Mechanism-based cancer prevention approaches: targets, examples, and the use of transgenic mice

Chemotherapeutic potential of betanin/capecitabine combination targeting colon cancer: experimental and bioinformatic studies exploring NFκB and cyclin D1 interplay

Introduction: Betanin (C₂₄H₂₆N₂O₁₃) is safe to use as food additives approved by the FDA with anti-inflammatory and anticancer effects in many types of cancer cell lines. The current experiment was designed to test the chemotherapeutic effect of the combination of betanin with the standard chemotherapeutic agent, capecitabine, against chemically induced colon cancer in mice. Methods: Bioinformatic approach was designed to get information about the possible mechanisms through which the drugs may control cancer development. Five groups of mice were assigned as, (i) saline, (ii) colon cancer, (iii) betanin, (iv) capecitabine and (v) betanin/capecitabine. Drugs were given orally for a period of six weeks. Colon tissues were separated and used for biological assays and histopathology. Results: In addition, the mRNA expression of TNF-α (4.58-fold), NFκB (5.33-fold), IL-1β (4.99-fold), cyclin D1 (4.07-fold), and IL-6 (3.55-fold) and protein levels showed several folds increases versus the saline group. Tumor histopathology scores in the colon cancer group (including cryptic distortion and hyperplasia) and immunostaining for NFκB (2.94-fold) were high while periodic-acid Schiff staining demonstrated poor mucin content (33% of the saline group). These pathologic manifestations were reduced remarkably in betanin/capecitabine group. Conclusion: Collectively, our findings demonstrated the usefulness of betanin/capecitabine combination in targeting colon cancer and highlighted that betanin is a promising adjuvant therapy to capecitabine in treating colon cancer patients.

A PDE Model of Breast Tumor Progression in MMTV-PyMT Mice

The evolution of breast tumors greatly depends on the interaction network among different cell types, including immune cells and cancer cells in the tumor. This study takes advantage of newly collected rich spatio-temporal mouse data to develop a data-driven mathematical model of breast tumors that considers cells' location and key interactions in the tumor. The results show that cancer cells have a minor presence in the area with the most overall immune cells, and the number of activated immune cells in the tumor is depleted over time when there is no influx of immune cells. Interestingly, in the case of the influx of immune cells, the highest concentrations of both T cells and cancer cells are in the boundary of the tumor, as we use the Robin boundary condition to model the influx of immune cells. In other words, the influx of immune cells causes a dominant outward advection for cancer cells. We also investigate the effect of cells' diffusion and immune cells' influx rates in the dynamics of cells in the tumor micro-environment. Sensitivity analyses indicate that cancer cells and adipocytes' diffusion rates are the most sensitive parameters, followed by influx and diffusion rates of cytotoxic T cells, implying that targeting them is a possible treatment strategy for breast cancer.

Investigating key cell types and molecules dynamics in PyMT mice model of breast cancer through a mathematical model

The most common kind of cancer among women is breast cancer. Understanding the tumor microenvironment and the interactions between individual cells and cytokines assists us in arriving at more effective treatments. Here, we develop a data-driven mathematical model to investigate the dynamics of key cell types and cytokines involved in breast cancer development. We use time-course gene expression profiles of a mouse model to estimate the relative abundance of cells and cytokines. We then employ a least-squares optimization method to evaluate the model's parameters based on the mice data. The resulting dynamics of the cells and cytokines obtained from the optimal set of parameters exhibit a decent agreement between the data and predictions. We perform a sensitivity analysis to identify the crucial parameters of the model and then perform a local bifurcation on them. The results reveal a strong connection between adipocytes, IL6, and the cancer population, suggesting them as potential targets for therapies.

In silico design and in vitro assessment of anti-Helicobacter pylori compounds as potential small-molecule arginase inhibitors

Related to a variety of gastrointestinal disorders ranging from gastric ulcer to gastric adenocarcinoma, the infection caused by the gram-negative bacteria Helicobacter pylori (H. pylori) poses as a great threat to human health; hence, the search for new treatments is a global priority. The H. pylori arginase (HPA) protein has been widely studied as one of the main virulence factors of this bacterium, being involved in the prevention of nitric oxide-mediated bacterial cell death, which is a central component of innate immunity. Given the growing need for the development of new drugs capable of combating the infection by H. pylori, the present work describes the search for new HPA inhibitors, using virtual screening techniques based on molecular docking followed by the evaluation of the proposed modes of interaction at the HPA active site. In vitro studies of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), followed by cytotoxicity activity in gastric adenocarcinoma and non-cancer cells, were performed. The results highlighted compounds 6, 11, and 13 as potential inhibitors of HPA; within these compounds, the results indicated 13 presented an improved activity toward H. pylori killing, with MIC and MBC both at 64 µg/mL. Moreover, compound 13 also presented a selectivity index of 8.3, thus being more selective for gastric adenocarcinoma cells compared to the commercial drug cisplatin. Overall, the present work demonstrates the search strategy based on in silico and in vitro techniques is able to support the rational design of new anti-H. pylori drugs.

Intermittent and Periodic Fasting, Hormones, and Cancer Prevention

The restriction of proteins, amino acids or sugars can have profound effects on the levels of hormones and factors including growth hormone, IGF-1 and insulin. In turn, these can regulate intracellular signaling pathways as well as cellular damage and aging, but also multisystem regeneration. Both intermittent (IF) and periodic fasting (PF) have been shown to have both acute and long-term effects on these hormones. Here, we review the effects of nutrients and fasting on hormones and genes established to affect aging and cancer. We describe the link between dietary interventions and genetic pathways affecting the levels of these hormones and focus on the mechanisms responsible for the cancer preventive effects. We propose that IF and PF can reduce tumor incidence both by delaying aging and preventing DNA damage and immunosenescence and also by killing damaged, pre-cancerous and cancer cells.

Using the Key Characteristics of Carcinogens to Develop Research on Chemical Mixtures and Cancer

BACKGROUND

People are exposed to numerous chemicals throughout their lifetimes. Many of these chemicals display one or more of the key characteristics of carcinogens or interact with processes described in the hallmarks of cancer. Therefore, evaluating the effects of chemical mixtures on cancer development is an important pursuit. Challenges involved in designing research studies to evaluate the joint action of chemicals on cancer risk include the time taken to perform the experiments because of the long latency and choosing an appropriate experimental design.

OBJECTIVES

The objectives of this work are to present the case for developing a research program on mixtures of environmental chemicals and cancer risk and describe recommended approaches.

METHODS

A working group comprising the coauthors focused attention on the design of mixtures studies to inform cancer risk assessment as part of a larger effort to refine the key characteristics of carcinogens and explore their application. Working group members reviewed the key characteristics of carcinogens, hallmarks of cancer, and mixtures research for other disease end points. The group discussed options for developing tractable projects to evaluate the joint effects of environmental chemicals on cancer development.

