Resveratrol inhibits cyclooxygenase-2 transcription in human mammary epithelial cells

Resveratrol, Endocrine Disrupting Chemicals, Neurodegenerative Diseases and Depression: Genes, Transcription Factors, microRNAs, and Sponges Involved

We aimed to examine the molecular basis of the positive effect of resveratrol against amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), cognitive impairment (CI), and depression induced by a mixture of bisphenol A (BPA), BPS, and BPF. The CTD, GeneMania, Metascape, SwissADME, Cytoscape, MIENTURNET, miRNAsong, and Autodock Vina were the fundamental tools for analysis. Resveratrol exerts its protective effects on selected diseases induced by a mixture of BPA, BPS, and BPF through the following genes: PTGS2 and GSR for ALS; INS, IL6, BDNF, and SOD1 for PD; BDNF, CASP3, TNF, INS, IGF1, IL1B for CI; and BDNF, PTGS2, and IL6 for depression. Detoxification was noted as the most important for ALS, dopamine metabolism for PD, apoptosis for CI, and the selenium micronutrient network for depression. hsa-miR-377-3p, hsa-miR-1-3p, hsa-miR-128-3p, and hsa-miR-204-5p were highlighted. We created and tested in silico sponges that inhibited these miRNAs. NFE2L2, BACH1, PPARG, and NR4A3 were listed as the key transcription factors implicated in resveratrol's protective effect against harmful studied chemicals. Furthermore, resveratrol's physicochemical properties and pharmacokinetics are consistent with its therapeutic benefits in ALS, PD, CI, and depression, owing to its high gastrointestinal absorption, drug-likeness, non-P-glycoprotein substrate, and capacity to penetrate the blood-brain barrier.

Molecular mechanisms associated with the chemoprotective role of protocatechuic acid and its potential benefits in the amelioration of doxorubicin-induced cardiotoxicity: A review

Since its discovery in the 1960 s, doxorubicin (DOX) has constantly elicited the broadest spectrum of cancerocidal activity against human cancers. However, cardiotoxicity caused by DOX directly as well as its metabolites is a great source of concern over the continuous use of DOX in chemotherapy. While the exact mechanism of DOX-induced cardiotoxicity is yet to be completely understood, recent studies indicate oxidative stress, inflammation, and several forms of cell death as key pathogenic mechanisms that underpin the etiology of doxorubicin-induced cardiotoxicity (DIC). Notably, these key mechanistic events are believed to be negatively regulated by 3,4-dihydroxybenzoic acid or protocatechuic acid (PCA)-a plant-based phytochemical with proven anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Here, we review the experimental findings detailing the potential ameliorative effects of PCA under exposure to DOX. We also discuss molecular insights into the pathophysiology of DIC, highlighting the potential intervention points where the use of PCA as a veritable chemoprotective agent may ameliorate DOX-induced cardiotoxicities as well as toxicities due to other anticancer drugs like cisplatin. While we acknowledge that controlled oral administration of PCA during chemotherapy may be insufficient to eliminate all toxicities due to DOX treatment, we propose that the ability of PCA to block oxidative stress, attenuate inflammation, and abrogate several forms of cardiomyocyte cell death underlines its great promise in the amelioration of DIC.

Impact of Mediterranean Diet Food Choices and Physical Activity on Serum Metabolic Profile in Healthy Adolescents: Findings from the DIMENU Project

Adolescent nutrition and healthy dietary patterns, particularly the Mediterranean diet (MD), have been associated with improved health status and decreased risk of various chronic and metabolic diseases later in life. The aim of this study was to evaluate the impact of the Mediterranean food choices on lipid and glycemic metabolic profile in the total population and in adolescents grouped according to their physical activity (PA) levels at the time of recruitment (T0) and after six months from the administration of a personalized Mediterranean meal plan (T1). As part of the DIMENU study, 85 adolescents underwent measurements of lipid and glucose metabolic profile at T0 and T1. Using three positive items from KIDMED test related to the consumption of typical Mediterranean food (olive oil, fish, and nuts) and three negative items on dietary habits (going to fast-food, consuming biscuits, and candies), we categorized adolescents into six sets in which biochemical parameters were analyzed. In the total sample, significant reductions in serum total cholesterol, LDL, and glucose concentrations were observed for all the sets over the study period. Notably, active subjects, who had a better serum metabolic profile, showed significant improvements of glycemic control after 6 month follow up, while in sedentary adolescents and in those performing moderate PA significant reduction in glycemia, total cholesterol, and LDL was found in all sets. In conclusion, adopting the typical Mediterranean food choices led to a significant reduction in glucose and lipid profile in healthy adolescents, thus making the MD and PA a winning combination for health status.

Antiproliferative and Apoptotic Properties of Andrographolide Against Human Colon Cancer DLD1 Cell Line

BACKGROUND

In recent years, natural products have received great attention for cancer prevention owing to their various health benefits, noticeable lack of toxicity and side effects, and the limitations of chemotherapeutic agents. Andrographolide, a labdane diterpenoid is a principal bioactive constituent of Andrographis paniculata Nees, exhibits significant anticancer activity.

OBJECTIVE

The efficacy of andrographolide on colon cancer cells is yet to be elucidated completely. Therefore, we investigated the anticancer efficiency of andrographolide in colon cancer DLD1 cell line.

METHODS

Antiproliferative activity of andrographolide on DLD1 cells was evaluated by MTT assay, LDH release assay, morphological analysis and colony formation assay. Induction of apoptosis was determined by DAPI staining, Annexin V-FITC staining assay, and caspase-3 activation assay. Role of andrographolide induced cellular reactive oxygen species (ROS) and its association with apoptosis induction in DLD1 cells was elucidated by DCFDA dye. Synergistic ability of andrographolide with 5- fluorouracil (5-FU) and paclitaxel (PTX) was evaluated by MTT assay.

RESULTS

Results of the present study indicated that andrographolide declined cell viability of DLD1 cells in a concentration and time-dependent manner. Andrographolide induced apoptosis via nuclear condensation, phosphatidylserine externalization and caspase-3 activation. It also augmented cellular ROS levels which were in turn associated with apoptosis induction in DLD1 cells. Moreover, andrographolide displayed synergistic activity with 5-FU and PTX against DLD1 cells.

CONCLUSION

The present study showed that andrographolide demonstrated antiproliferative and apoptotic properties, moreover it also displayed synergistic effect with chemotherapeutic drugs in colon cancer DLD1 cells.

