Combination cancer chemoprevention with green tea extract and sulindac shown in intestinal tumor formation in Min mice

Natural Products for Cancer Prevention and Interception: Preclinical and Clinical Studies and Funding Opportunities

Multiple agents derived from natural products (NPs) have been evaluated for cancer prevention and interception, either alone or in combination. The National Cancer Institute (NCI) is very interested in advancing research to identify additional agents that, alone or in combination, may prove useful in cancer prevention. Below, we provide an overview of NP studies in cancer prevention and interception, both individual agents and combination interventions. Given that findings from many preclinical studies evaluating individual agents have generally not been confirmed in human studies, our focus with individual NPs in this review is on studies involving humans, especially clinical trials. Fewer combination intervention studies have been conducted, so we have broadened our review to include preclinical studies. We conclude with how the Division of Cancer Prevention (DCP) within the NCI is providing funding to encourage the research community to propose natural product studies in cancer prevention and interception to advance the field.

Potential Therapeutic Targets of Epigallocatechin Gallate (EGCG), the Most Abundant Catechin in Green Tea, and Its Role in the Therapy of Various Types of Cancer

Epigallocatechin-3-gallate (EGCG), an active compound of green tea and its role in diseases cure and prevention has been proven. Its role in diseases management can be attributed to its antioxidant and anti-inflammatory properties. The anti-cancer role of this green tea compound has been confirmed in various types of cancer and is still being under explored. EGCG has been proven to possess a chemopreventive effect through inhibition of carcinogenesis process such as initiation, promotion, and progression. In addition, this catechin has proven its role in cancer management through modulating various cell signaling pathways such as regulating proliferation, apoptosis, angiogenesis and killing of various types of cancer cells. The additive or synergistic effect of epigallocatechin with chemopreventive agents has been verified as it reduces the toxicities and enhances the anti-cancerous effects. Despite its effectiveness and safety, the implications of EGCG in cancer prevention is certainly still discussed due to a poor bioavailability. Several studies have shown the ability to overcome poor bioavailability through nanotechnology-based strategies such as encapsulation, liposome, micelles, nanoparticles and various other formulation. In this review, we encapsulate therapeutic implication of EGCG in cancer management and the mechanisms of action are discussed with an emphasis on human clinical trials.

A Review on Dietary Intervention in Obesity Associated Colon Cancer

Background: Colorectal cancer (CRC) is one of the major causes of morbidity and mortality. According to National Cancer Registry, the incidence of colorectal cancer in Peninsular Malaysia increases with age. The incidence is highest among Chinese population but lower among Indians and Malays. Many reviews have suggested that obesity may be associated with a higher risk (>50%) of colorectal cancer. Methods: This study collects a comprehensive data from the literature review available from respective journals on dietary intervention and the chemo-protective mechanisms of a few natural resources in obesity -associated colon cancer based on previous and current studies. Results: In obesity-associated colon cancer, the genes of interest and pathways that are mainly involved include NFκB, P13K/Akt, and MAPK pathways, and FTO, leptin, Cyclin D, MMPs, and STAT3 genes. Dietary modification is one of the alternative steps in early prevention of colon cancer. It has been proposed that the components present in certain foods may have the ability to protect against many diseases including the prevention of cancer. Conclusion: There are many factors that lead to obesity-associated colon cancer and the mechanisms behind it is still undergoing intensive research. This review aims to scrutinize research as well as reviews that have been previously reported on obesity associated colorectal cancer and the beneficial effects of including antioxidants-rich foods such as vegetables and fruits in the diet to reduce the risk of obesity associated colorectal cancer.

Effects of Intestinal Microbial⁻Elaborated Butyrate on Oncogenic Signaling Pathways

The intestinal microbiota is well known to have multiple benefits on human health, including cancer prevention and treatment. The effects are partially mediated by microbiota-produced short chain fatty acids (SCFAs) such as butyrate, propionate and acetate. The anti-cancer effect of butyrate has been demonstrated in cancer cell cultures and animal models of cancer. Butyrate, as a signaling molecule, has effects on multiple signaling pathways. The most studied effect is its inhibition on histone deacetylase (HDAC), which leads to alterations of several important oncogenic signaling pathways such as JAK2/STAT3, VEGF. Butyrate can interfere with both mitochondrial apoptotic and extrinsic apoptotic pathways. In addition, butyrate also reduces gut inflammation by promoting T-regulatory cell differentiation with decreased activities of the NF-κB and STAT3 pathways. Through PKC and Wnt pathways, butyrate increases cancer cell differentiation. Furthermore, butyrate regulates oncogenic signaling molecules through microRNAs and methylation. Therefore, butyrate has the potential to be incorporated into cancer prevention and treatment regimens. In this review we summarize recent progress in butyrate research and discuss the future development of butyrate as an anti-cancer agent with emphasis on its effects on oncogenic signaling pathways. The low bioavailability of butyrate is a problem, which precludes clinical application. The disadvantage of butyrate for medicinal applications may be overcome by several approaches including nano-delivery, analogue development and combination use with other anti-cancer agents or phytochemicals.

Green Tea Polyphenols Inhibit Colorectal Tumorigenesis in Azoxymethane-Treated F344 Rats

In studying the cancer-preventive activities of green tea polyphenols, we previously demonstrated that dietary administration of polyphenon E (PPE) inhibited the formation of aberrant crypt foci (ACF) in the colon of azoxymethane (AOM)-treated F344 rats. Herein, we reported cancer-preventive activity of PPE using colorectal cancer as an end point. F344 rats were given two weekly injections of AOM, and then maintained on a 20% high-fat diet with or without 0.24% PPE for 34 wk. In the control group, 83% of rats developed colorectal tumors. Dietary PPE treatment significantly increased the plasma and colonic levels of tea polyphenols, and decreased tumor multiplicity and tumor size. Histological analysis indicated that PPE significantly decreased the incidence of adenocarcinoma, and the multiplicity of adenocarcinoma as well as the multiplicity of adenoma. PPE treatment significantly decreased plasma levels of proinflammatory eicosanoids, prostaglandin E2, and leukotriene B4. It also decreased β-catenin nuclear expression, induced apoptosis, and increased expression levels of RXRα, β, and γ in adenocarcinomas. In conclusion, our results convincingly demonstrated the inhibitory effects of orally administered PPE on colon carcinogenesis in AOM-treated rats and suggested possible biomarkers for the biological effects of green tea polyphenols.

