Diallyl disulfide induces ERK phosphorylation and alters gene expression profiles in human colon tumor cells

The Therapeutic Potential of MAPK/ERK Inhibitors in the Treatment of Colorectal Cancer

The MAPK/ERK signaling pathway regulates cancer cell proliferation, apoptosis, inflammation, angiogenesis, metastasis and drug resistance. Mutations and up-regulation of components of the MAPK/ERK signaling pathway, as well as over-activation of this critical signaling pathway, are frequently observed in colorectal carcinomas. Targeting the MAPK/ERK signaling pathway, using specific pharmacological inhibitors, elicits potent anti-tumor effects, supporting the therapeutic potential of these inhibitors in the treatment of CRC. Several drugs have recently been developed for the inhibition of the MEK/ERK pathway in preclinical and clinical settings, such as MEK162 and MK-2206. MEK1/2 inhibitors demonstrate promising efficacy and anticancer activity for the treatment of this malignancy. This review summarizes the current knowledge on the role of the MAPK/ERK signaling pathway in the pathogenesis of CRC and the potential clinical value of synthetic inhibitors of this pathway in preventing CRC progression for a better understanding, and hence, better management of colorectal cancer.

Garlic constituents for cancer prevention and therapy: From phytochemistry to novel formulations

Garlic (Allium sativum L.) is one of the oldest plants cultivated for its dietary and medicinal values. This incredible plant is endowed with various pharmacological attributes, such as antimicrobial, antiarthritic, antithrombotic, antitumor, hypoglycemic, and hypolipidemic activities. Among the various beneficial pharmacological effects of garlic, the anticancer activity is presumably the most studied. The consumption of garlic provides strong protection against cancer risk. Taking into account the multi-targeted actions and absence of considerable toxicity, a few active metabolites of garlic are probably to play crucial roles in the killing of cancerous cells. Garlic contains several bioactive molecules with anticancer actions and these include diallyl trisulfide, allicin, diallyl disulfide, diallyl sulfide, and allyl mercaptan. The effects of various garlic-derived products, their phytoconstituents and nanoformulations have been evaluated against skin, prostate, ovarian, breast, gastric, colorectal, oral, liver, and pancreatic cancers. Garlic extract, its phytocompounds and their nanoformulations have been shown to inhibit the different stages of cancer, including initiation, promotion, and progression. Besides, these bioactive metabolites alter the peroxidation of lipid, activity of nitric oxide synthetase, nuclear factor-κB, epidermal growth factor receptor, and protein kinase C, cell cycle, and survival signaling. The current comprehensive review portrays the functions of garlic, its bioactive constituents and nanoformulations against several types of cancers and explores the possibility of developing these agents as anticancer pharmaceuticals.

Antileukemic activity of sulfoxide nutraceutical allicin against THP-1 cells is associated with premature phosphatidylserine exposure in human erythrocytes

Background

Allicin (ACN), a sulfoxide in freshly crushed garlic, is known for its diverse bioactive properties. Among the most notable effects of ACN is its antitumor activity against a wide array of cancer types. Thus, ACN may be a promising anticancer therapeutic. Nevertheless, chemotherapy-induced anemia is a major obstacle in cancer management with a prevalence of up to 70%. Although the pathophysiology behind it remains elusive, a number of medications known to cause anemia in patients have been shown to induce premature programmed cell death in red blood cells (RBCs) known as eryptosis. This study, thus, investigates the anticancer potential of ACN against THP-1 monocytic leukemia cells, its toxic effects on human RBCs, and delineate the underlying biochemical mechanisms.

Methods

Cytotoxicity was detected using the MTT assay, while hemoglobin leakage was used as a surrogate for hemolysis which was photometrically measured. Major eryptotic events were examined using flow cytometry with fluorescent probes. Phosphatidylserine (PS) exposure was detected by Annexin-V-FITC, cytosolic calcium with Fluo4/AM, and reactive oxygen species with H₂DCFDA.

Results

Our results show that ACN induces hemolysis in a dose-dependent fashion, which is significantly abrogated in absence of extracellular calcium. Moreover, ACN stimulates PS exposure, intracellular calcium overload, and oxidative stress. Using small-molecule inhibitors, we demonstrate that the pro-eryptotic activity of ACN is ameliorated in presence of zVAD(OMe)-FMK, SB203580, and D4476.

Conclusion

ACN possesses both hemolytic and eryptotic properties mediated through elevated intracellular calcium levels, oxidative stress, caspase, p38 MAPK, and CK1α.

Garlic and its Active Compounds: A Potential Candidate in The Prevention of Cancer by Modulating Various Cell Signalling Pathways

BACKGROUND

Cancer is a multi-factorial disease including alterations in the cell signalling pathways. Currently, several drugs are in use to treat cancer but such drugs show negative side effects on normal cells and cause severe toxicity.

METHODS

The current research is mainly focused on medicinal plants with potential therapeutic efficacy in the treatment of cancer without any adverse effects on normal cells. In this regard, garlic and its active compounds including diallyl sulfide, diallyl trisulfide, ajoene, and allicin have been established to suppress the growth of cancer and killing of cancer cells.

RESULT

The review focuses on garlic and its active compounds chemopreventive effect through modulating various cell signalling pathways. Additionally, garlic and its active compound were established to induce cell cycle arrest at the G0/G1 phase and G2/M phases in cancer cells, increase the expression of tumor suppressor genes, inhibit the angiogenesis process, induction of apoptosis and modulation of various other genetic pathways.

CONCLUSION

This review sketches the diverse chemopreventive activities of garlic and their active ingredients in the management of cancer mainly focusing on cell signalling pathways.

UBN2 promotes tumor progression via the Ras/MAPK pathway and predicts poor prognosis in colorectal cancer

Background

Ubinuclein-2 (UBN2) is a nuclear protein that interacts with many transcription factors. The molecular role and mechanism of UBN2 in the development and progression of cancers, including colorectal cancer (CRC), is not well understood. The current study explored the role of UBN2 in the development and progression CRC.

Methods

Oncomine network and The Cancer Genome Atlas (TCGA) database were downloaded and Gene Set Enrichment Analysis (GSEA) was performed to compare the UBN2′s expression between normal and tumor tissues, as well as the potential correlation of UBN2 expression with signaling pathways. Immunohistochemistry (IHC), qRT-PCR and Western blotting were performed to determine the expression of UBN2 in CRC tissues or cell lines. In vitro proliferation and invasion assays, and orthotopic mouse metastatic model were used to analyze the effect of UBN2 on the development and progression of CRC.

