The chemopreventive and chemotherapeutic potentials of tea polyphenols

Advances in the Anti-Atherosclerotic Mechanisms of Epigallocatechin Gallate

Atherosclerosis (AS) is a common clinical sickness and the major pathological basis of ischemic cardiocerebrovascular diseases (CCVDs). The pathogenesis of AS involves a variety of risk factors, and there is a lack of effective preventive and curative drugs that can completely treat AS. In recent years, with the improvement of people's living standards and changes in dietary habits, the morbidity and mortality rates of AS are on the rise, and the age of onset tends to be younger. The formation of AS is closely related to a variety of factors, and the main factors include lipid metabolism disorders, endothelial damage, inflammation, unstable plaques, etc. Epigallocatechin gallate (EGCG), as one of the main components of catechins, has a variety of pharmacological effects, and its role in the prevention of AS and the protection of cardiovascular and cerebral blood vessels has been highly valued. Recent epidemiological investigations and various in vivo and ex vivo experiments have shown that EGCG is capable of resisting atherosclerosis and reducing the morbidity and mortality of AS. In this paper, we reviewed the anti-AS effects of EGCG and its mechanisms in recent years, including the regulation of lipid metabolism, regulation of intestinal flora disorders, improvement of vascular endothelial cell functions, inhibition of inflammatory factors expression, regulation of inflammatory signaling pathways, inhibition of matrix metalloproteinase (MMP) expression, and inhibition of platelet aggregation, which are helpful for the prevention of cardiocerebrovascular diseases.

Paternal Combined Botanicals Contribute to the Prevention of Estrogen Receptor-Negative Mammary Cancer in Transgenic Mice

BACKGROUND

Parental nutritional interventions have considerably affected gametogenesis and embryogenesis, leading to the differential susceptibility of offspring to chronic diseases such as cancer. Moreover, combinatorial bioactive diets are more efficacious in ameliorating epigenetic aberrations in tumorigenesis.

OBJECTIVES

We sought to investigate the transgenerational influence and epigenetic regulation of paternal sulforaphane (SFN)-rich broccoli sprouts (BSp) and epigallocatechin-3-gallate (EGCG)-rich green tea polyphenols (GTPs) consumption in the prevention of estrogen receptor-negative [ER(-)] mammary cancer in transgenic mice.

METHODS

Human breast cancer cells were used to detect cell viability and epigenetic-related gene expression after treatment with EGCG and/or SFN. Twenty-four C3 or HER2/neu males were randomly assigned into 4 groups and treated with control, 26% BSp (w/w) in food, 0.5% GTPs (w/v) in drinking water or combined BSp and GTPs for 7 wk before mating. Tumor growth of nontreated female pups was monitored weekly for 19 wk (C3) and 25 wk (HER2/neu). Tumor- and epigenetic-related protein expression and enzyme activities in mammary tumors were measured. Sperms were isolated from treated males for RNA sequencing and reduced-representation bisulfite sequencing analysis. Data were analyzed with a 2-factor or 3-factor analysis of variance.

RESULTS

EGCG and SFN inhibited breast cancer cell growth via epigenetic regulation. Combined BSp and GTPs synergistically (combination index < 1) suppressed tumor growth over time (P < 0.001) in 2 mouse models. Key tumor-related proteins were found differentially expressed (P < 0.05) along with epigenetic regulations in offspring mammary tumors. The transcriptome profile of sperm derived from dietary-treated males revealed differentially expressed genes correlated with spermatogenesis and breast cancer progression. DNA methylomes of the sperm and further integrated analysis with transcriptomes indicate that DNA methylation alone may not contribute to sufficient regulation in dietary-treated sperm pronucleus, leading to offspring tumor suppression.

CONCLUSIONS

Collectively, paternal consumption of combined BSp and GTPs shows potential for preventing ER(-) mammary cancer through transgenerational effects. J Nutr 2023;xx:xx-xx.

Virgin Olive Oil By-Products: Biological Activity of Phenolic Extract of Pâté on AGS Gastric Cells

Pâté is a by-product of olive oil production which represents an abundant source of phenolic compounds and can be used for food formulation, reducing its environmental impact and promoting a circular economy. In this context, the effects of a hydroalcoholic extract of pâté were evaluated for the first time in an AGS human cell line commonly used as model of gastric mucosa. Pâté was obtained from Tuscan olives; the total phenolic content was 16.6 mg/g dried extract, with verbascoside and secoiridoid derivatives as the most abundant phenols. The phenolic pâté extract did not alter viability, distribution of cell cycle phases or proliferation and migration of AGS cells at the tested concentrations. Seven enzymes were chosen to investigate the metabolic effect of the pâté extract in the context of oxidative stress. Pâté produced a statistically significant increase in the activity of key enzymes of some metabolic pathways: Lactate dehydrogenase, Enolase, Pyruvate kinase, Glucose 6-phosphate dehydrogenase, Citrate synthase, 3-Hydroxyacyl-CoA dehydrogenase and Hexokinase. Pre-treatments with the extract of pâté at 100 µg/mL or 200 µg/mL, as observed through PCA analysis, appeared able to counteract the enzymatic activity alterations due to oxidative stress induced by H₂O₂ 1 mM and 2 mM. The results indicate that dried pâté, due to its phenolic components, can be proposed as a new functional food ingredient.

