Combination of S-allylcysteine and lycopene induces apoptosis by modulating Bcl-2, Bax, Bim and caspases during experimental gastric carcinogenesis

Therapeutic effects of S-allyl-L-cysteine in a mouse endometriosis model and its immunomodulatory effects via regulation of T cell subsets and cytokine expression

BACKGROUND

Endometriosis is a female hormone-dependent gynecological disorder characterized by chronic inflammation. Therefore, the development of novel treatment strategies that can diminish the side effects of the long-term use of hormone-based drugs has been emphasized. S-Allyl-L-cysteine (SAC) is the major constituent of aged garlic extracts. Although the therapeutic effects resulting from the antioxidant properties of SAC have been extensively studied in inflammatory diseases, the therapeutic efficacy of SAC in endometriosis has not been described. In this study, we investigated the therapeutic potential of SAC for endometriosis using a mouse model.

METHODS

An endometriosis mouse model was surgically induced, and oral treatment with 30 mg/kg SAC was administered daily for 28 days. The development of endometriotic lesions was assessed by histological analysis, and the expression profiles of adhesion-, apoptosis-, and inflammation-related genes were evaluated by PCR. Flow cytometric analysis of mouse spleen was conducted to assess changes in lymphocyte subpopulations.

RESULTS

SAC treatment significantly inhibited endometriotic lesion growth. Transcriptional expression analysis revealed the antiadhesion and apoptosis-promoting effects of SAC. In particular, SAC showed an effective immune modulatory response by altering splenic CD4+ and CD8+ T cell subsets and inflammatory cytokine production in the spleen and endometriotic lesions.

CONCLUSION

This study newly elucidates the inhibitory effects of SAC on the growth of endometriosis in a mouse model and describes its immunomodulatory effects.

S-allyl-cysteine triggers cytotoxic events in rat glioblastoma RG2 and C6 cells and improves the effect of temozolomide through the regulation of oxidative responses

Glioblastoma (GBM) is an aggressive form of cancer affecting the Central Nervous System (CNS) of thousands of people every year. Redox alterations have been shown to play a key role in the development and progression of these tumors as Reactive Oxygen Species (ROS) formation is involved in the modulation of several signaling pathways, transcription factors, and cytokine formation. The second-generation oral alkylating agent temozolomide (TMZ) is the first-line chemotherapeutic drug used to treat of GBM, though patients often develop primary and secondary resistance, reducing its efficacy. Antioxidants represent promising and potential coadjutant agents as they can reduce excessive ROS formation derived from chemo- and radiotherapy, while decreasing pharmacological resistance. S-allyl-cysteine (SAC) has been shown to inhibit the proliferation of several types of cancer cells, though its precise antiproliferative mechanisms remain poorly investigated. To date, SAC effects have been poorly explored in GBM cells. Here, we investigated the effects of SAC in vitro, either alone or in combination with TMZ, on several toxic and modulatory endpoints-including oxidative stress markers and transcriptional regulation-in two glioblastoma cell lines from rats, RG2 and C6, to elucidate some of the biochemical and cellular mechanisms underlying its antiproliferative properties. SAC (1-750 µM) decreased cell viability in both cell lines in a concentration-dependent manner, although C6 cells were more resistant to SAC at several of the tested concentrations. TMZ also produced a concentration-dependent effect, decreasing cell viability of both cell lines. In combination, SAC (1 µM or 100 µM) and TMZ (500 µM) enhanced the effects of each other. SAC also augmented the lipoperoxidative effect of TMZ and reduced cell antioxidant resistance in both cell lines by decreasing the TMZ-induced increase in the GSH/GSSG ratio. In RG2 and C6 cells, SAC per se had no effect on Nrf2/ARE binding activity, while in RG2 cells TMZ and the combination of SAC + TMZ decreased this activity. Our results demonstrate that SAC, alone or in combination with TMZ, exerts antitumor effects mediated by regulatory mechanisms of redox activity responses. SAC is also a safe drug for testing in other models as it produces non-toxic effects in primary astrocytes. Combined, these effects suggest that SAC affords antioxidant properties and potential antitumor efficacy against GBM.

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

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

In silico and in vitro investigation of anticancer effect of newly synthesized nonivamide-s-allyl cysteine ester

Nonivamide (NOV), less pungent analogue of capsaicin present in various Capsicum species is known for various biological properties. S-allyl cysteine (SAC) abundantly present in aged garlic extract is gaining importance for anticancer property. NOV was esterified with SAC to increase the biological activity. In silico ADME analysis revealed the drug-likeness of NOV-SAC. Molecular docking and dynamics simulation analysis were done to understand the interaction of NOV-SAC with therapeutic target proteins (human estrogen receptor α, tumo protein negative regulator mouse double minute 2, B-cell lymphoma 2 and cyclin-dependent kinase 2) to treat cancer. NOV-SAC interacted with these proteins stably with favorable binding energy which was calculated through MMGBSA method. In line with in silico results, NOV-SAC showed antiproliferative activity against breast cancer cell line (MCF-7). NOV-SAC treatment increased ROS generation, decreased the antioxidant level, arrested cells at G1/S phase, disrupted mitochondrial membrane potential and initiated DNA fragmentation. The expression of p53 is increased by NOV-SAC treatment, in concordance the ratio of Bcl-2/Bax was decreased. Altogether, NOV-SAC was synthesized for the first time and it induced apoptosis in MCF-7 cells through triggering ROS generation and increasing the expression of p53. The in silico results has been mirrored in in vitro analysis of NOV-SAC against cancer cell line.Communicated by Ramaswamy H. Sarma.

Purification, Identification, and Properties of a Novel Carotenoid Produced by Arthrobacter sp. QL17 Isolated from Mount Qomolangma

The genus Arthrobacter is a source of many natural products that are critical in the development of new medicines. Here, we isolated a novel carotenoid from Arthrobacter sp. QL17 and characterized its properties. The carotenoid was extracted with methanol, and purified by column chromatography and semi-preparative HPLC. Based on micrOTOF-Q and NMR analyses, the pigment was chemically characterized as 2,2′-((((1E,3E,5E,7E,9E,11E,13E,15E,17E,19E)-3,7,14,18-tetramethylicosa-1,3,5,7,9,11,13,15,17,19-decaene-1,20-diyl)bis(2,2,4-trimethylcyclohex-3-ene-3,1-diyl)) bis(ethan-2-yl-1-ylidene))bi(propane-1,3-diol), and named arthroxanthin. The biological activities of arthroxanthin were evaluated with DPPH, ABTS and MTT assays. Arthroxanthin exhibited excellent radical scavenging properties, as shown for 2, 20-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-n-(3, 2-ethyl-benzothiazole-6-sulfonic acid) ammonium salt (ABTS), respectively, with IC50s of 69.8 and 21.5 µg/mL. It also showed moderate anticancer activities against HepG2, Hela, MDAB-231, SW480, and MKN-45 with IC50 values of 107.6, 150.4, 143.4, 195.9, and 145.5 μg/mL, respectively. Therefore, arthroxanthin derived from Arthrobacter sp. QL17 may be a potent antioxidant and anticancer agent for food and pharmaceutical use.