Resveratrol attenuates TLR-4 mediated inflammation and elicits therapeutic potential in models of sepsis

Sepsis is a potentially fatal condition triggered by systemic inflammatory response to infection. Due to the heightened immune reactivity and multi-organ pathology, treatment options are limited and several clinical trials have not produced the desired outcome, hence the interest in the discovery of novel therapeutic strategies. The polyphenol resveratrol (RSV) has shown promise against several pathological states, including acute and chronic inflammation. In this study, we evaluated its therapeutic potential in a murine model of sepsis and in patients undergoing transrectal ultrasound biopsy. RSV was able to inhibit lipopolysaccharide (LPS) stimulated inflammatory responses through blocking Phospholipase D (PLD) and its downstream signaling molecules SphK1, ERK1/2 and NF-κB. In addition, RSV treatment resulted in the downregulation of MyD88, an adaptor molecule in the TLR4 signaling pathway, and this effect at least in part, involved RSV-induced autophagy. Notably, RSV protected mice against polymicrobial septic shock induced upon cecal ligation and puncture, and inhibited pro-inflammatory cytokine production by human monocytes from transrectal ultrasound (TRUS) biopsy patients. Together, these findings demonstrate the immune regulatory activity of RSV and highlight its therapeutic potential in the management of sepsis.

Effects of a natural polyphenol on nicotine-induced pancreatic cancer cell proliferation

INTRODUCTION

Resveratrol (trans-3, 4’, 5-trihydroxystilbene), a phytoalexin derived from the skin of grapes and other fruits, has anti-inflammatory and anti-oxidant effects. Its anti-carcinogenic effects are closely associated with its antioxidant activity; thus, the use of resveratrol as a possible cancer chemo-preventive is considered to be an important area of investigation. In this study we have examined the inhibitory effects of resveratrol in nicotine induced proliferation of pancreatic cancer cells.

METHODS

Cultured AR42J cells were incubated with 100 μM nicotine for 3 min and with 100 μM resveratrol for 30 min, either alone or in combination. Proliferation assays were conducted for a period of 0 to 96 h in serum media, incubated with nicotine and resveratrol, and evaluated by MTT assay. Protein was measured in lysed cells and activation of MAPK signals was measured by western blot using purified p-ERK antibody. Co-localization of activated ERK signals was confirmed by FITC conjugated ERK antibody using immunofluorescence assay and confocal microscopy. Biomarker of lipid peroxidation was determined in cell lysates by malondialdehyde (MDA) bioassay.

RESULTS

Resveratrol significantly suppressed the nicotine-induced proliferation of acinar cells compared to untreated controls (p<0.05). Mitogen activated protein kinase (MAPK) analysis revealed up-regulation of p-ERK expression by nicotine (p<0.05) that was suppressed significantly by resveratrol (p<0.05). Co-localization of activated ERK signals was confirmed by FITC conjugated ERK antibody, and this response was reduced significantly by resveratrol. Nicotine-induced malondialdehyde formation was also suppressed by resveratrol (p<0.05).

CONCLUSIONS

The data suggest that resveratrol suppressed nicotine-induced AR42J cell proliferation. The proliferation of AR42J cells by nicotine is associated with activation of MAPK signals and induction of protein oxidation. Resveratrol suppressed lipid peroxidation and P-ERK activated signals induced by nicotine. We conclude that resveratrol acts as an effective antioxidant in reversing the nicotine induced pancreatic cancer cell proliferation.

Phyto-polyphenols as potential inhibitors of breast cancer metastasis

Breast cancer is the most common cancer among women as metastasis is currently the main cause of mortality. Breast cancer cells undergoing metastasis acquire resistance to death signals and increase of cellular motility and invasiveness.Plants are rich in polyphenolic compounds, many of them with known medicinal effects. Various phyto-polyphenols have also been demonstrated to suppress cancer growth. Their mechanism of action is usually pleiotropic as they target multiple signaling pathways regulating key cellular processes such as proliferation, apoptosis and differentiation. Importantly, some phyto- polyphenols show low level of toxicity to untransformed cells, but selective suppressing effects on cancer cells proliferation and differentiation.In this review, we summarize the current information about the mechanism of action of some phyto-polyphenols that have demonstrated anti-carcinogenic activities in vitro and in vivo. Gained knowledge of how these natural polyphenolic compounds work can give us a clue for the development of novel anti-metastatic agents.

The Paradox of p53: What, How, and Why?

Unlike the rather stereotypic image by which it was portrayed until not too many years ago, p53 is now increasingly emerging as a multifaceted transcription factor that can sometimes exert opposing effects on biological processes. This includes pro-survival activities that seem to contradict p53's canonical proapoptotic features, as well as opposing effects on cell migration, metabolism, and differentiation. Such antagonistic bifunctionality (balancing both positive and negative signals) bestows p53 with an ideal attribute to govern homeostasis. The molecular mechanisms underpinning the paradoxical activities of p53 may be related to a protein conformational spectrum (from canonical wild-type to "pseudomutant"), diversity of DNA response elements, and/or higher-order chromatin configuration. Altogether, this functional flexibility positions p53 as a transcriptional "super hub" that dictates cell homeostasis, and ultimately cell fate, by governing a hierarchy of other functional hubs. Deciphering the mechanisms by which p53 determines which hubs to engage, and how one might modulate the preferences of p53, remains a major challenge for both basic science and translational cancer medicine.

Regulation of Cellular Metabolism and Hypoxia by p53

The p53 protein is essential for the implementation of the cellular response to challenging environmental conditions. Reacting to stochastic nutrient stress, p53 integrates the activity of key metabolite-sensing pathways to coordinate an appropriate cell response. During starvation, p53 activity augments cell survival pathways, inhibits unnecessary growth, and promotes efficient nutrient generation, utilization, and conservation. Similarly, during oxygen stress, p53 facilitates redirection of cellular metabolism toward energy generation through nonoxidative means, the suppression of reactive oxygen species (ROS) generation, and ROS detoxification-promoting cell survival. However, if adverse conditions are too acute or persistent, p53 can switch roles to implement canonical cell killing. The ability of p53 to regulate metabolism is a powerful feature of p53 biology that can both promote cell survival and act as a check on the inappropriate proliferation of cancer cells.

Metabolic regulation by p53 family members

The function of p53 is best understood in response to genotoxic stress, but increasing evidence suggests that p53 also plays a key role in the regulation of metabolic homeostasis. p53 and its family members directly influence various metabolic pathways, enabling cells to respond to metabolic stress. These functions are likely to be important for restraining the development of cancer but could also have a profound effect on the development of metabolic diseases, including diabetes. A better understanding of the metabolic functions of p53 family members may aid in the identification of therapeutic targets and reveal novel uses for p53-modulating drugs.