Versatile oligomers and polymers from flavonoids – a new approach to synthesis

Antioxidant oligomers and polymers have been prepared from two flavonoids, catechin and quercetin, using a new facile technique.

Inflammation as Cause for Scar Cancers of the Lung

The molecular and cellular basis of inflammation has become a topic of great interest of late because of the association between mechanisms of inflammation and risk for cancer. Inflammatory-mediated events, such as the production of reactive oxygen species (ROS), the activation of growth factors (for wound repair), and the altering of signal-transduction processes to activate cell-proliferation (to replace necrotic/apoptotic tissue cells), events that also can occur independently of inflammation, are all considered to be components of risk for a variety of cancers. Using scar cancer of the lung as an example, mechanisms of inflammation associated with recurring infections with Mycobacterium tuberculosisare discussed in the context that they may, in fact, be the major or sole cause of a cancer. Production of ROS, prostaglandins, leukotrienes, and cytokines in pulmonary tissues is greatly enhanced due to a cell-mediated immune response against macrophages infected with M. tuberculosis. These responses lead to the extensive fibrosis associated with recurring infections, possibly leading to decreased clearance of lymph and lymph-associated particles from the infected region. They also will enhance rates of cell division by inhibiting synthesis of P21, leading to enhanced progression from G0 arrest to G1 phase, from G1 to Sphase, and from G2 to M phase of the cell cycle. By increasing rates of oxidative DNA damage and inhibiting apoptosis by enhancing synthesis of BCL-2, mutagenesis of progeny cells is enhanced, and these effects coupled with enhanced angiogenesis stimulated by COX-2 products lead to an environment that is highly conducive to tumorigenesis. Based on the evidence, it appears that but for an inflammatory response to recurring infections, some cases of scar cancer would not exist. By making appropriate lifestyle and dietary changes, a variety of anti-inflammatory effects can be produced, which should attenuate inflammation-induced risk for cancer.

Prevention and treatment of cancers by immune modulating nutrients

Epidemiological and laboratory data support the protective effects of bioactive nutrients in our diets for various diseases. Along with various factors, such as genetic history, alcohol, smoking, exercise, and dietary choices play a vital role in affecting an individual's immune responses toward a transforming cell, by either preventing or accelerating a neoplastic transformation. Ample evidence suggests that dietary nutrients control the inflammatory and protumorigenic responses in immune cells. Immunoprevention is usually associated with the modulation of immune responses that help in resolving the inflammation, thus improving clinical outcome. Various metabolic pathway-related nutrients, including glutamine, arginine, vitamins, minerals, and long-chain fatty acids, are important components of immunonutrient mixes. Epidemiological studies related to these substances have reported different results, with no or minimal effects. However, several studies suggest that these nutrients may have immune-modulating effects that may lower cancer risk. Preclinical studies submit that most of these components may provide beneficial effects. The present review discusses the available data, the immune-modulating functions of these nutrients, and how these substances could be used to study immune modulation in a neoplastic environment. Further research will help to determine whether the mechanistic signaling pathways in immune cells altered by nutrients can be exploited for cancer prevention and treatment.

Efficient functionalisation of dextran-aldehyde with catechin: potential applications in the treatment of cancer

Dextran aldehyde was functionalised with up to 38 wt% catechin and the resulting conjugate demonstrated cytotoxic efficacy against neuroblastoma cells.

Investigate the binding of catechins to trypsin using docking and molecular dynamics simulation

To explore the inhibitory mechanism of catechins for digestive enzymes, we investigated the binding mode of catechins to a typical digestive enzyme-trypsin and analyzed the structure-activity relationship of catechins, using an integration of molecular docking, molecular dynamics simulation and binding free energy calculation. We found that catechins with different structures bound to a conservative pocket S1 of trypsin, which is comprised of residues 189–195, 214–220 and 225–228. In the trypsin-catechin complexes, Asp189 by forming strong hydrogen bonding, and Gln192, Trp215 and Gly216 through hydrophobic interactions, all significantly contribute to the binding of catechins. The number and the position of hydroxyl and aromatic groups, the structure of stereoisomers, and the orientation of catechins in the binding pocket S1 of trypsin all affect the binding affinity. The binding affinity is in the order of Epigallocatechin gallate (EGCG) > Epicatechin gallate (ECG) > Epicatechin (EC) > Epigallocatechin (EGC), and 2R-3R EGCG shows the strongest binding affinity out of other stereoisomers. Meanwhile, the synergic conformational changes of residues and catechins were also analyzed. These findings will be helpful in understanding the knowledge of interactions between catechins and trypsin and referable for the design of novel polyphenol based functional food and nutriceutical formulas.

Primary cancer prevention by green tea, and tertiary cancer prevention by the combination of green tea catechins and anticancer compounds

Green tea is a daily beverage, a non-oxidized non-fermented product containing at least four green tea catechins. Considering our first results when repeated applications of (-)-epigallocatechin gallate (EGCG) prevented tumor promotion in mouse skin, we have continued to look at green tea as a possible cancer preventive agent. 1) The 10-year prospective cohort study by Drs. K. Nakachi and K. Imai revealed that drinking 10 Japanese-size cups (120 mL/cup) of green tea per day delayed cancer onset in humans by 7.3 years among females and by 3.2 years among males. The delay of cancer onset is of course significant evidence of primary cancer prevention in humans. 2) In collaboration with Dr. H. Moriwaki’s group we successfully presented a prototype of tertiary cancer prevention showing that 10 Japanese-size cups of green tea daily, supplemented with tablets of green tea extract (G.T.E), reduced recurrence of colorectal adenomas in polypectomy patients by 51.6% (from 31% to 15%). 3) In 1999, we first reported that the combination of green tea catechins and non-steroidal anti-inflammatory drugs showed synergistic anticancer effects in both in vitro and in vivo experiments, along with elucidation of the mechanism. 4) Further studies by other investigators have revealed that various combinations of EGCG or green tea extract and anticancer compounds inhibit tumor volume in xenograft mouse models implanted with various human cancer cell lines. Green tea is a cancer preventive, and green tea catechins act as synergists with anticancer compounds.