RESULTS AND DISCUSSION

Three approaches for developing a research program to evaluate the effects of mixtures on cancer development were proposed: a chemical screening approach, a transgenic model-based approach, and a disease-centered approach. Advantages and disadvantages of each are discussed. https://doi.org/10.1289/EHP8525.

Inflammation-Related Carcinogenesis: Lessons from Animal Models to Clinical Aspects

Simple Summary

In multicellular organisms, inflammation is the body’s most primitive and essential protective response against any external agent. Inflammation, however, not only causes various modern diseases such as cardiovascular disorders, neurological disorders, autoimmune diseases, metabolic syndrome, infectious diseases, and cancer but also shortens the healthy life expectancy. This review focuses on the onset of carcinogenesis due to chronic inflammation caused by pathogen infections and inhalation/ingestion of foreign substances. This study summarizes animal models associated with inflammation-related carcinogenesis by organ. By determining factors common to inflammatory carcinogenesis models, we examined strategies for the prevention and treatment of inflammatory carcinogenesis in humans.

Abstract

Inflammation-related carcinogenesis has long been known as one of the carcinogenesis patterns in humans. Common carcinogenic factors are inflammation caused by infection with pathogens or the uptake of foreign substances from the environment into the body. Inflammation-related carcinogenesis as a cause for cancer-related death worldwide accounts for approximately 20%, and the incidence varies widely by continent, country, and even region of the country and can be affected by economic status or development. Many novel approaches are currently available concerning the development of animal models to elucidate inflammation-related carcinogenesis. By learning from the oldest to the latest animal models for each organ, we sought to uncover the essential common causes of inflammation-related carcinogenesis. This review confirmed that a common etiology of organ-specific animal models that mimic human inflammation-related carcinogenesis is prolonged exudation of inflammatory cells. Genotoxicity or epigenetic modifications by inflammatory cells resulted in gene mutations or altered gene expression, respectively. Inflammatory cytokines/growth factors released from inflammatory cells promote cell proliferation and repair tissue injury, and inflammation serves as a “carcinogenic niche”, because these fundamental biological events are common to all types of carcinogenesis, not just inflammation-related carcinogenesis. Since clinical strategies are needed to prevent carcinogenesis, we propose the therapeutic apheresis of inflammatory cells as a means of eliminating fundamental cause of inflammation-related carcinogenesis.

A review of nutrition and dietary interventions in oncology

The complex cellular mechanisms and inter-related pathways of cancer proliferation, evasion, and metastasis remain an emerging field of research. Over the last several decades, nutritional research has prominent role in identifying emerging adjuvant therapies in our fight against cancer. Nutritional and dietary interventions are being explored to improve the morbidity and mortality for cancer patients worldwide. In this review, we examine several dietary interventions and their proposed mechanisms against cancer as well as identifying limitations in the currently available literature. This review provides a comprehensive review of the cancer metabolism, dietary interventions used during cancer treatment, anti metabolic drugs, and their impact on nutritional deficiencies along with a critical review of the following diets: caloric restriction, intermittent fasting, ketogenic diet, Mediterranean diet, Japanese diet, and vegan diet.

Sulfonylpiperazines based on a flavone as antioxidant and cytotoxic agents

Chrysin-based sulfonylpiperazines 7a-k were synthesized and investigated for their in vitro free radical scavenging potential as well as cytotoxic efficacies against selected cancer cell lines. Cytotoxicity of the new compounds toward noncancer cells was confirmed using the SRB assay against Madin-Darby Canine Kidney cells. Reaction of piperazine with different substituted benzenesulfonyl chlorides in triethylamine furnished sulfonylpiperazines (3a-k), which were then allowed to react with 7-(4-bromobutoxy)-5-hydroxy-2-phenyl-4H-chromen-4-one (6) prepared reacting chrysin with 1,4-dibromobutane to give the final derivatives 7a-k. The results concluded that chrysin-sulfonylpiperazines exerted better antioxidant and anticancer efficacies than previously studied chrysin-piperazine precursors. For example, compounds 7h, 7j, and 7k with 4-OCF₃ , 4-OCH₃ , and 2,4-diOCH₃ groups exhibited the best antioxidant potential against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals. Moreover, halogenated analogues (7b, 7c, 7g, and 7h) demonstrated promising anticancer potential against SK-OV3, HeLa, and HT-29 cell lines, whereas those bearing a methoxy functional group (7j and 7k) had beneficial effects against the cell lines A-549 and HT-29. Thus, it can be confirmed from the bioassay results that the overall structural design as well as proper substitution is crucial to deliver the anticipated biological effects. Spectroscopic techniques such as FT-IR, ¹ H NMR, ¹³ C NMR, mass and elemental analysis (CHN) were carried out to confirm the final structures.

Phenylsulfonyl piperazine bridged [1,3]dioxolo[4,5-g]chromenones as promising antiproliferative and antioxidant agents

Two series of sulfonylpiperazines linked [1,3]dioxolo[4,5-g]chromenones were synthesized featuring phenyl (7a-k) and chalcone (12a-k) bridge representing flavones or homoisoflavonoids core. New molecules are synthesized utilizing aldol condensation to inspect as antioxidants against DPPH and ABTS⁺ and antiproliferative agents toward selected human cancer cell lines. Cytotoxicity of new compounds was confirmed using SRB assay against non-cancer MDCK cell line. The results concluded that both individual structures of 7 and 12 were vital for modulating pharmacological potencies and presence of different electron withdrawing and electron donating functional group(s) on the phenylsulfonyl entity yielded varied biological effects. Substituent h (OCF₃) and j, k (OCH₃) were found to play a crucial role scavenging DPPH and ABTS⁺ as well as inhibiting cancer cell lines SK-OV-3 and HT-29. Moreover, molecules bearing halogen atom(s) such as substituent b-g expressed excellent inhibitory potential against HeLa and A-549 cancerous cell lines. Bioassay data displayed some interesting structure-activity relationships which are discussed in this paper. The results justified that tested derivatives are promising antioxidants and cytotoxic agents and warrant further structural optimization and bioassay studies. Spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR and elemental analysis (CHN) were carried out to confirm the final structures.

Phytochemicals: Extraction, Isolation, and Identification of Bioactive Compounds from Plant Extracts

There are concerns about using synthetic phenolic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) as food additives because of the reported negative effects on human health. Thus, a replacement of these synthetics by antioxidant extractions from various foods has been proposed. More than 8000 different phenolic compounds have been characterized; fruits and vegetables are the prime sources of natural antioxidants. In order to extract, measure, and identify bioactive compounds from a wide variety of fruits and vegetables, researchers use multiple techniques and methods. This review includes a brief description of a wide range of different assays. The antioxidant, antimicrobial, and anticancer properties of phenolic natural products from fruits and vegetables are also discussed.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis.

