Beneficial effects of tea and its polyphenols against prostate cancer

Modulation of Gut Microbial Biomarkers and Metabolites in Cancer Management by Tea Compounds

Cancers are causing millions of deaths and leaving a huge clinical and economic burden. High costs of cancer drugs are limiting their access to the growing number of cancer cases. The development of more affordable alternative therapy could reach more patients. As gut microbiota plays a significant role in the development and treatment of cancer, microbiome-targeted therapy has gained more attention in recent years. Dietary and natural compounds can modulate gut microbiota composition while providing broader and more accessible access to medicine. Tea compounds have been shown to have anti-cancer properties as well as modulate the gut microbiota and their related metabolites. However, there is no comprehensive review that focuses on the gut modulatory effects of tea compounds and their impact on reshaping the metabolic profiles, particularly in cancer models. In this review, the effects of different tea compounds on gut microbiota in cancer settings are discussed. Furthermore, the relationship between these modulated bacteria and their related metabolites, along with the mechanisms of how these changes led to cancer intervention are summarized.

Immunomodulatory, Anticancer, and Antimicrobial Effects of Rice Bran Grown in Iraq: An In Vitro and In Vivo Study

Emerging evidence supports the role of rice bran in cancer prevention. Studies were conducted on multiple rice cultivars. However, limited studies were conducted on rice cultivars in the Middle East. In this study, rice bran growing in Iraq (O. sativa ssp. Japonica, cultivars: Amber Barka) was evaluated for its effect on preventing cancer and stimulating the immune system. Rice bran was collected from local mills in Al-Najaf (south of Iraq). Several solvent extracts (ethanol, methanol, n-hexane, and water) were prepared by maceration. MTT assay was used to measure the antiproliferative effects of extracts against a panel of cancer cell lines. The ability of each extract to induce apoptosis and inhibit angiogenesis was measured using standard ELISA kits. The effect of extracts on the immune system was evaluated using a lymphocyte proliferation assay, a pinocytic activity assay, a phagocytic activity assay, and a Th1/Th2 cytokine detection kit. A microbroth dilution method was used to detect the antimicrobial activity of each extract against different microbial strains. LC-MS analysis was used to detect the phytochemical composition of extracts, while DPPH assay was used to determine the antioxidant activity. For the in vivo study, rice bran was added to mouse fodder at 10% and 20%. Mice were treated for two weeks using mouse fodder supplemented with rice bran. In the third week of the experiment, EMT6/P breast cancer cells (1 × 10⁶ cells/mL) were injected subcutaneously into the abdominal area of each mouse. The dimensions of the grown tumors were measured after 14 days of tumor inoculation. A microbroth dilution method was used to evaluate the antimicrobial activity of rice bran extracts against three bacterial strains. The highest antiproliferative activity was observed in ethanol and n-hexane extracts. Ethanol and methanol extract showed the highest activity to induce apoptosis and inhibit angiogenesis. Both extracts were also effective to enhance immunity by activating lymphocytes and phagocytes proliferation with modulations of cytokine levels. The incorporation of rice bran in mice food caused a 20% regression in tumor development and growth compared with the negative control. All extracts exhibited limited antimicrobial activity against tested microorganisms. Methanol extract showed antioxidant activity with an IC₅₀ value of 114 µg/mL. LC-MS analysis revealed the presence of multiple phytochemicals in rice bran including apiin, ferulic acid, and succinic acid. Rice bran is a rich source of active phytochemicals that may inhibit cancer and stimulate the immune system. Rice bran's biological activities could be due to the presence of multiple synergistically active phytochemicals. Further studies are needed to understand the exact mechanisms of action of rice bran.

Polyphenon E Effects on Gene Expression in PC-3 Prostate Cancer Cells

Polyphenon E (Poly E) is a standardized, caffeine-free green tea extract with defined polyphenol content. Poly E is reported to confer chemoprotective activity against prostate cancer (PCa) progression in the TRAMP model of human PCa, and has shown limited activity against human PCa in human trials. The molecular mechanisms of the observed Poly E chemopreventive activity against PCa are not fully understood. We hypothesized that Poly E treatment of PCa cells induces gene expression changes, which could underpin the molecular mechanisms of the limited Poly E chemoprevention activity against PCa. PC-3 cells were cultured in complete growth media supplemented with varied Poly E concentrations for 24 h, then RNA was isolated for comparative DNA microarray (0 vs. 200 mg/L Poly E) and subsequent TaqMan qRT-PCR analyses. Microarray data for 54,613 genes were filtered for >2-fold expression level changes, with 8319 genes increased and 6176 genes decreased. Eight genes involved in key signaling or regulatory pathways were selected for qRT-PCR. Two genes increased expression significantly, MXD1 (13.98-fold; p = 0.0003) and RGS4 (21.98-fold; p = 0.0011), by qRT-PCR. MXD1 and RGS4 significantly increased gene expression in Poly E-treated PC-3 cells, and the MXD1 gene expression increases were Poly E dose-dependent.

The Influence of Green and Black Tea Infusion Parameters on Total Polyphenol Content and Antioxidant Activity by ABTS and DPPH Assays

Tea contains about 230 chemical bioactive compounds, of which polyphenols represent the most considerable fraction (30% of total dry weight). These compounds have relevant nutritional and pharmacological effects on human health, exerting antioxidant activities against oxidative stress-induced damage. The industrial processes applied in tea production can lead to qualitative and quantitative changes in the phenolic content and composition and in antioxidant properties, thus influencing their potential biological activities. Meanwhile, the procedure for tea preparation may influence the quantity of the extracted phenolic compounds. In this study, the effects of different infusion parameters, such as the water type used for infusion (tap water, distilled water, and natural mineral water), time (3, 5, and 10 min), temperature (T = 80 °C and 100 °C), and pH (ranged between 3 and 9) were considered. The optimal infusion variables resulting from the study were obtained by extracting phenolic compounds at T = 100 °C for 10 min, both for green (916.12–1169.81 mg GAE/g) and black (932.03–1126.62 mg GAE/g) bagged tea samples, respectively.

Verbascoside inhibits the epithelial-mesenchymal transition of prostate cancer cells through high-mobility group box 1/receptor for advanced glycation end-products/TGF-β pathway

INTRODUCTION

Prostate cancer has significant mortality and metastasis rate in the male. Unfortunately, effective treatment for patients with advanced prostate cancer is still lacking. Verbascoside, a phenylethanoid glycoside, displays various pharmacological properties, such as the anti-cancer activities. The present study aimed to evaluate the effects of purified verbascoside on human prostate cancer and the associated molecular mechanisms.