Association between tea drinking and plasma folate concentration among women aged 18-30 years in China

OBJECTIVE

Association was found between tea and neural tube defects. However, few studies investigated the relationship between tea consumption and blood folate levels. We aimed to investigate the association between tea consumption and plasma folate concentrations among women aged 18-30 years in different ethnicities of China.

DESIGN

Data were obtained from a national cross-sectional study conducted from 2005 to 2006 of women aged 18-30 years in China. Socio-demographic characteristics and lifestyle were obtained from a questionnaire. Dietary folate intake was determined by 24-h dietary recall. Plasma folate concentrations were measured by a microbiological assay. Multiple linear regression model was used to calculate partial regression coefficients after adjusting for confounding factors.

SETTING

Nine provinces or autonomous regions in China.

PARTICIPANTS

A total of 2932 women aged 18-30 years in China.

RESULTS

After stratifying by ethnicity and tea type, tea consumption was significantly positively associated with plasma folate levels in Han women who drank unfermented tea weekly (β = 0·067, and P = 0·037) or daily (β = 0·119, and P = 0·031) and in Uighur women who drank fermented tea weekly (β = 0·325, and P = 0·028). For women who drank unfermented tea in Han ethnicity, weekly and daily tea drinkers had 6·77 % (95 % CI: 6·36 %, 7·21 %) and 7·13 % (95 % CI: 6·40 %, 7·96 %) increase in plasma folate concentration compared with no tea drinkers.

CONCLUSIONS

There is a suggestion of possible positive association between unfermented tea drinking in Han ethnicity and plasma folate concentrations, for Chinese women aged 18-30 years. The relationship between tea drinking in other ethnic groups and plasma folate still needs to be further explored.

Adiponectin Role in Neurodegenerative Diseases: Focus on Nutrition Review

Adiponectin is an adipokine produced by adipose tissue. It has numerous beneficial effects. In particular, it improves metabolic effects and glucose homeostasis, lipid profile, and is involved in the regulation of cytokine profile and immune cell production, having anti-inflammatory and immune-regulatory effects. Adiponectin’s role is already known in immune diseases and also in neurodegenerative diseases. Neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, are a set of diseases of the central nervous system, characterized by a chronic and selective process of neuron cell death, which occurs mainly in relation to oxidative stress and neuroinflammation. Lifestyle is able to influence the development of these diseases. In particular, unhealthy nutrition on gut microbiota, influences its composition and predisposition to develop many diseases such as neurodegenerative diseases, given the importance of the “gut-brain” axis. There is a strong interplay between Adiponectin, gut microbiota, and brain-gut axis. For these reasons, a healthy diet composed of healthy nutrients such as probiotics, prebiotics, polyphenols, can prevent many metabolic and inflammatory diseases such as neurodegenerative diseases and obesity. The special Adiponectin role should be taken into account also, in order to be able to use this component as a therapeutic molecule.

Drug-Related Carcinogenesis: Risk Factors and Approaches for Its Prevention

The review summarizes the data on the role of metabolic and repair systems in the mechanisms of therapy-related carcinogenesis and the effect of their polymorphism on the cancer development risk. The carcinogenic activity of different types of drugs, from the anticancer agents to analgesics, antipyretics, immunomodulators, hormones, natural remedies, and non-cancer drugs, is described. Possible approaches for the prevention of drug-related cancer induction at the initiation and promotion stages are discussed.

Bioactive Phenolic Compounds in the Modulation of Central and Peripheral Nervous System Cancers: Facts and Misdeeds

Efficacious therapies are not available for the cure of both gliomas and glioneuronal tumors, which represent the most numerous and heterogeneous primary cancers of the central nervous system (CNS), and for neoplasms of the peripheral nervous system (PNS), which can be divided into benign tumors, mainly represented by schwannomas and neurofibromas, and malignant tumors of the peripheral nerve sheath (MPNST). Increased cellular oxidative stress and other metabolic aspects have been reported as potential etiologies in the nervous system tumors. Thus polyphenols have been tested as effective natural compounds likely useful for the prevention and therapy of this group of neoplasms, because of their antioxidant and anti-inflammatory activity. However, polyphenols show poor intestinal absorption due to individual intestinal microbiota content, poor bioavailability, and difficulty in passing the blood-brain barrier (BBB). Recently, polymeric nanoparticle-based polyphenol delivery improved their gastrointestinal absorption, their bioavailability, and entry into defined target organs. Herein, we summarize recent findings about the primary polyphenols employed for nervous system tumor prevention and treatment. We describe the limitations of their application in clinical practice and the new strategies aimed at enhancing their bioavailability and targeted delivery.