Molecular Targets of Natural Compounds with Anti-Cancer Properties

Cancer is the second leading cause of death in humans. Despite rapid developments in diagnostic methods and therapies, metastasis and resistance to administrated drugs are the main obstacles to successful treatment. Therefore, the main challenge should be the diagnosis and design of optimal therapeutic strategies for patients to increase their chances of responding positively to treatment and increase their life expectancy. In many types of cancer, a deregulation of multiple pathways has been found. This includes disturbances in cellular metabolism, cell cycle, apoptosis, angiogenesis, or epigenetic modifications. Additionally, signals received from the microenvironment may significantly contribute to cancer development. Chemical agents obtained from natural sources seem to be very attractive alternatives to synthetic compounds. They can exhibit similar anti-cancer potential, usually with reduced side effects. It was reported that natural compounds obtained from fruits and vegetables, e.g., polyphenols, flavonoids, stilbenes, carotenoids and acetogenins, might be effective against cancer cells in vitro and in vivo. Several published results indicate the activity of natural compounds on protein expression by its influence on transcription factors. They could also be involved in alterations in cellular response, cell signaling and epigenetic modifications. Such natural components could be used in our diet for anti-cancer protection. In this review, the activities of natural compounds, including anti-cancer properties, are described. The influence of natural agents on cancer cell metabolism, proliferation, signal transduction and epigenetic modifications is highlighted.

Omics Technologies to Enhance Plant Based Functional Foods: An Overview

Functional foods are natural products of plants that have health benefits beyond necessary nutrition. Functional foods are abundant in fruits, vegetables, spices, beverages and some are found in cereals, millets, pulses and oilseeds. Efforts to identify functional foods in our diet and their beneficial aspects are limited to few crops. Advances in sequencing and availability of different omics technologies have given opportunity to utilize these tools to enhance the functional components of the foods, thus ensuring the nutritional security. Integrated omics approaches including genomics, transcriptomics, proteomics, metabolomics coupled with artificial intelligence and machine learning approaches can be used to improve the crops. This review provides insights into omics studies that are carried out to find the active components and crop improvement by enhancing the functional compounds in different plants including cereals, millets, pulses, oilseeds, fruits, vegetables, spices, beverages and medicinal plants. There is a need to characterize functional foods that are being used in traditional medicines, as well as utilization of this knowledge to improve the staple foods in order to tackle malnutrition and hunger more effectively.

Multifaceted Effects of Lycopene: A Boulevard to the Multitarget-Based Treatment for Cancer

Lycopene is a pigment belonging to the group of carotenoids and it is among the most carefully studied antioxidants found especially in fruit and vegetables. As a carotenoid, lycopene exerts beneficial effects on human health by protecting lipids, proteins, and DNA from damage by oxidation. Lycopene is a powerful oxygen inactivator in the singlet state. This is suggestive of the fact that lycopene harbors comparatively stronger antioxidant properties over other carotenoids normally present in plasma. Lycopene is also reported to hinder cancer cell proliferation. The uncontrolled, rapid division of cells is a characteristic of the metabolism of cancer cells. Evidently, lycopene causes a delay in the progression of the cell cycle, which explains its antitumor activity. Furthermore, lycopene can block cell transformation by reducing the loss of contact inhibition of cancer cells. This paper collects recent studies of scientific evidence that show the multiple beneficial properties of lycopene, which acts with different molecular and cellular mechanisms.

Elucidation of S-Allylcysteine Role in Inducing Apoptosis by Inhibiting PD-L1 Expression in Human Lung Cancer Cells

AIM

The aim of this study is to explore the therapeutic potential of S-allylcysteine (SAC) organosulphur compound as a potent immune checkpoint inhibitor PD-L1.

BACKGROUND

Natural compounds have been showing tremendous anticancerous potential via suppressing the expression of genes involved in the development and progression of several carcinomas. This has further motivated us to explore the therapeutic potential of organosulphur compounds as potent immune checkpoint inhibitors.

OBJECTIVE

Our study was designed to elucidate the potential of S-allylcysteine (SAC) as significant PD-L1 (immune checkpoint) inhibitor in human lung cancer A549 cancer cell line by using both the in vitro and in silico approaches.

METHODS

Anticancerous effect of the SAC on lung cancer cells was determined by using the MTT cell viability. Apoptotic induction was confirmed by Hoechst staining, percent caspase-3 activity as well as gene expression analysis by real time PCR. Reactive Oxygen Species (ROS) was estimated by DCFDA method. Additionally, ligand-target protein interaction was analysed by molecular docking.

RESULT

Cell growth and proliferation was significantly reduced in SAC treated A549 cells in a concentration and time.dependent manner. The effect of SAC on apoptotic induction was analyzed by enhanced nuclear condensation, increased percent caspase-3 activity as well as modulation of apoptotic genes. Furthermore, SAC treatment also resulted in reduced expression of PD-L1 and HIF-1α. Additionally, in silico analysis also supported the in vitro findings by showing efficient docking with PD-L1 immune checkpoint target.

CONCLUSION

Therefore, our results clearly suggested that SAC could serve as a novel chemotherapeutic candidate for the treatment of lung cancer by inhibiting immune checkpoint target PD-L1 in human lung cancer cells. Additionally, our study also explained a novel molecular mechanism of its antitumor activity.

Effects of lycopene on ovarian cancer cell line SKOV3 in vitro: Suppressed proliferation and enhanced apoptosis

AIMS

This study aims to investigate the influences of lycopene on ovarian cancer cells SKOV3 in vitro and the corresponding mechanism.

METHODS

SKOV3 cultures were divided into four groups and treated with lycopene at 0 (the control group), 1 × 10^-6, 1 × 10^-5 and 1 × 10^-4 mol/L respectively. The proliferation rate of SKOV3 cells was determined using MTT colorimetric assay, and the apoptosis rate of SKOV3 cells was measured using flow cytometry. Western blotting was used to detect the expressions of Bax and Bcl-2.

RESULTS

When compared with the control group, the proliferation rates of SKOV3 cells in the three lycopene groups were significantly lower (P < 0.05) while the apoptosis rates were significantly higher (P < 0.05). After lycopene treatment, the protein expression of Bax (an apoptotic protein) in SKOV3 cells increased significantly, and the protein expression of Bcl-2 (an anti-apoptotic protein) decreased significantly.

CONCLUSION

Lycopene could inhibit the proliferation of SKOV3 cells and enhance their apoptosis in vitro. The induction of cell apoptosis might be mediated by up-regulating Bax expression and down-regulating Bcl-2 expression.

Lycopene: Is it Beneficial to Human Health as an Antioxidant?