Synergistic enhancement of anticancer effects on numerous human cancer cell lines treated with the combination of EGCG, other green tea catechins, and anticancer compounds

PURPOSE

In 2008, we reported that 10 Japanese-size cups of green tea daily, supplemented with tablets of green tea extract (GTE), reduced the recurrence of colorectal adenoma by 51.6% in patients after polypectomy. Based on these results, we paid special attention to Japanese cancer patients, who consume green tea every day and are administered anticancer drugs. This encouraged us to study whether the combination of green tea catechins and anticancer drugs has the potential to enhance the efficacy of the drugs.

RESULTS AND DISCUSSION

The combination of GTE and NSAIDs synergistically inhibited tumor development in rodents through the activation of the GADD153-DR5-TRAIL apoptotic pathway. Since then, this study was further extended by various investigators to the combinations of EGCG and other green tea catechins with anticancer compounds, the latter of which include NSAIDs, phytochemicals, and anticancer drugs. In order to demonstrate whether diversity of the combinations would generally induce synergistic anticancer effects on numerous human cancer cell lines, we studied the results of 42 in vitro combination experiments and the synergistic inhibition of tumor volume of 13 combination experiments using xenograft mouse models, which were previously reported by other investigators. The various combinations of EGCG and anticancer compounds induced similar synergistic anticancer effects for both in vitro and in vivo experiments, and showed an average reduction in tumor volume by 70.3%. Considering the evidence showing that treatment with EGCG inhibited self-renewal of cancer stem cells, the combination shows a great advantage.

CONCLUSION

Green tea is a cancer preventive for humans, showing a new trend of green tea catechins as synergists with anticancer compounds.

Modulation of the pharmacokinetics, therapeutic and adverse effects of NSAIDs by Chinese herbal medicines

INTRODUCTION

Concomitant use of NSAIDs and Chinese herbal medicines (CHMs) is frequent, yet summarized information on their interactions is lacking.

AREAS COVERED

A systematic review of literature in four evidence-based English databases was performed. Articles which reported CHMs altering the pharmacokinetics, therapeutic and adverse effects of NSAIDs were identified and summarized. Such interactions may lead to beneficial, detrimental or no change in outcomes. The current review covers four therapeutic effects of NSAIDs, including: i) anti-inflammatory; ii) analgesic; iii) antiplatelet, cardiovascular and cerebrovascular; and iv) anticancer effects and four adverse effects of NSAIDs, including: i) gastrointestinal ulcer; ii) nephrotoxicity; iii) hepatotoxicity; and iv) antiplatelet effects and bleeding.

EXPERT OPINION

While majority of CHMs demonstrated effectiveness in alleviating NSAIDs-induced adverse effects and potentiating the therapeutic effects, this review provides insights for development of CHMs as add-on medications to NSAIDs therapies. However, since limited information was from well-designed clinical trials, the findings are not yet conclusive and more clinical studies are warranted to provide guidance for healthcare professionals. In future, researches on interactions between NSAIDs and CHMs are expected to grow and modern approaches such as pharmacogenomics might enhance the throughput and accuracy of identifying clinically relevant interactions.

Understanding CAM Natural Health Products: Implications of Use Among Cancer Patients and Survivors

Herbs, vitamins, and other natural health products are being used by cancer patients and survivors with increasing prevalence in the United States. These complementary and alternative medicine (CAM) products, which are also referred to as natural health products in Canada and abroad, are used during cancer treatment and the survivorship period to ease the burden of symptoms such as pain, fatigue, insomnia, anxiety, and depression and hence improve overall quality of life. Data indicate that while patients choose these products for self-treatment, they often do not inform their health-care providers, thereby presenting the potential for negative interactions. This article gives an overview of CAM natural health products, including discussion of herbs, vitamins, and other supplements such as minerals, enzymes, and more. Related research is presented, and implications for advanced practitioners are discussed. Insights into guiding safe and effective use among patients as well as appropriate decision-making strategies are explored.

The flavonoid chrysin attenuates colorectal pathological remodeling reducing the number and severity of pre-neoplastic lesions in rats exposed to the carcinogen 1,2-dimethylhydrazine

Phenolic compounds are naturally occurring, bioactive substances with marked antioxidant and anti-inflammatory potential. The flavonoid chrysin, found in high levels in honey bee propolis, inhibits the activity of enzymes involved in carcinogenesis. We have investigated the effect of chrysin on pre-neoplastic colorectal lesions (ACF, aberrant crypt foci) in a rat model of chemical carcinogenesis induced by 1,2-dimethylhydrazine (DMH). Female Wistar rats weighing 137.2 ± 24.3 g received weekly one subcutaneous injection of DMH (20 mg/kg) for 10 weeks. The animals were divided into five groups each with seven animals: Group 1, 0.9% saline; Group 2, DMH+0.9% saline; Group 3, DMH+chrysin (10 mg/kg); Group 4, DMH+chrysin (100 mg/kg); Group 5, DMH+chrysin (200 mg/kg). Groups 2 and 3 showed a significant increase in ACF number, nucleolus organizer regions per enterocyte nucleus and nitrite/nitrate serum levels compared with Group 1. Groups 4 and 5 presented a significant reduction in all these parameters compared with Group 2. The levels of antioxidant minerals (copper, magnesium, selenium, zinc) and the number of enteroendocrine and mucin-producing cells were significantly reduced in Groups 2 and 3 but were similar in Groups 4 and 5 compared with Group 1. Chrysin, at 100 mg/kg and 200 mg/kg, was effective in attenuating pathological colorectal remodeling, reducing the number of pre-neoplastic lesions in rats exposed to DMH. Some of these effects might be attributable to the recovery of antioxidant mineral levels, a reduction in systemic nitrosative stress and an inhibition of the cellular proliferation induced by this flavonoid.