Modulation of inflammatory signaling pathways by phytochemicals in ovarian cancer

Inflammation has been suggested to be involved in cancer development and progression. Many clinical and experimental studies have shown that inflammation could contribute to ovarian carcinogenesis through activation of the NF-κB and AP-1 pathways by chronic inflammatory mediators. Phytochemicals, which are natural compounds derived from fruits and vegetables, have shown anti-inflammatory and anti-cancer effects. Due to their relatively low toxicity and easy accessibility, phytochemicals have been investigated for their chemopreventive potential against various cancers. In this review, we discuss the role of phytochemicals in preventing ovarian cancer through anti-inflammatory mechanisms.

The antioxidant resveratrol protects against chondrocyte apoptosis via effects on mitochondrial polarization and ATP production

OBJECTIVE

To determine the effects of the antioxidant resveratrol on the functions of human chondrocytes in osteoarthritis (OA).

METHODS

Chondrocytes and cartilage explants were isolated from OA patients undergoing knee replacement surgery. Effects of resveratrol in the presence or absence of interleukin-1beta (IL-1beta) stimulation were assessed by measurement of prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4)) synthesis, cyclooxygenase (COX) activity, matrix metalloproteinase (MMP) expression, and proteoglycan production. To explore the mechanisms of action of resveratrol, its effects on mitochondrial function and apoptosis were examined by assessing mitochondrial membrane potential, ATP levels, cytochrome c release, and annexin V staining.

RESULTS

Resveratrol inhibited both spontaneous and IL-1beta-induced PGE(2) production by >20% (P < 0.05) and by 80% (P < 0.001), respectively; similarly, LTB(4) production was reduced by >50% (P < 0.05). The production of PGE(2) was inhibited via a 70-90% suppression of COX-2 expression and enzyme activity (P < 0.05). Resveratrol also promoted anabolic effects in OA explant cultures, by elevating proteoglycan synthesis and decreasing production of MMPs 1, 3, and 13. Pretreatment of OA chondrocytes with resveratrol blocked mitochondrial membrane depolarization, loss of mitochondrial biomass, and IL-1beta-induced ATP depletion. Similarly, IL-1beta-mediated induction of the apoptotic markers cytochrome c and annexin V was also inhibited by resveratrol. Exogenous addition of PGE(2) abolished the protective effects of resveratrol on mitochondrial membrane integrity, ATP levels, expression of apoptotic markers, and DNA fragmentation.

CONCLUSION

Resveratrol protects against IL-1beta-induced catabolic effects and prevents chondrocyte apoptosis via its inhibition of mitochondrial membrane depolarization and ATP depletion. These beneficial effects of resveratrol are due, in part, to its capacity to inhibit COX-2-derived PGE(2) synthesis. Resveratrol may therefore protect against oxidant injury and apoptosis, which are main features of progressive OA.

Resveratrol inhibits prostaglandin formation in IL-1beta-stimulated SK-N-SH neuronal cells

Resveratrol, a polyphenol present in grapes and red wine, has been studied due to its vast pharmacological activity. It has been demonstrated that resveratrol inhibits production of inflammatory mediators in different in vitro and in vivo models. Our group recently demonstrated that resveratrol reduced the production of prostaglandin (PG) E₂ and 8-isoprostane in rat activated microglia. In a microglial-neuronal coculture, resveratrol reduced neuronal death induced by activated microglia. However, less is known about its direct roles in neurons. In the present study, we investigated the effects of resveratrol on interleukin (IL)-1β stimulated SK-N-SH cells. Resveratrol (0.1-5 μM) did not reduce the expression of cyclooxygenase (COX)-2 and microsomal PGE₂ synthase-1 (mPGES-1), although it drastically reduced PGE₂ and PGD₂ content in IL-1β-stimulated SK-N-SH cells. This effect was due, in part, to a reduction in COX enzymatic activity, mainly COX-2, at lower doses of resveratrol. The production of 8-iso-PGF_2α, a marker of cellular free radical generation, was significantly reduced by resveratrol. The present work provides evidence that resveratrol reduces the formation of prostaglandins in neuroblastoma cells by reducing the enzymatic activity of inducible enzymes, such as COX-2, and not the transcription of the PG synthases, as demonstrated elsewhere.

Resveratrol addiction: to die or not to die

Resveratrol, a polyphenol derived from red grapes, berries, and peanuts, has been shown to mediate death of a wide variety of cells. The mechanisms by which resveratrol mediates cell death include necrosis, apoptosis, autophagy, and others. While most studies suggest that resveratrol kills tumor cells selectively, evidence is emerging that certain normal cells such as endothelial cells, lymphocytes, and chondrocytes are vulnerable to resveratrol. Cell killing by this stilbene may be mediated through any of numerous mechanisms that involve activation of mitochondria and of death caspases; upregulation of cyclin-dependent kinase inhibitors, tumor suppressor gene products, or death-inducing cytokines and cytokine receptors; or downregulation of cell survival proteins (survivin, cFLIP, cIAPs, X-linked inhibitor of apoptosis protein (XIAP), bcl-2, bcl-XL) or inhibition of cell survival kinases (e.g., mitogen-activiated protein kinases (MAPKs), AKT/phosphoinositide 3-kinase (PI3K), PKC, EGFR kinase) and survival transcription factors (nuclear factor-kappaB (NF-kappaB), activating protein 1 (AP-1), HIF-1alpha, signal transducer and activator of transcription (STAT3)). Induction of any of these pathways by resveratrol leads to cell death. While cell death is a hallmark of resveratrol, this polyphenol also has been linked with suppression of inflammation, arthritis, and cardiovascular diseases and delaying of aging. These attributes of resveratrol are discussed in detail in this review.

Resveratrol and chemoprevention

Resveratrol is a phytoalexin, highly abundant in skins of red grapes and moderately abundant in peanuts and blueberries. Originally a constituent of oriental medicines, it has lately been rediscovered for a plethora of beneficial properties such as anti-cancer, anti-aging, antiviral, cardiovascular and neuroprotective effects, thereby making it one of the most sought after phytochemicals for supplementing human diet. Studies done in various laboratories have shown its modulatory effects on multitudes of cell signaling and gene expression pathways. Although most of its effects have been observed in cultured cells, quite a few have also been validated in whole animals as well. It is thus necessary to have a comprehensive look at all those effects of resveratrol in an organismal context. The following review summarizes the effects of resveratrol in the context of chemoprevention.