It is well known that free oxygen radicals play an important role in the pathogenesis of several chronic disorders. Antioxidants are known as potential scavengers of reactive oxygen species that can protect biologic membranes against oxidative damage. Recent interest in phytochemicals has increased because of their protective effects against free oxygen radicals. Lycopene, which belongs to the carotenoid family, is the most effective singlet oxygen scavenger in vitro of all the carotenoids. Foods that contain lycopene and related supplements have been reported to prevent chronic diseases including cancer, asthma, and cardiovascular disorders. The aim of the article was to give a brief review of the antioxidant properties and beneficial health effects of lycopene.

A novel red pigment from marine Arthrobacter sp. G20 with specific anticancer activity

AIMS

Bacterial pigments are promising compounds in the prevention and treatment of various cancers. In the current study, the antioxidant, cytotoxic and antimicrobial effects of a red pigment obtained from a marine bacterial strain were investigated.

METHODS AND RESULTS

Optimization of the pigment production by the marine strain was conducted using the one-factor-at-a-time approach. Chemical identification of the pigment was achieved by UV-visible, FTIR and HPLC analyses. The biological activities of the pigment were evaluated by DPPH, MTT and microbroth dilution assays. The strain was identified as Arthrobacter, and its pigment was related to carotenoids. The EC₅₀ antioxidant activity of the pigment was evaluated as 4·5 mg ml^-1 . It showed moderate anticancer effects on an oesophageal cancer cell line, KYSE30, while no inhibition was observed on normal HDF (human dermal fibroblasts) cells. The pigment had no antibacterial effects on the four tested strains.

CONCLUSION

The antitumour activity of a carotenoid-related pigment from Arthrobacter sp. was reported for the first time.

SIGNIFICANCE AND IMPACT OF THE STUDY

Marine environments are interesting sources for the identification of novel bioproducts. The identification of carotenoid pigments from marine bacteria with remarkable antioxidant and anticancer activities would result in better insights into the potential pharmaceutical applications of carotenoids and marine environments.

Pharmacological Intervention through Dietary Nutraceuticals in Gastrointestinal Neoplasia

Neoplastic conditions associated with gastrointestinal (GI) tract are common worldwide with colorectal cancer alone accounting for the third leading rate of cancer incidence. Other GI malignancies such as esophageal carcinoma have shown an increasing trend in the last few years. The poor survival statistics of these fatal cancer diseases highlight the need for multiple alternative treatment options along with effective prophylactic strategies. Worldwide geographical variation in cancer incidence indicates a correlation between dietary habits and cancer risk. Epidemiological studies have suggested that populations with high intake of certain dietary agents in their regular meals have lower cancer rates. Thus, an impressive embodiment of evidence supports the concept that dietary factors are key modulators of cancer including those of GI origin. Preclinical studies on animal models of carcinogenesis have reflected the pharmacological significance of certain dietary agents called as nutraceuticals in the chemoprevention of GI neoplasia. These include stilbenes (from red grapes and red wine), isoflavones (from soy), carotenoids (from tomatoes), curcuminoids (from spice turmeric), catechins (from green tea), and various other small plant metabolites (from fruits, vegetables, and cereals). Pleiotropic action mechanisms have been reported for these diet-derived chemopreventive agents to retard, block, or reverse carcinogenesis. This review presents a prophylactic approach to primary prevention of GI cancers by highlighting the translational potential of plant-derived nutraceuticals from epidemiological, laboratory, and clinical studies, for the better management of these cancers through consumption of nutraceutical rich diets and their intervention in cancer therapeutics.

Targeting Apoptosis with Dietary Bioactive Agents

Apoptosis, a form of programmed cell death, is a pivotal defense against the occurrence of cancer and is essential to metazoans in maintaining tissue homeostasis. Apoptosis exhibits a distinctive phenotype and involves elimination of potentially deleterious cells. Many diseases have been associated with aberrantly regulated apoptotic cell death, ultimately leading to inhibition of apoptosis and propagation of diseases such as cancer. Elucidation of the critical events associated with carcinogenesis provides the opportunity for dietary intervention to prevent cancer development through induction of apoptosis, Particularly by bioactive agents or functional foods. Diet is a significant environmental factor in the overall cancer process and can exacerbate or interfere with carcinogenesis. Apoptosis occurs primarily through two well-recognized pathways in cells, including the Intrinsic, or mitochondrial-mediated, effector mechanism and the extrinsic, or death receptor-mediated, effector mechanism. In addition to diet's effects on protein expression and function, evidence is also accumulating that a large number of dietary food components can exert effects on the human genome, either directly or indirectly, to modulate gene expression. In fact, many diet-related genes are involved in carcinogenesis as well as apoptosis, and thus are ultimately molecular targets for dietary chemopreventlon. There are multiple steps within pathways in which dietary components can alter gene expression and phenotypes of cells and thus influence cancer outcomes (nutritional transcriptomic effect). Thus, apoptosis is an emerging therapeutic target of bioactive agents of diet. In this review, the process of apoptosis is discussed and the potential mechanistic interaction of bioactive agents, as components of functional foods, is explored within the context of apoptosis.

Fisetin Enhances Chemotherapeutic Effect of Cabazitaxel against Human Prostate Cancer Cells

Although treatment of prostate cancer has improved over the past several years, taxanes, such as cabazitaxel, remain the only form of effective chemotherapy that improves survival in patients with metastatic castration-resistant prostate cancer. However, the effectiveness of this class of drugs has been associated with various side effects and drug resistance. We previously reported that fisetin, a hydroxyflavone, is a microtubule-stabilizing agent and inhibits prostate cancer cell proliferation, migration, and invasion and suggested its use as an adjuvant for treatment of prostate and other cancer types. In this study, we investigated the effect of fisetin in combination with cabazitaxel with the objective to achieve maximum therapeutic benefit, reduce dose and toxicity, and minimize or delay the induction of drug resistance and metastasis. Our data show for the first time that a combination of fisetin (20 μmol/L) enhances cabazitaxel (5 nmol/L) and synergistically reduces 22Rν1, PC-3M-luc-6, and C4-2 cell viability and metastatic properties with minimal adverse effects on normal prostate epithelial cells. In addition, the combination of fisetin with cabazitaxel was associated with inhibition of proliferation and enhancement of apoptosis. Furthermore, combination treatment resulted in the inhibition of tumor growth, invasion, and metastasis when assessed in two in vivo xenograft mouse models. These results provide evidence that fisetin may have therapeutic benefit for patients with advanced prostate cancer through enhancing the efficacy of cabazitaxel under both androgen-dependent and androgen-independent conditions. This study underscores the benefit of the combination of fisetin with cabazitaxel for the treatment of advanced and resistant prostate cancer and possibly other cancer types. Mol Cancer Ther; 15(12); 2863-74. ©2016 AACR.

Anticancer Effect of Lycopene in Gastric Carcinogenesis

Gastric cancer ranks as the most common cancer and the second leading cause of cancer-related death in the world. Risk factors of gastric carcinogenesis include oxidative stress, DNA damage, Helicobacter pylori infection, bad eating habits, and smoking. Since oxidative stress is related to DNA damage, smoking, and H. pylori infection, scavenging of reactive oxygen species may be beneficial for prevention of gastric carcinogenesis. Lycopene, one of the naturally occurring carotenoids, has unique structural and chemical features that contributes to a potent antioxidant activity. It shows a potential anticancer activity and reduces gastric cancer incidence. This review will summarize anticancer effect and mechanism of lycopene on gastric carcinogenesis based on the recent experimental and clinical studies.