MATERIALS AND METHODS

The human prostate cancer cell lines, Du-145 and PC-3, were treated with various concentrations of verbascoside (0.1, 1, 10 μM) for 24 h followed by the examination of cell viability using MTT and trypan blue exclusion assays. Cell migration and invasion capacities were assessed by wound healing assay and transwell system. Western blot and immunofluorescence staining were used to detect the expression of epithelial-mesenchymal transition (EMT)-associated factors, components of transforming growth factor (TGF-β)/Smad signaling, and high-mobility group box (HMGB)/receptor for advanced glycation end-products (RAGE) axis.

RESULTS

Verbascoside treatment significantly inhibited cell proliferation, migration, and invasion abilities of Du-145 and PC-3 cells. We showed that verbascoside decreased the expression of EMT promotors, Snail and Slug, and increased the expression of E-cadherin. Moreover, the expression level of alpha-smooth muscle actin was downregulated by verbascoside as well. Besides, we found that the TGF-β pathway was suppressed, which was demonstrated by the diminished expression of type I and II TGF-β receptors and phosphorylated Smad2/3 along with the upregulated Smad7. Our data suggested that this downregulation of TGF-β signaling was mediated by repression of HMGB 1 (HMGB1)/RAGE axis.

CONCLUSION

Verbascoside mitigated the cell proliferation and aggressiveness of prostate cancer via downregulation of TGF-β-associated EMT progression through HMGB1/RAGE suppression. Collectively, our findings revealed that verbascoside may be a beneficial dietary supplement for prostate cancer patients.

Topoisomerase II Poisons: Converting Essential Enzymes into Molecular Scissors

The extensive length, compaction, and interwound nature of DNA, together with its controlled and restricted movement in eukaryotic cells, create a number of topological issues that profoundly affect all of the functions of the genetic material. Topoisomerases are essential enzymes that modulate the topological structure of the double helix, including the regulation of DNA under- and overwinding and the removal of tangles and knots from the genome. Type II topoisomerases alter DNA topology by generating a transient double-stranded break in one DNA segment and allowing another segment to pass through the DNA gate. These enzymes are involved in a number of critical nuclear processes in eukaryotic cells, such as DNA replication, transcription, and recombination, and are required for proper chromosome structure and segregation. However, because type II topoisomerases generate double-stranded breaks in the genetic material, they also are intrinsically dangerous enzymes that have the capacity to fragment the genome. As a result of this dualistic nature, type II topoisomerases are the targets for a number of widely prescribed anticancer drugs. This article will describe the structure and catalytic mechanism of eukaryotic type II topoisomerases and will go on to discuss the actions of topoisomerase II poisons, which are compounds that stabilize DNA breaks generated by the type II enzyme and convert these essential enzymes into "molecular scissors." Topoisomerase II poisons represent a broad range of structural classes and include anticancer drugs, dietary components, and environmental chemicals.

The role of nutritional interventions in prostate cancer: A review

The high prevalence rate in conjunction with the long latency period made prostate cancer (PCa) an attractive and reasonable candidate for preventive measures. So far, several dietary and nutritional interventions have been implemented and studied with the aim of preventing the development or delaying the progression of PCa. Calorie restriction accompanied by weight loss has been shown to be associated with decreased likelihood of aggressive PCa. Supplements have played a major role in nutritional interventions. While genistein and lycopene seemed promising as preventive agents, minerals such as zinc and selenium were shown to be devoid of protective effects. The role of vitamins has been widely studied, with special emphasis on vitamins with antioxidant properties. Data related to Vitamin A and Vitamin C were rather controversial and positive effects were of insignificant magnitude. Vitamin E was associated with a decreased risk of PCa in high-risk groups like smokers. However, when it comes to Vitamin D, the serum levels might affect the risk of PCa. While deficiency of this vitamin was associated with increased risk, high serum levels imposed the risk of aggressive disease. Despite the seemingly promising effects of dietary measures on PCa, no firm recommendation could be made due to the limitations of the studies and evidence. However, the majority of these advices could be followed by the patients with the intent of living a healthy lifestyle.

Evaluating the radioprotective effect of single dose and daily oral consumption of green tea, grape seed, and coffee bean extracts against gamma irradiation

INTRODUCTION

The aim of this study was to investigate and compare the radio-protective effect of green tea, grape seed, and coffee bean extracts in different oral consumption methods in mice.

MATERIALS AND METHODS

In this experimental-quantitative study 150 mice in 15 equally sized groups were used. For each extract, two groups received 200 mg/kg of herbal extracts' combination for 7 and 30 consecutive days before irradiation, and one group received 800 mg/kg of the extract 2 h before irradiation (3 Gy gamma-rays of Co-60). The similar groups were classified to receive a combination of the plant extracts (green tea, grape seed, and coffee bean). Irradiation without consuming plant extract (irradiated group), and a control group were also devised. Alkaline comet and micronucleus assays were used to investigate the radioprotective effect on mice blood and bone marrow cells, respectively.

RESULTS

Consumption of all plant extracts significantly decreased the radiation damage to blood and bone marrow cells, compared to the irradiated group (p < 0.01), with grape seed extract showing higher protective effect. Continuous daily oral consumption (one week/month) showed a significant higher radioprotective effect compared to single consumption (p < 0.05). Continuous consumption of the combination of the extracts showed a higher radio-protection in comparison to each of the plant extracts (p < 0.03).

CONCLUSIONS

The radioprotective effect of continuous consumption (for one week/month) of the plant extracts was greater than single dose. In continuous consumption protocols, we found the synergetic property and higher radioprotective effect of the plant extract combination compared to each one.

Characterizing relationship between chemicals and in vitro bioactivities of teas made by six typical processing methods using a single Camellia sinensis cultivar, Meizhan

Processing method is considered as a major factor that affects biotransformation of phytochemicals in tea and leads to diverse flavor and bioactivity of tea. In the present work, six typical tea manufacturing processings were employed to compare the effect on chemical composition of teas through using leaves of the single tea cultivar – – Camellia sinensis var. Meizhan. And in vitro antioxidant activity, inhibition against α-glucosidase and three lipid metabolism enzymes of these teas were also investigated, the relationships among them were analyzed further. As fresh leaves were processed into six categories of teas, the content of total catechins (TCs) has decreased in varying degrees while theaflavins (TFs) has increased. The antioxidant capacity composite index (ACCI) from high to low were green tea, yellow tea, oolong tea, white tea, dark tea, and black tea with the range from 98.44 to 58.38, which dominated by the content of TCs. Furthermore, all categories of teas possessed an inhibition effect on the pancreatic lipase (PL), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-COA reductase), lecithin cholesterol acyltransferase (LCAT), and α-glucosidase. The inhibition rate of PL and α-glucosidase appears to be positively influenced by TFs content (r =0.863, r =0.857, p < 0.05) while that of LCAT showed significant positive correlations with the content of tea polyphonels (TPs) (r = 0.902, p < 0.01). These results provide a better understanding of the relationships between processing method and chemical components of tea. It is suggested that various tea categories possess potential healthy effects which could serve as promising nutritional supplements.