Cancer chemopreventive and therapeutic potential of resveratrol: mechanistic perspectives

A plant kingdom is considered as a gold mine for the discovery of many biologically active substances with therapeutic values. Resveratrol (3,5,4'-trihydroxystilbene), a naturally occurring polyphenol, exhibits pleiotropic health beneficial effects including anti-oxidant, anti-inflammatory, cardioprotective and anti-tumor activities. Currently, numerous preclinical findings suggest resveratrol as a promising nature's arsenal for cancer prevention and treatment. A remarkable progress in dissecting the molecular mechanisms underlying anti-cancer properties of resveratrol has been achieved in the past decade. As a potential anti-cancer agent, resveratrol has been shown to inhibit or retard the growth of various cancer cells in culture and implanted tumors in vivo. The compound significantly inhibits experimental tumorigenesis in a wide range of animal models. Resveratrol targets many components of intracellular signaling pathways including pro-inflammatory mediators, regulators of cell survival and apoptosis, and tumor angiogenic and metastatic switches by modulating a distinct set of upstream kinases, transcription factors and their regulators. This review summarizes the diverse molecular targets of resveratrol with a special focus on those involved in fine-tuning of orchestrated intracellular signal transduction.

Metabolism and Disposition of Resveratrol in the Isolated Perfused Rat Liver: Role of Mrp2 in the Biliary Excretion of Glucuronides

In this study, the hepatic metabolism and transport system for resveratrol was examined in isolated perfused livers from Wistar and Mrp2-deficient TR(-) rats. Based on extensive metabolism to six glucuronides and sulfates (M1-M6), the hepatic extraction ratio and clearance of resveratrol was very high in Wistar and TR(-) rats (E: 0.998 vs. 0.999; Cl: 34.9 mL/min vs. 36.0 mL/min). However, biliary excretion and efflux of conjugates differs greatly in TR(-) rats. While cumulative biliary excretion of the glucuronides M1, M2, M3, and M5 dropped dramatically to 0-6%, their efflux into perfusate increased by 3.6-, 1.8-, 2.5-, and 1.5-fold. In contrast, biliary secretion of the sulfates M4 and M6 was partially maintained in the Mrp2-deficient rats (61% and 39%) with a concomitant decline of their efflux into perfusate by 33.2% and 78.1%. This indicates that Mrp2 exclusively mediates the biliary excretion of resveratrol glucuronides but only partly that of sulfates. Cumulative secretion of unconjugated resveratrol into bile of TR(-) rats was only reduced by 40%, and into perfusate by 19%, suggesting only a minor role of Mrp2 in resveratrol elimination. In summary, resveratrol was dose-dependently metabolized to several conjugates whereby the canalicular transporter Mrp2 selectively mediated the biliary excretion of glucuronides.

trans-Resveratrol induces apoptosis in human breast cancer cells MCF-7 by the activation of MAP kinases pathways

Polyphenols represent a large class of plant-derived molecules with a general chemical structure that act as potent free radical scavengers. They have long been recognized to possess several therapeutic activities ranging from anti-thrombotic to antioxidant. Moreover, the capability of polyphenols to act as reducing or oxidizing molecules depends on the presence of environmental metals and on the concentrations used. In this work we demonstrated that the stilbene trans-resveratrol was able to commit human breast cancer MCF-7 cells to apoptosis. Mainly, we evidenced a pivotal role of the mitochondria in this phenomenon as cytochrome c release into the cytosol was found after the treatment. We further showed that trans-resveratrol was able to affect cellular redox state. In particular, it induced an early production of ROS and lipid oxidation, and only later compromised the GSH/GSSG ratio. This mode of action was mirrored by a temporally different activation of JNK and p38(MAPK), with the former rapidly induced and the latter weakly activated at long intervals. The results obtained demonstrate a pro-apoptotic activity for trans-resveratrol, and suggest a preferential activation of different classes of MAP kinases in response to different oxidative stimuli (ROS versus GSH/GSSG alteration).

Strategies for cancer prevention: the role of diet

Linkages between diet habits and cancer risk have surfaced from a multitude of epidemiological and preclinical studies. Collectively these studies provide rather compelling evidence that dietary components modify the incidence and biological behavior of tumors. While the risk of breast, prostate, colon, lung and liver cancers are frequently associated with dietary patterns, inconsistencies are not uncommon. These inconsistencies likely reflect the multi-factorial and complex nature of cancer and the specificity that individual dietary constituents have in modifying cancer related genetic pathways. The complexity of defining the role of diet is underscored by the numerous and diverse essential and non-essential components that may alter one or more phases of the cancer process. The explosive increase in the recognition of genes and pathways for regulating cell growth and development, and evaluating the response to hormones and other chemicals synthesized by the body, offers exciting opportunities for unraveling the molecular targets by which dietary components influence cancer prevention. It is recognized that all cells have unique ‘signatures’ that are characterized by active and inactive genes and cellular products. It is certainly plausible that bridging knowledge about these unique cellular characteristics with the molecular targets for nutrients can be used to assist in optimizing nutrition and minimizing cancer risk.

Resveratrol does not ameliorate muscle wasting in different types of cancer cachexia models

BACKGROUND & AIMS

Resveratrol has been reported to have antitumoural effects and recently it has been demonstrated that resveratrol partially blocks skeletal muscle wasting by interfering with NF-kappaB activation. We decided to investigate the potential anti-wasting properties of resveratrol on different models of cancer cachexia in experimental animals.

METHODS AND RESULTS

Incubations of isolated extensor digitorum longus muscles in the presence of 30 microM of resveratrol caused a significant decrease in the rate of protein degradation. However, administration of resveratrol in vivo to both rats bearing the Yoshida AH-130 ascites hepatoma (at the dose of 1 mg/kg body weight) and mice bearing the Lewis lung carcinoma (at two different doses, 5 and 25 mg/kg body weight) had no effect on skeletal muscle mass or body weight in tumour-bearing rodents. In addition, a combination of resveratrol (3 mg/kg body weight) and fish oil was also unable to induce any changes in skeletal muscle weights.

CONCLUSIONS

It is therefore concluded from this study that resveratrol is unable to influence muscle mass in vivo and has no potential role as anticachectic agent for the treatment of muscle wasting associated with tumour growth.

Oxyresveratrol dampens neuroimmune responses in vivo: a selective effect on TNF-α

Consumption of nutrients rich in hydroxystilbenes has been promoted because of their health benefits, including dampening of inflammatory responses. However, few studies have examined their effects in vivo. Here, we show that the hydroxystilbene oxyresveratrol (trans-2,3′,4,5′-tetrahydroxystilbene: o-RES) blocked hypothermia but caused no significant effect on the febrile response to the immune stimulus, bacterial LPS in rats. This was associated with a reduction in the LPS-induced plasma cytokine, tumor necrosis factor (TNF)-α, but not IL-6. Both IL-6-stimulated STAT-3 and LPS-induced cycoloxygenase-2 expression in the hypothalamus were not affected by o-RES. These data strongly suggest that the o-RES-induced dampening of neuroimmune responses is largely due to its inhibitory effect on TNF-α production. In contrast to in vitro experiments, o-RES has no direct effect on NF-κB signaling pathway in vivo. The specific inhibitory effect of o-RES on TNF-α opens new avenues for the clinical use of o-RES in pathological conditions where excessive production of TNF-α is deleterious.