Analysis of lifespan-promoting effect of garlic extract by an integrated metabolo-proteomics approach

The beneficial effects of garlic (Allium sativum) consumption in treating human diseases have been reported worldwide over a long period of human history. The strong antioxidant effect of garlic extract (GE) has also recently been claimed to prevent cancer, thrombus formation, cardiovascular disease and some age-related maladies. Using Caenorhabditis elegans as a model organism, aqueous GE was herein shown to increase the expression of longevity-related FOXO transcription factor daf-16 and extend lifespan by 20%. By employing microarray and proteomics analysis on C. elegans treated with aqueous GE, we have systematically mapped 229 genes and 46 proteins with differential expression profiles, which included many metabolic enzymes and yolky egg vitellogenins. To investigate the garlic components functionally involved in longevity, an integrated metabolo-proteomics approach was employed to identify metabolites and protein components associated with treatment of aqueous GE. Among potential lifespan-promoting substances, mannose-binding lectin and N-acetylcysteine were found to increase daf-16 expression. Our study points to the fact that the lifespan-promoting effect of aqueous GE may entail the DAF-16-mediated signaling pathway. The result also highlights the utility of metabolo-proteomics for unraveling the complexity and intricacy involved in the metabolism of natural products in vivo.

Diet-based strategies for cancer chemoprevention: the role of combination regimens using dietary bioactive components

Chemopreventive agents that the general population can consume for prolonged periods of time with minimal risk of any side effects are of great interest to all in search of a solution to the pervasive incidence of cancer. Dietary bioactive components have been found to modulate many deregulated molecular pathways associated with the initiation and progression of different types of cancer. Combination regimens with dietary bioactive components are a promising strategy for cancer chemoprevention because they may offer enhanced protective effects against cancer development but cause little or no adverse effects. This article provides an overview of studies examining the combination of dietary bioactive components for the chemoprevention of major types of cancer. A better understanding of existing research on the combination of dietary bioactive components will provide an important basis for the rational design of future combination studies and the successful development of cancer chemoprevention strategies.

S-allylcysteine, a garlic derivative, suppresses proliferation and induces apoptosis in human ovarian cancer cells in vitro

AIM

To investigate the effects of S-allylcysteine (SAC), a water-soluble garlic derivative, on human ovarian cancer cells in vitro.

METHODS

Human epithelial ovarian cancer cell line A2780 was tested. Cell proliferation was examined with CCK-8 and colony formation assays. Cell cycle was analyzed with flow cytometry. Cell apoptosis was studied using Hoechst 33258 staining and Annexin V/PI staining with flow cytometry. The migration and invasion of A2780 cells were examined with transwell and wound healing assays. The expression of relevant proteins was detected with Western blot assays.

RESULTS

SAC (1-100 mmol/L) inhibited the proliferation of A2780 cells in dose- and time-dependent manners (the IC50 value was approximately 25 mmol/L at 48 h, and less than 6.25 mmol/L at 96 h). Furthermore, SAC dose-dependently inhibited the colony formation of A2780 cells. Treatment of A2780 cells with SAC resulted in G1/S phase arrest and induced apoptosis, accompanied by decreased expression of pro-caspase-3, Parp-1 and Bcl-2, and increased expression of active caspase-3 and Bax. SAC treatment significantly reduced the migration of A2780 cells, and markedly decreased the protein expression of Wnt5a, p-AKT and c-Jun, which were the key proteins involved in proliferation and metastasis.

CONCLUSION

SAC suppresses proliferation and induces apoptosis in A2780 ovarian cancer cells in vitro.

What are the roles of calorie restriction and diet quality in promoting healthy longevity?

Epidemiological and experimental data indicate that diet plays a central role in the pathogenesis of many age-associated chronic diseases, and in the biology of aging itself. Data from several animal studies suggest that the degree and time of calorie restriction (CR) onset, the timing of food intake as well as diet composition, play major roles in promoting health and longevity, breaking the old dogma that only calorie intake is important in extending healthy lifespan. Data from human studies indicate that long-term CR with adequate intake of nutrients results in several metabolic adaptations that reduce the risk of developing type 2 diabetes, hypertension, cardiovascular disease and cancer. Moreover, CR opposes the expected age-associated alterations in myocardial stiffness, autonomic function, and gene expression in the human skeletal muscle. However, it is possible that some of the beneficial effects on metabolic health are not entirely due to CR, but to the high quality diets consumed by the CR practitioners, as suggested by data collected in individuals consuming strict vegan diets. More studies are needed to understand the interactions among single nutrient modifications (e.g. protein/aminoacid, fatty acids, vitamins, phytochemicals, and minerals), the degree of CR and the frequency of food consumption in modulating anti-aging metabolic and molecular pathways, and in the prevention of age-associated diseases.

Multiple molecular and cellular mechanisms of action of lycopene in cancer inhibition

Epidemiological studies suggest that including fruits, vegetables, and whole grains in regular dietary intake might prevent and reverse cellular carcinogenesis, reducing the incidence of primary tumours. Bioactive components present in food can simultaneously modulate more than one carcinogenic process, including cancer metabolism, hormonal balance, transcriptional activity, cell-cycle control, apoptosis, inflammation, angiogenesis and metastasis. Some studies have shown an inverse correlation between a diet rich in fruits, vegetables, and carotenoids and a low incidence of different types of cancer. Lycopene, the predominant carotenoid found in tomatoes, exhibits a high antioxidant capacity and has been shown to prevent cancer, as evidenced by clinical trials and studies in cell culture and animal models. In vitro studies have shown that lycopene treatment can selectively arrest cell growth and induce apoptosis in cancer cells without affecting normal cells. In vivo studies have revealed that lycopene treatment inhibits tumour growth in the liver, lung, prostate, breast, and colon. Clinical studies have shown that lycopene protects against prostate cancer. One of the main challenges in cancer prevention is the integration of new molecular findings into clinical practice. Thus, the identification of molecular biomarkers associated with lycopene levels is essential for improving our understanding of the mechanisms underlying its antineoplastic activity.

Synergistic induction of apoptosis by sulindac and simvastatin in A549 human lung cancer cells via reactive oxygen species-dependent mitochondrial dysfunction

Prevention of lung cancer is more feasible and holds greater promise when different agents are used in combination to target multiple processes during carcinogenesis. The mechanisms by which non-steroidal anti-inflammatory drugs and statins inhibit cancer cell growth and induce apoptosis are not fully understood. This study was designed to investigate lung cancer chemoprevention through a mechanism-based approach using sulindac at low doses in combination with simvastatin. We found that sulindac-induced cytotoxicity was significantly enhanced in the presence of simvastatin. The combination of sulindac and simvastatin induced more extensive caspase-dependent apoptosis in A549 cells compared to that induced with either drug alone. The combination of sulindac and simvastatin also increased the loss of mitochondrial transmembrane potential (∆Ψm) and the cytosolic release of cytochrome c. In addition, ROS generation in cells treated with both sulindac and simvastatin was markedly increased compared to cells treated with either sulindac or simvastatin alone. The enhancement of ROS generation by sulindac and simvastatin was abrogated by pretreatment with NAC, which also prevented apoptosis and mitochondrial dysfunction induced by sulindac and simvastatin. These results suggest that sulindac and simvastatin-induced ROS generation in A549 lung cancer cells causes their accumulation in mitochondria, triggering the release of apoptogenic molecules from the mitochondria to the cytosol, and thus leading to caspase activation and cell death.