Dietary Inflammatory Index and Risk of Colorectal Adenoma Recurrence: A Pooled Analysis

No studies have evaluated the association between the dietary inflammatory index (DII) and colorectal adenoma recurrence. DII scores were calculated from a baseline food frequency questionnaire. Participants (n = 1727) were 40-80 years of age, enrolled in two Phase III clinical trials, who had ≥1 colorectal adenoma(s) removed within 6 months of study registration, and a follow-up colonoscopy during the trial. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). No statistically significant associations were found between DII and odds of colorectal adenoma recurrence [ORs (95% CIs) = 0.93 (0.73, 1.18) and 0.95 (0.73, 1.22)] for subjects in the second and third DII tertiles, respectively, compared to those in the lowest tertile (Ptrend = 0.72). No associations were found for recurrent colorectal adenoma characteristics, including advanced recurrent adenomas, large size, villous histology, or anatomic location. While our study did not support an association between a proinflammatory diet and colorectal adenoma recurrence, future studies are warranted to elucidate the role of a proinflammatory diet on the early stages of colorectal carcinogenesis.

Novel Transgenic Mouse Model for Studying Human Serum Albumin as a Biomarker of Carcinogenic Exposure

Albumin is a commonly used serum protein for studying human exposure to xenobiotic compounds, including therapeutics and environmental pollutants. Often, the reactivity of albumin with xenobiotic compounds is studied ex vivo with human albumin or plasma/serum samples. Some studies have characterized the reactivity of albumin with chemicals in rodent models; however, differences between the orthologous peptide sequences of human and rodent albumins can result in the formation of different types of chemical-protein adducts with different interaction sites or peptide sequences. Our goal is to generate a human albumin transgenic mouse model that can be used to establish human protein biomarkers of exposure to hazardous xenobiotics for human risk assessment via animal studies. We have developed a human albumin transgenic mouse model and characterized the genotype and phenotype of the transgenic mice. The presence of the human albumin gene in the genome of the model mouse was confirmed by genomic PCR analysis, whereas liver-specific expression of the transgenic human albumin mRNA was validated by RT-PCR analysis. Further immunoblot and mass spectrometry analyses indicated that the transgenic human albumin protein is a full-length, mature protein, which is less abundant than the endogenous mouse albumin that coexists in the serum of the transgenic mouse. The transgenic protein was able to form ex vivo adducts with a genotoxic metabolite of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a procarcinogenic heterocyclic aromatic amine formed in cooked meat. This novel human albumin transgenic mouse model will facilitate the development and validation of albumin-carcinogen adducts as biomarkers of xenobiotic exposure and/or toxicity in humans.

BRCA1 and BRCA2 protect against oxidative DNA damage converted into double-strand breaks during DNA replication

BRCA1 and BRCA2 mutation carriers are predisposed to develop breast and ovarian cancers, but the reasons for this tissue specificity are unknown. Breast epithelial cells are known to contain elevated levels of oxidative DNA damage, triggered by hormonally driven growth and its effect on cell metabolism. BRCA1- or BRCA2-deficient cells were found to be more sensitive to oxidative stress, modeled by treatment with patho-physiologic concentrations of hydrogen peroxide. Hydrogen peroxide exposure leads to oxidative DNA damage induced DNA double strand breaks (DSB) in BRCA-deficient cells causing them to accumulate in S-phase. In addition, after hydrogen peroxide treatment, BRCA deficient cells showed impaired Rad51 foci which are dependent on an intact BRCA1-BRCA2 pathway. These DSB resulted in an increase in chromatid-type aberrations, which are characteristic for BRCA1 and BRCA2-deficient cells. The most common result of oxidative DNA damage induced processing of S-phase DSB is an interstitial chromatid deletion, but insertions and exchanges were also seen in BRCA deficient cells. Thus, BRCA1 and BRCA2 are essential for the repair of oxidative DNA damage repair intermediates that persist into S-phase and produce DSB. The implication is that oxidative stress plays a role in the etiology of hereditary breast cancer.

Modeling cutaneous squamous carcinoma development in the mouse

Cutaneous squamous cell carcinoma (SCC) is one of the most common cancers in Caucasian populations and is associated with a significant risk of morbidity and mortality. The classic mouse model for studying SCC involves two-stage chemical carcinogenesis, which has been instrumental in the evolution of the concept of multistage carcinogenesis, as widely applied to both human and mouse cancers. Much is now known about the sequence of biological and genetic events that occur in this skin carcinogenesis model and the factors that can influence the course of tumor development, such as perturbations in the oncogene/tumor-suppressor signaling pathways involved, the nature of the target cell that acquires the first genetic hit, and the role of inflammation. Increasingly, studies of tumor-initiating cells, malignant progression, and metastasis in mouse skin cancer models will have the potential to inform future approaches to treatment and chemoprevention of human squamous malignancies.

Involvement of EZH2, SUV39H1, G9a and associated molecules in pathogenesis of urethane induced mouse lung tumors: potential targets for cancer control

In the present study, we showed the correlation of EZH2, SUV39H1 or G9a expression and histone modifications with the urethane induced mouse lung tumorigenesis in the presence or absence of antitumor agent, inositol hexaphosphate (IP6). Tumorigenesis and the molecular events involved therein were studied at 1, 4, 12 or 36 weeks after the exposure. There were no tumors at 1 or 4 weeks but tumors started appearing at 12 weeks and grew further till 36 weeks after urethane exposure. Among the molecular events, upregulation of EZH2 and SUV39H1 expressions appeared to be time dependent, but G9a expression was altered significantly only at later stages of 12 or 36 weeks. Alteration in miR-138 expression supports the upregulation of its target, EZH2. H3K9me2, H3K27me3 or H4K20me3 was found to be altered at 12 or 36 weeks. However, ChIP analysis of p16 and MLH1 promoters showed their binding with H3K9me2 and H3K27me3 which was maximum at 36 weeks. Thus, histone modification and their interactions with gene promoter resulted in the reduced expression of p16 and MLH1. IP6 prevented the incidence and the size of urethane induced lung tumors. IP6 also prevented the urethane induced alterations in EZH2, SUV39H1, G9a expressions and histone modifications. Our results suggest that the alterations in the histone modification pathways involving EZH2 and SUV39H1 expressions are among the early events in urethane induced mouse lung tumorigenesis and could be exploited for cancer control.