Resveratrol interferes with AKT activity and triggers apoptosis in human uterine cancer cells

Background

Endometrial cancer is the fourth most prominent cancer among all feminine cancers in the Western world. Resveratrol, a natural anti-oxidant found in red wine emerging as a novel anticancer agent, exerts antiproliferative and pro-apoptotic activity in various cancer cell types, but its effect on uterine cancer cells is poorly understood. At the molecular level, resveratrol has been reported to inhibit cyclooxygenase (COX) expression and/or activity; in endometrial cancer cells, COX-2 is overexpressed and confers cellular resistance to apoptosis. The aim of the present study was to determine if resveratrol could exert anti-proliferative and pro-apoptotic activity over uterine cancer cells upon inhibition of COX-2 expression and/or activity. Six different human uterine cancer cell lines were used as a model (HeLa, Hec-1A, KLE, RL95-2, Ishikawa and EN-1078D).

Results and discussion

High-dose of resveratrol triggered apoptosis in five out of six uterine cancer cell lines, as judged from Hoechst nuclear staining and effector caspase cleavage. In accordance, uterine cancer cell proliferation was decreased. Resveratrol also reduced cellular levels of the phosphorylated/active form of anti-apoptotic kinase AKT. Endogenous COX-2 protein levels were decreased, concomitant with a decrease in production of COX metabolites PGE2 and PGF2α, in each uterine cancer cell line expressing detectable levels of COX-1 and/or COX-2 in presence of resveratrol. Although COX expression was identified as a target of resveratrol in uterine cancer cells, inhibition of COX activity or exogenously added PGE2 did not modulate the effect of resveratrol on cellular proliferation.

Conclusion

High-dose of resveratrol exerts tumoricidal activity over uterine cancer cells and regulates COX expression. In these cells, resveratrol would not directly target COX activity, but possibly other enzymes involved in prostaglandin synthesis that act downstream of the COXs.

Caspase-2 triggers Bax-Bak-dependent and -independent cell death in colon cancer cells treated with resveratrol

Polyphenol phytoalexin (resveratrol), found in grapes and red wine is a strong chemopreventive agent with promising safety records with human consumption and unique forms of cell death induction in a variety of tumor cells. However, the mechanism of resveratrol-induced apoptosis upstream of mitochondria is still not defined. The results from this study suggest that caspase-2 activation occurs upstream of mitochondria in resveratrol-treated cells. The upstream activation of caspase-2 is not dependent on its antioxidant property or NF-kappaB inhibition. The activated caspase-2 triggers mitochondrial apoptotic events by inducing conformational changes in Bax/Bak with subsequent release of cytochrome c, apoptosis-inducing factor, and endonuclease G. Caspase-8 activation seems to be independent of these events and does not appear to be mediated by classical death receptor processing or downstream caspases. Both caspase-2 and caspase-8 contribute toward the mitochondrial translocation of Bid, since neither caspase-8 inhibition nor caspase-2 inhibition could prevent translocation of Bid DsRed into mitochondria. Caspase-2 inhibitors or antisense silencing of caspase-2 prevented cell death induced by resveratrol and partially prevented processing of downstream caspases, including caspase-9, caspase-3, and caspase-8. Studies using mouse embryonic fibroblasts deficient for both Bax and Bak indicate the contribution of both Bax and Bak in mediating cell death induced by resveratrol and the existence of Bax/Bak-independent cell death possibly through caspase-8- or caspase-2-mediated mitochondria-independent downstream caspase processing.

The roles of polyphenols in cancer chemoprevention

Oxidative stress imposed by reactive oxygen species (ROS) plays a crucial role in the pathophysiology associated with neoplasia, atherosclerosis, and neurodegenerative diseases. The ROS-induced development of cancer involves malignant transformation due to altered gene expression through epigenetic mechanisms as well as DNA mutations. Considerable attention has been focused on identifying naturally occurring antioxidative phenolic phytochemicals that are able to decrease ROS levels, but the efficacies of antioxidant therapies have been equivocal at best. Several studies have shown that some antioxidants exhibit prooxidant activity under certain conditions and potential carcinogenicity under others, and that dietary supplementation with large amounts of a single antioxidant may be deleterious to human health. This article reviews the intracellular signaling pathways that respond to oxidative stress and how they are modulated by naturally occurring polyphenols. The possible toxicity and carcinogenicity of polyphenols is also discussed.

Alterations in the expression of the apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) in human melanoma and identification of the therapeutic potential of resveratrol as an APE/Ref-1 inhibitor

Apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) is a multifunctional protein involved in DNA base excision repair and redox regulation of many transcription factors. In different melanoma cell lines, we found that both nucleus and cytoplasm exhibited higher levels of Ref-1 compared with normal melanocytes. Similar increases of Ref-1 expression, detected by immunohistofluorescence, were also evident in nevi and malignant melanoma biopsies compared with normal skin, which were predominantly localized in the nucleus. Using recombinant adenovirus Adref-1, encoding full-length Ref-1, we transiently overexpressed APE/Ref-1 in human melanocytes, which protected these cells from UVB-induced apoptosis and increased foci formation in culture. Ref-1 overexpression also protected melanoma cells from cisplatin- or H2O2-induced apoptosis, whereas increased apoptosis was observed with Ref-1 antisense construct infection. These observations suggested that intracellular Ref-1 levels played an important role in sensitization of melanoma cells to apoptosis. Electrophoretic mobility shift assay results showed that in both cultured primary and metastatic melanomas DNA-binding activities of activator protein-1 and nuclear factor-kappaB were significantly diminished or shifted when anti-APE/Ref-1 antibody was added to deplete APE/Ref-1 from the binding complexes. Induced nuclear factor-kappaB transcriptional activities were also evident after Ref-1 overexpression. Furthermore, using three-dimensional molecular structure modeling and virtual screening, we found that resveratrol, a natural compound found in fruits and vegetables, docks into a druggable pocket of Ref-1 protein. In vitro studies revealed that resveratrol inhibited, in a dose-dependent manner, Ref-1-activated activator protein-1 DNA-binding activities as well as Ref-1 endonuclease activities and rendered melanoma cells more sensitive to dacarbazine treatment.