Results

The analysis of UBN2 expression using Oncomine network showed that UBN2 was upregulated in CRC tissues compared to matched adjacent normal intestinal epithelial tissues. IHC, qRT-PCR and Western blotting confirmed that UBN2 expression is higher in CRC tissues compared with matched adjacent normal intestinal epithelial tissues. In addition, analyses of TCGA data revealed that high UBN2 expression was associated with advanced stages of lymph node metastasis, distant metastasis, and short survival time in CRC patients. IHC showed that high UBN2 expression is correlated with advanced stages of CRC. Moreover, UBN2 is highly expressed in the liver metastatic lesions. Furthermore, knockdown of UBN2 inhibited the growth, invasiveness and metastasis of CRC cells via regulation of the Ras/MAPK signaling pathway.

Conclusion

The current study demonstrates that UBN2 promotes tumor progression in CRC. UBN2 may be used as a promising biomarker for predicting the prognosis of CRC patients.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0848-4) contains supplementary material, which is available to authorized users.

Bioactive Nutrients and Nutrigenomics in Age-Related Diseases

The increased life expectancy and the expansion of the elderly population are stimulating research into aging. Aging may be viewed as a multifactorial process that results from the interaction of genetic and environmental factors, which include lifestyle. Human molecular processes are influenced by physiological pathways as well as exogenous factors, which include the diet. Dietary components have substantive effects on metabolic health; for instance, bioactive molecules capable of selectively modulating specific metabolic pathways affect the development/progression of cardiovascular and neoplastic disease. As bioactive nutrients are increasingly identified, their clinical and molecular chemopreventive effects are being characterized and systematic analyses encompassing the "omics" technologies (transcriptomics, proteomics and metabolomics) are being conducted to explore their action. The evolving field of molecular pathological epidemiology has unique strength to investigate the effects of dietary and lifestyle exposure on clinical outcomes. The mounting body of knowledge regarding diet-related health status and disease risk is expected to lead in the near future to the development of improved diagnostic procedures and therapeutic strategies targeting processes relevant to nutrition. The state of the art of aging and nutrigenomics research and the molecular mechanisms underlying the beneficial effects of bioactive nutrients on the main aging-related disorders are reviewed herein.

The role of nutrition related genes and nutrigenetics in understanding the pathogenesis of cancer

Nutrition has a predominant and recognizable role in health management. Nutrigenetics is the science that identifies and characterizes gene variants associated with differential response to nutrients and relating this variation to variable disease states especially cancer. This arises from the epidemiological fact that cancer accounts for a high proportion of total morbidity and mortality in adults throughout the world. There is much evidence to support that genetic factors play a key role in the development of cancer; these genetic factors such as DNA instability and gene alterations are affected by nutrition. Nutrition may also lead to aberrant DNA methylation, which in turn contributes to carcinogenesis. The aim of this work is to clarify the basic knowledge about the vital role of nutrition-related genes in various disease states, especially cancer, and to identify nutrigenetics as a new concept that could highlight the relation between nutrition and gene expression. This may help to understand the mechanism and pathogenesis of cancer. The cause of cancer is a complex interplay mechanism of genetic and environmental factors. Dietary nutrient intake is an essential environmental factor and there is a marked variation in cancer development with the same dietary intake between individuals. This could be explained by the variation in their genetic polymorphisms, which leads to emergence of the concept of nutrigenomics and nutrigenetics.

Upregulation of miR-34a by diallyl disulfide suppresses invasion and induces apoptosis in SGC-7901 cells through inhibition of the PI3K/Akt signaling pathway

Diallyl disulfide (DADS) exerts anticarcinogenic activity in various types of cancer. However, the mechanism underlying its anticarcinogenic activity remains to be elucidated. The aim of the present study was to explore the mechanism of the anticarcinogenic activity of DADS in gastric cancer (GC). The expression levels of microRNA (miR)-34a in GC and normal tissues were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression of miR-34a was also measured using RT-qPCR in SGC-7901 cells following treatment with DADS. In addition, the effect of DADS on the invasion capability of SGC-7901 cells was observed in the presence of miR-34a or anti-miR-34a using a Matrigel invasion assay. Furthermore, in identical conditions, the apoptosis of SGC-7901 cells was observed using flow cytometry. Finally, the present study investigated the effects of DADS and miR-34a on the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway in vitro. The level of miR-34a in GC tissues was reduced compared with that in adjacent normal tissues (P<0.05). Treatment with DADS upregulated miR-34a expression in SGC-7901 cells (P<0.05). In the Matrigel invasion assay, DADS inhibited the invasive capability of SGC-7901 cells (P<0.05 vs. control), which was improved by overexpression of miR-34a (P<0.01 vs. control) but reduced by downregulation of miR-34a (P<0.05 vs. DADS treatment group). Furthermore, DADS induced apoptosis of SGC-7901 cells (P<0.05 vs. control); and DADS and miR-34a synergistically enhanced apoptosis of SGC-7901 cells (P<0.01 vs. control). In addition, DADS and miR-34a inhibited the expression levels of phosphorylated (p)-PI3K and p-Akt (P<0.05 vs. control). By contrast, downregulation of miR-34a alleviated the decrease in p-PI3K and p-Akt expression induced by DADS (P<0.05 vs. DADS treatment group). Cell viability was reduced with increasing concentrations of DADS, however, DADS did not affect cell viability following inhibition of the PI3K/Akt signaling pathway. In conclusion, DADS suppresses invasion and induces apoptosis of SGC-7901 cells by upregulation of miR-34a, via inhibition of the PI3K-Akt signaling pathway.