Chemopreventive and therapeutic effects of nimbolide in cancer: the underlying mechanisms

Cancer chemoprevention is a strategy taken to block, reverse or retard the multistep process of carcinogenesis, including the blockage of its vital morphogenetic milestones viz. normal-preneoplasia-neoplasia-metastasis. Naturally occurring phytochemicals are becoming increasingly popular over synthetic drugs for several reasons, including safety, efficacy and easy availability. Nimbolide, a triterpene derived from the leaves and flowers of neem, is widely used in traditional medical practices for treating various human ailments. The neem limonoid exhibits multiple pharmacological effects among which its anticancer activity is the most promising. The preclinical and mechanistic studies carried over the decades have shown that nimbolide inhibits tumorigenesis and metastasis without any toxicity and unwanted side effects. Nimbolide exhibits anticancer activity through selective modulation of multiple cell signaling pathways linked to inflammation, survival, growth, invasion, angiogenesis and metastasis. The present review highlights the current knowledge on molecular targets that contribute to the observed anticancer activity of nimbolide related to (i) inhibition of carcinogenic activation and induction of antioxidant and carcinogen detoxification enzymes, (ii) induction of growth arrest and apoptosis; and (iii) suppression of proinflammatory signaling pathways related to cancer progression.

The effect of resveratrol and its methylthio-derivatives on NF-κB and AP-1 signaling pathways in HaCaT keratinocytes

BACKGROUND

Resveratrol is a natural stilbene derivative whose chemopreventive activity has been well established. Our previous studies have shown that modification of the stilbene backbone with the methylthio group may influence selectivity and inhibitory potency toward P450 isozymes. The aim of this study was to further investigate the mechanism of their potential chemopreventive activity by evaluating the effect of two 4'-methylthio-trans-stilbene derivatives possessing one (3-M-4'-MTS; S2) and two (3,5-DM-4'-MTS; S5) additional methoxy groups on constitutive nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activation in immortalized human HaCaT keratinocytes.

METHODS

The synthesis of MTS was performed as described earlier. Translocation of NF-κB and AP-1 was evaluated by Western blot analysis. Binding of p65 (NF-κB) and c-Jun and c-Fos subunits (AP-1) to consensus oligonucleotide was assessed by ELISA. Real-time PCR and Western blot were used to evaluate COX-2 and iNOS expression.

RESULTS

We found differential modulation of signaling pathways depending on the stilbene structure after 24h of cells treatment. The S2 compound, in contrast to S5 and resveratrol, significantly reduced NF-κB activation by blocking the translocation of the p65 subunit to the nucleus, and decreasing IκB kinase activity. All compounds, but particularly S5, increased c-Jun binding to the AP-1 consensus sequence, while c-Fos binding was not affected.

CONCLUSIONS

We conclude that methylthiostilbenes differently modulate constitutive signal transduction pathways in HaCaT cells. These observations should be taken into account in designing new stilbene derivatives with potential chemopreventive activity.

Cytotoxic activity of aqueous extracts of Anogeissus leiocarpus and Terminalia avicennioides root barks against Ehrlich ascites carcinoma cells

Objectives:

Folkloric claims on the use of a mixture of Anogeissus leiocarpus and Terminalia avicennioides root barks in tumor management exist without scientific evidence. This study aimed at investigating the phytochemical constituents and in vitro antiproliferative activity of these plants and their mixture.

Materials and Methods:

Phytochemical screening was carried out on the aqueous extracts after which various concentrations (0 to 1 000 μg/ml) were incubated with Ehrlich ascites carcinoma cell lines for 3 and 24 hours.

Results:

The extracts contained alkaloids, tannins, flavonoids, phenolics, saponins, phlobatannins, and terpenes. The separate extracts and their 1:1 mixture significantly (P<0.05) decreased the computed percentage viability of the cell lines in a dose- and time-dependent manner.

Conclusions:

The antiproliferative activity may be due to the presence of the bioactive compounds in the extracts and has a potential in the management of tumor.

Selectively starving cancer cells through dietary manipulation: methods and clinical implications

As the link between obesity and metabolic syndrome and cancer becomes clearer, the need to determine the optimal way to incorporate dietary manipulation in the treatment of cancer patients becomes increasingly important. Metabolic-based therapies, such as caloric restriction, intermittent fasting and a ketogenic diet, have the ability to decrease the incidence of spontaneous tumors and slow the growth of primary tumors, and may have an effect on distant metastases in animal models. Despite the abundance of preclinical data demonstrating the benefit of dietary modification for cancer, to date there are few clinical trials targeting diet as an intervention for cancer patients. We hypothesize that this may be due, in part, to the fact that several different types of diet modification exist with no clear recommendations regarding the optimal method. This article will delineate three commonly used methods of dietary manipulation to assess the potential of each as a regimen for cancer therapy.

Extremely low-frequency electromagnetic fields cause DNA strand breaks in normal cells

BACKGROUND

Extremely low frequency electromagnetic fields aren't considered as a real carcinogenic agent despite the fact that some studies have showed impairment of the DNA integrity in different cells lines. The aim of this study was evaluation of the late effects of a 100 Hz and 5.6 mT electromagnetic field, applied continuously or discontinuously, on the DNA integrity of Vero cells assessed by alkaline Comet assay and by cell cycle analysis. Normal Vero cells were exposed to extremely low frequency electromagnetic fields (100 Hz, 5.6 mT) for 45 minutes. The Comet assay and cell cycle analysis were performed 48 hours after the treatment.

RESULTS

Exposed samples presented an increase of the number of cells with high damaged DNA as compared with non-exposed cells. Quantitative evaluation of the comet assay showed a significantly (<0.001) increase of the tail lengths, of the quantity of DNA in tail and of Olive tail moments, respectively. Cell cycle analysis showed an increase of the frequency of the cells in S phase, proving the occurrence of single strand breaks. The most probable mechanism of induction of the registered effects is the production of different types of reactive oxygen species.

CONCLUSIONS

The analysis of the registered comet indices and of cell cycle showed that extremely low frequency electromagnetic field of 100 Hz and 5.6 mT had a genotoxic impact on Vero cells.

Loss of miR-10a activates lpo and collaborates with activated Wnt signaling in inducing intestinal neoplasia in female mice

miRNAs are small regulatory RNAs that, due to their considerable potential to target a wide range of mRNAs, are implicated in essentially all biological process, including cancer. miR-10a is particularly interesting considering its conserved location in the Hox cluster of developmental regulators. A role for this microRNA has been described in developmental regulation as well as for various cancers. However, previous miR-10a studies are exclusively based on transient knockdowns of this miRNA and to extensively study miR-10a loss we have generated a miR-10a knock out mouse. Here we show that, in the Apc^min mouse model of intestinal neoplasia, female miR-10a deficient mice develop significantly more adenomas than miR-10^+/+ and male controls. We further found that Lpo is extensively upregulated in the intestinal epithelium of mice deprived of miR-10a. Using in vitro assays, we demonstrate that the primary miR-10a target KLF4 can upregulate transcription of Lpo, whereas siRNA knockdown of KLF4 reduces LPO levels in HCT-116 cells. Furthermore, Klf4 is upregulated in the intestines of miR-10a knockout mice. Lpo has previously been shown to have the capacity to oxidize estrogens into potent depurinating mutagens, creating an instable genomic environment that can cause initiation of cancer. Therefore, we postulate that Lpo upregulation in the intestinal epithelium of miR-10a deficient mice together with the predominant abundance of estrogens in female animals mainly accounts for the sex-related cancer phenotype we observed. This suggests that miR-10a could be used as a potent diagnostic marker for discovering groups of women that are at high risk of developing colorectal carcinoma, which today is one of the leading causes of cancer-related deaths.