Advances in gastric cancer prevention

Gastric cancer is a multifactorial neoplastic pathology numbering among its causes both environmental and genetic predisposing factors. It is mainly diffused in South America and South-East Asia, where it shows the highest morbility percentages and it is relatively scarcely diffused in Western countries and North America. Although molecular mechanisms leading to gastric cancer development are only partially known, three main causes are well characterized: Helicobacter pylori (H. pylori) infection, diet rich in salted and/or smoked food and red meat, and epithelial cadherin (E-cadherin) mutations. Unhealthy diet and H. pylori infection are able to induce in stomach cancer cells genotypic and phenotypic transformation, but their effects may be crossed by a diet rich in vegetables and fresh fruits. Various authors have recently focused their attention on the importance of a well balanced diet, suggesting a necessary dietary education starting from childhood. A constant surveillance will be necessary in people carrying E-cadherin mutations, since they are highly prone in developing gastric cancer, also within the inner stomach layers. Above all in the United States, several carriers decided to undergo a gastrectomy, preferring changing their lifestyle than living with the awareness of the development of a possible gastric cancer. This kind of choice is strictly personal, hence a decision cannot be suggested within the clinical management. Here we summarize the key points of gastric cancer prevention analyzing possible strategies referred to the different predisposing factors. We will discuss about the effects of diet, H. pylori infection and E-cadherin mutations and how each of them can be handled.

Carcinoma of the stomach: A review of epidemiology, pathogenesis, molecular genetics and chemoprevention

Carcinoma of the stomach is still the second most common cause of cancer death worldwide, although the incidence and mortality have fallen dramatically over the last 50 years in many regions. The incidence of gastric cancer varies in different parts of the world and among various ethnic groups. Despite advances in diagnosis and treatment, the 5-year survival rate of stomach cancer is only 20 per cent. Stomach cancer can be classified into intestinal and diffuse types based on epidemiological and clinicopathological features. The etiology of gastric cancer is multifactorial and includes both dietary and nondietary factors. The major diet-related risk factors implicated in stomach cancer development include high content of nitrates and high salt intake. Accumulating evidence has implicated the role of Helicobacter pylori (H. pylori) infection in the pathogenesis of gastric cancer. The development of gastric cancer is a complex, multistep process involving multiple genetic and epigenetic alterations of oncogenes, tumor suppressor genes, DNA repair genes, cell cycle regulators, and signaling molecules. A plausible program for gastric cancer prevention involves intake of a balanced diet containing fruits and vegetables, improved sanitation and hygiene, screening and treatment of H. pylori infection, and follow-up of precancerous lesions. The fact that diet plays an important role in the etiology of gastric cancer offers scope for nutritional chemoprevention. Animal models have been extensively used to analyze the stepwise evolution of gastric carcinogenesis and to test dietary chemopreventive agents. Development of multitargeted preventive and therapeutic strategies for gastric cancer is a major challenge for the future.

Synergistic anti-tumor activity of isochaihulactone and paclitaxel on human lung cancer cells

Drug resistance frequently develops in tumors during chemotherapy. Therefore, to improve the clinical outcome, more effective and tolerable combination treatment strategies are needed. Here, we show that isochaihulactone (K8) enhanced paclitaxel-induced apoptotic death in human lung cancer cells, and the enhancing effect was related to increased NSAID-activated gene-1 (NAG-1) expression. CalcuSyn software was used to evaluate the synergistic interaction of K8 and paclitaxel on human lung cancer cells; the synergistic effect of K8 in combination with paclitaxel was increased more than either of these drugs alone. Furthermore, the activity of ERK1/2 was enhanced by the combination of K8 and paclitaxel, and an ERK1/2 inhibitor dramatically inhibited NAG-1 expression in human lung cancer cells. Therefore, this synergistic apoptotic effect in human lung cancer cells may be directly associated with K8-induced NAG-1 expression through ERK1/2 activation. Moreover, over-expression of NAG-1 enhanced K8/paclitaxel-induced apoptosis in human lung cancer cells. In addition, treatment of nude mice with K8 combined with paclitaxel induced phospho-ERK1/2 and NAG-1 expression in vivo. Targeting of NAG-1 signaling could enhance therapeutic efficacy in lung cancer. Our results reveal that activation of NAG-1 by K8 enhanced the therapeutic efficacy of paclitaxel in human lung cancer cells via the ERK1/2 signaling pathway.

Inhibitory effects of combination of lycopene and genistein on 7,12- dimethyl benz(a)anthracene-induced breast cancer in rats

Breast cancer is one of the most common cancers in women. Carotenoids and soy isoflavones have been postulated to have breast cancer preventive effects. We investigated the potential preventive effects of lycopene and genistein, alone and in combination, on breast cancer development in female Wistar rats treated with 7,12-dimethylbenz[a]anthracene (DMBA), a carcinogen known to induce breast tumors. Mammary carcinogenesis was initiated by a single, oral gavage of DMBA (80 mg/kg body weight) at 55 days of animal age. Fifty female Wistar rats were divided into 5 experimental groups having 10 animals per group: Group 1 (normal control), Group 2 (DMBA control), Group 3 (DMBA + lycopene), Group 4 (DMBA + genistein), and Group 5 (DMBA + lycopene and genistein). Rats were fed either lycopene (20 mg /kg bw) or genistein (2 mg /kg bw) by oral gavage (3 times per week) starting 2 wk prior to DMBA injection. Treatment was continued for 20 wk. Rats treated with DMBA developed mammary tumors with 100% tumor incidence during the 20-wk study. Inhibition of mammary cancer incidence by lycopene (70%), genistein (60%) and their combination (40%) was observed. Tumor weight decreased by 48%, 61%, and 67%, and mean tumor volume decreased by 18%, 35%, and 65% with lycopene, genistein, and lycopene + genistein, respectively (P < 0.01 for the combination). The proportions of adenocarcinoma masses decreased with lycopene and genistein combination (P < 0.05). Administration of lycopene and genistein combination suppressed breast cancer development and was associated with a decrease in MDA, 8-isoprostane, and 8-OhdG levels and with an increase in serum lycopene and genistein levels. Animals administered DMBA developed breast cancer, which was associated with increased expression of Bcl-2 and decreased expression of Bax, caspase 3, and caspase 9 in mammary tissues. Administration of genistein and lycopene in combination was more effective in inhibiting DMBA-induced breast tumors and modulating the expression of apoptosis associated proteins than the administration of each agent alone. Our results suggest that lycopene and genistein are potent antioxidants and, when given in combination, offer maximum protection against DMBA-induced mammary carcinogenesis.