Challenging the effectiveness of green tea in primary and tertiary cancer prevention

PURPOSE

Drinking green tea daily is part of Japanese culture, and various studies have revealed that green tea is a cancer preventive. We here review our progress in cancer prevention with green tea on 12 main topics, from basic to clinical level. TOPICS AND METHODS: Biochemical and biological studies of green tea catechins, a prospective cohort study, preclinical safety trials with tablets of green tea extract, double-blind randomized clinical phase II prevention trial for recurrence of colorectal adenomas, and synergistically enhanced inhibition by the combination of green tea catechins and anticancer drugs. All results were significant, including human studies with informed consent.

RESULTS

Drinking 10 Japanese-size cups of green tea per day delayed the cancer onset of humans 7 years for females. For tertiary cancer prevention, consuming 10 cups of green tea per day fortified by green tea tablets, 50 %, significantly prevented the recurrence of colorectal adenomas. A minimum effective amount of green tea catechins for cancer prevention was found in humans. In addition, the combination of green tea catechins and anticancer drugs engendered a new cancer therapeutic strategy.

CONCLUSION

The consumption of 10 Japanese-size cups of green tea per day is a significant factor in primary cancer prevention for the general population, and the preventive effect on recurrence of colorectal adenomas in patients is vital evidence in tertiary cancer prevention.

Green tea: an effective synergist with anticancer drugs for tertiary cancer prevention

Green tea is now an acknowledged cancer preventive in Japan. Based on evidence that colorectal adenomas and prostate cancer in humans have been prevented, we review here the concept that the combination of anticancer drugs with green tea catechin synergistically induces apoptosis of human cancer cells, inhibits tumor formation in mice, and enhances inhibition of tumor growth in xenograft mouse models. As a molecular mechanism by the combination, the induction of growth arrest and DNA damage-inducible 153 (GADD153, CHOP) gene expression is discussed in relation to death receptor 5 and TRAIL-apoptotic pathway. The combination of anticancer drugs with green tea could be a new cancer therapeutic strategy in humans.

Mechanistic issues concerning cancer prevention by tea catechins

The cancer preventive activities of tea (Camellia sinensis, Theaceae) have been demonstrated in animal models for cancers at different organ sites and suggested by some epidemiological studies. Many mechanisms for cancer prevention have been proposed based on studies in cell lines, which demonstrated the modulation of signal transduction and metabolic pathways by (-)-epigallocatechin-3-gallate (EGCG), the most abundant and active polyphenol in green tea. These molecular events may result in cellular changes, such as enhancement of apoptosis, suppression of cell proliferation, and inhibition of angiogenesis. Nevertheless, it is not known whether these are the molecular mechanisms of inhibition of carcinogenesis in animals and humans. This article discusses the key issues involved in extrapolating results from cell line studies to mechanistic information in vivo and in translating animal studies to human cancer prevention.

Cancer prevention by tea: Evidence from laboratory studies

The cancer preventive activities of tea (Camellia sinensis Theaceae) have been studied extensively. Inhibition of tumorigenesis by green tea extracts and tea polyphenols has been demonstrated in different animal models, including those for cancers of the skin, lung, oral cavity, esophagus, stomach, small intestine, colon, bladder, liver, pancreas, prostate, and mammary glands. Many studies in cell lines have demonstrated the modulation of signal transduction and metabolic pathways by (-)-epigallocatechin-3-gallate (EGCG), the most abundant and active polyphenol in green tea. These molecular events can result in cellular changes, such as enhancement of apoptosis, suppression of cell proliferation, and inhibition of angiogenesis. Nevertheless, the molecular mechanisms of inhibition of carcinogenesis in animals and humans remain to be further investigated. Future research directions in this area are discussed.

EGCG, green tea polyphenols and their synthetic analogs and prodrugs for human cancer prevention and treatment

Cancer-preventive effects of tea polyphenols, especially epigallocatechin-3-gallate (EGCG), have been demonstrated by epidemiological, preclinical, and clinical studies. Green tea polyphenols such as EGCG have the potential to affect multiple biological pathways, including gene expression, growth factor-mediated pathways, the mitogen-activated protein kinase-dependent pathway, and the ubiquitin/proteasome degradation pathway. Therefore, identification of the molecular targets of EGCG should greatly facilitate a better understanding of the mechanisms underlying its anticancer and cancer-preventive activities. Performing structure-activity relationship (SAR) studies could also greatly enhance the discovery of novel tea polyphenol analogs as potential anticancer and cancer-preventive agents. In this chapter, we review the relevant literature as it relates to the effects of natural and synthetic green tea polyphenols and EGCG analogs on human cancer cells and their potential molecular targets as well as their antitumor effects. We also discuss the implications of green tea polyphenols in cancer prevention.

New cancer treatment strategy using combination of green tea catechins and anticancer drugs

Green tea is now recognized as the most effective cancer preventive beverage. In one study, 10 Japanese-size cups of green tea daily supplemented with tablets of green tea extract limited the recurrence of colorectal polyps in humans to 50%. Thus, cancer patients who consume green tea and take anticancer drugs will have double prevention. We studied the effects of combining (-)-epigallocatechin gallate (EGCG) and anticancer drugs, focusing on inhibition of cell growth and induction of apoptosis. Numerous anticancer drugs, such as tamoxifen, COX-2 inhibitors, and retinoids were used for the experiments, and the combination of EGCG and COX-2 inhibitors consistently induced the enhancement of apoptosis. To study the mechanism of the enhancement, we paid special attention to the enhanced expressions of DDIT3 (growth arrest and DNA damage-inducible 153, GADD153), GADD45A, and CDKN1A (p21/WAF1/CIP1) genes, based on our previous evidence that a combination of EGCG and sulindac specifically induced upregulated expression of GADD153 and p21 genes in PC-9 lung cancer cells. The synergistic enhancements of apoptosis and GADD153 gene expression in human non-small cell lung cancer cells by the combination of EGCG and celecoxib were mediated through the activation of the MAPK signaling pathway. This article reviews the synergistic enhancement of apoptosis, gene expression, and anticancer effects using various combinations of EGCG and anticancer drugs, including the combination of (-)-epicatechin (EC) and curcumin. Based on the evidence, we present a new concept: green tea catechins as synergists with anticancer drugs.