Posttranscriptional regulation by microRNA molecules constitutes an important mechanism for gene regulation and numerous studies have demonstrated a correlation between deregulated microRNA levels and diseases, such as cancer. However, genetics studies linking individual microRNAs to the etiology of cancer remain scarce. Here, we provide causal evidence for the involvement of the conserved microRNA miR-10a in the development of intestinal adenomas in the face of activated Wnt signaling. Interestingly, we find that loss of miR-10a mediates an increase in intestinal adenomas in female mice only and delineate the pathway to involve aberrant upregulation of the miR-10a target Klf4 and subsequent transcriptional activation of the Lpo gene encoding the antibacterial protein Lactoperoxidase. Lpo, in turn, has previously been demonstrated to oxidize estrogens into DNA-damaging mutagens.

Prevention of Helicobacter pylori-induced gastric cancers in gerbils by a DNA demethylating agent

Suppression of aberrant DNA methylation is a novel approach to cancer prevention, but, so far, the efficacy of the strategy has not been evaluated in cancers associated with chronic inflammation. Gastric cancers induced by Helicobacter pylori infection are known to involve aberrant DNA methylation and associated with severe chronic inflammation in their early stages. Here, we aimed to clarify whether suppression of aberrant DNA methylation can prevent H. pylori-induced gastric cancers using a Mongolian gerbil model. Administration of a DNA demethylating agent, 5-aza-2'-deoxycytidine (5-aza-dC), to gerbils (0.125 mg/kg for 50-55 weeks) decreased the incidence of gastric cancers induced by H. pylori infection and N-methyl-N-nitrosourea (MNU) treatment from 55.2% to 23.3% (P < 0.05). In gastric epithelial cells, DNA methylation levels of six CpG islands (HE6, HG2, SB1, SB5, SF12, and SH6) decreased to 46% to 68% (P < 0.05) of gerbils without 5-aza-dC treatment. Also, the global DNA methylation level decreased from 83.0% ± 4.5% to 80.3% ± 4.4% (mean ± SD) by 5-aza-dC treatment (P < 0.05). By 5-aza-dC treatment, Il1b and Nos2 were downregulated (42% and 58% of gerbils without, respectively) but Tnf was upregulated (187%), suggesting that 5-aza-dC treatment induced dysregulation of inflammatory responses. No obvious adverse effect of 5-aza-dC treatment was observed, besides testicular atrophy. These results showed that 5-aza-dC treatment can prevent H. pylori-induced gastric cancers and suggested that removal of induced DNA methylation and/or suppression of DNA methylation induction can become a target for prevention of chronic inflammation-associated cancers.

Chemopreventive effects of the juice of Vitis coignetiae Pulliat on two-stage mouse skin carcinogenesis

Our study revealed the inhibitory effect of Vitis coignetiae Pulliat, known as Yamabudo in Japan, at the stages of multi-step carcinogenesis. The juice of Vitis coignetiae (Y-grape juice) was antimutagenic toward dimethylbenzo[a]anthracene (DMBA), aflatoxin B1, and benzo[a]pyrene in the Ames test. The Y-grape juice was also antigenotoxic in the micronucleus test using HepG2 cells toward DMBA and aflatoxin B1. Topical and oral administration of the Y-grape juice to mice inhibited the induction of inflammation of 12-O-tetradecanoylphorbol-13-acetate (TPA). Topical and oral administration of the Y-grape juice significantly decreased the incidence and mean number of tumors in mice skin with the 2-stage tumorigenesis protocol. To elucidate the mechanisms underlying the antiinflammatory and antitumor promotion activity of the Y-grape juice, the effect of Y-grape juice on cyclooxygenase-2 (COX-2) activity in mouse ear treated with TPA was studied. Both topical and oral application of the Y-grape juice inhibited the TPA-induced increase in COX-2 activity. Caftaric acid, isolated and identified from the Y-grape juice, was antimutagenic toward DMBA and prevented TPA-induced inflammation in mice, suggesting caftaric acid participates in chemopreventive effect/activities of Y-grape juice.

The effect of caffeic acid phenethyl ester analogues in a modified resistant hepatocyte model

We present a study of the chemoprotective effects of two caffeic acid phenethyl ester (CAPE)-related structures: LQM717 and LQM706. The modified resistant hepatocyte model in rats was used to study the chemoprevention of these CAPE analogues, which are inexpensive and easily obtained. In the liver cancer model used, we detected extensive necrosis and lipid peroxidation after 24 h, many altered hepatic foci, putatively preneoplastic lesions with γ-glutamyl transpeptidase staining after 30 days, and liver tumors at 12 months. We tested the effect of the CAPE analogues on necrosis, lipid peroxidation, proliferation, p65 activation, altered hepatic foci, and tumors. Both compounds exerted protective effects on lipid peroxidation, necrosis, cell proliferation, p65 activation, and preneoplastic lesions. Rats under a carcinogenic protocol showed a 52, 71.74, and 51.6% decrease in the number of preneoplastic nodules when pretreated with CAPE, LQM706, and LQM717, respectively. At 12 months after carcinogenic treatment, eight of eight rats developed liver cancer, whereas in the group of rats that received pretreatment with CAPE, LQM706, or LQM717, 62.5, 83.3, or 42.85%, respectively, had tumors. In conclusion, LQM717 has the potential to enhance chemoprotection activity much better than CAPE by markedly reducing the formation of liver cancers in this model, and this is a compound that is easy to obtain.