Allicin alleviates inflammation of trinitrobenzenesulfonic acid-induced rats and suppresses P38 and JNK pathways in Caco-2 cells

Background. Allicin has anti-inflammatory, antioxidative and proapoptotic properties. Aims. To evaluate the effects and investigate the mechanism of allicin on trinitrobenzenesulfonic acid-induced colitis, specifically with mesalazine or sulfasalazine. Methods. 80 rats were divided equally into 8 groups: control; trinitrobenzenesulfonic acid; allicin prevention; allicin; mesalazine; sulfasalazine; allicin + sulfasalazine, and mesalazine + allicin. Systemic and colonic inflammation parameters were analysed. In addition, protein and culture medium of Caco-2 cells treated with various concentrations of IL-1β or allicin were collected for investigation of IL-8, NF-κB p65 P38, ERK, and JNK. One-way ANOVA and Kruskal-Wallis H test were used for parametric and nonparametric tests, respectively. Results. Allicin reduced the body weight loss of trinitrobenzenesulfonic acid-induced rats, histological score, serum TNF-α and IL-1β levels, and colon IL-1β mRNA level and induced serum IL-4 level, particularly in combination with mesalazine. In addition, 1 ng/mL IL-1β stimulated the P38, ERK, and JNK pathways, whereas pretreatment with allicin depressed this phenomenon, except for the ERK pathway. Conclusions. The inflammation induced by trinitrobenzenesulfonic acid is mitigated significantly by allicin treatment, particularly combined with mesalazine. Allicin inhibits the P38 and JNK pathways and the expression of NF-κB which explained the potential anti-inflammatory mechanisms of allicin.

Role of H2S Donors in Cancer Biology

Hydrogen sulfide (H2S) donors including organosulfur compounds (OSC), inorganic sulfide salts, and synthetic compounds are useful tools in studies to elucidate the effects of H2S in cancer biology. Studies using such donors have shown the ability of H2S to suppress tumor growth both in vitro and in vivo, with some of them suggesting the selectivity of its cytotoxic effects to cancer cells. In addition to promoting cancer cell death, H2S donors were also found to inhibit cancer angiogenesis and metastasis. The underlying mechanisms for the anticancer activities of H2S involve (1) cell signaling pathways, such as MAPK and STAT; (2) cell cycle regulation; (3) microRNAs regulation; and (4) cancer metabolism and pH regulation. Altogether, compiling evidences have demonstrated the great potential of using H2S donors as anticancer agents. Nevertheless, the application and development of H2S for therapy are still facing challenges as identification of molecular targets of H2S awaits further investigation.

Effect of allyl sulfides from garlic essential oil on intracellular ca2+ levels in renal tubular cells

Diallyl sulfide (1), diallyl disulfide (2), and diallyl trisulfide (3), which are major organosulfur compounds of garlic (Allium sativum), are recognized as a group of potential chemopreventive compounds. In this study, the early signaling effects of 3 were examined on Madin-Darby canine kidney (MDCK) cells loaded with the Ca(2+)-sensitive dye fura-2. It was found that 3 caused an immediate and sustained increase of [Ca(2+)](i) in a concentration-dependent manner (EC(50) = 40 μM). Compound 3 also induced a [Ca(2+)](i) elevation when extracellular Ca(2+) was removed, but the magnitude was reduced by 45%. In Ca(2+)-free medium, the 3-induced [Ca(2+)](i) level was abolished by depleting stored Ca(2+) with 1 μM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor). Elevation of [Ca(2+)](i) caused by 3 in the Ca(2+)-containing medium was not affected by modulation of protein kinase C activity. The 3-induced Ca(2+) influx was inhibited by nifedipine and nicardipine (1 μM). U73122, an inhibitor of phospholipase C, abolished ATP (but not the 3-induced [Ca(2+)](i) level). These findings suggest that 3 induced a significant [Ca(2+)](i) elevation in MDCK renal tubular cells by stimulating both extracellular Ca(2+) influx and thapsigargin-sensitive intracellular Ca(2+) release via as yet unidentified mechanisms. Furthermore, the order of the allyl sulfide-induced [Ca(2+)](i) elevation and cell viability was 1 < 2 < 3. The differential effect of allyl sulfides on Ca(2+) signaling and cell death appears to correlate with the number of sulfur atoms in the structure of these allyl sulfides.

The Effect of Diallyl Polysulfanes on Cellular Signaling Cascades

Diallyl polysulfanes, such as diallyl trisulfide and diallyl tetrasulfide, are regarded as a group of potential chemopreventive compounds as they have been proven to be effective inhibitors of cancer cells. These agents have been implicated in signal transductions, including the generation of Reactive Oxygen Species (ROS), Endoplasmic Reticulum (ER) stress, mitogen-activated protein kinase (MAPK) signaling, regulation of cell cycle progression, and induction of apoptosis. Nonetheless, certain aspects of the diallyl polysulfane triggered inhibitory effects on cancer cells are still not clear. Understanding the targeted signaling pathways may help to develop new strategies to treat cancer and other diseases. This review is therefore aimed at addressing the targeting of specific intracellular signal transduction cascades by these diallyl polysulfanes in order to shed some light on possible mechanisms of action of these compounds.

Apoptosis induction in human lung adenocarcinoma cells by oil-soluble allyl sulfides: triggers, pathways, and modulators

DAS (diallyl sulfide), DADS (diallyl disulfide), and DATS (diallyl trisulfide) are major oil-soluble allyl sulfides (OAS) that represent major garlic constituents. The anticarcinogenic and antimutagenic effects of these substances have been extensively studied during the last decades. Previous reports suggest that induction of apoptosis by OASs might contribute to their chemopreventive effects. In this study, we report that OASs DADS and DATS induce significant apoptosis in human lung adenocarcinoma A549 cells, whereas DAS does not. Differential modulation of reactive oxygen intermediates (ROI) and mitochondria membrane potential (MMP) may account for the apoptotic effects of DADS and DATS. The underlying molecular mechanisms of apoptosis induction by both compounds include activation of C-Jun N-terminal kinase (JNK), up-regulation of p53, and down-regulation of bcl-2 expression. In our test series, up-regulation of extracellular signal-regulated protein kinase (ERK) was dispensable for apoptosis induction; DAS, DADS, or DATS did not modify expression of MAPK p38, bax, and bcl-xL. Further investigation revealed that the specific JNK inhibitor SP600125 and the antioxidant NAC blocked DADS and DATS-induced apoptosis, whereas ERK inhibitors did not. Additionally, our data provide the first evidence that Fas-mediated cell death pathway is partly involved in DADS but not DATS-mediated cell death. Taken together, our work has elucidated the triggers, important modulators, and signal transduction pathways in DADS and DATS-mediated apoptosis.