Chemoprevention of head and neck cancer with green tea polyphenols

Recently, squamous cell carcinoma of the head and neck chemoprevention research has made major advances with novel clinical trial designs suited for the purpose, use of biomarkers to identify high-risk patients, and the emergence of numerous molecularly targeted agents and natural dietary compounds. Among many natural compounds, green tea polyphenols, particularly (-)-epigallocatechin-3-gallate (EGCG), possess remarkable potential as chemopreventive agents. EGCG modulates several key molecular signaling pathways at multiple levels and has synergistic or additive effects when combined with many other natural or synthetic compounds. This review will provide an update of the potential of green tea polyphenols, particularly EGCG, for the chemoprevention of squamous cell carcinoma of the head and neck.

Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study

BACKGROUND

Experimental studies indicate the chemopreventive properties of green tea extract (GTE) on colorectal cancer. Epidemiologically, green tea consumption of > 10 cups daily reduced colorectal cancer risk in Japanese. Because colorectal adenomas are the precursors to most sporadic colorectal cancers, we conducted a randomized trial to determine the preventive effect of GTE supplements on metachronous colorectal adenomas by raising green tea consumption in the target population from an average of 6 cups (1.5 g GTE) daily to > or = 10 cups equivalent (2.5 g GTE) by supplemental GTE tablets.

METHODS

We recruited 136 patients, removed their colorectal adenomas by endoscopic polypectomy, and 1 year later confirmed the clean colon (i.e., no polyp) at the second colonoscopy. The patients were then randomized into two groups while maintaining their lifestyle on green tea drinking: 71 patients supplemented with 1.5 g GTE per day for 12 months and 65 control patients without supplementation. Follow-up colonoscopy was conducted 12 months later in 125 patients (65 in the control group and 60 in the GTE group).

RESULTS

The incidence of metachronous adenomas at the end-point colonoscopy was 31% (20 of 65) in the control group and 15% (9 of 60) in the GTE group (relative risk, 0.49; 95% confidence interval, 0.24-0.99; P < 0.05). The size of relapsed adenomas was also smaller in the GTE group than in the control group (P < 0.001). No serious adverse events occurred in the GTE group.

CONCLUSION

GTE is an effective supplement for the chemoprevention of metachronous colorectal adenomas.

Green tea catechin as a chemical chaperone in cancer prevention

Green tea catechins have recently gained significant acceptance as a cancer preventive, and one of the important features of catechins is their interactions with various target molecules. We recently found a functional and structural similarity between catechins and chaperones: Stochastic conformational analysis in silico revealed numerous conformations of (-)-epigallocatechin gallate, (-)-epicatechin gallate and (-)-epigallocatechin, showing a unique flexibility and mobility of the catechin molecules and suggesting the significance of a galloyl group in conformational variation. Since these conformations result in interaction with various types of molecules, we think that green tea catechin induces cancer preventive activity mediated through a chaperone-like property.

Combination chemoprevention of hamster buccal pouch carcinogenesis by bovine milk lactoferrin and black tea polyphenols

Combination chemoprevention is a promising approach for oral cancer prevention. The authors evaluated the combined chemopreventive effects of bovine milk lactoferrin (bLF) and black tea polyphenols (Polyphenon-B) in a clinically relevant in vivo model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis. Although dietary administration of bLF and Polyphenon-B alone significantly reduced the tumor incidence, combined administration of bLF and polyphenon-B was more effective in inhibiting DMBA-induced genotoxicity and development of HBP carcinomas by modulation of carcinogen-metabolizing enzymes and cellular redox status. These results suggest that a "designer item" approach will be useful for human oral cancer prevention strategies.

Elevation protective role of Camellia sinensis and Urtica dioica infusion against trichloroacetic acid-exposed in rats

This study was designed to investigate the protective effects of two traditionally used Turkish medicinal plants, Camellia sinensis (CS) and Urtica dioica L. (UD), beverages used against chemical carcinogen trichloroacetic acid (TCA)-exposure in rats. The preventive potential of the plant infusions was evaluated by measuring the level of serum marker enzymes, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine phosphokinase (CPK), acid phosphatase (ACP), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH); antioxidant defense systems, reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT); and lipid peroxidation (malondialdehyde, MDA) content in various organs of rats. Twenty four healthy rats were randomly allotted into four experimental groups: A (untreated control), B (only TCA-treated), C (TCA+CS treated) and D (TCA+UD treated). At the end of the 50 days, the plant infusions possessed chemoprotective effects, deduced by the remaining TCA-induced increased serum damage marker enzyme, lipid peroxidation and antioxidative system in rats compared with those of the control and TCA-exposed rats. According to the results, while the levels of AST, ALT and CPK increased in group B, no significant changes were observed in groups C and D. The MDA content slightly increased in tissues of all groups, being higher in group B. Antioxidant enzyme activities such as SOD and CAT increased significantly in the brain, liver and kidney of group B while they did not change significantly except for in the kidney in groups C and D. The GSH level and the ancillary enzyme GR activity did not change significantly in organs of all groups. On the other hand, the drug metabolizing enzyme, GST, activity decreased significantly in the brain, liver and kidney of group D while slight changes were observed for the other groups. The results revealed that TCA exposure induced oxidative stress in rat tissues, however, in plant beverage supplemented groups, a significant protective effect of CS and UD against TCA-induced oxidative injury was recorded. Hence, the study revealed that the constituents present in CS and UD impart protection against carcinogenic chemical induced oxidative injury that may result in the development of cancer. Also the observations, along with changes, suggest that both CS and UD may possess preventive potential during a 50-day protective exposure.

