umbilical vein endothelial cells (HUVEC). Sauchinone inhibited the phosphorylation and degradation of IκB-α, as well as the nuclear translocation of nuclear factor kappa B (NF-κB) p65 caused by the stimulation of high glucose. In addition, sauchinone induced heme oxygenase (HO)-1 expression through nuclear translocation of nuclear factor E2-related factor 2 in HUVEC. The effects of sauchinone on the high glucose-induced expression of VCAM-1 and ICAM-1 and nuclear translocation of NF-κB p65 were partially reversed by transfection of the cells with HO-1 siRNA. These findings suggest that sauchinone-induced HO-1 expression plays a key role in the vascular protective effects of sauchinone in HUVEC.

The natural product honokiol inhibits calcineurin inhibitor-induced and Ras-mediated tumor promoting pathways

Although calcineurin inhibitors (CNIs) are very useful in preventing allograft rejection, they can mediate a rapid progression of post-transplantation malignancies. The CNI cyclosporine A (CsA) can promote renal tumor growth through activation of the proto-oncogene ras and over-expression of the angiogenic cytokine VEGF; the ras activation also induces over-expression of the cytoprotective enzyme HO-1, which promotes survival of renal cancer cells. Here, we show that the natural product honokiol significantly inhibited CsA-induced and Ras-mediated survival of renal cancer cells through the down-regulations of VEGF and HO-1. Thus, honokiol treatment may help to prevent tumor-promoting effects of CsA in transplant patients.

Potential therapeutic effects of natural heme oxygenase-1 inducers in cardiovascular diseases

SIGNIFICANCE

Many physiological effects of natural antioxidants, their extracts or their major active components, have been reported in recent decades. Most of these compounds are characterized by a phenolic structure, similar to that of α-tocopherol, and present antioxidant properties that have been demonstrated both in vitro and in vivo. Polyphenols may increase the capacity of endogenous antioxidant defenses and modulate the cellular redox state. Such effects may have wide-ranging consequences for cellular growth and differentiation.

CRITICAL ISSUES

The majority of in vitro and in vivo studies conducted so far have attributed the protective effect of bioactive polyphenols to their chemical reactivity toward free radicals and their capacity to prevent the oxidation of important intracellular components. One possible protective molecular mechanism of polyphenols is nuclear factor erythroid 2-related factor (Nrf2) activation, which in turn regulates a number of detoxification enzymes.

RECENT ADVANCES

Among the latter, the heme oxygenase-1 (HO-1) pathway is likely to contribute to the established and powerful antioxidant/anti-inflammatory properties of polyphenols. In this context, it is interesting to note that induction of HO-1 expression by means of natural compounds contributes to prevention of cardiovascular diseases in various experimental models.

FUTURE DIRECTIONS

The focus of this review is on the role of natural HO-1 inducers as a potential therapeutic strategy to protect the cardiovascular system against various stressors in several pathological conditions.

Evaluation of Cissus quadrangularis extracts as an inhibitor of COX, 5-LOX, and proinflammatory mediators

ETHNOPHARMACOLOGICAL RELEVANCE

Cissus quadrangularis is an ancient medicinal plant. It is an active ingredient of one Ayurvedic formula called "Laksha Gogglu". Its stem is used in food preparation in India. Traditionally it is used to treat various diseases like asthma, indigestion, ear diseases, irregular menstruation, skin diseases, piles, fractured bones, etc.

AIM OF THE STUDY

This study aimed to evaluate the ability of the plant extracts to inhibit cycloxygenase (COX-1), cycloxygenase (COX-2), and 5-lipoxygenase (5-LOX) enzyme activity. Western blot analysis was also carried out in the quest to determine the effect of active acetone fraction of Cissus quadrangularis (AFCQ) on proinflammatory mediators as acetone extract is found to be the most effective in this study.

MATERIALS AND METHODS

The differential extract of the stem were tested for enzyme inhibition of COX and 5-LOX using spectroscopic and polarigraphic method. Effective acetone extract was partially purified by silica column, one of the active fraction showed dual inhibition against COX and 5-LOX. Western blotting shows downregulation of proinflammatory mediators as well as upregulation of phase-II enzymes.