Use of conventional and -omics based methods for health claims of dietary antioxidants: a critical overview

This article describes the principles and limitations of methods used to investigate reactive oxygen species (ROS) protective properties of dietary constituents and is aimed at providing a better understanding of the requirements for science based health claims of antioxidant (AO) effects of foods. A number of currently used biochemical measurements aimed of determining the total antioxidant capacity and oxidised lipids and proteins are carried out under unphysiological conditions and are prone to artefact formation. Probably the most reliable approaches are measurements of isoprostanes as a parameter of lipid peroxidation and determination of oxidative DNA damage. Also the design of the experimental models has a strong impact on the reliability of AO studies: the common strategy is the identification of AO by in vitro screening with cell lines. This approach is based on the assumption that protection towards ROS is due to scavenging, but recent findings indicate that activation of transcription factors which regulate genes involved in antioxidant defence plays a key role in the mode of action of AO. These processes are not adequately represented in cell lines. Another shortcoming of in vitro experiments is that AO are metabolised in vivo and that most cell lines are lacking enzymes which catalyse these reactions. Compounds with large molecular configurations (chlorophylls, anthocyans and polyphenolics) are potent AO in vitro, but weak or no effects were observed in animal/human studies with realistic doses as they are poorly absorbed. The development of -omics approaches will improve the scientific basis for health claims. The evaluation of results from microarray and proteomics studies shows that it is not possible to establish a general signature of alterations of transcription and protein patterns by AO. However, it was shown that alterations of gene expression and protein levels caused by experimentally induced oxidative stress and ROS related diseases can be normalised by dietary AO.

Anti-inflammatory, antiproliferative, and cytoprotective activity of NO chimera nitrates of use in cancer chemoprevention

Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown promise in colorectal cancer (CRC), but they are compromised by gastrotoxicity. NO-NSAIDs are hybrid nitrates conjugated to an NSAID designed to exploit the gastroprotective properties of NO bioactivity. The NO chimera ethyl 2-((2,3-bis(nitrooxy)propyl)disulfanyl)benzoate (GT-094), a novel nitrate containing an NSAID and disulfide pharmacophores, is effective in vivo in rat models of CRC and is a lead compound for design of agents of use in CRC. Preferred chemopreventive agents possess 1) antiproliferative and 2) anti-inflammatory actions and 3) the ability to induce cytoprotective phase 2 enzymes. To determine the contribution of each pharmacophore to the biological activity of GT-094, these three biological activities were studied in vitro in compounds that deconstructed the structural elements of the lead GT-094. The anti-inflammatory and antiproliferative actions of GT-094 in vivo were recapitulated in vitro, and GT-094 was seen to induce phase 2 enzymes via the antioxidant responsive element. In the variety of colon, macrophage-like, and liver cell lines studied, the evidence from structure-activity relationships was that the disulfide structural element of GT-094 is the dominant contributor in vitro to the anti-inflammatory activity, antiproliferation, and enzyme induction. The results provide a direction for lead compound refinement. The evidence for a contribution from the NO mimetic activity of nitrates in vitro was equivocal, and combinations of nitrates with acetylsalicylic acid were inactive.

Nutrition and cancer: essential elements for a roadmap

Personalizing nutrition for cancer prevention and therapy will require a comprehensive understanding of "genotypes/phenotypes" in order to identify, evaluate, and prioritize appropriate points for dietary intervention. This nutritional preemption roadmap must begin with accurately assessing intakes/exposures of which bioactive food component(s) is needed to bring about a desired response in critical cellular processes (carcinogen metabolism, DNA repair, cell proliferation, apoptosis, inflammation, immunity, differentiation, angiogenesis, hormonal regulation and cellular energetic) within an individual. Understanding this "individuality" through a better understanding of the "omics" is fundamental to arriving at the correct destination and thus interpreting biological variables which establish the magnitude or direction of a response to bioactive food components.

Phytochemical regulation of UDP-glucuronosyltransferases: implications for cancer prevention

Uridine 5'-diphospho-glucuronosyltransferases (UGTs) are Phase II biotransformation enzymes that metabolize endogenous and exogenous compounds, some of which have been associated with cancer risk. Many phytochemicals have been shown to induce UGTs in humans, rodents, and cell culture systems. Because UGTs maintain hormone balance and facilitate excretion of potentially carcinogenic compounds, regulation of their expression and activity may affect cancer risk. Phytochemicals regulate transcription factors such as the nuclear factor-erythroid 2-related factor 2 (Nrf2), aryl hydrocarbon, and pregnane X receptors as well as proteins in several signal transduction cascades that converge on Nrf2 to stimulate UGT expression. This induction can be modified by several factors, including phytochemical dose and bioavailability and interindividual variation in enzyme expression. In this review, we summarize the knowledge of dietary modulation of UGTs, particularly by phytochemicals, and discuss the potential mechanisms by which phytochemicals regulate UGT transcription.

Mass spectrometry in nutrition: understanding dietary health effects at the molecular level

In modern nutrition research, mass spectrometry has developed into a tool to assess health, sensory as well as quality and safety aspects of food. In this review, we focus on health-related benefits of food components and, accordingly, on biomarkers of exposure (bioavailability) and bioefficacy. Current nutrition research focuses on unraveling the link between dietary patterns, individual foods or food constituents and the physiological effects at cellular, tissue and whole body level after acute and chronic uptake. The bioavailability of bioactive food constituents as well as dose-effect correlations are key information to understand the impact of food on defined health outcomes. Both strongly depend on appropriate analytical tools to identify and quantify minute amounts of individual compounds in highly complex matrices--food or biological fluids--and to monitor molecular changes in the body in a highly specific and sensitive manner. Based on these requirements, mass spectrometry has become the analytical method of choice with broad applications throughout all areas of nutrition research. The current review focuses on selected areas of application: protein and peptide as well as nutrient and metabolite analysis.

Does garlic reduce risk of colorectal cancer? A systematic review

Colorectal cancer (CRC) is the 3rd leading cause of cancer death in the United States and the 2nd leading cause of cancer death in Australia. Environmental factors play important roles in the multiple-stage process of CRC and nutritional intervention has been identified as playing a major role in its prevention. The aim of this study was to review systematically the scientific evidence from all studies conducted over the last decade that examined effects of garlic on CRC. Levels of evidence were ranked from level I to level V according to study designs and the quality of each study was assessed against a set of quality criteria based on those used by the National Health and Medical Research Council in Australia. One randomized controlled trial (RCT, level II) reported a statistically significant 29% reduction in both size and number of colon adenomas in CRC patients taking aged garlic extract. Five of 8 case control/cohort studies (level III) suggested a protective effect of high intake of raw/cooked garlic and 2 of 8 of these studies suggested a protective effect for distal colon. A published meta-analysis (level III) of 7 of these studies confirmed this inverse association, with a 30% reduction in relative risk. Eleven animal studies (level V) demonstrated a significant anticarcinogenic effect of garlic and/or its active constituents. On balance, there is consistent scientific evidence derived from RCT of animal studies reporting protective effects of garlic on CRC despite great heterogeneity of measures of intakes among human epidemiological studies.