Redox-sensitive transcription factors as prime targets for chemoprevention with anti-inflammatory and antioxidative phytochemicals

Oxidative stress has been implicated in various pathological conditions including cancer. However, the human body has an intrinsic ability to fight against oxidative stress. A wide array of phase 2 detoxifying or antioxidant enzymes constitutes a fundamental cellular defense system against oxidative and electrophilic insults. Transcriptional activation of genes encoding detoxifying and antioxidant enzymes by NF-E2 related factor 2 (Nrf2), a member of the cap'n'collar family of basic leucine zipper transcription factors, may protect cells and tissues from oxidative damage. Many chemopreventive and chemoprotective phytochemicals have been found to enhance cellular antioxidant capacity through activation of this particular transcription factor, thereby blocking initiation of carcinogenesis. A new horizon in chemoprevention research is the recent discovery of molecular links between inflammation and cancer. Components of the cell signaling pathways, especially those that converge on redox-sensitive transcription factors, including nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) involved in mediating inflammatory response, have been implicated in carcinogenesis. A wide variety of chemopreventive and chemoprotective agents can alter or correct undesired cellular functions caused by abnormal proinflammatory signal transmission mediated by inappropriately activated NF-kappaB and AP-1. The modulation of cellular signaling by anti-inflammatory phytochemicals hence provides a rational and pragmatic strategy for molecular target-based chemoprevention.

Toward a unified theory of caloric restriction and longevity regulation

The diet known as calorie restriction (CR) is the most reproducible way to extend the lifespan of mammals. Many of the early hypotheses to explain this effect were based on it being a passive alteration in metabolism. Yet, recent data from yeast, worms, flies, and mammals support the idea that CR is not simply a passive effect but an active, highly conserved stress response that evolved early in life's history to increase an organism's chance of surviving adversity. This perspective updates the evidence for and against the various hypotheses of CR, and concludes that many of them can be synthesized into a single, unifying hypothesis. This has important implications for how we might develop novel medicines that can harness these newly discovered innate mechanisms of disease resistance and survival.

Is COX-2 a perpetrator or a protector? Selective COX-2 inhibitors remain controversial

COX-2(cyclooxygenase-2) has sparked a surge in pharmaceutical interest since its discovery at the beginning of the 1990s. Several COX-2 selective inhibitors that avoid gastrointestinal side effects have been successfully launched into the market in recent years. The first selective COX-2 inhibitor, celecoxib, entered the market in December 1998 [corrected] However, there are a few organs that physiologically and functionally express COX-2, particularly the glomeruli of the kidney and the cortex of the brain. Inhibition of COX-2 expression in these organs possibly causes heart attack and stroke in long-term COX-2 inhibitor users. Recently, a USA Food and Drug Agency (FDA) advisory panel re-evaluated COX-2 inhibitors and unanimously concluded that the entire class of COX-2 inhibitors increase the risk of cardiovascular problems. Thus the use of COX-2 inhibitors is still controversial, and there is a challenge for not only pharmacologists, but also the pharmaceutical industry, to develop improved painkilling and anti-inflammatory drugs. This may involve exploring a new generation of COX-2 inhibitors with different inhibitory mechanisms through computer-aided design, screening different sources of inhibitors with lower selectivity, or seeking completely new targets. Synthetic COX-2 inhibitors have high selectivity and the advantage of irreversible inhibition, whereas naturally derived COX-2 inhibitors have lower selectivity and fewer side effects, with the medical effects in general not being as striking as those achieved using synthetic inhibitors. This review discusses the mechanism of COX-2 inhibitor therapy and a possible new way of exploration in the development of anti-inflammatory, analgetic, and antipyretic drugs.

Resveratrol: Preventing properties against vascular alterations and ageing

Cardiovascular diseases are the leading cause of death in developed countries where the common pathological substrate underlying this process is atherosclerosis. Several new concepts have emerged in relation to mechanisms that contribute to the regulation of the vascular diseases and associated inflammatory effects. Recently, potential antioxidants (vitamin E, polyphenols) have received much attention as potential anti-atherosclerotic agents. Among the polyphenols with health benefic properties, resveratrol, a phytoalexin of grape, seem to be a good candidate protecting the vascular walls from oxidation, inflammation, platelet aggregation, and thrombus formation. In this review, we focus on the mechanism of resveratrol cardiovascular benefic effects. We analyze, in relation with the different steps of atherosclerotic process, the resveratrol properties at multiple levels, such as cellular signaling, enzymatic pathways, apoptosis, and gene expression. We show and discuss the relationship with reactive oxygen species, regulation of pro-inflammatory genes including cycloxygenases and cytokines in molecular inflammatory and aging processes, and how the regulation of these activites by resveratrol can lead to a prevention of vascular diseases.

Synthesis and inhibitory effects of pinosylvin derivatives on prostaglandin E2 production in lipopolysaccharide-induced mouse macrophage cells

A series of natural stilbenoids, pinosylvin and its derivatives, were synthesized and evaluated for the inhibitory activity of prostaglandin E(2) production in lipopolysaccharide-induced RAW 264.7 cells. Potential inhibitors, including 3,5-dimethoxy-trans-stilbene and 3-hydroxy-5-benzyloxy-trans-stilbene, have been newly identified, and thus providing chemical leads for the further development of anti-inflammatory or cancer chemopreventive agents.

Molecular basis of chemoprevention by resveratrol: NF-kappaB and AP-1 as potential targets

Recently, chemoprevention by the use of naturally occurring substances is considered as a priority to reduce the ever-increasing incidence of cancer. The intervention of multistage carcinogenesis by modulating intracellular signaling pathways may provide molecular basis of chemoprevention with a wide variety of dietary phytochemicals. Resveratrol, a red wine polyphenol, has been studied extensively for the chemopreventive activity in the context of its ability to interfere with the multistage carcinogenesis. Numerous intracellular signaling cascades converge with the activation of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), which act independently or coordinately to regulate expression of target genes. These ubiquitous eukaryotic transcription factors mediate pleiotropic effects on cellular transformation and tumor promotion. This review aims to update the molecular mechanisms underlying chemoprevention by resveratrol with special focus on its effect on cellular signaling cascades mediated by NF-kappaB and AP-1.

Transcription factors in the cellular signaling network as prime targets of chemopreventive phytochemicals

Accumulating evidence from epidemiologic and laboratory studies support an inverse relationship between a regular consumption of fruits and vegetables and the risk of specific cancers. Numerous phytochemicals derived from edible plants have been reported to possess ability to interfere with a specific stage of carcinogenic process. Multiple mechanisms have been proposed to account for the anti-carcinogenic actions of dietary constituents, but more attention has recently focussed on intracellular signaling cascades as common molecular targets of a wide variety of chemopreventive phytochemicals.