RESULTS

AFCQ extract showed COX and 5-LOX inhibition with IC(50) values of 7 μg/ml, 0.4 μg/ml, and 20 μg/ml for COX-1, COX-2 and 5-LOX respectively. It also showed anti-inflammatory activity on RAW 264.7 cell line with IC(50) value 65 μg/ml. In addition to this it is showing inhibition of proinflammatory mediators like iNOS and TNFα, along with translocation of Nrf-2 and upregulation of HO-1.

CONCLUSION

AFCQ is a COX and 5-LOX inhibitor isolated from the stems of Cissus quadrangularis. It is also effectively downregulate the iNOS, TNFα, and upregulation of HO-1.

Heme oxygenase 1 is induced by miR-155 via reduced BACH1 translation in endothelial cells

Heme oxygenase 1 (HO-1) is a stress-inducible enzyme that degrades redox-active heme-producing biliverdin, carbon monoxide, and Fe(2+). It protects cells under various stress conditions and mediates anti-inflammatory and vasodilatory effects in the endothelium. The expression of HMOX1, the HO-1 gene, is highly inducible and its transcriptional regulation is complex. HMOX1 is induced by various proinflammatory stimuli via NF-κB in human endothelial cells, but functional NF-κB-binding elements have not been identified from the human gene. However, the regulation of HMOX1 by the antioxidant-response element is firmly established, with the transcription factor BACH1 serving as a repressor and Nrf2 as an enhancer. miR-155 is one of the TNFα-inducible endothelial microRNAs predicted to bind to the BACH1 mRNA. Oligonucleotides mimicking miR-155 efficiently inhibited BACH1 protein translation, resulting in a concentration-dependent increase in HMOX1 mRNA and protein expression in human umbilical vein endothelial cells. Moreover, endogenous miR-155 was upregulated by TNFα via an NF-κB-dependent mechanism with a subsequent increase in HMOX1 expression. We propose that increased HMOX1 expression in endothelial cells by TNFα results from miR-155-induced repression of BACH1 rather than direct induction of HMOX1 via NF-κB, and that miR-155 is cytoprotective during inflammation by elevating HO-1 expression in endothelial cells.

The heme oxygenase-1 protein is overexpressed in human renal cancer cells following activation of the Ras-Raf-ERK pathway and mediates anti-apoptotic signal

The stress-inducible cytoprotective enzyme heme oxygenase-1 (HO-1) may play a critical role in the growth and metastasis of tumors. We demonstrated that overexpressed HO-1 promotes the survival of renal cancer cells by inhibiting cellular apoptosis; we also showed that the proto-oncogene H-Ras becomes activated in these cells under stress following treatment with immunosuppressive agents. However, it is not known if there is an association between Ras activation and HO-1 overexpression. Here, we examined if the activation of H-Ras pathway could induce HO-1, and promote the survival of renal cancer cells (786-0 and Caki-1). In co-transfection assays, using HO-1 promoter-luciferase construct, we found that the activated H-Ras, H-Ras(12V), promoted HO-1 transcriptional activation. The inhibition of endogenous H-Ras by specific dominant-negative mutant/siRNA markedly ablated the HO-1 promoter activity. Active H-Ras increased HO-1 mRNA and protein expression. Moreover, transfection with effector domain mutant constructs of active H-Ras showed that H-Ras-induced HO-1 overexpression was primarily mediated through the Raf signaling pathway. Using pharmacological inhibitor, we observed that ERK is a critical intermediary molecule for Ras-Raf-induced HO-1 expression. Activation of H-Ras and ERK promoted nuclear translocation of the transcription factor Nrf2 for its binding to the specific sequence of HO-1 promoter. The knockdown of Nrf2 significantly inhibited H-Ras-induced HO-1 transcription. Finally, by FACS analysis using Annexin-V staining, we demonstrated that the H-Ras-ERK-induced and HO-1-mediated pathway could protect renal cancer cells from apoptosis. Thus, targeting the Ras-Raf-ERK pathway for HO-1 overexpression may serve as novel therapeutics for the treatment of renal cancer.