Erk is involved in the differentiation induced by diallyl disulfide in the human gastric cancer cell line MGC803

Diallyl disulfide (DADS) is a major constituent of garlic. Previously, we found that DADS both inhibited proliferation in human gastric cancer cells in vitro and in vivo, and induced G2/M arrest. In this study, we investigated whether this differentiation effect was induced by DADS in human gastric cancer MGC803 cells, and whether it was related to an alteration in ERK activity. The results showed that the growth of MGC803 cells was inhibited by DADS. Cells treated with DADS displayed a lower nucleocytoplasmic ratio and tended to form gland and intercellular conjunction structures. The ConA-mediated cell agglutination ratio and cells' ALP specific activity decreased. In MGC803 cells, dye transfer was limited to a few cells neighbouring the dye-injected cell and to a depth of 1-2 layers beneath the scrape site. However, after treatment with DADS, the LY (Lucifer Yellow) was transferred to several cells immediately neighbouring the microinjected cell and to a depth of 2-4 cell layers from the scrape site. This indicated that DADS induced differentiation in MGC803 cells. Western blot analysis revealed that although DADS did not influence the quantity of ERK1/2 protein expressed, it did decrease its phosphorylation in a concentration-dependent manner, compared with the controls. At 30 mg x L(-1), DADS inhibited the activation of ERK1/2 in 15-30 min. These results suggested that the DADS-induced differentiation of MGC803 cells involved an alteration of the ERK1/2 signaling pathway.

Colon cancer chemoprevention by a novel NO chimera that shows anti-inflammatory and antiproliferative activity in vitro and in vivo

Chemopreventive agents in colorectal cancer possess either antiproliferative or anti-inflammatory actions. Nonsteroidal anti-inflammatory drugs (NSAID) and cyclooxygenase-2 inhibitors have shown promise, but are compromised by side effects. Nitric oxide donor NSAIDs are organic nitrates conjugated via a labile linker to an NSAID, originally designed for use in pain relief, that have shown efficacy in colorectal cancer chemoprevention. The NO chimera, GT-094, is a novel nitrate containing an NSAID and disulfide pharmacophores, a lead compound for the design of agents specifically for colorectal cancer. GT-094 is the first nitrate reported to reduce aberrant crypt foci (by 45%) when administered after carcinogen in the standard azoxymethane rat model of colorectal cancer. Analysis of proximal and distal colon tissue from 8- and 28-week rat/azoxymethane studies showed that GT-094 treatment reduced colon crypt proliferation by 30% to 69%, reduced inducible NO synthase (iNOS) levels by 33% to 67%, reduced poly(ADP-ribose)polymerase-1 expression and cleavage 2- to 4-fold, and elevated levels of p27 in the distal colon 3-fold. Studies in cancer cell cultures recapitulated actions of GT-094: antiproliferative activity and transient G(2)-M phase cell cycle block were measured in Caco-2 cells; apoptotic activity was examined but not observed; anti-inflammatory activity was seen in the inhibition of up-regulation of iNOS and endogenous NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells. In summary, antiproliferative, anti-inflammatory, and cytoprotective activity observed in vivo and in vitro support GT-094 as a lead compound for the design of NO chimeras for colorectal cancer chemoprevention.

Nutritional Proteomics: Methods and Concepts for Research in Nutritional Science

Nutritional proteomics or nutriproteomics is the application of proteomics methodology to nutrition-related research but also represents the interaction of bioactive food ingredients with proteins, whereby the interaction with proteins occurs in two basically specific ways. Firstly, the effect of nutrients on protein expression, which can be monitored by protein mapping, and secondly, the interaction of nutrients with proteins by post-translational modifications or small-molecule protein interactions. These interactions result in changes to the three-dimensional structure of such effected proteins. As a consequence, their original functions are modulated, resulting for example in reduced activity in the case of enzymes or changes in ability of recognition between molecules such as protein-protein interactions and ligand-receptor interactions. The characterization of such modifications together with functional data from established biochemical and physiological methods will result in a better understanding of the interplay between bioactive dietary components and diet-related diseases such as cancer, diabetes or neurodegenerative diseases. The occurrence of such modifications can possibly be additionally used as biomarkers in the diagnosis and therapy of these diseases as well as biomarkers for the efficacy or safety of selected nutrients.

Induction of apoptosis and transient increase of phosphorylated MAPKs by diallyl disulfide treatment in human nasopharyngeal carcinoma CNE2 cells

This study was undertaken to elucidate the effect of diallyl disulfide (DADS), an oil-soluble organosulfur compound found in garlic, in suppressing human nasopharyngeal carcinoma cells. A potent increase (of at least 9-fold) in apoptotic cells has accompanied 1) a decrease in cell viability, 2) a increase of the fraction of S-phase cells by up to 63.8%, and 3) a transient increase of the phospho-p38 and phospho-p42/44 (phosphorylated p38 MAPK and phosphorylated p42/44 MAPK) in a time- and concentration-dependent manner. These results indicate that DADS can induce apoptosis in human nasopharyngeal carcinoma cells via, at least partly, S-phase block of the cell cycle, related to a rise in MAPK phosphorylation.

In vivo treatment by diallyl disulfide increases histone acetylation in rat colonocytes

Diallyl disulfide (DADS) is an organosulfur compound from garlic which exhibits various anticarcinogenic properties including inhibition of tumor cell proliferation. DADS antiproliferative effects were previously associated with an increase in histone acetylation in two human tumor colon cell lines, suggesting that DADS-induced histone hyperacetylation could be one of the mechanisms involved in its protective properties on colon carcinogenesis. The effects of DADS on histone H4 and H3 acetylation levels were investigated in vivo in colonocytes isolated from non-tumoral rat. Administrated by intracaecal perfusion or gavage, DADS increases histone H4 and H3 acetylation in colonocytes. Moreover, data generated using cDNA expression arrays suggest that DADS could modulate the expression of a subset of genes. These results suggest the involvement of histone acetylation in modulation of gene expression by DADS in normal rat colonocytes, which might play a role in its biological effects as well as in its anticarcinogenic properties in vivo.