Nutritional modulation of the intestinal microbiota; future opportunities for the prevention and treatment of neuroimmune and neuroinflammatory disease

The gut-brain axis refers to the bidirectional communication between the enteric nervous system and the central nervous system. Mounting evidence supports the premise that the intestinal microbiota plays a pivotal role in its function and has led to the more common and perhaps more accurate term gut-microbiota-brain axis. Numerous studies have identified associations between an altered microbiome and neuroimmune and neuroinflammatory diseases. In most cases, it is unknown if these associations are cause or effect; notwithstanding, maintaining or restoring homeostasis of the microbiota may represent future opportunities when treating or preventing these diseases. In recent years, several studies have identified the diet as a primary contributing factor in shaping the composition of the gut microbiota and, in turn, the mucosal and systemic immune systems. In this review, we will discuss the potential opportunities and challenges with respect to modifying and shaping the microbiota through diet and nutrition in order to treat or prevent neuroimmune and neuroinflammatory disease.

Black tea increases hypertonic stress resistance in C. elegans

Here we identified that BTE (black tea extract), within the studied concentration range, is more effective than GTE (green tea extract) in protecting C. elegans against hypertonic stress, by enhancing survival after exposure to various salts, and alleviating suffered motility loss and body shrinkage. The mechanism of such protection may be due to the ability of black tea to induce the conserved WNK/GCK signaling pathway and down-regulation of the expression levels of nlp-29. Intriguingly, black tea does not relieve hypertonicity-induced protein damage. The findings implicate the potential health benefits of black tea consumed worldwide.

Theaflavins attenuate ethanol‑induced oxidative stress and cell apoptosis in gastric mucosa epithelial cells via downregulation of the mitogen‑activated protein kinase pathway

Ethanol‑induced diseases of the gastric mucosa are the most common and refractory diseases of gastrointestinal system in clinic, and are mediated by oxidative stress and apoptosis pathways. Theaflavins (TFs) are considered to be antioxidants. The present study aimed to determine the molecular mechanism underlying the ability of TFs to attenuate ethanol‑induced oxidative stress and apoptosis in GES‑1 gastric mucosa epithelial cells. A Cell Counting Kit‑8 (CCK‑8) assay was performed to investigate the cell viability of GES‑1 cells following administration of ethanol (0.5 mol/l) and subsequent treatment with TFs (20, 40 and 80 µg/ml) for specific time intervals. A carboxyfluorescein diacetate succinimidyl ester assay was used to measure proliferation and further investigate the results of the CCK‑8 assay. Flow cytometry was performed to measure reactive oxygen species (ROS) levels and the apoptosis rates of GES‑1 cells. Furthermore, levels of oxidative stress‑associated factors, including malondialdehyde, superoxide dismutase and glutathione, were investigated using commercial kits. Reverse transcription‑quantitative polymerase chain reaction and western blot assays were performed to determine the expression levels of apoptosis‑associated factors, as well as the phosphorylation levels of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38 kinase (p38). The results of the present study demonstrated that treatment with ethanol inhibited GES‑1 cell proliferation, and enhanced ROS levels and apoptosis rates, potentially via downregulation of B‑cell lymphoma‑2 (Bcl‑2) expression and upregulation of Bcl‑2‑associated X and caspase‑3 expression levels, as well as enhancing the phosphorylation levels of ERK, JNK and p38. However, treatment with TFs was revealed to attenuate the effects of ethanol administration on GES‑1 cells in a dose‑dependent manner. In conclusion, TFs may attenuate ethanol‑induced oxidative stress and apoptosis in gastric mucosa epithelial cells via downregulation of various mitogen‑activated protein kinase pathways.

Perspectives on the recent developments with green tea polyphenols in drug discovery

INTRODUCTION

Increasing evidence has expanded the role of green tea from a traditional beverage to a source of pharmacologically active molecules with diverse health benefits. However, conclusive clinical results are needed to better elucidate the cancer-preventive and therapeutic effects of green tea polyphenols (GTPs). Areas covered: The authors describe GTPs' chemical compositions and metabolic biotransformations, and their recent developments in drug discovery, focusing on their cancer chemopreventive and therapeutic effects. They then review the recent development of GTP-loaded nanoparticles and GTP prodrugs. Expert opinion: GTPs possess potent anticarcinogenic activities through interfering with the initiation, development and progression phases of cancer. There are several challenges (e.g. poor bioavailability) in developing GTPs as therapeutic agents. Use of nanoparticle-based delivery systems has provided unique advantages over purified GTPs. However, there is still a need to determine the actual magnitude and pharmacological mechanisms of GTPs encapsulated in nanoparticles, in order to address newly emerging safety issues associated with the potential 'local overdose' effect. The use of Pro- epigallocatechin gallate (Pro-EGCG) as a prodrug appears to offer improved in vitro stability as well as better in vivo bioavailability and efficacies in a number of animal studies, suggesting its potential as a therapeutic agent for further study and development.