Influence of lipophilicity on the interactions of hydroxy stilbenes with cytochrome P450 3A4

Resveratrol, a polyphenol found in red wine, was recently suggested to act as an irreversible, mechanism-based inactivator of cytochrome P450 3A4 (CYP3A4). We found a significant inhibition of human CYP3A4-dependent transformation of cyclosporine by resveratrol, with IC50 = 4.5 microM. We studied the kinetics parameters of CYP3A4 transformation of resveratrol and structurally related, naturally occurring stilbenes. Resveratrol, piceid, resveratroloside, 5,4'-dihydroxy-3-O-methoxystilbene, and 5,3-dihydroxy-4'-O-methoxystilbene were all shown to inhibit hydroxylation of testosterone by CYP3A4. Both methoxy-stilbenes had lower IC50 values, ranging from 0.43 to 0.47 microM, suggesting that lipophilicity rather than number or positions of free hydroxyls (3,5 or 5,4') determines the CYP3A4 inhibition capacity of polyphenols. In line with these findings, both glucosyl-stilbenes were found to be weak inhibitors of CYP3A4. The affinity of the enzyme towards methoxy-stilbenes, expressed as apparent Km, was indeed higher than those for the parent resveratrol and its glucosides, in CYP3A4 reaction mixtures. Vmax values were similar, except for piceid. These results support the role of lipophilicity in the interaction of polyphenols with CYP3A4. It is suggested that selective structural modifications of substrates add significantly to knowledge acquired through molecular modifications of the enzyme.

Inhibition of osteogenesis in vitro by a cigarette smoke-associated hydrocarbon combined with Porphyromonas gingivalis lipopolysaccharide: reversal by resveratrol

BACKGROUND

Smoking and infection with Gram-negative bacterial pathogens are risk factors for alveolar bone loss. The aims of this study were: 1) to examine the combined effects of an aryl hydrocarbon, benzo[a]pyrene (BaP), that is concentrated in cigarette smoke, and lipopolysaccharide (LPS) extracted from Porphyromonas gingivalis on osteogenesis in a rat bone marrow cell (RBMC) model of osteogenesis; and 2) to determine whether resveratrol (Res), an aryl hydrocarbon receptor antagonist, could reverse the putative inhibitory effects of BaP + LPS on osteogenesis.

METHODS

LPS of P. gingivalis strain 2561 was introduced in various concentrations to the RBMC in 96-well plates and kept in culture for 8 to 12 days. The same protocol was used for studying BaP and LPS + BaP combinations. Following the incubation periods, parameters of osteogenesis were measured, including formation of mineralized bone nodules, alkaline phosphatase activity, and total cell protein. Transcription of the pro-inflammatory cytokine interleukin (IL)-1beta in the cultures was determined by reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Bone nodule formation generally decreased significantly with increasing LPS concentrations (P<0.05), whereas total cell protein decreased only slightly (P>0.05). BaP in previously high concentrations alone also caused a significant dose-dependent decrease in bone nodule formation (P<0.05) but when half maximal doses were used, significant decreases were most often seen when LPS was added. Hence, in combination, the inhibitory effects of LPS + BaP on osteogenesis were additive, inhibiting bone nodule formation up to 9-fold. Resveratrol partially reversed the inhibitory effects of low concentrations of LPS alone, and completely reversed the inhibition of nodule formation when low concentrations of LPS were combined with BaP. IL-1beta expression generally fluctuated inversely to the inhibitory activity of LPS, LPS + BaP, and LPS + BaP + Res combinations.

CONCLUSIONS

Smoke-derived aryl hydrocarbons and bacterial LPS may act additively to inhibit bone formation. The findings may explain, in part, why net periodontal bone loss is greater and bone healing is less successful in smokers than non-smokers with periodontal infections. Reversal of the inhibitory effects in vitro by resveratrol suggests that this phytoalexin should be studied further for its potential therapeutic value, given its aryl hydrocarbon receptor antagonism and apparent anti-inflammatory activity.

Resveratrol inhibits phorbol ester-induced cyclooxygenase-2 expression in mouse skin: MAPKs and AP-1 as potential molecular targets

Multiple lines of evidence from laboratory studies suggest that resveratrol, a polyphenolic antioxidant present in grapes, has potent chemopreventive activity. Resveratrol has been reported to inhibit chemically-induced carcinogenesis in mouse skin, but the underlying mechanisms remain unclarified. Since an abnormally elevated level of cyclooxygenase-2 (COX-2) has been implicated in carcinogenesis, we investigated the effect of resveratrol on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced COX-2 expression in mouse skin. Pretreatment of dorsal skin of female ICR mice with resveratrol inhibited TPA-induced COX-2 expression in a dose dependent manner. To elucidate the molecular mechanism underlying COX-2 inhibition by resveratrol, we examined its effect on TPA-induced activation of mitogen-activated protein kinases (MAPK) and transcription factors which regulate COX-2 expression. Resveratrol pretreatment resulted in a decrease in the phosphorylation of extracellular signal-regulated protein kinase (ERK) as well as the catalytic activity of ERK and p38 MAPK. In addition, resveratrol prevented TPA-induced DNA binding of activator protein-1 (AP-1). Taken together, suppression of COX-2 expression by blocking the activation of MAPKs and AP-1 may represent possible molecular mechanisms responsible for previously reported anti-tumor promoting effects of resveratrol on mouse skin carcinogenesis.

Review article: chemoprevention of colorectal cancer

Colorectal cancer is a disease with a high mortality at present, due to the late stage at which many cases present. Attention is therefore focusing on preventative strategies for colorectal cancer given that polyps appear to be identifiable and treatable precursor lesions of this disease. Endoscopic polypectomy has been shown to reduce the incidence of colorectal cancer and there is a good case for endoscopic screening of the general population. However, this will require a large amount of manpower and resources and its success will also depend on the overall compliance of the population. Epidemiological studies have shown that individuals reporting a regular intake of aspirin and other non-steroidal anti-inflammatory drugs have a reduced risk of developing colorectal polyps and cancer. Similarly, a number of natural substances, such as calcium and folate, when supplemented regularly in the diet, have also been linked to a possible decreased incidence of colorectal cancer. This has led to the concept of using such agents to reduce the number of cases of colorectal cancer. In this article, we review the current evidence for the use of these and other agents for the chemoprevention of colorectal cancer, together with theories as to their possible mechanisms of action.

Cancer chemoprevention with dietary phytochemicals

Chemoprevention refers to the use of agents to inhibit, reverse or retard tumorigenesis. Numerous phytochemicals derived from edible plants have been reported to interfere with a specific stage of the carcinogenic process. Many mechanisms have been shown to account for the anticarcinogenic actions of dietary constituents, but attention has recently been focused on intracellular-signalling cascades as common molecular targets for various chemopreventive phytochemicals.