Induction of apoptosis and histone hyperacetylation by diallyl disulfide in prostate cancer cell line PC-3

Prostate cancer is the most invasive and frequently occurred cancer in men. In the initial stages, it is androgen dependent and the androgen ablation therapy is effective at this stage. In the final stages, it becomes androgen-independent and is unresponsive to androgen ablation therapy. At this stage, induction of apoptosis is considered as a better strategy to control cancer. Histone acetylation and deacetylation are involved in transcriptional activation and transcriptional repression, respectively. Diallyl disulfide (DADS) induced histone hyperacetylation can be correlated with the expression of antiproliferative genes. Induction of apoptosis by DADS has been correlated with histone acetylation. In the present study, DADS, oil soluble organosulfur compound of garlic, has been studied for its effect on histone acetylation and induction of apoptosis in prostate cancer cells in vitro. The induction of apoptosis has been demonstrated by annexin V-FITC binding assay. Extent of apoptosis has been assessed measuring the activity of caspase-3. The results have shown that DADS induced apoptosis in prostate cancer cells in a dose dependent manner. At both 25 and 40 microM concentrations, DADS increased the number of both early and late apoptotic cells. Histone hyperacetylation was also observed in DADS treated cells. It is concluded that DADS, induces apoptosis by influencing histone acetylation in prostate cancer cells.

Diallyl disulfide suppresses growth of HL-60 cell through increasing histone acetylation and p21WAF1 expression in vivo and in vitro

AIM

To examine the differentiation induction and growth inhibition of HL-60 cells by diallyl disulfide (DADS), and its relationship with the alterations of histone acetylation and p21(WAF1) expression in vitro and in vivo.

METHODS

Differentiation was studied by nitroblue tetrazolium (NBT) reduction of HL-60 cell in vitro. HL-60 cells 5x10(6) were injected into the right side of the peritoneal cavity of severe combined immunodeficiency (SCID) mice. When the peritoneal neoplasms were detected, the SCID mice were randomly divided into 3 groups and received an ip injection of vehicle alone (NS), DADS or sodium butyrate (SB). The growth inhibition of peritoneal neoplasms induced by DADS was observed by a growth curve. The cycle distribution of HL-60 cells in SCID mice was monitored by flow cytometry. The expression of acetylated histone H3, H4 and p21(WAF1) were measured by Western blot.

RESULTS

After treatment with DADS for 0-72 h, the NBT reduction ability of HL-60 cells increased in a time-dependent manner, compared with no treatment of HL-60 cells. In the HL-60 cells treated with DADS for 24 h, the expression of acetylated histone H3, H4, and p21(WAF1) increased obviously. After treatment with DADS, tumor growth was markedly suppressed. HL-60 cells from mice treated with DADS were blocked in the G1 phase, from 25.4% to 63.4%. The tumors from the mice treated with DADS showed an increase of acetylated histone H3, H4, and p21(WAF1).

CONCLUSION

DADS could induce differentiation and inhibit the growth of HL-60 cells through increasing the expression of acetylated histone H3, H4, and p21(WAF1) in vitro and in vivo.

Diallyl disulfide increases CDKN1A promoter-associated histone acetylation in human colon tumor cell lines

Diallyl disulfide (DADS) is an organosulfur compound from garlic, which inhibits colon tumor cell proliferation. In a previous study, we have shown that in Caco-2 and HT-29 cells DADS (200 microM) increases global histone acetylation, CDKN1A mRNA, and p21(waf1) protein levels and induces G2/M cell cycle arrest. These results suggested that DADS could inhibit cell proliferation through at least in part a transcriptional activation of CDKN1A expression involving histone acetylation. In this study, using chromatin immunoprecipitation assays, we demonstrate that in Caco-2 and HT-29 cells histone H4 and/or H3 acetylation is increased within CDKN1A promoter after 3 and 6 h treatments with DADS. These results strongly suggest that histone acetylation, a molecular mechanism implicated in the regulation of gene expression, could account for the induction of CDKN1A expression and the antiproliferating effects of DADS in colon tumor cells.

Protective effects of garlic sulfur compounds against DNA damage induced by direct- and indirect-acting genotoxic agents in HepG2 cells

The aim of this study was to assess the antigenotoxic activity of several garlic organosulfur compounds (OSC) in the human hepatoma cell line HepG2, using comet assay. The OSC selected were allicin (DADSO), diallyl sulfide (DAS), diallyl disulfide (DADS), S-allyl cysteine (SAC) and allyl mercaptan (AM). To explore their potential mechanisms of action, two approaches were performed: (i) a pre-treatment protocol which allowed study of the possible modulation of drug metabolism enzymes by OSC before treatment of the cells with the genotoxic agent; (ii) a co-treatment protocol by which the ability of OSC to scavenge direct-acting compounds was assessed. Preliminary studies showed that, over the concentration range tested (5-100 microM), the studied OSC neither affected cell viability nor induced DNA damage by themselves. In the pre-treatment protocol, aflatoxin B1 genotoxicity was significantly reduced by all the OSC tested except AM. DADS was the most efficient OSC in reducing benzo(a)pyrene genotoxicity. SAC and AM significantly decreased DNA breaks in HepG2 cells treated with dimethylnitrosamine. Additionally, all the OSC studied were shown to decrease the genotoxicity of the direct-acting compounds, hydrogen peroxide and methyl methanesulfonate. This study demonstrated that garlic OSC displayed antigenotoxic activity in human metabolically competent cells.