An Improved Weighted Partial Least Squares Method Coupled with Near Infrared Spectroscopy for Rapid Determination of Multiple Components and Anti-Oxidant Activity of Pu-Erh Tea

Background: Pu-erh tea is a unique microbially fermented tea, which distinctive chemical constituents and activities are worthy of systematic study. Near infrared spectroscopy (NIR) coupled with suitable chemometrics approaches can rapidly and accurately quantitatively analyze multiple compounds in samples. Methods: In this study, an improved weighted partial least squares (PLS) algorithm combined with near infrared spectroscopy (NIR) was used to construct a fast calibration model for determining four main components, i.e., tea polyphenols, tea polysaccharide, total flavonoids, theanine content, and further determine the total antioxidant capacity of pu-erh tea. Results: The final correlation coefficients R square for tea polyphenols, tea polysaccharide, total flavonoids content, theanine content, and total antioxidant capacity were 0.8288, 0.8403, 0.8415, 0.8537 and 0.8682, respectively. Conclusions: The current study provided a comprehensive study of four main ingredients and activity of pu-erh tea, and demonstrated that NIR spectroscopy technology coupled with multivariate calibration analysis could be successfully applied to pu-erh tea quality assessment.

Combinatorial bioactive botanicals re-sensitize tamoxifen treatment in ER-negative breast cancer via epigenetic reactivation of ERα expression

Conventional cancer prevention has primarily focused on single chemopreventive compounds that may not be sufficiently efficacious. We sought to investigate potential combinatorial effects of epigenetic bioactive botanicals including epigallocatechin-3-gallate (EGCG) in green tea polyphenols (GTPs) and sulforaphane (SFN) in broccoli sprouts (BSp) on neutralizing epigenetic aberrations in estrogen receptor-α (ERα) leading to enhanced anti-hormone therapeutic efficacy in ERα-negative breast cancer. Our results showed that this combinatorial treatment re-sensitized ERα-dependent cellular inhibitory responses to an estrogen antagonist, tamoxifen (TAM), via at least in part, epigenetic reactivation of ERα expression in ERα-negative breast cancer cells. Further in vivo studies revealed the combinatorial diets of GTPs and BSp significantly inhibited breast tumor growth in ERα-negative mouse xenografts, especially when combined with TAM treatment. This novel treatment regimen can lead to remodeling of the chromatin structure by histone modifications and recruitment changes of transcriptional factor complex in the ERα promoter thereby contributing to ERα reactivation and re-sensitized chemotherapeutic efficacy of anti-hormone therapy. Our studies indicate that combinatorial bioactive botanicals from GTPs and BSp are highly effective in inhibiting ERα-negative breast cancer due at least in part to epigenetic reactivation of ERα, which in turn increases TAM-dependent anti-estrogen chemosensitivity in vitro and in vivo.

Designing a broad-spectrum integrative approach for cancer prevention and treatment

Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are not reliant upon the same mechanisms as those which have been targeted). To address these limitations, an international task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspects of relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a wide range of high-priority targets (74 in total) that could be modified to improve patient outcomes. For these targets, corresponding low-toxicity therapeutic approaches were then suggested, many of which were phytochemicals. Proposed actions on each target and all of the approaches were further reviewed for known effects on other hallmark areas and the tumor microenvironment. Potential contrary or procarcinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixed evidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of the relationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. This novel approach has potential to be relatively inexpensive, it should help us address stages and types of cancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for future research is offered.

Combinatorial epigenetic mechanisms and efficacy of early breast cancer inhibition by nutritive botanicals

Aim:

Aberrant epigenetic events are important contributors to the pathogenesis of different types of cancers and dietary botanicals with epigenetic properties can influence early cancer development leading to cancer prevention effects. We sought to investigate potential combinatorial effects of bioactive dietary components including green tea polyphenols (GTPs) and broccoli sprouts (BSp) on neutralizing epigenetic aberrations during breast tumorigenesis.

Materials & methods:

The combinatorial effects were evaluated in a breast cancer transformation cellular system and breast cancer mouse xenografts.

Results & conclusion:

Combined treatment with epigallocatechin-3-gallate in GTPs and sulforaphane in BSp resulted in a synergistic inhibition of breast cancer cellular growth. Further studies revealed this combination led to genome-wide epigenetic alterations. Combinatorial diets significantly inhibited tumor growth in breast cancer mouse xenografts. Collectively, these studies indicate that combined GTPs and BSp are highly effective in inhibiting early breast cancer development by, at least in part, regulating epigenetic mechanisms.