Anthocyanins from Chinese bayberry extract protect β cells from oxidative stress-mediated injury via HO-1 upregulation

Oxidative stress plays a pivotal role during the islet transplantation procedure, and antioxidant supplementation may protect grafts against oxidative injury. Chinese bayberry is one of six Myrica species native to China, and we demonstrated here that anthocyanins from Chinese bayberry extract (CBE) protect pancreatic β cells (INS-1) against hydrogen peroxide (H(2)O(2))-induced necrosis and apoptosis. Anthocyanins time- and dose-dependently upregulated heme oxygenase-1 (HO-1) gene expression in β cells and primary islets. HO-1 knockdown increased H(2)O(2)-induced cell death and attenuated the cytoprotective effect of anthocyanins. Anthocyanin treatment activated ERK1/2 and PI3K/Akt signaling, and ERK1/2 and PI3K inhibitors partially attenuated anthocyanin-mediated induction of HO-1. Additionally, β cells pretreated with anthocyanins displayed a decreased extent of apoptosis after transplantation. In summary, these results suggest that anthocyanins in CBE protect β cells from H(2)O(2)-induced cell injury via ERK1/2- and PI3K/Akt-mediated HO-1 upregulation.

Sulforaphane inhibits endothelial lipase expression through NF-κB in endothelial cells

OBJECTIVE

Endothelial lipase (EL) is a new member of triacylglycerol lipase family that has been shown to decrease high-density lipoprotein (HDL) cholesterol levels leading to increased risk of atherosclerosis. Its expression is increased during inflammation and by inflammatory cytokines. Sulforaphane (SFN) is a naturally occurring isothiocyanate present in cruciferous vegetables that has antioxidant and anti-inflammatory effects. Nuclear factor (NF)-κB is one of the molecular targets for SFN-mediated protective effects. Our aim was therefore to assess whether SFN could impact on EL expression via modulation of NF-κB pathway.

METHODS AND RESULTS

Quantitative PCR and Western blot results demonstrated that SFN inhibited tumor necrosis factor (TNF)-α-mediated induction of EL in human umbilical vein endothelial cells (HUVEC). Lentiviral transduction of HUVEC with mutated form of IκB-α (IκBM) as well as silencing of NF-κB subunit p65 using RNA interference revealed that TNF-α-mediated induction of EL is mediated through NF-κB pathway. In addition, a total of five NF-κB binding sites were found in LIPG gene, which encodes EL. SFN inhibited binding of NF-κB to these sites analyzed by chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA). SFN also inhibited TNF-α mediated phosphorylation of IκB kinase (IKK) 1/2 and IκB-α.

CONCLUSIONS

Collectively, these results indicate that SFN inhibits EL expression via inhibition of NF-κB which may have a beneficial effect on HDL cholesterol levels.

Dietary phenolics: chemistry, bioavailability and effects on health

There is much epidemiological evidence that diets rich in fruit and vegetables can reduce the incidence of non-communicable diseases such as cardiovascular diseases, diabetes, cancer and stroke. These protective effects are attributed, in part, to phenolic secondary metabolites. This review summarizes the chemistry, biosynthesis and occurrence of the compounds involved, namely the C6-C3-C6 flavonoids-anthocyanins, dihydrochalcones, flavan-3-ols, flavanones, flavones, flavonols and isoflavones. It also includes tannins, phenolic acids, hydroxycinnamates and stilbenes and the transformation of plant phenols associated with food processing (for example, production of black tea, roasted coffee and matured wines), these latter often being the major dietary sources. Events that occur following ingestion are discussed, in particular, the deglycosylation, glucuronidation, sulfation and methylation steps that occur at various points during passage through the wall of the small intestine into the circulatory system and subsequent transport to the liver in the portal vein.We also summarise the fate of compounds that are not absorbed in the small intestine, but which pass into the large intestine where they are degraded by the colonic microflora to phenolic acids, which can be absorbed into the circulatory system and subjected to phase II metabolism prior to excretion. Initially, the protective effect of dietary phenolics was thought to be due to their antioxidant properties which resulted in a lowering of the levels of free radicals within the body.However, there is now emerging evidence that themetabolites of dietary phenolics,which appear in the circulatory systemin nmol/L to low mmol/L concentrations, exertmodulatory effects in cells through selective actions on different components of the intracellular signalling cascades vital for cellular functions such as growth, proliferation and apoptosis. In addition, the intracellular concentrations required to affect cell signalling pathways are considerably lower than those required to impact on antioxidant capacity. The mechanisms underlying these processes are discussed.