Myricitrin from Combretum lanceolatum Exhibits Inhibitory Effect on DNA-Topoisomerase Type IIα and Protective Effect Against In Vivo Doxorubicin-Induced Mutagenicity

Flavonoids-compounds abundant in balanced daily diets-have been extensively investigated for biological activity. The pronounced antiproliferative effects of flavonoids have prompted studies to elucidate their mode of action against tumor cells. The anticancer properties of myricetin, a 3',4',5'-tri-hydroxylated flavonol, have been confirmed for a number of neoplasms, but myricitrin, its 3-O-rhamnoside derivative found in fruits and other parts of edible plants, has been scarcely investigated as a chemopreventive agent. This study evaluated the antiproliferative potential of myricitrin obtained from Combretum lanceolatum (Combretaceae) against MCF7 (breast), PC-3 (prostate), HT-29 (colon), 786-0 (kidney), and HL-60 (acute promyelocytic leukemia) cancer cell lines, using the sulforhodamine B and tetrazolium salt assays. Myricitrin proved most effective in inhibiting growth of HL-60 cells (GI₅₀ = 53.4 μmol·L^-1), yet showed weak antiproliferative activity against other cell lines. Possible cytotoxic mechanisms involving inhibition of topoisomerases I and IIα by myricitrin were also evaluated, revealing inhibitory activity only against topoisomerase IIα. The results suggested that topoisomerase IIα inhibition is the probable mechanism responsible for the antiproliferative activity of myricitrin. In vivo mutagenicity by myricitrin and its possible antimutagenic effect on doxorubicin-induced DNA damage were also investigated by performing the somatic mutation and recombination test (SMART) on Drosophila melanogaster. Myricitrin proved nonmutagenic to the offspring of standard (ST) and high-bioactivation (HB) crosses, while cotreatments with doxorubicin revealed the antimutagenic properties of myricitrin, even under conditions of high metabolic activation.

Protein Binding Characteristics of the Principal Green Tea Catechins: A QCM Study Comparing Crude Extract to Pure EGCG

Label-free detection methods such as the quartz crystal microbalance (QCM) are well suited to the analysis of molecular interactions in complex mixtures such as crude botanical extracts. In the present study, the binding characteristics of epigallocatechin gallate (EGCG) and crude green tea extract solutions to bovine serum albumin (BSA) have been investigated. The adsorbed mass levels onto BSA-functionalized surfaces were measured at various solution concentrations. Langmuir and Freundlich isotherms were used to model the adsorption data. The Langmuir isotherm better described the adsorption behavior with correlations of 0.68 and 0.70 for the EGCG and the crude extract solutions, respectively. The better fit of the Langmuir model indicates that adsorption occurs homogeneously and that aggregation is negligible. The mass saturation is estimated to be 58% higher for the crude green tea solution as compared to the pure EGCG solution (7.9 ng/cm² for green tea and 5 ng/cm² for EGCG). The increased adsorption for the crude extract indicates that the additional tea chemical constituents are binding to alternate sites on the protein molecule and that competitive binding is a nondominant effect. However, a reduced adsorption rate for the crude extract was also observed, indicating some presence of competitive mechanisms. The results demonstrate the utility of the QCM for the analysis of protein binding in crude mixtures as well as pure compounds.

Nutritional Relevance of Flavonoids in Disease Prevention

Flavonoids are not essential nutrients in that their absence from the diet does not produce deficiency conditions in animals and man. However, many have important similarities to pharmacological agents used in the treatment of disease. Their role as dietary components in disease prevention is less clear. Many potentially anti-carcinogenic and anti-atherogenic effects observed in cell cultures will not be of nutritional relevance unless flavonoids gain access to appropriate cellular sites. The bioavailability of flavonoids will depend on numerous factors including molecular structure, the amount consumed, the food matrix, degree of bioconversion in the gut and tissues, the nutrient status of the host and genetic factors. Moreover, extensive and rapid intestinal and hepatic metabolism of flavonoids suggests that the body may treat them as xenobiotic and potentially toxic compounds requiring rapid elimination. Consequently, in addition to potential health benefits, possible adverse effects of flavonoids in the diet also need to be considered when assessing their roles in the prevention of degenerative diseases.

Possible Mechanisms of Green Tea and Its Constituents against Cancer

A number of epidemiological, clinical, and experimental researches have indicated that administration of green tea appears to have anti-cancer activity. According to findings of laboratory cell culture studies, a diverse mechanism has been observed underlying the effects of green tea catechins against cancer. These mechanisms include anti-oxidant activity, cell cycle regulation, receptor tyrosine kinase pathway inhibition, immune system modulation, and epigenetic modification control. This review discusses the results of these studies to provide more insight into the effects of green tea administration on cancers observed to date in this research field.

Kushui Rose (R. Setate x R. Rugosa) decoction exerts antitumor effects in C. elegans by downregulating Ras/MAPK pathway and resisting oxidative stress

Kushui rose (R. Setate x R. Rugosa) (KR) is a traditional Chinese medicine proven to be a potent antioxidant, and used for thousands of years. Approximately 30% of all human cancers relevant to mutational activated Ras, and over-activated Ras are accompanied by increased accumulation of reactive oxygen species (ROS). Thus, one way of developing anticancer drugs is to reduce ROS accumulation. Therefore, KR was predicted to have potential to combat over-activated Ras-related cancer. C. elegans with let‑60(gf)/ras mutant, which exhibited tumor-like symptoms of the multivulva phenotype, was employed to determine the effect of KR on Ras/MAPK pathway. Other strains of worms and H2DCF-DA dye were also applied to study the antioxidant stress capacity of KR. This study was aimed to determine whether KR has a potential effect on combat over-activated Ras-related cancer through resistance to oxidative stress. Our results showed that Kushui rose decoction (KRD) has potent antioxidant activity in vitro, and can inhibit over-activated Ras in vivo. Further, KRD significantly suppressed over-activated Ras/MAPK pathway by regulating oxidative stress-related proteins, such as forkhead transcription factor (DAF-16), glutathione S-transferase-4 (GST-4), superoxide dismutases (SODs) and heat shock protein-16.2 (HSP-16.2). However, essential oil and hydrosol of KR had no effect on over-activated Ras. Thus these results reminded us that people usually soak rose in hot water to prepare 'rose tea' as an effective way for health care. Thus, KRD was demonstrated to be a potential drug candidate for combating over-activated Ras-related cancer as an antioxidant.