Effect of polyphenols on glucose and lactate transport by breast cancer cells

One of the cancer molecular hallmarks is a deviant energetic metabolism, known as the Warburg effect, whereby the rate of glucose uptake is significantly increased and a high rate of glycolysis and lactic acid production occurs even when oxygen is present-"aerobic lactatogenesis". Accordingly, GLUT1 and MCT1, which are the main glucose and lactate transporters in cancer cells, respectively, have been proposed as oncogenes and are currently seen as potential therapeutic targets in cancer treatment. Polyphenols, commonly contained in fruits and vegetables, have long been associated with a protective role against cancer. Generally considered as nontoxic, dietary polyphenols are considered ideal chemopreventive and possibly chemotherapeutic agents. Several mechanisms of action of polyphenols in breast cancer cells have been proposed including modulation of intracellular signaling, induction of apoptosis through redox regulation or modulation of epigenetic alterations. Additionally, in vitro studies have shown that several polyphenols act as specific inhibitors of glucose transport in breast cancer cell lines and an association between their anticarcinogenic effect and inhibition of glucose cellular uptake has been described. Also, some polyphenols were found to inhibit lactate transport. Importantly, some polyphenols behave as inhibitors of both glucose and lactate cellular uptake by breast cancer cells and these compounds are thus very interesting in the context of a chemopreventive effect, because they deplete breast cancer cells of their two most important energy suppliers. So, the antimetabolic effect of polyphenols should be regarded as a mechanism of action contributing to their chemopreventive/chemotherapeutic potential in relation to breast cancer.

Tea polyphenols EGCG and TF restrict tongue and liver carcinogenesis simultaneously induced by N-nitrosodiethylamine in mice

The aim of this study is to understand the molecular mechanisms of N-nitrosodiethylamine (NDEA) induced multi-organ carcinogenesis in tongue and liver of the same mouse and restriction of carcinogenesis by Epigallocatechin gallate (EGCG) and Theaflavin (TF), if any. For that purpose, cellular proliferation/apoptosis, prevalence of CD44 positive stem cell population and expressions of some key regulatory genes of self renewal Wnt and Hedgehog (Hh) pathways and some of their associated genes were analyzed in the NDEA induced tongue and liver lesions in absence or presence of EGCG/TF. Chronic NDEA exposure in oral cavity could decrease mice body weights and induce tongue and liver carcinogenesis with similar histological stages (severe dysplasia up to 30thweeks of NDEA administration). Increasing mice body weights were seen in continuous and post EGCG/TF treated groups. EGCG/TF treatment could restrict both the carcinogenesis at similar histological stages showing potential chemopreventive effect in continuous treated groups (mild dysplasia) followed by pre treatment (moderate dysplasia) and therapeutic efficacy in post treated groups (mild dysplasia) up to 30thweek. The mechanism of carcinogenesis by NDEA and restriction by the EGCG/TF in both tongue and liver were similar and found to be associated with modulation in cellular proliferation/apoptosis and prevalence of CD44 positive population. The up-regulation of self renewal Wnt/β-catenin, Hh/Gli1 pathways and their associated genes Cyclin D1, cMyc and EGFR along with down regulation of E-cadherin seen during the carcinogenesis processes were found to be modulated during the restriction processes by EGCG/TF.

Role of Viral miRNAs and Epigenetic Modifications in Epstein-Barr Virus-Associated Gastric Carcinogenesis

MicroRNAs are short (21–23 nucleotides), noncoding RNAs that typically silence posttranscriptional gene expression through interaction with target messenger RNAs. Currently, miRNAs have been identified in almost all studied multicellular eukaryotes in the plant and animal kingdoms. Additionally, recent studies reported that miRNAs can also be encoded by certain single-cell eukaryotes and by viruses. The vast majority of viral miRNAs are encoded by the herpesviruses family. These DNA viruses including Epstein-Barr virus encode their own miRNAs and/or manipulate the expression of cellular miRNAs to facilitate respective infection cycles. Modulation of the control pathways of miRNAs expression is often involved in the promotion of tumorigenesis through a specific cascade of transduction signals. Notably, latent infection with Epstein-Barr virus is considered liable of causing several types of malignancies, including the majority of gastric carcinoma cases detected worldwide. In this review, we describe the role of the Epstein-Barr virus in gastric carcinogenesis, summarizing the functions of the Epstein-Barr virus-encoded viral proteins and related epigenetic alterations as well as the roles of Epstein-Barr virus-encoded and virally modulated cellular miRNAs.