Short-term calorie and protein restriction provide partial protection from chemotoxicity but do not delay glioma progression

Short-term starvation (STS) protects normal cells while simultaneously sensitizing malignant cells to high-dose chemotherapeutic drugs in mice and possibly patients. The fasting-dependent protection of normal cells and sensitization of malignant cells depends, in part, on reduced levels of insulin-like growth factor-1 (IGF-1) and glucose. Calorie restricted diets with defined macronutrient (carbohydrate, protein, fat) ratios were evaluated for the effects on stress sensitization markers and protection in mice treated with high-dose chemotherapy. We show that short-term CR significantly reduced both glucose and IGF-1 levels, but when specific macronutrient deficiencies were tested, only the complete lack of proteins reduced IGF-1 levels. Short-term 50% CR combined with either severe protein-deficiency or ketogenic diets improved chemotoxicity resistance similarly to the standard 50% CR, but did not result in the high protection caused by STS. Notably, a high protein diet reversed the beneficial effects of short-term CR. In a subcutaneous mouse model of glioma, feeding a low protein (4% calories from protein) diet for more than 20days did not delay tumor progression once the tumor became palpable. Also, cycles of short-term (3days) 50% CR did not augment the chemotherapy efficacy of cisplatin in a murine breast cancer model. These results indicate that the protection from chemotoxicity and retardation of the progression of certain tumors achieved with fasting is not obtained with short-term calorie and/or macronutrient restriction.

Xanthones from mangosteen extracts as natural chemopreventive agents: potential anticancer drugs

Despite decades of research, the treatment and management of malignant tumors still remain a formidable challenge for public health. New strategies for cancer treatment are being developed, and one of the most promising treatment strategies involves the application of chemopreventive agents. The search for novel and effective cancer chemopreventive agents has led to the identification of various naturally occurring compounds. Xanthones, from the pericarp, whole fruit, heartwood, and leaf of mangosteen (Garcinia mangostana Linn., GML), are known to possess a wide spectrum of pharmacologic properties, including antioxidant, anti- tumor, anti-allergic, anti-inflammatory, anti-bacterial, anti-fungal, and anti-viral activities. The potential chemopreventive and chemotherapeutic activities of xanthones have been demonstrated in different stages of carcinogenesis (initiation, promotion, and progression) and are known to control cell division and growth, apoptosis, inflammation, and metastasis. Multiple lines of evidence from numerous in vitro and in vivo studies have confirmed that xanthones inhibit proliferation of a wide range of human tumor cell types by modulating various targets and signaling transduction pathways. Here we provide a concise and comprehensive review of preclinical data and assess the observed anticancer effects of xanthones, supporting its remarkable potential as an anticancer agent.

Insights into the beneficial effect of caloric/ dietary restriction for a healthy and prolonged life

Over the last several years, new evidence has kept pouring in about the remarkable effect of caloric restriction (CR) on the conspicuous bedfellows- aging and cancer. Through the use of various animal models, it is now well established that by reducing calorie intake one can not only increase life span but, also, lower the risk of various age related diseases such as cancer. Cancer cells are believed to be more dependent on glycolysis for their energy requirements than normal cells and, therefore, can be easily targeted by alteration in the energy-metabolic pathways, a hallmark of CR. Apart from inhibiting the growth of transplantable tumors, CR has been also shown to inhibit the development of spontaneous, radiation, and chemically induced tumors. The question regarding the potentiality of the anti-tumor effect of CR in humans has been in part answered by the resistance of a cohort of women, who had suffered from anorexia in their early life, to breast cancer. However, human research on the beneficial effect of CR is still at an early stage and needs further validation. Though the complete mechanism of the anti-tumor effect of CR is far from clear, the plausible involvement of nutrient sensing pathways or IGF-1 pathways proposed for its anti-aging action cannot be overruled. In fact, cancer cell lines, mutant for proteins involved in IGF-1 pathways, failed to respond to CR. In addition, CR decreases the levels of many growth factors, anabolic hormones, inflammatory cytokines, and oxidative markers that are deregulated in several cancers. In this review, we discuss the anti-tumor effect of CR, describing experiments done in vitro in tumor models and in vivo in mouse models in which the tumor was induced by means of radiation or chemical exposure, expressing oncogenes or deleting tumor suppression genes. We also discuss the proposed mechanisms of CR anti-tumor action. Lastly, we argue the necessity of gene expression studies in cancerous versus normal cells upon CR.

Rutin Ameliorates Cyclophosphamide-induced Reproductive Toxicity in Male Rats

Cyclophosphamide (CYC) as an anticancer alkylating agent has been known as a male reproductive toxicant. This study was aimed to evaluate the protective effect of rutin (RUT) on CYC-induced reproductive toxicity. Sexually mature Wistar rats (weighing 199 ± 10 g with five animals in each group) were given CYC (15 mg/kg) and/or RUT (30 mg/kg) twice a week via gavage for 4 weeks. The sperm counts, sperm motility, sperm morphology, daily sperm production (DSP), testicular, and epididymal antioxidant systems: superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione reductase (GR), glutathione-S-transferase (GST), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and testicular steroidogenic enzymes (3β-hydroxysteroid dehydrogenase and 17β-HSD and spermatogenesis marker enzymes (lactate dehydrogenase (LDH), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP), acid phosphatase (ACP) in the testes, epididymis and seminal vesicles were investigated at the end of the fourth week. By the end of the fourth week, RUT prevented lower sperm counts, sperm motility, DSP, and higher abnormal sperm numbers induced by CYC. In testes, RUT decreased SOD, LDH, and SDH and increased CAT, 3β-HSD, 17β-HSD, ALP, and ACP induced by CYC. In epididymis, RUT increased SOD, CAT, GSH, GSH-Px, GR, GST SDH, ALP and ACP and decreased MDA and LDH induced by CYC. In seminal vesicles, marker enzymes were unchanged in rats given CYC alone or in combination with RUT. It appears that RUT ameliorates CYC reproductive toxicity at the investigated dose.

Arecanut as an emerging etiology of oral cancers in India

Arecanut (AN) usage is widespread in Asian countries, especially India and Taiwan. The incidence of oral cancer is increasing day by day, but there is no exponential increase with tobacco usage. Especially in the country like Taiwan where betel quid mostly do not contain tobacco, AN can be correlated with the increased incidence of cancer. There are different studies in the literature about AN and oral cancer but none of them have concluded with the definite pathway for carcinogenesis. The present paper includes reviews of the literature for AN and oral cancer and summarizes the possible mechanisms associated with AN-induced carcinogenesis; and we have also tried to propose pathway of carcinogenesis.

Tumor microsomal metabolism of the food toxicant, benzo(a)pyrene, in ApcMin mouse model of colon cancer

The present study was conducted to investigate whether colon tumors were capable of metabolizing benzo(a)pyrene (BaP), and fluoranthene (FLA), two toxicants that belong to the polycyclic aromatic hydrocarbon family of compounds. Microsomes were isolated from the colon tumors of Apc( Min ) mice that received subchronic doses of 50 μg/kg BaP and incubated with either BaP or FLA (3 μM each) alone or in combination and appropriate control groups that received nothing. Subsequent to incubation, samples were extracted with ethyl acetate and analyzed for BaP and FLA metabolites by reverse-phase HPLC equipped with fluorescence detection. Microsomes from tumor tissues were found to metabolize BaP to a greater extent than those from the non-tumor tissues. The rate of BaP metabolism (picomoles of metabolite per minute per milligram of protein) was found to be more when microsomes from BaP-pretreated mice were exposed to BaP alone and FLA in combination with BaP, compared to controls. The microsomes from BaP-preexposed mice generated greater proportion of BaP 7,8-diol and BaP 3,6- and 6,12-diones compared to other experimental groups. Additionally, microsomes from BaP-pretreated mice produced greater proportion of FLA 2, 3-diol and 2, 3 D FLA when microsomes were incubated with FLA alone or a combination of BaP and FLA. Our studies revealed that the tumor microsomes were competent to metabolize BaP and FLA either singly or in combination. The biotransformation of BaP and FLA as a consequence of prior and simultaneous exposure to BaP may influence the growth of tumors. Our findings may have relevance to human long-term dietary intake of these toxicants and the consequent acceleration of the colon carcinogenesis process.