Resveratrol is a potent inducer of apoptosis in human melanoma cells

Resveratrol is a plant polyphenol found in grapes and red wine. It has been found to have beneficial effects on the cardiovascular system. Resveratrol also inhibits the growth of various tumor cell lines in vitro and inhibits carcinogenesis in vivo. In this study we examined the effect of resveratrol on growth of two human melanoma cell lines. We found that this plant polyphenol inhibited growth and induced apoptosis in both cell lines, with the amelanotic cell line A375 being more sensitive. The potential involvement of different MAP kinases in the action of resveratrol was also examined. Although resveratrol did not alter the phosphorylation of p38 or JNK MAP kinases in either cell line, it induced phosphorylation of ERK1/2 in A375, but not in SK-mel28 cells. These results suggest that in vivo studies of the effect of resveratrol on melanoma are warranted and that this plant polyphenol might have effectiveness as either a therapeutic or chemopreventive agent against melanoma.

Resveratrol inhibits proliferation and induces apoptosis in human pancreatic cancer cells

INTRODUCTION

Because of lack of early diagnosis and poor therapeutic responsiveness, median survival in patients with pancreatic cancer is <6 months, and survival beyond 5 years is rare. Thus, another dimension in chemotherapeutic agents for pancreatic cancer would be beneficial to control metastatic and unresectable disease. Resveratrol, a natural product from grapes, has been shown to be chemopreventive for carcinogen-induced skin cancer and also to inhibit proliferation of oral squamous, breast, colonic, and prostate cancer cells.

AIM

To investigate the effect of resveratrol in pancreatic cancer.

METHODOLOGY

To evaluate the potential role of resveratrol on pancreatic cancer cell proliferation, two human pancreatic cancer cell lines, PANC-1 and AsPC-1, were used.

RESULTS

Resveratrol inhibited proliferation of both PANC-1 and AsPC-1 in a concentration- and time-dependent manner as measured by [ H]thymidine incorporation. Cell number of both PANC-1 and AsPC-1 was also significantly decreased following 48 and 72 hours of treatment with 100 micromol/L resveratrol. The growth inhibition induced by resveratrol was accompanied by apoptotic morphologic changes, characterized by cell rounding and cell membrane blebbing suggesting apoptosis. Propidium iodide staining of DNA, measured by flow cytometry, showed a dramatic increase in the fraction of sub-G0/G1 cells following resveratrol treatment in both PANC-1 and AsPC-1. The substantial apoptosis inducted by resveratrol on these two cell lines was confirmed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay.

CONCLUSION

These findings suggest that the natural product resveratrol may have a potent antiproliferative effect on human pancreatic cancer with induction of apoptosis. Resveratrol is likely to be valuable for the management and prevention of human pancreatic cancer.

Antiangiogenic mechanisms of diet-derived polyphenols

Accumulating evidence demonstrates that polyphenols in natural products are beneficial against human lethal diseases such as cancer and metastasis. The underlying mechanisms of anti-cancer effects are complex. Recent studies show that several polyphenols, including epigallocatechin-3-gallate (EGCG) in green tea and resveratrol in red wine, inhibit angiogenesis when administrated orally. These polyphenols have direct effects on suppression of angiogenesis in several standard animal angiogenesis models. Because angiogenesis is involved in many diseases such as cancer, diabetic retinopathy and chronic inflammations, the discovery of these polyphenols as angiogenesis inhibitors has shed light on the health beneficial mechanisms of natural products, which are rich in these molecules. At the molecular level, recent studies have provided important information on how these molecules inhibit endothelial cell growth. Perhaps the greatest therapeutic advantage of these small natural molecules over large protein compounds is that they can be administrated orally without causing severe side effects. It is anticipated that more polyphenols in natural products will be discovered as angiogenesis inhibitors and that these natural polyphenols could serve as leading structures in the discovery of more potent, synthetic angiogenesis inhibitors.

Inhibition of gastric cancer cell proliferation by resveratrol: role of nitric oxide

Resveratrol is a dietary phytochemical that has been shown to inhibit proliferation of a number of cell lines, and it behaves as a chemopreventive agent in assays that measure the three stages of carcinogenesis. We tested for its chemopreventive potential against gastric cancer by determining its interaction with signaling mechanisms that contribute to the proliferation of transformed cells. Low levels of exogenous reactive oxygen (H(2)O(2)) stimulated [(3)H]thymidine uptake in human gastric adenocarcinoma SNU-1 cells, whereas resveratrol suppressed both synthesis of DNA and generation of endogenous O(2)(-) but stimulated nitric oxide (NO) synthase (NOS) activity. To address the role of NO in the antioxidant action of resveratrol, we measured the effect of sodium nitroprusside (SNP), an NO donor, on O(2)(-) generation and on [(3)H]thymidine incorporation. SNP inhibited DNA synthesis and suppressed ionomycin-stimulated O(2)(-) generation in a concentration-dependent manner. Our results revealed that the antioxidant action of resveratrol toward gastric adenocarcinoma SNU-1 cells may reside in its ability to stimulate NOS to produce low levels of NO, which, in turn, exert antioxidant action. Resveratrol-induced inhibition of SNU-1 proliferation may be partly dependent on NO formation, and we hypothesize that resveratrol exerts its antiproliferative action by interfering with the action of endogenously produced reactive oxygen. These data are supportive of the action of NO against reactive oxygen and suggest that a resveratrol-rich diet may be chemopreventive against gastric cancer.

Inhibition of carcinogenesis by dietary polyphenolic compounds

Plants consumed by humans contain thousands of phenolic compounds. The effects of dietary polyphenols are of great current interest due to their antioxidative and possible anticarcinogenic activities. A popular belief is that dietary polyphenols are anticarcinogens because they are antioxidants, but direct evidence for this supposition is lacking. This chapter reviews the inhibition of tumorigenesis by phenolic acids and derivatives, tea and catechins, isoflavones and soy preparations, quercetin and other flavonoids, resveratrol, and lignans as well as the mechanisms involved based on studies in vivo and in vitro. Polyphenols may inhibit carcinogenesis by affecting the molecular events in the initiation, promotion, and progression stages. Isoflavones and lignans may influence tumor formation by affecting estrogen-related activities. The bioavailability of the dietary polyphenols is discussed extensively, because the tissue levels of the effective compounds determine the biological activity. Understanding the bioavailability and blood and tissue levels of polyphenols is also important in extrapolating results from studies in cell lines to animal models and humans. Epidemiological studies concerning polyphenol consumption and human cancer risk suggest the protective effects of certain food items and polyphenols, but more studies are needed for clear-cut conclusions. Perspectives on the application of dietary polyphenols for the prevention of human cancer and possible concerns on the consumption of excessive amounts of polyphenols are discussed.