The role of natural polyphenols in cell signaling and cytoprotection against cancer development

The cytoprotective and anticancer action of dietary in-taken natural polyphenols has for long been attributed only to their direct radical scavenging activities. Currently it is well supported that those compounds display a broad spectrum of biological and pharmacological outcomes mediated by their complex metabolism, interaction with gut microbiota as well as direct interactions of their metabolites with key cellular signaling proteins. The beneficial effects of natural polyphenols and their synthetic derivatives are extensively studied in context of cancer prophylaxis and therapy. Herein we focus on cell signaling to explain the beneficial role of polyphenols at the three stages of cancer development: we review the recent proceedings about the impact of polyphenols on the cytoprotective antioxidant response and their proapoptotic action at the premalignant stage, and finally we present data showing how phenolic acids (e.g., caffeic, chlorogenic acids) and flavonols (e.g., quercetin) hamper the development of metastatic cancer.

Tea polyphenols epigallocatechin gallete and theaflavin restrict mouse liver carcinogenesis through modulation of self-renewal Wnt and hedgehog pathways

The aim of this study is to evaluate chemopreventive and therapeutic efficacy of tea polyphenols epigallocatechin gallete (EGCG) and theaflavin (TF) on self-renewal Wnt and Hedgehog (Hh) pathways during CCl4/N-nitosodiethylamine-induced mouse liver carcinogenesis. For this purpose, the effect of EGCG/TF was investigated in liver lesions of different groups at pre-, continuous and post initiation stages of carcinogenesis. Comparatively increased body weights were evident due to EGCG/TF treatment than carcinogen control mice. Both EGCG and TF could restrict the development of hepatocellular carcinoma at 30th week of carcinogen application showing potential chemoprevention in continuous treated group (mild dysplasia) followed by pretreated (moderate dysplasia) and therapeutic efficacy in posttreated group (mild dysplasia). This restriction was associated with significantly reduced proliferation, increased apoptosis, decreased prevalence of hepatocyte progenitor cell (AFP) and stem cell population (CD44) irrespective of EGCG/TF treatments. The EGCG/TF could modulate the Wnt pathway by reducing β-catenin and phospho-β-catenin-Y-654 expressions along with up-regulation of sFRP1 (secreted frizzled-related protein 1) and adenomatosis polyposis coli during the restriction. In case of the Hh pathway, EGCG/TF could also reduce expressions of glioma-associated oncogene homolog 1 (Gli1) and SMO (smoothened homolog) along with up-regulation of PTCH1 (patched homolog 1). As a result, in Wnt/Hh regulatory pathways decreased expressions of β-catenin/Gli1 target genes like CyclinD1, cMyc and EGFR/phospho-EGFR-Y-1173 and up-regulation of E-cadherin were seen during the restriction. Thus, the restriction of liver carcinogenesis by EGCG/TF was due to reduction in hepatocyte progenitor cell/stem cell population along with modulation of Wnt/Hh and other regulatory pathways.

Epigenetics in breast and prostate cancer

Most recent investigations into cancer etiology have identified a key role played by epigenetics. Specifically, aberrant DNA and histone modifications which silence tumor suppressor genes or promote oncogenes have been demonstrated in multiple cancer models. While the role of epigenetics in several solid tumor cancers such as colorectal cancer are well established, there is emerging evidence that epigenetics also plays a critical role in breast and prostate cancer. In breast cancer, DNA methylation profiles have been linked to hormone receptor status and tumor progression. Similarly in prostate cancer, epigenetic patterns have been associated with androgen receptor status and response to therapy. The regulation of key receptor pathways and activities which affect clinical therapy treatment options by epigenetics renders this field high priority for elucidating mechanisms and potential targets. A new set of methylation arrays are now available to screen epigenetic changes and provide the cutting-edge tools needed to perform such investigations. The role of nutritional interventions affecting epigenetic changes particularly holds promise. Ultimately, determining the causes and outcomes from epigenetic changes will inform translational applications for utilization as biomarkers for risk and prognosis as well as candidates for therapy.

Tea consumption and risk of head and neck cancer

Background

The current study evaluated the association between tea consumption and head and neck cancer (HNC) in Taiwan, where tea is a major agricultural product and a popular beverage.

Methods

Interviews regarding tea consumption (frequency, duration, and types) were conducted with 396 HNC cases and 413 controls. Unconditional logistic regression was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) of HNC risk associated with tea drinking, adjusted for sex, age, education, cigarette smoking, betel quid chewing, and alcohol drinking.

Results

A reduced HNC risk associated with tea drinking (OR for every cup per day = 0.96, 95% CI: 0.93–0.99; OR for ≧5 cups per day = 0.60, 95% CI: 0.39–0.94) was observed. The association was especially significant for pharyngeal cancer (OR for every cup per day = 0.93, 95% CI: 0.88–0.98; OR for ≧5 cups per day = 0.32, 95% CI: 0.16–0.66). A significant inverse association between HNC and tea consumption was observed particularly for green tea.

Conclusions

This study suggests that tea drinking may reduce the risk of HNC. The anticancer property of tea, if proven, may offer a natural chemopreventive measure to reduce the occurrence of HNC.