Synergistic effects of multiple treatments, and both DNA and RNA direct bindings on, green tea catechins

This article reviews two main topics: (1) the synergistic effects of multiple treatments with green tea catechin and (2) the direct binding of (-)-epigallocatechin gallate (EGCG) to both DNA and RNA molecules. Japanese drink green tea throughout the day, so we studied whether multiple treatments of cells with EGCG would enhance the expression of apoptosis-related genes, such as growth arrest and DNA damage-inducible gene (GADD153) and cyclin-dependent kinase inhibitor gene (p21(waf1)): The results suggest that the synergistic enhancement of both GADD153 and p21(waf1) gene expressions by multiple treatments plays a significant role in human cancer prevention with green tea beverage. Our previous observation-that nucleic acids extracted from catechin-treated cells are colored-allowed us to speculate that catechins directly interact with nucleic acids. Surface plasmon resonance assay (Biacore) indicated that four catechins, EGCG, (-)-epicatechin gallate (ECG), (+)-gallocatechin gallate (GCG), and (+)-catechin gallate (CG), bound to DNA oligomers. Cold spray ionization mass spectrometry (CSI-MS) analysis showed that one to three EGCG molecules bound to single-stranded 18 mers of DNA and RNA. Moreover, one or two molecules of EGCG bound to double-stranded AG:CT oligomers of various nucleotide lengths. Double-stranded DNA (dsDNA) oligomers were detected only as EGCG-bound forms at high temperature, whereas at low temperature both the free and bound forms were detected, suggesting that EGCG protects double-stranded DNA oligomers from double-stranded melting into single-stranded DNA. We assume that catechins accumulate in both double-stranded DNA and RNA molecules through multiple administrations of green tea beverage in in vivo, and that the accumulated green tea catechins play a significant role for human cancer prevention.

Inhibition of carcinogenesis by tea constituents

The possible cancer preventive activity of tea has received much attention in recent years. The inhibitory activities of tea and tea constituents against carcinogenesis at different organ sites have been demonstrated in many animal models. The effect of tea consumption on human cancers, however, remains inconclusive. The mechanisms of action of tea polyphenols, especially EGCG, the most abundant and active catechin, have been extensively investigated. Most of the studies, however, were based on cell culture systems, and these mechanisms need to be evaluated and verified in animal models or humans in order to gain more understanding on the effect of tea consumption on human cancer. Human intervention trials are warranted to determine the possible prevention of cancer of specific sites by preparation of tea constituents.

Tea polyphenols for health promotion

People have been consuming brewed tea from the leaves of the Camellia sinensis plant for almost 50 centuries. Although health benefits have been attributed to tea, especially green tea consumption since the beginning of its history, scientific investigations of this beverage and its constituents have been underway for less than three decades. Currently, tea, in the form of green or black tea, next to water, is the most widely consumed beverage in the world. In vitro and animal studies provide strong evidence that polyphenols derived from tea may possess the bioactivity to affect the pathogenesis of several chronic diseases. Among all tea polyphenols, epigallocatechin-3-gallate has been shown to be responsible for much of the health promoting ability of green tea. Tea and tea preparations have been shown to inhibit tumorigenesis in a variety of animal models of carcinogenesis. However, with increasing interest in the health promoting properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and health benefits of tea with special reference to cancer and cardiovascular diseases.

Isolation, purification and identification of ellagic acid derivatives, catechins, and procyanidins from the root bark of Anisophyllea dichostyla R. Br

The root bark of Anisophyllea dichostyla R. Br. is traditionally used in the Democratic Republic Congo for the treatment of several conditions such as anorexia, fatigue and intestinal infections. We have identified and quantitated several polyphenol antioxidants in the methanol extract of the root bark (120g). The polyphenol content (3.32g/kg) was predominantly ellagitannins (25%) and polyhydroxyflavan-3-ols (catechins and procyanidins, 75%) with 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside and (-)-epicatechin as the major species in each class. These two compounds and the following species were identified unequivocally by NMR spectroscopy: (+)-catechin, (-)-epicatechin 3-O-gallate, 3-O-methyl ellagic acid, 3,3'-di-O-methyl ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside, and 3'-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. The following additional compounds were purified by semi-preparative HPLC and tentatively identified on the basis of UV spectra, HPLC-ESI-MS and nano-ESI-MS-MS: (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), epicatechin-(4beta-->8)-epicatechin (procyanidin B(2)), an (epi)catechin trimer, 3-O-methyl ellagic acid 4-O-beta-d-glucopyranoside, (-)-epicatechin 3-O-vanillate, 3,4-methylenedioxo ellagic acid 4'-O- beta-d-glucopyranoside, and 3,3'-di-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. Fractionation of the raw extract by column chromatography on silicic acid yielded 10 fractions. In the hypoxanthine/xanthine oxidase antioxidant assay system, CC-9 which contained a range of polyphenols dominated by (-)-epicatechin-O-gallate proved to be the most potent antioxidant fraction (IC(50)=52 micro g/mL) in terms of ROS scavenging. In terms of XO inhibition CC-8, dominated by (epi)catechin trimer and which also contained appreciable amounts of 3'-O-methyl ellagic acid 4'-O-beta-d-xylopyranoside, as well as the catechins (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), and (-)-epicatechin 3-O-gallate, proved to be the most potent (IC(50)=36 micro g/mL).

Tea and cancer prevention: molecular mechanisms and human relevance

Tea made from the leaves of the plant Camellia sinensis is a popular beverage. The possible cancer-preventive activity of tea and tea polyphenols has been studied extensively. This article briefly reviews studies in animal models, cell lines, and possible relevance of these studies to the prevention of human cancer. The cancer-preventive activity of tea constituents have been demonstrated in many animal models including cancer of the skin, lung, oral cavity, esophagus, stomach, liver, pancreas, small intestine, colon, bladder, prostate, and mammary gland. The major active constituents are polyphenols, of which (-)-epigallocatechin-3-gallate (EGCG) is most abundant, most active, and most studied, and caffeine. The molecular mechanisms of the cancer-preventive action, however, are just beginning to be understood. Studies in cell lines led to the proposal of many mechanisms on the action of EGCG. However, mechanisms based on studies with very high concentrations of EGCG may not be relevant to cancer prevention in vivo. The autooxidation of EGCG in cell culture may also produce activities that do not occur in many internal organs. In contrast to the cancer prevention activity demonstrated in different animal models, no such conclusion can be convincingly drawn from epidemiological studies on tea consumption and human cancers. Even though the human data are inconclusive, tea constituents may still be used for the prevention of cancer at selected organ sites if sufficient concentrations of the agent can be delivered to these organs. Some interesting examples in this area are discussed.