Effect of lycopene on caspase-3 enzyme activation in liver of methanol-intoxicated rats: comparison with fomepizole

Lycopene is one of the major carotenoids and is found almost exclusively in tomatoes and tomato products. This study was performed to evaluate the effect of lycopene on methanol-induced liver injury and to compare the results with those after fomepizole, which is used in treatment of methanol intoxication. Experiments were carried out with 30 female Wistar rats weighting 180-200 g. Rats were injected with a intraperitoneally dose of 3 g/kg methanol as a 50% solution in isotonic saline once for intoxication. Rats were pretreated with fomepizole (50 mg/kg) and/or lycopene (10 mg/kg) before methanol. After 24 hours all the drug-treated and intoxicated rats were sacrificed under anesthesia. Malondialdehyde (MDA) levels were determined in order to assess lipid peroxidation, and caspase-3 activity was determined by immunostaining of liver tissues to evaluate apoptosis. Methanol administration significantly increased the MDA level and caspase-3 activity in liver. Pretreatment with lycopene and/or fomepizole decreased the MDA levels significantly. Similarly, lycopene and fomepizole decreased methanol-induced caspase-3 activity. The findings of the present study demonstrate that methanol intoxication causes hepatic toxicity in rats and that this is likely a result of reactive oxygen species and apoptosis induction. Lycopene has protective effects against methanol-induced hepatic injury similar to fomepizole. It was demonstrated for the first time that both lycopene and fomepizole prevent methanol-induced hepatic injury by reducing the increase of lipid oxidation and caspase-3 activation.

Differential effects of lycopene consumed in tomato paste and lycopene in the form of a purified extract on target genes of cancer prostatic cells

BACKGROUND

Prospective studies indicate that tomato consumers are protected against prostate cancer. Lycopene has been hypothesized to be responsible for tomato health benefits.

OBJECTIVE

Our aim was to differentiate the effects of tomato matrix from those of lycopene by using lycopene-rich red tomatoes, lycopene-free yellow tomatoes, and purified lycopene.

DESIGN

Thirty healthy men (aged 50-70 y old) were randomly assigned to 2 groups after a 2-wk washout period. In a crossover design, each group consumed yellow and red tomato paste (200 g/d, which provided 0 and 16 mg lycopene, respectively) as part of their regular diet for 1 wk separated by 2 wk of washout. Then, in a parallel design, the first group underwent supplementation with purified lycopene (16 mg/d) for 1 wk, whereas the second group received a placebo. Sera collected before and after the interventions were incubated with lymph node cancer prostate cells to measure the expression of 45 target genes.

RESULTS

Circulating lycopene concentration increased only after consumption of red tomato paste and purified lycopene. Lipid profile, antioxidant status, prostate-specific antigen, and insulin-like growth factor I were not modified by consumption of tomato pastes and lycopene. We observed significant up-regulation of IGFBP-3 and Bax:Bcl-2 ratio and down-regulation of cyclin-D1, p53, and Nrf-2 after cell incubation with sera from men who consumed red tomato paste when compared with sera collected after the first washout period, with intermediate values for yellow tomato paste consumption. Cell incubation with sera from men who consumed purified lycopene led to significant up-regulation of IGFBP-3, c-fos, and uPAR compared with sera collected after placebo consumption.

CONCLUSION

Dietary lycopene can affect gene expression whether or not it is included in its food matrix. This trial was registered by the French Health Ministry at http://www.sante-sports.gouv.fr as 2006-A00396-45.

Nutrition and gastric cancer risk: an update

Data from epidemiologic, experimental, and animal studies indicate that diet plays an important role in the etiology of gastric cancer. High intake of fresh fruits and vegetables, lycopene and lycopene-containing food products, and potentially vitamin C and selenium may reduce the risk for gastric cancer. Data also suggest that high intake of nitrosamines, processed meat products, salt and salted foods, and overweight and obesity are associated with increased risk for gastric cancer. However, current data provide little support for an association of beta-carotene, vitamin E, and alcohol consumption with risk for gastric cancer.

Lycopene in cancer prevention and treatment

Dietary intake of lycopene is inversely associated with the risk of many cancers. Preclinical studies show that lycopene has potent in vitro and in vivo antitumor effects, suggesting potential preventive and therapeutic roles for the compound. However, clinical trials with lycopene have only recently been started, and available clinical data preclude firm conclusions with regard to its use in cancer prevention and treatment. Further mechanistic studies and randomized controlled clinical intervention trials with lycopene involving cancer patients are warranted.

Evidence of a novel docetaxel sensitizer, garlic-derived S-allylmercaptocysteine, as a treatment option for hormone refractory prostate cancer

The recent introduction of docetaxel in the treatment of hormone refractory prostate cancer (HRPC) has made a small but significant impact on patient survival. However, its effect is limited by intolerance and resistance. The aim of our study was to investigate if the garlic-derived compound, S-allylmercaptocysteine (SAMC), was able to act as a docetaxel sensitizing agent. First, the effect of SAMC on docetaxel sensitivity was examined on 3 HRPC cell lines by colony forming assay. We found that SAMC increased the efficacy of docetaxel on colony forming inhibition by 9-50% compared to single agent treatment. Second, using the HRPC CWR22R nude mice model, we found that the combination of SAMC and docetaxel was 53% more potent than docetaxel alone (p = 0.037). In addition, there was no additive toxicity in the mice treated with the combination therapy evidenced by histological and functional analysis of liver, kidney and bone marrow. These results suggest that SAMC is able to increase the anticancer effect of docetaxel without causing additional toxic effect in vivo. Third, flow cytometry and Western blotting analysis on HRPC cell lines demonstrated that SAMC promoted docetaxel-induced G2/M phase cell cycle arrest and apoptotic induction. In addition, immunohistochemistry on CWR22R xenograft revealed a suppression of Bcl-2 expression and upregulation of E-cadherin in the SAMC and docetaxel treated animals. These results suggest that SAMC may promote docetaxel-induced cell death through promoting G2/M cell cycle arrest and apoptosis. Our study implies a potential role for SAMC in improving docetaxel based chemotherapy for the treatment of HRPC.

Biomarkers for diet and cancer prevention research: potentials and challenges

As cancer incidence is projected to increase for decades there is a need for effective preventive strategies. Fortunately, evidence continues to mount that altering dietary habits is an effective and cost-efficient approach for reducing cancer risk and for modifying the biological behavior of tumors. Predictive, validated and sensitive biomarkers, including those that reliably evaluate "intake" or exposure to a specific food or bioactive component, that assess one or more specific biological "effects" that are linked to cancer, and that effectively predict individual "susceptibility" as a function of nutrient-nutrient interactions and genetics, are fundamental to evaluating who will benefit most from dietary interventions. These biomarkers must be readily accessible, easily and reliably assayed, and predictive of a key process(es) involved in cancer. The response to a food is determined not only by the effective concentration of the bioactive food component(s) reaching the target tissue, but also by the amount of the target requiring modification. Thus, this threshold response to foods and their components will vary from individual to individual. The key to understanding a personalized response is a greater knowledge of nutrigenomics, proteomics and metabolomics.