Epigenetic induction of tissue inhibitor of matrix metalloproteinase-3 by green tea polyphenols in breast cancer cells

Aberrant epigenetic silencing of the tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) gene that negatively regulates matrix metalloproteinases (MMPs) activity has been implicated in the pathogenesis and metastasis of breast cancer. In the present study, we demonstrate that green tea polyphenols (GTP) and its major constituent, epigallocatechin-3-gallate (EGCG) mediate epigenetic induction of TIMP-3 levels and play a key role in suppressing invasiveness and gelatinolytic activity of MMP-2 and MMP-9 in breast cancer cells. Treatment of MCF-7 and MDA-MB-231 breast cancer cells with 20 µM EGCG and 10 µg/mL GTP for 72 h significantly induces TIMP-3 mRNA and protein levels. Interestingly, investigations into the molecular mechanism revealed that TIMP-3 repression in breast cancer cells is mediated by epigenetic silencing mechanism(s) involving increased activity of the enhancer of zeste homolog 2 (EZH2) and class I histone deacetylases (HDACs), independent of promoter DNA hypermethylation. Treatment of breast cancer cells with GTP and EGCG significantly reduced EZH2 and class I HDAC protein levels. Furthermore, transcriptional activation of TIMP-3 was found to be associated with decreased EZH2 localization and H3K27 trimethylation enrichment at the TIMP-3 promoter with a concomitant increase in histone H3K9/18 acetylation. Our findings highlight TIMP-3 induction as a key epigenetic event modulated by GTPs in restoring the MMP:TIMP balance to delay breast cancer progression and invasion.

Immunity: plants as effective mediators

In the domain of nutrition, exploring the diet-health linkages is major area of research. The outcomes of such interventions led to widespread acceptance of functional and nutraceutical foods; however, augmenting immunity is a major concern of dietary regimens. Indeed, the immune system is incredible arrangement of specific organs and cells that enabled humans to carry out defense against undesired responses. Its proper functionality is essential to maintain the body homeostasis. Array of plants and their components hold immunomodulating properties. Their possible inclusion in diets could explore new therapeutic avenues to enhanced immunity against diseases. The review intended to highlight the importance of garlic (Allium sativum), green tea (Camellia sinensis), ginger (Zingiber officinale), purple coneflower (Echinacea), black cumin (Nigella sativa), licorice (Glycyrrhiza glabra), Astragalus and St. John's wort (Hypericum perforatum) as natural immune boosters. These plants are bestowed with functional ingredients that may provide protection against various menaces. Modes of their actions include boosting and functioning of immune system, activation and suppression of immune specialized cells, interfering in several pathways that eventually led to improvement in immune responses and defense system. In addition, some of these plants carry free radical scavenging and anti-inflammatory activities that are helpful against cancer insurgence. Nevertheless, interaction between drugs and herbs/botanicals should be well investigated before recommended for their safe use, and such information must be disseminated to the allied stakeholders.

Disposable biosensor based on platinum nanoparticles-reduced graphene oxide-laccase biocomposite for the determination of total polyphenolic content

A disposable amperometric biosensor was developed for the detection of total polyphenolic compounds from tea infusions. The biosensor was designed by modifying the surface of a carbon screen-printed electrode with platinum nanoparticles and reduced graphene oxide, followed by the laccase drop-casting and stabilization in neutralised 1% Nafion solution. The obtained biosensor was investigated by scanning electron microscopy and electrochemical techniques. It was observed that platinum nanoparticles-reduced graphene oxide composite had synergistic effects on the electron transfer and increased the electroactive surface area of the carbon screen-printed electrode. The constructed analytical tool showed a good linearity in the range 0.2-2 μM for caffeic acid and a limit of detection of 0.09 μM. The value of Michaelis-Menten apparent constant was calculated from the electrochemical version of Lineweaver-Burk equation to be 2.75 μM. This disposable laccase biosensor could be a valuable tool for the estimation of total polyphenolic content from tea infusions.

The activity against Ehrlich's ascites tumors of doxorubicin contained in self assembled, cell receptor targeted nanoparticle with simultaneous oral delivery of the green tea polyphenol epigallocatechin-3-gallate