Dietary patterns and prostate cancer risk in Japanese: the Japan Public Health Center-based Prospective Study (JPHC Study)

PURPOSE

The development of prostate cancer may be impacted by environmental factors, including diet. The aim of this study was to evaluate the association between dietary patterns and risk of prostate cancer in a large prospective cohort study among Japanese men.

METHODS

A total of 43,469 men who participated in the Japan Public Health Center-based Prospective Study were followed from 1995 to 1998 to the end of 2012, during which 1,156 cases of prostate cancer were newly identified. Dietary intake was assessed using a validated food frequency questionnaire in the 5-year follow-up survey.

RESULTS

Three major dietary patterns were derived using exploratory factors analysis: prudent, westernized, and traditional dietary patterns. The westernized dietary pattern was associated with a higher risk of total prostate cancer (HR: 1.22; 95% CI 1.00-1.49; p trend = 0.021), localized cancer (HR: 1.24; 95% CI 0.97-1.57; p trend = 0.045), and advanced cancer (HR: 1.23; 95% CI 0.82-1.84; p trend = 0.233). The prudent dietary pattern was associated with a lower risk of total and localized prostate cancer, with respective multivariable HRs for the highest and lowest quintiles of 0.71 (95% CI 0.50-1.02; p trend = 0.037) and 0.63 (95% CI 0.38-1.03; p trend = 0.048) among subjects detected by subjective symptoms. No association was found between the traditional dietary pattern and prostate cancer risk among our subjects.

CONCLUSION

Our results suggest that a western-style diet may lead to a higher risk of prostate cancer in the total population, whereas the prudent diet contributes to a lower risk among subjects detected by subjective symptoms.

Dual Roles of Oxidative Stress in Metal Carcinogenesis

It has been well established that environmental and occupational exposure to heavy metal causes cancer in several organs. Although the exact mechanism of heavy metal carcinogenesis remains elusive, metal-generated reactive oxygen species (ROS) are essential. ROS can play two roles in metal carcinogenesis; two stages in the process of metal carcinogenesis differ in the amounts of ROS activating a dual redox-mediated mechanism. In the early stage of metal carcinogenesis, ROS acts in an oncogenic role. However, in the late stage of metal carcinogenesis, ROS plays an antioncogenic role. Similarly, NF-E2-related factor 2 (Nrf2) also has two different roles, which makes it a key molecule for separating metal carcinogenesis into two different stages. In the early stage, inducible Nrf2 fights against elevated ROS to decrease cell transformation by its antioxidant protection property. In the late stage, constitutively activated Nrf2 manipulates reduced ROS to perform a comfortable environment for apoptosis resistance through an oncogenic role. Interestingly, a cunning carcinogenic mechanism takes advantage of the dual role of Nrf2 to implement the dual role of ROS through a series of redox adaption mechanisms. In this review, we discuss the paradox in the rationales behind the two opposite ROS roles and focus on their potential pharmacological application. The dual role of ROS represents a 'double-edged sword' with many possible novel ROS-mediated strategies in cancer therapy in metal carcinogenesis.

ROS-modulated therapeutic approaches in cancer treatment

PURPOSE

Reactive oxygen species (ROS) are produced in cancer cells as a result of increased metabolic rate, dysfunction of mitochondria, elevated cell signaling, expression of oncogenes and increased peroxisome activities. Certain level of ROS is required by cancer cells, above or below which lead to cytotoxicity in cancer cells. This biochemical aspect can be exploited to develop novel therapeutic agents to preferentially and selectively target cancer cells.

METHODS

We searched various electronic databases including PubMed, Web of Science, and Google Scholar for peer-reviewed english-language articles. Selected articles ranging from research papers, clinical studies, and review articles on the ROS production in living systems, its role in cancer development and cancer treatment, and the role of microbiota in ROS-dependent cancer therapy were analyzed.

RESULTS

This review highlights oxidative stress in tumors, underlying mechanisms of different relationships of ROS and cancer cells, different ROS-mediated therapeutic strategies and the emerging role of microbiota in cancer therapy.

CONCLUSION

Cancer cells exhibit increased ROS stress and disturbed redox homeostasis which lead to ROS adaptations. ROS-dependent anticancer therapies including ROS scavenging anticancer therapy and ROS boosting anticancer therapy have shown promising results in vitro as well as in vivo. In addition, response to cancer therapy is modulated by the human microbiota which plays a critical role in systemic body functions.

Shengmai Formula suppressed over-activated Ras/MAPK pathway in C. elegans by opening mitochondrial permeability transition pore via regulating cyclophilin D

Since about 30% of all human cancers contain mutationally activated Ras, down regulating the over-activation of Ras/MAPK pathway represents a viable approach for treating cancers. Over-activation of Ras/MAPK pathway is accompanied by accumulation of reactive oxygen species (ROS). One approach for developing anti-cancer drugs is to target ROS production and their accumulation. To test this idea, we have employed C. elegans of let-60 (gf) mutant, which contain over-activated let-60 (the homolog of mammalian ras) and exhibit tumor-like symptom of multivulva phenotype, to determine whether anti-oxidants can affect their tumor-like phenotype. Specifically we studied the effect of Shengmai formula (SM), a traditional Chinese medicine that has strong anti-oxidant activity, on the physiology of let-60 (gf) mutants. Unexpectedly, we found that SM treatment led to the opening of mitochondrial permeability transition pore by regulating cyclophilin D and then triggered oxidative stress and related signaling pathway activation, including p53, JNK, and p38/MAPK pathways. Finally, SM induced mitochondrial pathway of apoptosis and inhibited the tumor-like symptom of the multivulva phenotype of let-60(gf) mutants. Our results provide evidences to support that SM act as a pro-oxidant agent and could serve as a potential drug candidate for combating over-activated Ras-related cancer.