Combined inhibitory effects of green tea polyphenols and selective cyclooxygenase-2 inhibitors on the growth of human prostate cancer cells both in vitro and in vivo

PURPOSE

Cyclooxygenase-2 (COX-2) inhibitors hold promise for cancer chemoprevention; however, recent toxicity concerns suggest that new strategies are needed. One approach to overcome this limitation is to use lower doses of COX-2 inhibitors in combination with other established agents with complementary mechanisms. In this study, the effect of (-)epigallocatechin-3-gallate (EGCG), a promising chemopreventive agent from green tea, was tested alone and in combination with specific COX-2 inhibitors on the growth of human prostate cancer cells both in vitro and in vivo.

EXPERIMENTAL DESIGN

Human prostate cancer cells LNCaP, PC-3, and CWR22Rnu1 were treated with EGCG and NS398 alone and in combination, and their effect on growth and apoptosis was evaluated. In vivo, athymic nude mice implanted with androgen-sensitive CWR22Rnu1 cells were given green tea polyphenols (0.1% in drinking water) and celecoxib (5 mg/kg, i.p., daily, 5 days per week), alone and in combination, and their effect on tumor growth was evaluated.

RESULTS

Combination of EGCG (10-40 micromol/L) and NS-398 (10 micromol/L) resulted in enhanced (a) cell growth inhibition; (b) apoptosis induction; (c) expression of Bax, pro-caspase-6, and pro-caspase-9, and poly(ADP)ribose polymerase cleavage; (d) inhibition of peroxisome proliferator activated receptor gamma; and (e) inhibition of nuclear factor-kappaB compared with the additive effects of the two agents alone, suggesting a possible synergism. In vivo, combination treatment with green tea polyphenols and celecoxib resulted in enhanced (a) tumor growth inhibition, (b) lowering of prostate-specific antigen levels, (c) lowering of insulin-like growth factor-I levels, and (d) circulating levels of serum insulin-like growth factor binding protein-3 compared with results of single-agent treatment.

CONCLUSIONS

These data suggest synergistic and/or additive effects of combinatorial chemopreventive agents and underscore the need for rational design of human clinical trials.

Modulatory effects of black tea polyphenols on oxidant-antioxidant profile and expression of proliferation, apoptosis, and angiogenesis-associated proteins in the rat forestomach carcinogenesis model

BACKGROUND

Chemoprevention by dietary constituents has emerged as a novel approach to control stomach cancer incidence. We therefore evaluated the chemopreventive effects of black tea polyphenols (Polyphenon-B) on oxidant-antioxidant status, cell proliferation, apoptosis, and angiogenesis during N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis.

METHODS

Male Wistar rats were divided into four groups. Rats in group 1 and 2 were given MNNG (150 mg/kg body weight) by intragastric intubation three times at 2 week intervals and followed for 26 weeks. Rats in group 2 received in addition a basal diet containing 0.05% Polyphenon-B. Group 3 animals were given 0.05% Polyphenon-B alone. Group 4 animals served as controls. The status of lipid peroxidation and antioxidants and the expression of the lipid peroxidation marker 4-hydroxy nonenal (4-HNE), proliferating cell nuclear antigen (PCNA), glutathiones-transferase (GST)-pi, Bcl-2, Bax, cytochrome C, caspase 3, cytokeratins, and vascular endothelial growth factor (VEGF) were used as biomarkers.

RESULTS

Intragastric administration of MNNG induced well-differentiated squamous cell carcinomas that showed diminished lipid and protein oxidation and an increase in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and invasive potential coupled with apoptosis evasion as revealed by upregulation of PCNA, GST-pi, Bcl-2, cytokeratins, and VEGF and downregulation of Bax, cytochrome C, and caspase 3 protein expression. Dietary administration of Polyphenon-B effectively suppressed MNNG-induced gastric carcinogenesis, as evidenced by modulation of oxidant-antioxidant status, inhibition of cell proliferation and infiltration, and angiogenesis associated with apoptosis induction.

CONCLUSIONS

The present study provides evidence that Polyphenon-B exerts multifunctional inhibitory effects on MNNG-induced gastric carcinogenesis and suggests that it can be developed as a potential chemopreventive agent.

Modulatory effects of black tea polyphenols on rat forestomach carcinogenesis

ABSTRACT The present study was designed to evaluate the chemopreventive effects of black tea polyphenols (Polyphenon-B) on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in Wistar rats. Intragastric administration of MNNG induced well-differentiated squamous cell carcinomas that showed diminished mitochondrial lipid and protein oxidation and an increase in antioxidants. In contrast to tumor tissue, the liver mitochondria of tumor-bearing animals showed elevated lipid and protein oxidation with compromised antioxidant defenses. Dietary administration of Polyphenon-B effectively suppressed MNNG-induced stomach tumors, modulated mitochondrial lipid and protein oxidation, and enhanced antioxidant enzyme activities in the stomach and liver. Our results suggest that Polyphenon-B may exert its chemopreventive effects by modulating mitochondrial cellular redox status in the tumor as well as in the host liver.

S-allylcysteine, a water-soluble garlic derivative, suppresses the growth of a human androgen-independent prostate cancer xenograft, CWR22R, under in vivo conditions

OBJECTIVE

To evaluate the effect of S-allylcysteine (SAC) on CWR22R, a human androgen-independent (AI) prostate cancer xenograft, in nude mice. Despite extensive research worldwide there is no effective way to control the growth of prostate cancer, and we previously reported that SAC and S-allylmercaptocysteine (SAMC), two water-soluble derivatives of garlic, inhibit cancer cell invasion through restoration of E-cadherin expression in vitro.

MATERIALS AND METHODS

The effects of SAC on tumour cell proliferation markers such as Ki-67 and proliferating cell nuclear antigen, and apoptotic regulators including Bcl-2 and cleaved caspase-3, were assessed by immunohistochemical staining. The inhibitory effects of SAC on prostate cancer invasion was examined by immunoreactivity of E-cadherin and its binding proteins alpha, beta and gamma-catenins. The serum prostate-specific antigen (PSA) level at three different times (initiation, middle and end of treatment) and toxicity of SAC on several organs after treatment were assessed.

RESULTS

Treatment with SAC resulted in inhibition of the growth of CWR22R, with no detectable toxic effect on nude mice. The SAC-induced growth reduction was correlated with a concurrent reduction in serum PSA level and proliferation rate of xenografts, together with an inhibition of invasion through the restoration of E-cadherin and gamma-catenin expression. Furthermore, the apoptotic rate of SAC-treated tumours increased together with a decrease in Bcl-2 and increase in cleaved caspase-3.

CONCLUSION

These results suggest that this garlic-derived compound might be a potential therapeutic agent for suppressing AI prostate cancer.