Investigation of the extracts from Bidens pilosa Linn. var. radiata Sch. Bip. for antioxidant activities and cytotoxicity against human tumor cells

The aim of this study was to evaluate antioxidant activities and cytotoxicity against human tumor cell lines of extracts from Bidens pilosa Linn. var. radiata Sch. Bip. (BP). Total phenolic and flavonoid contents of the extracts were determined by ultraviolet spectrophotometry. Furthermore, the antioxidant properties of different polarity fractions extracted from BP were evaluated using DPPH and ABTS radical scavenging test and FRAP assay. The ethyl acetate fraction (EE-BP) showed the highest antioxidant activity compared to other fractions. In addition, the anti-proliferative activities of the extracts on four human tumor cells, namely MCF-7, HepG2, MGC 803 and RKO, were investigated by MTT method. The EE-BP displayed the most remarkable anti-proliferative effect against the tumor cells, particularly RKO cell in dose- and time-dependent manner. The antioxidant activities and cytotoxicity correlated highly with the total phenolic and flavonoid contents, respectively. Furthermore, The active ingredient BP-6, namely 5,7,4'-trihydroxy-3,3'-dimethyl-flavonol, was isolated and purified with the purity above 99.00% and content of 0.15% in EE-BP detected by HPLC, which could significantly inhibit the proliferation of RKO cells with the IC(50) value of 6.66 μmol/l. In order to characterize the apoptotic RKO cells, flow cytometry and DNA fragmentation assay were performed. Apoptotic cell numbers increased in a dose-dependent manner after the treatment with different concentrations of EE-BP and BP-6 for 12 and 6 h, respectively. DNA ladders in apoptotic RKO cells could be easily visualized when exposed to 200 μg/ml of the EE-BP for 36 h. Taken together, our work indicated that BP had potentially therapeutic value against colorectal cancer.

Low-dose radiation therapy of cancer: role of immune enhancement

The efficacy of conventional radiation therapy, one of the most widely used treatment modalities of cancer, is limited by resistance of tumors as well as normal tissue toxicity. In the last decade, several studies have shown that protocols using low-dose radiation (LDR) are more effective in providing local tumor control with negligible normal tissue toxicity. LDR stimulates antioxidant capacity, repair of DNA damage, apoptosis and induction of immune responses, which might be collectively responsible for providing effective local tumor control. This article focuses on the immunostimulatory effects of LDR in in vivo models and its clinical efficacy, supporting the use of LDR regimens (alone or as adjuvant) as an anticancer treatment.

DFMO: targeted risk reduction therapy for colorectal neoplasia

Strategies to decrease intracellular polyamine levels have been studied for their efficacy in reducing colorectal cancer (CRC) risk. A successful strategy combined agents that decreased polyamine synthesis by inhibiting ornithine decarboxylase with difluoromethylornithine (DFMO), and increased cellular export of polyamines by activating the spermidine/spermine acetyl transferase with non-steroidal anti-inflammatory drugs (NSAIDs). A Phase III trial treating resected adenoma patients with DFMO plus sulindac demonstrated marked reduction of metachronous adenomas, advanced adenomas and multiple adenomas compared to placebo. This combination regimen was well-tolerated, however there was a non-significant excess of cardiovascular events in the treatment arm compared to placebo as well as modest ototoxicity. Targeting this therapy to people at elevated risk of CRC, and employing clinical and genetic predictors, should improve patient benefit and reduce the risk of side effects to improve the acceptability of this strategy.

Nutrition and melanoma prevention

Melanoma has continued to rise in incidence despite public efforts to promote sun protection behaviors. Because sunscreen use does not completely prevent skin cancer induced by ultraviolet radiation, additional chemopreventive methods for protecting against and reversing the effects of ultraviolet photodamage need evaluation. Recent years have brought increased interest in dietary factors, such as natural botanicals and vitamins, for the prevention of melanoma. This contribution provides a narrative review of the relevant, nutrition-related literature found by searching the keywords "melanoma chemoprevention," "nutrition and melanoma," "dietary botanicals and melanoma prevention," "green tea and melanoma," "vitamin D and melanoma," and "vitamin E and melanoma" in the PubMed database. Although randomized controlled trials of humans are lacking, basic science and epidemiologic studies show promising benefits of many natural products in chemoprevention for melanoma. Future studies, hopefully, will yield concrete answers and clarify the role of commonly available dietary nutrients in melanoma chemoprevention.

Chemopreventive activity of Azadirachta indica on two-stage skin carcinogenesis in murine model

The present study reports the chemopreventive activity of aqueous Azadirachta indica leaf extract (AAILE) in a murine two-stage skin carcinogenesis model. Skin tumors were induced by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) (500 nmol/100 µL for 2 weeks) followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) (1.7 nmol/100 µL of acetone, twice weekly) as a promoter. Male LACA mice were divided into four groups: control, DMBA/TPA, AAILE and AAILE + DMBA/TPA. AAILE was administered orally at a dose level of 300 mg/kg body weight thrice a week for 20 weeks. 100% tumor incidence was observed in the DMBA/TPA treated animals, whereas the AAILE + DMBA treated animals exhibited a tumor incidence of 58.3% only. A significant reduction in the mean tumor burden (54.5%) and mean tumor volume (45.6%) was observed in the mice that received AAILE along with DMBA/TPA. Topical application of DMBA/TPA to the skin resulted in well-developed carcinomas associated with decreased expression of pro-apoptotic protein such as caspase 3 and enhanced expression of antiapoptotic protein such as bcl-2 when compared with the control counterparts. However, adminstration of AAILE inhibited skin carcinogenesis with induction of pro-apoptotic proteins such as bax, caspase 3, caspase 9 and inhibition of antiapoptotic proteins such as bcl-2. These results suggest that the induction of apoptosis may be one of the mechanisms underlying the chemopreventive effects of A. indica.