Microarray-assisted pathway analysis identifies mitogen-activated protein kinase signaling as a mediator of resistance to the green tea polyphenol epigallocatechin 3-gallate in her-2/neu-overexpressing breast cancer cells

Overexpression of the epidermal growth factor receptor family member Her-2/neu in breast cancer leads to autophosphorylation of the receptor and induction of multiple downstream signaling pathways, including the Akt kinase to nuclear factor-kappaB (NF-kappaB) cascade that is associated with poor prognosis. Previously, we showed that the green tea polyphenol epigallocatechin 3-gallate (EGCG) inhibits growth of NF639 Her-2/neu-driven breast cancer cells via reducing receptor autophosphorylation and downstream Akt and NF-kappaB activities. Interestingly, upon prolonged culture in the presence of EGCG, cells resistant to the polyphenol could be isolated. Here, we report that resistant cells have lost tyrosine phosphorylation on the Her-2/neu receptor. Surprisingly, they displayed elevated NF-kappaB activity, and inhibition of this activity sensitized cells to EGCG. Data from microarray studies of the original and resistant NF639 populations of cells were subjected to Gene Set Enrichment Analysis pathway assessment, which revealed that the mitogen activated protein kinase (MAPK) pathway was activated in the resistant cells. Treatment of the resistant cells with the MAPK inhibitor U0216 reduced growth in soft agar and invasive phenotype, whereas the combination of EGCG and U0216 resulted in cells with a cobblestone epithelial phenotype. Thus, activation of the MAPK pathway mediates resistance to EGCG.

Potential synergism of natural products in the treatment of cancer

Cancer is the second leading cause of death worldwide. There is thus increased interest in alternative treatment modalities that include chemotherapy, hormonal supplements, surgery, radiation therapy, complementary or alterative medicine, used alone or in combination. Therefore patients who are subjected to combination treatments such as hormonal supplements or alternative medicine face considerable risk of drug-drug interactions. The administration of herbal drugs by patients without a physician's prior counseling is increasing globally and there is a possibility of herb-drug interactions too. Herbal drugs or extracts themselves contain a combination of active constituents, which interact within themselves and also between other prescribed pharmaceutical drugs to either enhance (synergize) or decrease (antagonize) the therapeutic effect. This review focuses on a number of reports of herb-drug interactions, their mechanism of action with a special emphasis on dietetic phytochemicals such as quercetin, genistein, curcumin and catechins. All phytochemicals tend to increase the therapeutic effect by blocking one or more targets of the signal transduction pathway, by increasing the bioavailability of the other drug or, by stabilizing the other drug in the system.

Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits cyclooxygenase-2 expression in colon carcinogenesis

Tea, one of the most widely consumed beverages worldwide, has been shown to have anti-cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX-2) occurs during colon tumorigenesis and inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti-cancer effect associated with green tea impacted COX-2 expression levels, human colorectal cancer cell lines HT-29 and HCA-7, were treated with (-)-epigallocatechin-3-gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX-2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX-2 expression were examined. We observed that EGCG down regulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX-2 expression resulted in decreased COX-2 promoter activity via inhibition of nuclear factor kappaB (NF-kappaB) activation. EGCG also promoted rapid mRNA decay mediated through the COX-2 3'untranslated region (3'UTR). In conclusion, these data suggest that inhibition of COX-2 is a mechanism for the anti-proliferative effect of green tea and emphasizes the role that dietary factors have as anti-cancer agents.

Targeting multiple signaling pathways by green tea polyphenol (-)-epigallocatechin-3-gallate

Cell signaling pathways, responsible for maintaining a balance between cell proliferation and death, have emerged as rational targets for the management of cancer. Emerging data amassed from various laboratories around the world suggests that green tea, particularly its major polyphenolic constituent (-)-epigallocatechin-3-gallate (EGCG), possesses remarkable cancer chemopreventive and therapeutic potential against various cancer sites in animal tumor bioassay systems and in some human epidemiologic studies. EGCG has been shown to modulate multiple signal transduction pathways in a fashion that controls the unwanted proliferation of cells, thereby imparting strong cancer chemopreventive as well as therapeutic effects. This review discusses the modulations of important signaling events by EGCG and their implications in cancer management.

Inhibition of intestinal tumorigenesis in Apcmin/+ mice by (-)-epigallocatechin-3-gallate, the major catechin in green tea

The present study was designed to investigate the effects of two main constituents of green tea, (-)-epigallocatechin-3-gallate (EGCG) and caffeine, on intestinal tumorigenesis in Apc(min/+) mice, a recognized mouse model for human intestinal cancer, and to elucidate possible mechanisms involved in the inhibitory action of the active constituent. We found that p.o. administration of EGCG at doses of 0.08% or 0.16% in drinking fluid significantly decreased small intestinal tumor formation by 37% or 47%, respectively, whereas caffeine at a dose of 0.044% in drinking fluid had no inhibitory activity against intestinal tumorigenesis. In another experiment, small intestinal tumorigenesis was inhibited in a dose-dependent manner by p.o. administration of EGCG in a dose range of 0.02% to 0.32%. P.o. administration of EGCG resulted in increased levels of E-cadherin and decreased levels of nuclear beta-catenin, c-Myc, phospho-Akt, and phospho-extracellular signal-regulated kinase 1/2 (ERK1/2) in small intestinal tumors. Treatment of HT29 human colon cancer cells with EGCG (12.5 or 20 micromol/L at different times) also increased protein levels of E-cadherin by 27% to 58%, induced the translocation of beta-catenin from nucleus to cytoplasm and plasma membrane, and decreased c-Myc and cyclin D1 (20 micromol/L EGCG for 24 hours). These results indicate that EGCG effectively inhibited intestinal tumorigenesis in Apc(min/+) mice, possibly through the attenuation of the carcinogenic events, which include aberrant nuclear beta-catenin and activated Akt and ERK signaling.