In vitro cytotoxicity, genotoxicity and antigenotoxicity assessment of Solanum lycocarpum hydroalcoholic extract

CONTEXT

Solanum lycocarpum A. St.-Hil. (Solanaceae), popularly known as 'fruta-do-lobo' (wolf fruit), 'lobeira' and 'jurubebão', is commonly used by native people of Central Brazil in powder form or as a hydroalcoholic extract for the management of diabetes and obesity and to decrease cholesterol levels.

OBJECTIVE

The present study determines the possible cytotoxic, genotoxic and antigenotoxic activities of hydroalcoholic extract of the S. lycocarpum fruits (SL).

MATERIALS AND METHODS

The clonogenic efficiency assay was used to determine the cytotoxicity. Three concentrations of SL (16, 32 and 64 μg/mL) were used for the evaluation of its genotoxic and antigenotoxic potential on V79 cells using the micronucleus and comet assays. In the antigenotoxicity assays, the cells were treated simultaneously with SL and the alkylating agent methyl methanesulphonate (MMS, 44 μg/mL for the micronucleus assay and 22 μg/mL for the comet assay) as an inducer of micronuclei and DNA damage.

RESULTS

The results showed that SL was cytotoxic at concentrations up to 64 μg/mL. No significant differences in the rate of chromosome or DNA damage were observed between cultures treated with SL and the control group. In addition, the frequencies of micronuclei and DNA damage induced by MMS were significantly reduced after treatment with SL. The damage reduction percentage ranged from 68.1% to 79.2% and 12.1% to 16.5% for micronucleus and comet assays, respectively.

DISCUSSION AND CONCLUSION

SL exerted no genotoxic effect and exhibited chemopreventive activity against both genomic and chromosome damage induced by MMS.

Comparison of bioactivities and phenolic composition of Choerospondias axillaris peels and fleshes

BACKGROUND

Choerospondias axillaris is both an edible and medicinal fruit. It has a growing popularity and economic importance due to its nutritive value and medicinal effects, but comprehensive information on the chemical composition and bioactivity of its fruits is still lacking. Therefore the aim of this study was to investigate the antioxidant, antimicrobial and antiproliferative effects and chemical composition of peel polyphenolic (PP) and flesh polyphenolic (FP) extracts from C. axillaris.

RESULTS

The phenolics and flavonoids of peel were significantly higher than those of flesh. Ultra-performance liquid chromatography (UPLC) and ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight-mass spectrometry (UPLC/ESI-QTOF-MS(2) ) analysis revealed that (+)-catechin and oligomeric procyanidins were the most abundant compounds in PP and FP. Both extracts exhibited strong ferric-reducing antioxidant power, total antioxidant activity and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(•) )-scavenging ability. PP showed a significantly higher antimicrobial effect against tested strains than that of FP, in a dose-dependent manner. Furthermore, both extracts inhibited the growth of HepG2 and Caco-2 cells in a dose- and time-dependent manner, with IC50 values of 39.31 and 47.49 µg mL(-1) to HepG2 cells and 101.90 and 102.61 µg mL(-1) to Caco-2 cells respectively.

CONCLUSION

This is the first detailed report on the chemical composition and bioactivities of C. axillaris fruits. © 2015 Society of Chemical Industry.

Role of epigenetic modifications in luminal breast cancer

Luminal breast cancers represent approximately 75% of cases. Explanations into the causes of endocrine resistance are complex and are generally ascribed to genomic mechanisms. Recently, attention has been drawn to the role of epigenetic modifications in hormone resistance. We review these here. Epigenetic modifications are reversible, heritable and include changes in DNA methylation patterns, modification of histones and altered microRNA expression levels that target the receptors or their signaling pathways. Large-scale analyses indicate distinct epigenomic profiles that distinguish breast cancers from normal and benign tissues. Taking advantage of the reversibility of epigenetic modifications, drugs that target epigenetic modifiers, given in combination with chemotherapies or endocrine therapies, may represent promising approaches to restoration of therapy responsiveness in these cases.

Dietary factors and risk for advanced prostate cancer

Prostate cancer is the second most common cancer among men worldwide. Although some nutrients have been linked to the development of total prostate cancer, it remains unclear whether these nutrients modulate the risk of its clinically significant form - advanced tumor. Therefore, this study sought to perform a systematic review of the literature on this topic. The papers reviewed were identified from PubMed using keywords diet and advanced, metastatic, or lethal prostate cancer. A total of 46 papers published until September 2012 met our eligibility criteria and thus were evaluated in this review. Epidemiologic studies have shown that, overall, the habitual consumption of a diet high in saturated fat, well-done meats, and calcium is associated with an increased risk for advanced prostate cancer. An inconsistent association was observed for intake of total meat, fruits, and vegetables. Although most case-control studies suggest that intake of these nutrients or foods significantly alters advanced prostate cancer risk, cohort studies yielded mixed results. No apparent effect of fish and zinc intake on advanced prostate cancer was found in most epidemiologic studies. Epidemiologic studies conducted to date have revealed that some dietary factors modulate the risk for advanced prostate cancer. If these findings are confirmed by more adequately powered epidemiologic studies, especially prospective cohort studies that measure the nutrients and their biochemical indicators, the risk of advanced prostate cancer, which is fatal and thus clinically significant, may be reduced by dietary modification or chemoprevention.

Inhibition of catalase by tea catechins in free and cellular state: a biophysical approach

Tea flavonoids bind to variety of enzymes and inhibit their activities. In the present study, binding and inhibition of catalase activity by catechins with respect to their structure-affinity relationship has been elucidated. Fluorimetrically determined binding constants for (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) with catalase were observed to be 2.27×106 M(-1) and 1.66×106 M(-1), respectively. Thermodynamic parameters evidence exothermic and spontaneous interaction between catechins and catalase. Major forces of interaction are suggested to be through hydrogen bonding along with electrostatic contributions and conformational changes. Distinct loss of α-helical structure of catalase by interaction with EGCG was captured in circular dichroism (CD) spectra. Gallated catechins demonstrated higher binding constants and inhibition efficacy than non-gallated catechins. EGCG exhibited maximum inhibition of pure catalase. It also inhibited cellular catalase in K562 cancer cells with significant increase in cellular ROS and suppression of cell viability (IC50 54.5 µM). These results decipher the molecular mechanism by which tea catechins interact with catalase and highlight the potential of gallated catechin like EGCG as an anticancer drug. EGCG may have other non-specific targets in the cell, but its anticancer property is mainly defined by ROS accumulation due to catalase inhibition.