Investigation of fruit peel extracts as sources for compounds with antioxidant and antiproliferative activities against human cell lines

The aim of this study was to evaluate antioxidant activity and cytotoxicity against human cell lines of fruit peel extracts from rambutan, mangosteen and coconut. The highest antioxidant activity was found from rambutan peel crude extract where the highest radical scavenging capacity via ABTS assay was from its ethyl acetate fraction with a TEAC value of 23.0mM/mg and the highest ferric ion reduction activity via FRAP assay was from its methanol fraction with an EC value of 20.2mM/mg. Importantly, using both assays, these fractions had a higher antioxidant activity than butylated hydroxyl toluene and vitamin E. It was shown that the ethyl acetate fraction of rambutan peel had the highest polyphenolic content with a gallic acid equivalent of 2.3mg/mL. The results indicate that the polyphenolic compounds are responsible for the observed antioxidant activity of the extracts. Interestingly, the hexane fraction of coconut peel showed a potent cytotoxic effect on KB cell line by MTT assay (IC(50)=7.7 microg/mL), and no detectable cytotoxicity toward normal cells. We concluded that the ethyl acetate fraction of rambutan peel is a promising resource for potential novel antioxidant agents whereas the hexane fraction of coconut peel may contain novel anticancer compounds.

Evaluation of Elephantopus scaber on the inhibition of chemical carcinogenesis and tumor development in mice

The effect of the active fraction of Elephantopus scaber L. (Asteraceae) (ES) on skin papillomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) as an initiator and croton oil as promoter was studied in mice. The active fraction of E. scaber (100 mg/kg) on topical application delayed the onset of papilloma formation and reduced the mean number of papillomas and the mean weight of papillomas per mouse. The intraperitoneal administration of the active fraction of E. scaber also had a significant effect on subcutaneous injection of 20-methylcholanthrene (20-MCA)-induced soft tissue sarcomas in mice. It inhibited the incidence of sarcomas and reduced the tumor diameter compared to MCA-treated control animals. The subcutaneous administration of the active fraction of E. scaber significantly inhibited the growth of subcutaneously transplanted DLA and EAC solid tumors, delayed the onset of tumor formation, and increased the life span of tumor bearing mice. The present study thus indicates the tumor inhibitory activity of the active fraction of E. scaber against chemically induced tumors and its ability to inhibit the development of solid tumors.

Calorie restriction and cancer prevention: metabolic and molecular mechanisms

An important discovery of recent years has been that lifestyle and environmental factors affect cancer initiation, promotion and progression, suggesting that many malignancies are preventable. Epidemiological studies strongly suggest that excessive adiposity, decreased physical activity, and unhealthy diets are key players in the pathogenesis and prognosis of many common cancers. In addition, calorie restriction (CR), without malnutrition, has been shown to be broadly effective in cancer prevention in laboratory strains of rodents. Adult-onset moderate CR also reduces cancer incidence by 50% in monkeys. Whether the antitumorigenic effects of CR will apply to humans is unknown, but CR results in a consistent reduction in circulating levels of growth factors, anabolic hormones, inflammatory cytokines and oxidative stress markers associated with various malignancies. Here, we discuss the link between nutritional interventions and cancer prevention with focus on the mechanisms that might be responsible for these effects in simple systems and mammals with a view to developing chemoprevention agents.

Resveratrol modulates pyrogallol-induced changes in hepatic toxicity markers, xenobiotic metabolizing enzymes and oxidative stress

Previously, we reported that pyrogallol, an anti-psoriatic agent, causes hepatotoxicity in experimental animals and silymarin, an herbal antioxidant, reduces pyrogallol-induced changes [Upadhyay, G., Kumar, A., Singh, M.P., 2007. Effect of silymarin on pyrogallol- and rifampicin-induced hepatotoxicity in mouse. Eur. J. Pharmacol. 565, 190-201.]. The present study was undertaken to assess the effect of resveratrol against pyrogallol-induced changes in hepatic damage markers, xenobiotic metabolizing enzymes and oxidative stress. Swiss albino mice were treated intraperitoneally, daily with pyrogallol (40 mg/kg), for one to four weeks, along with respective controls. In some set of experiments, animals were pre-treated with resveratrol (10 mg/kg), 2 h prior to pyrogallol treatment, along with respective controls. Alanine aminotransaminase, aspartate aminotransaminase and bilirubin were measured in blood plasma and mRNA expression of cytochrome P-450 (CYP) 1A1, CYP1A2, CYP2E1, glutathione-S-transferase (GST)-ya and GST-yc, catalytic activity of CYP1A1, CYP1A2, CYP2E1, GST, glutathione reductase and glutathione peroxidase, lipid peroxidation and reduced glutathione (GSH) level were measured in liver. Resveratrol reduced pyrogallol-mediated increase in alanine aminotransaminase, aspartate aminotransaminase, bilirubin, lipid peroxidation and mRNA expression and catalytic activity of CYP2E1 and CYP1A2. Pyrogallol-mediated decrease in GST-ya and GST-yc expressions, GST, glutathione peroxidase and glutathione reductase activities and GSH content was significantly attenuated in resveratrol co-treated animals. CYP1A1 expression and catalytic activity were not altered significantly in any treated groups. The results demonstrate that resveratrol modulates pyrogallol-induced changes in hepatic toxicity markers, xenobiotic metabolizing enzymes and oxidative stress.

Inhibitory effects of methanol extract of plum (Prunus salicina L., cv. 'Soldam') fruits against benzo(alpha)pyrene-induced toxicity in mice

This study was carried out to investigate the chemopreventive effects of immature plum extracts. The methanol extract of immature plums (plum 1), that are picked at 20-40 days before final harvest, has remarkably inhibited the growth of hepatoma HepG2 cells. The effects of immature plum extracts on hepatotoxicity in benzo(alpha)pyrene (B(alpha)P, carcinogen)-treated mice were investigated. Male ICR mice were pretreated with immature plum extracts (2.5 or 5 g/kg bw/day, for 5 days, i.p.) before treatment with B(alpha)P(0.5 mg/kg bw, i.p., single dose). The activities of serum aminotransferase, cytochrome P450 (CYPs) and the hepatic content of lipid peroxide were increased on B(alpha)P-treatment group than control, but those levels were significantly decreased by the pretreatment of immature plum extracts. The primary CYPs involved in the metabolism and bioactivation of B(alpha)P are CYP1A1. The pretreatment of immature plum extracts inhibited the induction of CYP1A1 expression. The activities of glutathione peroxidase, superoxide dismutase and catalase were decreased by the pretreatment of immature plum extracts more than with B(alpha)P alone. Whereas, the hepatic content of glutathione and glutathione S-transferase activity depleted by B(alpha)P was significantly increased (p > 0.05). These results suggest that immature plum extracts may counteract toxic effects of carcinogens, such as B(alpha)P, and therefore possess the chemopreventive efficacy.