Preclinical perspectives on garlic and cancer

Evidence continues to point to the anticancer properties of fresh garlic extracts, aged garlic, garlic oil, and a number of specific organosulfur compounds generated by processing garlic. These anticarcinogenic and antitumorigenic characteristics appear to arise through both dose- and temporal-related changes in a number of cellular events involved with the cancer process, including those involving drug metabolism, immunocompetence, cell cycle regulation, apoptosis, and angiogenesis. The ability of garlic and related allyl sulfur compounds to block tumors in the colon, lung, breast, and liver suggests general mechanisms that are not tissue specific. Whereas relatively few studies have compared the relative efficacy of water- and lipid-soluble allyl sulfur compounds, those that have when using chemically induced carcinogen models suggest little difference in response, whereas tumor proliferation/apoptosis is highly dependent on the species provided. A shift in sulfhydryl groups, alterations in glutathione:oxidized glutathione ratios, and resultant changes in cellular redox status may be involved in some of the phenotypic changes caused by allyl sulfur compounds. Such changes in thiols by allyl sulfurs may also account for the observed hyperphosphorylation of specific cell cycle proteins and the histone hyperacetylation that has been correlated with suppressed tumor cell proliferation. Whereas the anticarcinogenic and antitumorigenic data to date are impressive, additional studies are needed with more modest exposure to allyl sulfur compounds over prolonged periods. Likewise, additional studies are needed that incorporate transgenic and knockout models to assist in the identification of molecular targets for garlic and its associated allyl sulfur components.

Aged garlic extract inhibits angiogenesis and proliferation of colorectal carcinoma cells

Because colorectal cancer is likely to develop in many people at some point during their lives, prevention has become a high priority. Diet and nutrition play an important role during the multistep colon carcinogenic process. Garlic has been traditionally used as a spice and is well known for its medicinal properties; several studies have indicated its pharmacologic functions, including its anticarcinogenic properties. However, the mechanisms by which garlic can prevent colorectal cancer remain to be elucidated. This study investigated the effect of aged garlic extract (AGE) on the growth of colorectal cancer cells and their angiogenesis, which are important microenvironmental factors in carcinogenesis. AGE suppressed the proliferation of 3 different colorectal cancer cell lines-HT29, SW480, and SW620-in the same way, but its effects on the invasive activities of these 3 cell lines were different. the invasive activities of SW480 and SW620 cells were inhibited by AGE, whereas AGE had no effect on the invasive activity of Ht29 cells. The action of AGE appears to be dependent on the type of cancer cell. On the other hand, AGE enhanced the adhesion of endothelial cells to collagen and fibronectin and suppressed cell motility and invasion. AGE also inhibited the proliferation and tube formation of endothelial cells potently. These results suggest that AGE could prevent tumor formation by inhibiting angiogenesis through the suppression of endothelial cell motility, proliferation, and tube formation. AGE would be a good chemopreventive agent for colorectal cancer because of its antiproliferative action on colorectal carcinoma cells and inhibitory activity on angiogenesis.

Preclinical Perspectives on Garlic and Cancer

Evidence continues to point to the anticancer properties of fresh garlic extracts, aged garlic, garlic oil, and a number of specific organosulfur compounds generated by processing garlic. These anticarcinogenic and antitumorigenic characteristics appear to arise through both dose- and temporal-related changes in a number of cellular events involved with the cancer process, including those involving drug metabolism, immunocompetence, cell cycle regulation, apoptosis, and angiogenesis. The ability of garlic and related allyl sulfur compounds to block tumors in the colon, lung, breast, and liver suggests general mechanisms that are not tissue specific. Whereas relatively few studies have compared the relative efficacy of water- and lipid-soluble allyl sulfur compounds, those that have when using chemically induced carcinogen models suggest little difference in response, whereas tumor proliferation/apoptosis is highly dependent on the species provided. A shift in sulfhydryl groups, alterations in glutathione:oxidized glutathione ratios, and resultant changes in cellular redox status may be involved in some of the phenotypic changes caused by allyl sulfur compounds. Such changes in thiols by allyl sulfurs may also account for the observed hyperphosphorylation of specific cell cycle proteins and the histone hyperacetylation that has been correlated with suppressed tumor cell proliferation. Whereas the anticarcinogenic and antitumorigenic data to date are impressive, additional studies are needed with more modest exposure to allyl sulfur compounds over prolonged periods. Likewise, additional studies are needed that incorporate transgenic and knockout models to assist in the identification of molecular targets for garlic and its associated allyl sulfur components.

Redox-sensitive proteins are potential targets of garlic-derived mercaptocysteine derivatives

Molecular investigations support existing clinical and epidemiological data that garlic-derived allylsulfides reduce cancer risk. Various allylsulfides can diminish progression of cancer cells at either the G1/S or G2/M phase. Allylsulfide derivatives modify redox-sensitive signal pathways and cause growth inhibition, mitotic arrest, and apoptosis induction. Whether allylsulfides modify intracellular redox potentials by affecting the ratio of glutathione:glutathione disulfide and/or by interacting directly with sulfhydryl domains on regulatory or catalytic-signal proteins requires further investigation. To understand the possible biochemical mechanisms contributing to the protective effects of allylsulfides, we investigated the ability of these compounds to undergo enzyme-catalyzed transformations. In addition to catalyzing gamma-elimination reactions, gamma-cystathionase can perform beta-elimination reactions with cysteinyl S-conjugates derived from garlic extracts when the S-alkyl group (R) is larger than ethyl. The reaction products are pyruvate, ammonium, and a sulfur-containing fragment (RSH). beta-Lyase substrates of gamma-cystathionase thus far identified from garlic include: S-allyl-L-cysteine (R=CH2=CHCH2-), S-allylmercapto-L-cysteine (R=CH2=CHCH2S-), and S-propylmercapto-L-cysteine (R=CH3CH2CH2S-). Mercapto derivatives yield persulfide products (RSSH) that are potential sources of sulfane sulfur, which may modify protein function by reacting at important cysteinyl domains. Thus, beta-elimination reactions with cysteine S-conjugates in garlic may modify cancer-cell growth by targeting redox-sensitive signal proteins at sulfhydryl sites, thereby regulating cell proliferation and/or apoptotic responses. These interactions may be useful in identifying efficacy of garlic-derived compounds and/or developing other novel organosulfur compounds that may modify intracellular redox potentials or interact with thiols associated within cysteine domains in regulatory, catalytic, signal, or structural proteins.

The MAPK signalling pathways and colorectal cancer

There are three major subfamilies of mitogen-activated protein kinases (MAPK): the extracellular-signal-regulated kinases (ERK MAPK); the c-jun N-terminal kinase or stress-activated protein kinases (JNK or SAPK); and MAPK14. The ERK MAPK pathway is one of the most important for cell proliferation. The MAPK pathways are located downstream of many growth-factor receptors, including that for epidermal growth factor. Overexpression and activation of this receptor are commonly detected in colorectal cancer, and several lines of evidence indicate that overexpression and activation of ERK MAPK play an important part in progression of this cancer. ERK MAPK could be a molecular target for treatment of the disorder. This review focuses on the ERK MAPK signal-transduction pathway, the consequences of its dysregulation in colorectal cancer, and its potential as an approach to cancer treatment. Future challenges for the assessment of these targeted agents in the clinic are also presented.