Phytochemicals as Anticancer and Chemopreventive Topoisomerase II Poisons

Phytochemicals are a rich source of anticancer drugs and chemopreventive agents. Several of these chemicals appear to exert at least some of their effects through interactions with topoisomerase II, an essential enzyme that regulates DNA supercoiling and removes knots and tangles from the genome. Topoisomerase II-active phytochemicals function by stabilizing covalent protein-cleaved DNA complexes that are intermediates in the catalytic cycle of the enzyme. As a result, these compounds convert topoisomerase II to a cellular toxin that fragments the genome. Because of their mode of action, they are referred to as topoisomerase II poisons as opposed to catalytic inhibitors. The first sections of this article discuss DNA topology, the catalytic cycle of topoisomerase II, and the two mechanisms (interfacial vs. covalent) by which different classes of topoisomerase II poisons alter enzyme activity. Subsequent sections discuss the effects of several phytochemicals on the type II enzyme, including demethyl-epipodophyllotoxins (semisynthetic anticancer drugs) as well as flavones, flavonols, isoflavones, catechins, isothiocyanates, and curcumin (dietary chemopreventive agents). Finally, the leukemogenic potential of topoisomerase II-targeted phytochemicals is described.

Plant phytochemicals as epigenetic modulators: role in cancer chemoprevention

In recent years, "nutri-epigenetics," which focuses on the influence of dietary agents on epigenetic mechanism(s), has emerged as an exciting novel area in epigenetics research. Targeting of aberrant epigenetic modifications has gained considerable attention in cancer chemoprevention research because, unlike genetic changes, epigenetic alterations are reversible and occur during early carcinogenesis. Aberrant epigenetic mechanisms, such as promoter DNA methylation, histone modifications, and miRNA-mediated post-transcriptional alterations, can silence critical tumor suppressor genes, such as transcription factors, cell cycle regulators, nuclear receptors, signal transducers, and apoptosis-inducing and DNA repair gene products, and ultimately contribute to carcinogenesis. In an effort to identify and develop anticancer agents which cause minimal harm to normal cells while effectively killing cancer cells, a number of naturally occurring phytochemicals in food and medicinal plants have been investigated. This review highlights the potential role of plant-derived phytochemicals in targeting epigenetic alterations that occur during carcinogenesis, by modulating the activity or expression of DNA methyltransferases, histone modifying enzymes, and miRNAs. We present in detail the epigenetic mode of action of various phytochemicals and discuss their potential as safe and clinically useful chemopreventive strategies.

Epigenetic modifications by dietary phytochemicals: implications for personalized nutrition

In the last two decades, the study of epigenetic modification emerged as one of the major areas of cancer treatment targeted by dietary phytochemicals. Recent studies with various types of cancers revealed that the epigenetic modifications are associated with the food source corresponds to dietary phytochemicals. The dietary phytochemicals have been used in Asian countries for thousands of years to cure several diseases including cancer. They have been reported to modulate the several biological processes including histone modification, DNA methylation and non-coding microRNA expression. These events play a vital role in carcinogenesis. Various studies suggest that a number of dietary compounds present in vegetables, spices and other herbal products have epigenetic targets in cancer cells. Dietary phytochemicals have been reported to repair DNA damage by enhancing histone acetylation that helps to restrain cell death, and also alter DNA methylation. These phytochemicals are able to modulate epigenetic modifications and their targets to cure several cancers. Epigenetic aberrations dynamically contribute to cancer pathogenesis. Given the individualized traits of epigenetic biomarkers, the personalized nutrition will help us to prevent various types of cancer. In this review, we will discuss the effect of dietary phytochemicals on genetic and epigenetic modifications and how these modifications help to prevent various types of cancers and improve health outcomes.

Nanoformulation of natural products for prevention and therapy of prostate cancer

There is a need for developing improved therapeutic options for the management of prostate cancer, able to inhibit proliferation of precancerous and malignant lesions and/or to improve the effectiveness of conventional chemopreventive and chemotherapeutic agents. In this perspective, application of nanotechnology based strategies for the delivery of natural compounds for effective management of the disease is being actively researched. Here, after highlighting the most promising natural compounds for chemoprevention and chemotherapy of prostate cancer, the state of the art nanotherapeutics and the recent proof-of-concept of "nanochemoprevention", as well as the clinical development of promising targeted nanoprototypes for use in the prostate cancer treatment are being discussed.

The chemopreventive and chemotherapeutic potentials of tea polyphenols

Tea is the second most consumed beverage in the world reported to have multiple health benefits. Preventive and therapeutic benefits of tea polyphenols include enhanced general well being and anti-neoplastic effects. The pharmacologic action of tea is often attributed to various catechins present therein. Experiments conducted in cancer cell lines and animal models demonstrate that tea polyphenols protect against cellular damage caused by oxidative stress and altered immunity. Tea polyphenols modify various metabolic and signaling pathways in the regulation of proliferation, apoptosis, angiogenesis, and metastasis and therefore restrict clonal expansion of cancer cells. Tea polyphenols have been shown to reactivate tumor suppressors, block the unlimited replicative potential of cancer cells, and physically bind to nucleic acids involved in epigenetic alterations of gene regulation. Remarkable interest in green tea as a potential chemopreventive agent has been generated since recent epigenetic data showed that tea polyphenols have the potential to reverse epigenetic modifications which might otherwise be carcinogenic. Like green tea, black tea may also possess chemopreventive and chemotherapeutic potential; however, there is still not enough evidence available to make any conclusive statements. Here we present a brief description of tea polyphenols and discuss the findings of various in vitro and in vivo studies of the anticancer effects of tea polyphenols. Detailed discussion of various studies related to epigenetic changes caused by tea polyphenols leading to prevention of oncogenesis or cancer progression is included. Finally, we discuss on the scope and development of tea polyphenols in cancer prevention and therapy.

Human cancer chemoprevention: hurdles and challenges

Cancer is considered a disease of aging since the risk for developing the disease considerably increases with age. It is estimated that 77% of all cancers are diagnosed in people who fall within the age group of 55 or older. Also, it takes several years from initiation to the development of detectable cancer. One advantage of the long latency is that it provides numerous opportunities for intervention. While intervention approaches cannot be geared towards a whole population, they can nevertheless be directed towards a defined group of people who have a greater relative risk for developing the disease. The idea of cancer prevention through the use of nontoxic agents, preferably from dietary sources, has therefore emerged as an appropriate strategy for controlling the disease. An important aspect of chemoprevention is that agents can be designed for intervention at any stage during the multistage process of carcinogenesis. This process of slowing the progression of cancer is applicable to many cancers with long latency, including prostate cancer. Over the past two decades we have put considerable effort into identifying dietary substances in the form of extracts and pure compounds that can be used for the prevention of prostate and other cancers. Although cancer chemoprevention has proven to be a successful strategy in animals and, to some extent, we can say that the mission has been accomplished, its application to humans has met with limited success. This chapter will discuss various challenges associated with chemoprevention of cancer with the focus on studies with green tea and prostate cancer.