Expression of PCNA, cytokeratin, Bcl-2 and p53 during chemoprevention of hamster buccal pouch carcinogenesis by ethanolic neem (Azadirachta indica) leaf extract

OBJECTIVES

To evaluate the effect of ethanolic neem leaf extract (ENLE) on cell proliferation, differentiation and apoptosis associated proteins during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis.

DESIGN AND METHODS

Hamsters were divided into four groups. The right buccal pouches of animals in group 1 were painted with 0.5% DMBA three times a week. Animals in group 2 painted with DMBA as in group 1, received in addition, intragastric administration of ENLE (200 mg/kg bw) on days alternate to DMBA application. Group 3 animals were given ENLE (200 mg/kg bw) alone. Animals in group 4 served as control. All the animals were sacrificed after an experimental period of 14 weeks. The expression of proliferating cell nuclear antigen (PCNA), cytokeratin, Bcl-2 and p53 in the buccal pouch tissues were investigated using immunohistochemical staining. In addition, the expression of p53 was confirmed by Western blot analysis.

RESULTS

Topical application of DMBA for 14 weeks induced buccal pouch carcinomas associated with increased expression of PCNA, mutant p53 and Bcl-2 and decreased expression of cytokeratin. Administration of ENLE significantly inhibited the development of HBP carcinomas as revealed by decreased expression of PCNA, mutant p53 and Bcl-2 and overexpression of cytokeratin.

CONCLUSION

These findings suggest that ENLE exerts its anticancer properties by inhibiting cell proliferation and inducing differentiation and apoptosis.

Cancer chemoprevention with garlic and its constituents

Advance metastasized cancers are generally incurable; hence an effort to prolong the process of carcinogenesis through chemoprevention has emerged consistent with this notion. In recent years, a considerable attention has been placed to identify naturally occurring chemopreventive substances capable of inhibiting, retarding or reversing the process of carcinogenesis. A number of phenolic substances, particularly those present in dietary and medicinal plants, have been shown to possess substantial anticarcinogenic and antimutagenic activities. Epidemiological observations and laboratory studies, both in cell culture and animal models have indicated anticarcinogenic potential of garlic and its constituents, which has been traditionally used for varied human ailments around the world. Chemical analysis has indicated that protective effects of garlic appear to be related to the presence of organosulfur compounds mainly allyl derivatives. Several mechanisms have been presented to explain cancer chemopreventive effects of garlic-derived products. These include modulation in activity of several metabolizing enzymes that activate and detoxify carcinogens and inhibit DNA adduct formation, antioxidative and free radicals scavenging properties and regulation of cell proliferation, apoptosis and immune responses. Recent data show that garlic-derived products modulate cell-signaling pathways in a fashion that controls the unwanted proliferation of cells thereby imparting strong cancer chemopreventive as well as cancer therapeutic effects. This review discusses mechanistic basis of cancer chemopreventive effects of garlic-derived products, their implication in cancer management and ways and means to take these agents from bench to real life situations.

Modulatory effects of Azadirachta indica on benzo(a)pyrene-induced forestomach tumorigenesis in mice

AIM

To evaluate the chemopreventive effects of aqueous Azadirachta indica (A indica) leaf extract (AAILE) against benzo(a)pyrene [B(a)P]-induced forestomach tumorigenesis in Balb/c mice.

METHODS

Female Balb/c mice were divided into four groups of 10-12 animals each. For induction of forestomach tumors, starting from d 14 of the experi-ment, mice of B(a)P and B(a)P+A indica groups were given intra-gastric instillations of B(a)P (40 mg/kg), twice a week for four weeks. Mice of A indica and B(a)P+A indica groups were orally administered with AAILE (100 mg/kg), two weeks prior to B(a)P instillations till the end of the experiment. After 22 wk of the first B(a)P instillation, mice were sacrificed and the forestomachs were analyzed for development of tumors, scanning electron microscopy (SEM) and histopathology.

RESULTS

Tumor incidence was observed to be 100% in mice that received only B(a)P. However, treatment with AAILE reduced the tumor incidence by 58.4% as observed in mice of B(a)P+A indica group when compared to that of B(a)P group. Similarly, the tumor burden and multiplicity were seen to decrease by 87.3% and 69.6% respectively in mice of B(a)P+A indica group when compared to those of B(a)P group. Scanning electron microscopy analysis showed that AAILE treatment itself did not cause any abnormalities on the surface architecture of forestomach epithelium. In tumorous forestomach, surface disruption was observed. Over the forestomach tumors of B(a)P group of mice certain rounded structures were seen in addition to closely placed tongue-shaped squamous cells. Interestingly, these rounded structures were not observed in B(a)P + A indica group of mice. Histopathalogically, the tumors were identical and diagnosed to be papillomas. Mice from control and A indica groups of mice did not develop any forestomach tumors and showed normal histo-architecture.

CONCLUSION

The present data suggest that A indica exerts chemopreventive effects against B(a)P-induced forestomach tumors in murine model. Because of lack of toxicity and ubiquitous bioavailability, A indica may play a promising role in future drug discovery and development as far as chemoprevention of cancer is concerned.

Lycopene supplementation prevents smoke-induced changes in p53, p53 phosphorylation, cell proliferation, and apoptosis in the gastric mucosa of ferrets

Cigarette smoking increases the risk for gastric cancer. Higher intakes or blood levels of lycopene are associated with a decreased risk of gastric cancer. However, the biological mechanisms by which lycopene may protect against gastric carcinogenesis are poorly understood. We evaluated the effects of lycopene supplementation on smoke-induced changes in protein levels of p53, p53 target genes (p21(Waf1/Cip1) and Bax-1), cell proliferation, and apoptosis in the gastric mucosa of ferrets. Ferrets were assigned to cigarette smoke exposure or to no exposure and to no, low-dose, or high-dose lycopene supplementation (2 x 3 factorial design) for 9 wk. Lycopene concentrations were significantly elevated in a dose-dependent manner in the gastric mucosa of ferrets supplemented with lycopene alone, but were markedly reduced in ferrets supplemented with lycopene and exposed to smoke. Although ferrets were given lycopene containing 95% all-trans isomers, cis isomers were the predominant forms in the gastric mucosa. Total p53 and phosphorylated p53 levels were greater in ferrets exposed to smoke alone than in all other groups. Levels were approximately 300 and 500% of the controls, respectively. However, smoke-elevated total p53 and phosphorylated p53 were markedly attenuated by both doses of lycopene. p21(Waf1/Cip1), Bax-1, and cleaved caspase 3 were substantially decreased, whereas cyclin D1 and proliferating cellular nuclear antigen (PCNA) were increased in ferrets exposed to smoke alone. Lycopene prevented smoke-induced changes in p21(Waf1/Cip1), Bax-1, cleaved caspase 3, cyclin D1, and PCNA in a dose-dependent fashion. These data indicate that lycopene may prevent smoke exposure-induced changes in p53, p53 phosphorylation, p53 target genes, cell proliferation, and apoptosis in the gastric mucosa of ferrets.