Novel Disulfides with Antitumour Efficacy and Specificity

Some disulfides have previously been shown to possess antifungal and/or antileukaemic activity. Importantly, this cytotoxicity can be selective. We have previously shown that a subset of these compounds does not block the proliferative potential of normal, non-transformed cells. Based on these results and proposed mechanisms of action, a new set of structurally modified organosulfur compounds, including α-substituted disulfides and a thiosulfonate ester, have been prepared and evaluated for their potential as antileukaemic agents. Compounds were screened for antiproliferative activity against a panel of human cells derived from acute lymphocytic and acute myelogenous leukaemia, as well as non-transformed cells. We have identified five new disulfides and a thiosulfonate that can trigger tumour cells to undergo cell death by an apoptotic mechanism in a sensitive and specific manner.

Growth Suppressing Effect of Garlic Compound Diallyl Disulfide on Prostate Cancer Cell Line (PC-3) in Vitro

Prostate cancer is the most predominant cancer in men and prostate cancer related death increases every year. Till date, there is no effective therapy other than androgen ablation therapy. At this stage, induction of apoptosis is considered as a better strategy to control cancer. Previous studies reported that aged garlic extract suppresses cancer growth and enhances immune system against cancer. In the present study, diallyl disulfide, oil soluble organosulfur compound of garlic, was studied for its antiproliferative effect on prostate cancer cells in vitro. The suppression of cell growth was demonstrated by [(3)H]thymidine incorporation assay. Induction of DNA damage was assessed by agarose gel electrophoresis. The results showed that diallyl disulfide inhibited the growth of prostate cancer cells in a dose dependent manner, compared to the control. At 50 microM and 100 microM concentrations, diallyl disulfide induced DNA damage in PC-3 cells. It is concluded that diallyl disulfide, component of aged garlic extract, inhibits proliferation of prostate cancer cells through the induction of apoptosis.

Signal transduction pathways leading to cell cycle arrest and apoptosis induction in cancer cells by Allium vegetable-derived organosulfur compounds: a review

Epidemiological studies continue to support the premise that dietary intake of Allium vegetables (e.g., garlic, onions and so forth) may lower the risk of various types of cancer. Anticarcinogenic effect of Allium vegetables is attributed to organosulfur compounds (OSCs) that are generated upon processing of these vegetables. Preclinical studies have provided convincing evidence to indicate that Allium vegetable-derived OSCs including diallyl sulfide, diallyl disulfide and diallyl trisulfide are highly effective in affording protection against cancer in laboratory animals induced by a variety of chemical carcinogens. Inhibition of carcinogen activation through modulation of cytochrome P450-dependent monooxygenases and/or acceleration of carcinogen detoxification via induction of phase II enzymes (glutathione transferases, quinone reductase, etc.) are believed to be responsible for protective effects of OSCs against chemically induced cancers. More recent studies have indicated that some naturally occurring OSC analogues can suppress proliferation of cancer cells in culture and inhibit growth of transplanted tumor xenografts in vivo by inducing apoptosis and/or by perturbing cell cycle progression. This review summarizes current knowledge on signal transduction pathways leading to perturbations in cell cycle progression and apoptosis induction by OSCs.

Induction of detoxifying enzymes by garlic organosulfur compounds through transcription factor Nrf2: effect of chemical structure and stress signals

Garlic organosulfur compounds (OSCs) are recognized as a group of potential chemopreventive compounds. It is known that garlic OSCs can modulate drug metabolism systems, especially various phase II detoxifying enzymes, though the mechanism underlying their inductive effect on these enzymes remains largely unknown. In the present study, we investigated the transcriptional levels of NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO1) genes, the reporter activity mediated by antioxidant response element (ARE), and the protein level of transcription factor nuclear factor E2-related factor 2 (Nrf2), after administration of three major garlic OSCs--diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS)--in human hepatoma HepG2 cells. Our results showed that ARE activation and Nrf2 protein accumulation were well correlated with phase II gene expression induction. The structure-activity relationship study indicated that the third sulfur in the structure of OSCs contributed substantially to their bioactivities, and that allyl-containing OSCs were more potent than propyl-containing OSCs. To better understand the signaling events involved in the upregulation of detoxifying enzymes by DATS, ARE activity and Nrf2 protein levels were examined after transient transfection of HepG2 cells with mutant Nrf2, cotreatment with antioxidants, and pretreatment with protein kinase inhibitors. DATS-induced ARE activity was inhibited by dominant-negative Nrf2 Kelch-like ECH-associating protein 1 and constructs. Cotreatment with thiol antioxidants decreased the ARE activity and Nrf2 protein level induced by DATS. Three major mitogen-activated protein kinases (MAPKs)--extracellular signal-regulated protein kinase, c-Jun N-terminal kinase, and p38--were activated by DATS treatment. However, the inhibition of these MAPKs did not affect DATS-induced ARE activity. Pretreatment with various upstream protein kinase inhibitors showed that the protein kinase C pathway was not directly involved in DATS-induced ARE activity, but instead the calcium-dependent signaling pathway appeared to play a role in the DATS-induced cytoprotective effect.

Frontiers in nutrigenomics, proteomics, metabolomics and cancer prevention

While dietary habits continue to surface as a significant factor that may influence cancer incidence and tumor behavior, there is considerable scientific uncertainty about who will benefit most. Adequate [corrected] knowledge about how the responses depend on an individual's genetic background (nutrigenetic effects), the cumulative effects of food components on genetic expression profiles (nutritional transcriptomics and nutritional epigenomics effects), the occurrence and activity of proteins (proteomic effects) and/or the dose and temporal changes in cellular small molecular weight compounds (metabolomics effects) will [corrected] assist in identifying responders and non-responders. Expanding the information about similarities and differences in the "omic" responses across tissues will not only provide clues about specificity in response to bioactive food components but assist in the identification of surrogate tissues and biomarkers that can be used for predicting a response. Deciphering the importance of each of these potential sites of regulation will be particularly challenging but does hold promise in explaining many of the inconsistencies in the literature.