Green tea polyphenols causes cell cycle arrest and apoptosis in prostate cancer cells by suppressing class I histone deacetylases

Green tea polyphenols (GTPs) reactivate epigenetically silenced genes in cancer cells and trigger cell cycle arrest and apoptosis; however, the mechanisms whereby these effects occur are not well understood. We investigated the molecular mechanisms underlying the antiproliferative effects of GTP, which may be similar to those of histone deacetylase (HDAC) inhibitors. Exposure of human prostate cancer LNCaP cells (harboring wild-type p53) and PC-3 cells (lacking p53) with 10-80 μg/ml of GTP for 24 h resulted in dose-dependent inhibition of class I HDAC enzyme activity and its protein expression. GTP treatment causes an accumulation of acetylated histone H3 in total cellular chromatin, resulting in increased accessibility to bind with the promoter sequences of p21/waf1 and Bax, consistent with the effects elicited by an HDAC inhibitor, trichostatin A. GTP treatment also resulted in increased expression of p21/waf1 and Bax at the protein and message levels in these cells. Furthermore, treatment of cells with proteasome inhibitor, MG132 together with GTP prevented degradation of class I HDACs, compared with cells treated with GTP alone, indicating increased proteasomal degradation of class I HDACs by GTP. These alterations were consistent with G(0)-G(1) phase cell cycle arrest and induction of apoptosis in both cell lines. Our findings provide new insight into the mechanisms of GTP action in human prostate cancer cells irrespective of their p53 status and suggest a novel approach to prevention and/or therapy of prostate cancer achieved via HDAC inhibition.

Lack of chronic toxicity and carcinogenicity of dietary administrated catechin mixture in Wistar Hannover GALAS rats

Chronic toxicity and carcinogenicity of catechin mixture were examined in Wistar Hannover GALAS rats. Administration was in the diet at concentrations of 0, 0.02, 0.3, 1 or 3%. Slight increases in relative liver weight and centrilobular hypertrophy of hepatocytes associated with induction of CYP3A2 were found at the 3% in males of both studies. However, because there were no signs indicative of hepatotoxicity on serum biochemical and histopathological examinations, the changes observed in the liver were regarded as adaptation, and not adverse effects. The slight depressions of body weights at the 3% in females of the chronic toxicity study and in both sexes of the carcinogenicity study were observed. These decreases were because the diet at the highest concentration was frangible and nominal food consumption may not have reflected the actual food consumption resulting in decrease in caloric intake, rather than toxic effects. Thus it was concluded that catechin mixture had no toxicity. In addition, tumor incidences and types were comparable between treated and control groups. Based on the results, the no observed adverse effect levels estimated from the chronic toxicity study were 3% in both sexes equal to 1922.9 in males and 2525.7 mg/kg/day in females. Catechin mixture has no carcinogenic potential in male and female rats.

Reactive oxygen species: are they important for haematopoiesis?

The production of reactive oxygen species (ROS) has traditionally been related to deleterious effects for cells. However, it is now widely accepted that ROS can play an important role in regulating cellular signalling and gene expression. NADPH oxidase ROS production seems to be especially important in this regard. Some lines of evidence suggest that ROS may be important modulators of cell differentiation, including haematopoietic differentiation, in both physiologic and pathologic conditions. Here we shall review how ROS can regulate cell signalling and gene expression. We shall also focus on the importance of ROS for haematopoietic stem cell (HSC) biology and for haematopoietic differentiation. We shall review the involvement of ROS and NADPH oxidases in cancer, and in particular what is known about the relationship between ROS and haematological malignancies. Finally, we shall discuss the use of ROS as cancer therapeutic targets.

White tea extract induces apoptosis in non-small cell lung cancer cells: the role of peroxisome proliferator-activated receptor-{gamma} and 15-lipoxygenases

Emerging preclinical data suggests that tea possess anticarcinogenic and antimutagenic properties. We therefore hypothesize that white tea extract (WTE) is capable of favorably modulating apoptosis, a mechanism associated with lung tumorigenesis. We examined the effects of physiologically relevant doses of WTE on the induction of apoptosis in non-small cell lung cancer cell lines A549 (adenocarcinoma) and H520 (squamous cell carcinoma) cells. We further characterized the molecular mechanisms responsible for WTE-induced apoptosis, including the induction of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and the 15-lipoxygenase (15-LOX) signaling pathways. We found that WTE was effective in inducing apoptosis in both A549 and H520 cells, and inhibition of PPAR-gamma with GW9662 partially reversed WTE-induced apoptosis. We further show that WTE increased PPAR-gamma activation and mRNA expression, concomitantly increased 15(S)-hydroxy-eicosatetraenoic acid release, and upregulated 15-LOX-1 and 15-LOX-2 mRNA expression by A549 cells. Inhibition of 15-LOX with nordihydroguaiaretic acid (NGDA), as well as caffeic acid, abrogated WTE-induced PPAR-gamma activation and upregulation of PPAR-gamma mRNA expression in A549 cells. WTE also induced cyclin-dependent kinase inhibitor 1A mRNA expression and activated caspase-3. Inhibition of caspase-3 abrogated WTE-induced apoptosis. Our findings indicate that WTE is capable of inducing apoptosis in non-small cell lung cancer cell lines. The induction of apoptosis seems to be mediated, in part, through the upregulation of the PPAR-gamma and 15-LOX signaling pathways, with enhanced activation of caspase-3. Our findings support the future investigation of WTE as an antineoplastic and chemopreventive agent for lung cancer.