Doxorubicin (DOX) is a well-known anticancer drug used for the treatment of a wide variety of cancers. However, undesired toxicity of DOX limits its uses. To address the issue of minimizing toxicity of DOX by making it targeted towards cancer cells, DOX was entrapped in self-assembled 6-O-(3-hexadecyloxy-2-hydroxypropyl)-hyaluronic acid (HDHA) nanoparticles. We hypothesized that by encapsulating the drug in biodegradable nanoparticles, its therapeutic efficacy would improve, if targeted against cancer cells. We synthesized cell receptor targeted, DOX loaded HDHA nanoparticles (NPs) and non-targeted DOX loaded O-hexadecylated dextran (HDD) nanoparticles (NPs) and characterized them for their entrapment efficiency, percent yield, drug load, surface morphology, particle size and in vitro drug release. The anticancer efficacy of DOX loaded HDHA-NPs was evaluated by measuring the changes in tumor volumes, tumor weights, and mean survival rate of Swiss albino mice grafted with Ehrlich's ascites carcinoma (EAC) cells. For this, the animals were given HDHA-DOX-NPs (1.5 mg/kg b.wt.) intravenously and a green tea polyphenol, Epigallocatechin-3-gallate (EGCG) (20 mg/kg b.wt.), orally through gavage. The targeted NP dose with EGCG significantly increased mean survival time of the animals and enhanced the therapeutic efficacy of the drug compared to the non-targeted NPs and free DOX. Further, we showed that these NPs (HDD and HDHA) were more active in the presence of EGCG than DOX alone in inducing apoptosis in EAC cells as evident by an increase in sub-G1 cells (percent), Annexin V positive cells and chromatin condensation along with the reduction in mitochondrial membrane potential (MMP). The study demonstrates that DOX loaded HDHA-NPs along with EGCG significantly inhibit the growth of EAC cells with ∼38-fold dose advantage compared to DOX alone and thus opens a new dimension in cancer chemotherapy.

Mesenchymal and stem-like cell properties targeted in suppression of chronically-induced breast cell carcinogenesis

Stem-like cells and the epithelial-to-mesenchymal transition (EMT) program are postulated to play important roles in various stages of cancer development, but their roles in breast cell carcinogenesis and intervention remain to be clarified. We investigated stem-like cell- and EMT-associated properties and markers in breast epithelial cells chronically exposed to low-dose 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene in the presence and absence of the preventive agents green tea catechins and grape seed extract. Our results indicate that stem-like cell- and EMT-associated properties and markers should be seriously considered as new cancer-associated indicators for detecting breast cell carcinogenesis and as endpoints for intervention of carcinogenesis.

Antiproliferative activities of tea and herbal infusions

The consumption of tea and herbal infusions has increased rapidly in recent years. More and more people consume these infusions as daily beverages as well as for health purposes. The aim of this study was to supply new information on the antiproliferative function of these infusions for nutritionists and the general public. The in vitro antiproliferative activities of 60 different tea and herbal infusions on four cancer cell lines were evaluated by MTT assay. The results showed that some infusions strongly inhibited the proliferation of A549 (human lung cancer cells), MCF-7 (human breast cancer cells), HepG2 (human hepatoma cells) and HT-29 (human colon cancer cells), and decreased the viability of these cancer cell lines in a dose-dependent manner. In addition, some bioactive components in the infusions were also separated and determined by HPLC. The results suggested that some tea and herbal infusions may be potential dietary supplements for the prevention and treatment of cancer.

New insights into the mechanisms of green tea catechins in the chemoprevention of prostate cancer

Prostate cancer is the most commonly diagnosed cancer and second most common cause of cancer deaths in American men. Its long latency, slow progression, and high incidence rate make prostate cancer ideal for targeted chemopreventative therapies. Therefore, chemoprevention studies and clinical trials are essential for reducing the burden of prostate cancer on society. Epidemiological studies suggest that tea consumption has protective effects against a variety of human cancers, including that of the prostate. Laboratory and clinical studies have demonstrated that green tea components, specifically the green tea catechin (GTC) epigallocatechin gallate, can induce apoptosis, suppress progression, and inhibit invasion and metastasis of prostate cancer. Multiple mechanisms are involved in the chemoprevention of prostate cancer with GTCs; understanding and refining models of fundamental molecular pathways by which GTCs modulate prostate carcinogenesis is essential to apply the utilization of green tea for the chemoprevention of prostate cancer in clinical settings. The objective of this article is to review and summarize the most current literature focusing on the major mechanisms of GTC chemopreventative action on prostate cancer from laboratory, in vitro, and in vivo studies, and clinical chemoprevention trials.

MicroRNAs, diet, and cancer: new mechanistic insights on the epigenetic actions of phytochemicals

There is growing interest in the epigenetic mechanisms that impact human health and disease, including the role of microRNAs (miRNAs). These small (18-25 nucleotide), evolutionarily conserved, non-coding RNA molecules regulate gene expression in a post-transcriptional manner. Several well-orchestered regulatory mechanisms involving miRNAs have been identified, with the potential to target multiple signaling pathways dysregulated in cancer. Since the initial discovery of miRNAs, there has been progress towards therapeutic applications, and several natural and synthetic chemopreventive agents also have been evaluated as modulators of miRNA expression in different cancer types. This review summarizes the most up-to-date information related to miRNA biogenesis, and critically evaluates proposed miRNA regulatory mechanisms in relation to cancer signaling pathways, as well as other epigenetic modifications (DNA methylation patterns, histone marks) and their involvement in drug resistance. We also discuss the mechanisms by which dietary factors regulate miRNA expression, in the context of chemoprevention versus therapy.