Green tea polyphenol stimulates cancer preventive effects of celecoxib in human lung cancer cells by upregulation ofGADD153 gene

To more clearly understand the molecular mechanisms involved in synergistic enhancement of cancer preventive activity with the green tea polyphenol (-)-epigallocatechin gallate (EGCG), we examined the effects of cotreatment with EGCG plus celecoxib, a cyclooxygenase-2 selective inhibitor. We specifically looked for induction of apoptosis and expression of apoptosis related genes, with emphasis on growth arrest and DNA damage-inducible 153 (GADD153) gene, in human lung cancer cell line PC-9: Cotreatment with EGCG plus celecoxib strongly induced the expression of both GADD153 mRNA level and protein in PC-9 cells, while neither EGCG nor celecoxib alone did. However, cotreatment did not induce expression of other apoptosis related genes, p21(WAF1) and GADD45. Judging by upregulation of GADD153, only cotreatment with EGCG plus celecoxib synergistically induced apoptosis of PC-9 cells. Synergistic effects with the combination were also observed in 2 other lung cancer cell lines, A549 and ChaGo K-1. Furthermore, EGCG did not enhance GADD153 gene expression or apoptosis induction in PC-9 cells in combination with N-(4-hydroxyphenyl)retinamide or with aspirin. Thus, upregulation of GADD153 is closely correlated with synergistic enhancement of apoptosis with EGCG. Cotreatment also activated the mitogen-activated protein kinases (MAPKs), such as ERK1/2 and p38 MAPK: Preteatment with PD98059 (ERK1/2 inhibitor) and UO126 (selective MEK inhibitor) abrogated both upregulation of GADD153 and synergistic induction of apoptosis of PC-9 cells, while SB203580 (p38 MAPK inhibitor) did not do so, indicating that GADD153 expression was mediated through the ERK signaling pathway. These findings indicate that high upregulation of GADD153 is a key requirement for cancer prevention in combination with EGCG.

Green tea: Health benefits as cancer preventive for humans

Green tea is an acknowledged cancer preventive in Japan. The aim of this review article is to develop the concept of cancer prevention with green tea beverage for humans, which has largely been our exclusive research territory. This paper briefly reviews several topics, beginning with the introduction of our initial work on penta-O-galloyl-beta-D-glucose and (-)-epigallocatechin gallate (EGCG), the main constituent of green tea extract. The mechanisms of EGCG action, particularly the reduction of TNF-alpha are discussed, and we show how use of 3H-EGCG revealed a wide range of target organs for cancer prevention. The results of an epidemiological study in Saitama Prefecture allowed us to determine the cancer preventive amount of green tea-10 Japanese-size cups per day, about 2.5 g green tea extract-which made it possible for us to introduce the two-stage strategy of cancer prevention with green tea. The first stage is the delay of cancer onset for the general population. The second stage is the prevention of recurrence of cancer for patients following cancer treatment. Combination cancer prevention with green tea and cancer preventive drugs is proving especially beneficial for Japanese, who drink green tea every day. And finally, the stimulating comments of Prof. Jim Watson have encouraged green tea scientists.

Carnosol Inhibits -Catenin Tyrosine Phosphorylation and Prevents Adenoma Formation in the C57BL/6J/Min/+ (Min/+) Mouse

Carnosol, a constituent of the herb, rosemary, has shown beneficial medicinal and antitumor effects. Using the C57BL/6J/Min/+ (Min/+) mouse, a model of colonic tumorigenesis, we found that dietary administration of 0.1% carnosol decreased intestinal tumor multiplicity by 46%. Previous studies showed that tumor formation in the Min/+ mouse was associated with alterations in the adherens junctions, including an increased expression of tyrosine-phosphorylated β-catenin, dissociation of β-catenin from E-cadherin, and strongly reduced amounts of E-cadherin located at lateral plasma membranes of histologically normal enterocytes. Here, we confirm these findings and show that treatment of Min/+ intestinal tissue with carnosol restored both E-cadherin and β-catenin to these enterocyte membranes, yielding a phenotype similar to that of the Apc+/+ wild-type (WT) littermate. Moreover, treatment of WT intestine with the phosphatase inhibitor, pervanadate, removed E-cadherin and β-catenin from the lateral membranes of enterocytes, mimicking the appearance of the Min/+ tissue. Pretreatment of WT tissue with carnosol inhibited the pervanadate-inducible expression of tyrosine-phosphorylated β-catenin. Thus, the ApcMin allele produces adhesion defects that involve up-regulated expression of tyrosine-phosphorylated proteins, including β-catenin. Moreover, these data suggest that carnosol prevents Apc-associated intestinal tumorigenesis, potentially via its ability to enhance E-cadherin-mediated adhesion and suppress β-catenin tyrosine phosphorylation.

Cancer prevention with food factors: alone and in combination

Cancer prevention strategies making use of combined agents with distinct molecular mechanisms, rather than individual agents, are considered promising for higher efficacy and lower toxicity. Although there is increasing understanding of the synergistic combinations of synthetic agents, our knowledge regarding such combinations of food factors remains limited. We recently found that free radical generation suppressants from food items in combination with their scavengers at low concentrations exhibited notable synergistic effects in activated leukocytes, whereas combinations of agents with similar modes of action showed additive or antagonistic effects. For example, pound -)-epigallocatechin gallate (EGCG) from green tea has been shown to increase the endotoxin-induced production of proinflammatory mediators such as prostaglandin E(2) and tumor necrosis factor-alpha in RAW264.7 macrophages, whereas the soybean isoflavonoid genistein compensated for these inverse properties of EGCG, leading to marked suppression in combination. The present review briefly highlights the potential effectiveness of combinations of several agents with anti-oxidative and anti-inflammatory properties for cancer preventive strategies.

Antitumor Activity of Wheats With High Orthophenolic Content

The purpose of the present study is to develop in vitro assays for rapid screening of a large number of food samples that contain components that prevent tumor formation in vivo and to identify the components that contribute to this antitumor effect. Wheat samples representing numerous strains and cultivars were screened for their in vitro ability to kill a human colon cancer cell, CaCo2, in culture by trypan blue dye exclusion assay. Wheat samples were assayed for orthophenolic acid content by use of a colorimetric assay using a bathochromatic shift at 350 nm. Blood levels of specific orthophenols were determined by high-performance liquid chromatography/mass spectrometry. Wheat samples, which contained low, mid-, and high in vitro protective ability, were used to formulate balanced diets fed to Min mice. Wheat samples with high ability to kill CaCo2 cells in culture had high levels of orthophenolic acids and produced elevated blood caffeic acid levels when used in diets. These factors correlated positively with their ability to prevent tumor formation in Min mice. When fiber content was equal in diets the content of orthophenolic acids in wheats predicted the antitumor activity in vivo.