Pomegranate extract induces apoptosis in human prostate cancer cells by modulation of the IGF-IGFBP axis

The IGF axis is critical for the regulation of apoptosis in many human cancer cell lines. Recently, potent anti-tumorigenic effects of pomegranate juice and extracts have been reported. Consequently, pomegranate has potential not only as a treatment but also as a preventative measure against certain types of cancer, including prostate. In this study, we investigated the relationship between pomegranate-induced apoptosis in human prostate cancer cells and the IGF/IGFBP system. Treatment of LAPC4 prostate cancer cells with 10microg/ml POMx, a highly potent pomegranate extract prepared from skin and arils minus seeds and standardized to ellagitannin content (37% punicalagins by HPLC), resulted in inhibition of cell proliferation and induction of apoptosis. Interestingly, co-treatment with POMx and IGFBP-3 revealed synergistic stimulation of apoptosis and additive inhibition of cell growth. Western blot analysis revealed that treatment with POMx or POMx/IGFBP-3 combination resulted in increased JNK phosphorylation, and decreased Akt and mTOR activation, consistent with a growth inhibitory, pro-apoptotic function. We also investigated the relationship between IGF-1 and pomegranate-induced apoptosis in 22RV1 prostate cancer cells. Co-treatment with 100ng/ml IGF-1 completely blocked apoptosis induction by POMx. In contrast, IGF-I failed to inhibit POMx-induced apoptosis in R(-) cells, suggesting the importance of IGF-IR. POMx-treatment decreased Igf1 mRNA expression in a dose-dependent manner indicating that its actions also involve tumor-specific suppression of IGF-1. These studies revealed novel interactions between the IGF system and pomegranate-induced apoptosis.

Protective activity of Theobroma cacao L. phenolic extract on AML12 and MLP29 liver cells by preventing apoptosis and inducing autophagy

Theobroma cacao L. is known to have potential cardiovascular and cancer chemopreventive activities because of its high content of phenolic phytochemicals and their antioxidant capacities. In this work, we show for the first time that cocoa inhibits drug-triggered liver cytotoxicity by inducing autophagy. Phenolic-rich extracts of both unroasted and roasted cocoa prevented Celecoxib-induced cell viability inhibition in MLP29 liver cells because of the accumulation of G1 cells and cell death. Death prevented by cocoa had hallmarks of apoptosis such as the sub-G1 peak at flow cytometry and activation of Bax expression, together with down-regulation of Bcl-2, released cytochrome c in the cytosol with activation of Caspase 3, indicating that components of the apoptotic pathway such as Bax or upstream are major targets of cocoa phytochemicals. The protective effect of cocoa against liver cytotoxicity by Celecoxib was probably accounted for by inducing the autophagic process, as shown by enhanced Beclin 1 expression and accumulation of monodansylcadaverine in autolysosomes. This fact suggests that apoptosis was prevented by inducing autophagy. Finally, considering all these findings, we suggest that cocoa can be added to the list of natural chemopreventive agents whose potential in hepatopathy prevention and therapy should be evaluated.

Polyphenols from green tea and pomegranate for prevention of prostate cancer

Prostate cancer (PCa) is the most common non-cutaneous cancer diagnosed in North America with similar trends in many Western countries. Geographic, epidemiological and laboratory studies suggest a role for dietary constituents in the etiology as well as prevention of PCa. The rising incidence of PCa in several countries appears to be coincidental with adoption of western lifestyle. Increase in the incidence of PCa has also been found in Asian populations migrating to the west. These facts give numerous leads to explore testable PCa prevention strategies. There is growing evidence in support of use of dietary ingredients in prevention and treatment of PCa. While substantial data exists in favor of use of polyphenols from tea as PCa chemopreventive agent, interest in anti-cancer properties of polyphenols from pomegranate has recently emerged. This review summarizes current literature on the effects of polyphenols from green tea and pomegranate against PCa.

Green tea catechins suppress the DNA synthesis marker MCM7 in the TRAMP model of prostate cancer

Green tea catechins (GTCs) exert chemopreventive effects in many cancer models. Several studies implicate the DNA synthesis marker minichromosome maintenance protein 7 (MCM7) in prostate cancer progression, growth and invasion; representing a novel therapeutic target. In this study, we investigated the effect of GTCs on MCM7 expression in the transgenic adenocarcinoma mouse prostate model (TRAMP). DNA microarray, immunohistochemistry and western blot analysis showed that GTCs significantly suppressed MCM7 in the TRAMP mice treated with GTCs. Our study indicates that the cellular DNA replication factor MCM7 is involved in prostate cancer (CaP) and MCM7 gene expression was reduced by GTCs. Together, these results suggest a possible role of GTCs in CaP chemoprevention in which MCM7 plays a critical role.

A combination of micronutrients is beneficial in reducing the incidence of prostate cancer and increasing survival in the Lady transgenic model

We have previously shown that administration of a combination of micronutrients (selenium, vitamin E, and lycopene) inhibits prostate cancer (PCa) development in the Lady transgenic model. In the present study, we examine timing of initiation of micronutrients, and the effect of micronutrient combinations, on PCa development in Lady transgenic model. Transgenic males were randomized to either a control diet; control diet supplemented with human equivalent doses of vitamin E, selenium, and lycopene (E+S+L); or control diet supplemented with vitamin E and selenium (E+S). In separate experiments, the combination of E+S+L was initiated at varying time points (4, 8, 20, and 36 weeks of age). A combination of E+S+L resulted in a significant reduction in PCa and liver metastasis when intervention was commenced within 8 weeks of age (P < 0.0001). Immunohistochemical analysis revealed a strong correlation between disease-free state with up-regulation of the prognostic marker p27(Kip1) (P < 0.0001) and decreased expression of proliferating cell nuclear antigen and significantly increased apoptotic index (P < 0.0001). On the contrary, a combination of E+S was not effectual in preventing PCa, with a high proportion (84.6%) of animals developing PCa and a small proportion (11.5%) developing high-grade PIN. Early commencement of micronutrients (E+S+L) is beneficial in reducing PCa. Lycopene is an essential component of the combination and effective (when used with E+S) for PCa prevention. These observations provide support for their chemopreventive effect and some clues about their mechanism of action. These key findings will be complementary to the outcome from the Selenium and Vitamin E Chemoprevention Trial.

Apoptosis induction by sulfur-containing compounds in malignant and nonmalignant human cells

Plants have traditionally represented a main source for the discovery of many biologically active substances with therapeutic values. Sulfur-containing compounds exhibit pleiotropic biological effects supporting their potential use in multitargeted cancer prevention and treatment. As potential anti-cancer agents, they have been shown to inhibit or retard the growth of various cancer cells in culture and implanted tumors in vivo. The compounds significantly inhibit experimental tumorigenesis in a wide range of animal models. A critical and well-elucidated cellular mechanism involved in the anticancer activities of sulfur-containing compounds is the induction of apoptosis through the fine-tuning of orchestrated intracellular signal transduction. This review summarizes the established proapoptotic activities of sulfur-containing compounds in malignant and nonmalignant cells with a special focus on their molecular mechanisms. The potential toxicological implications of proapoptotic effects on normal cells will also be discussed.