Grape seed extract inhibits advanced human prostate tumor growth and angiogenesis and upregulates insulin-like growth factor binding protein-3

Cytogenetic effects of grape extracts (Vitis vinifera) and polyphenols on mitomycin C-induced sister chromatid exchanges (SCEs) in human blood lymphocytes

In the present study, the effects of extracts and polyphenol-rich fractions as well as monomer polyphenols identified in them, from both red and white grapes, on mitomycin C (MMC) induced sister chromatid exchanges (SCEs) in human peripheral blood lymphocytes were investigated. The grape extracts and two of the three polyphenol-rich fractions promoted MMC-induced SCEs at concentrations from 75 to 300 microg/mL. However, none of the extracts or fractions alone induced SCEs. Thus, these results suggest caution especially with regard to the use of grape extracts as dietary supplements. On the other hand, the fact that these extracts were not genotoxic alone may indicate a selective activity against genetically damaged cells. This is the first study regarding the clastogenic effects of grape extracts in human cells. Moreover, from the tested polyphenols, caffeic acid, gallic acid, and rutin hydrate enhanced MMC-induced clastogenicity, whereas ferulic acid, protocatechuic acid, (+)-catechin, (-)-epicatechin, and trans-resveratrol had no effect at concentrations between 5 and 100 microM. The differences in the chemical structures of the tested polyphenols may account for their differential effects on MMC clastogenicity.

The therapeutic and preventive effect of RRR-alpha-vitamin E succinate on prostate cancer via induction of insulin-like growth factor binding protein-3

PURPOSE

Insulin-like growth factor binding protein-3 (IGFBP-3) is a well-known antiproliferative and proapoptotic molecule in prostate cancer, suggesting that targeting IGFBP-3 might produce clinical benefits. In prostate cancer cells, RRR-alpha-vitamin E succinate (VES) inhibits cell proliferation and induces apoptosis, yet the mechanisms remain to be elucidated. We hypothesize that the protective effects of VES in prostate cancer are mediated by IGFBP-3 up-regulation. Using prostate cancer models, the involvement of IGFBP-3 in the anticancer effect of VES was investigated.

EXPERIMENTAL DESIGN

IGFBP-3 mRNA and protein were determined by real-time PCR and Western blotting in prostate cancer cells, xenografted tumors of nude mice, and prostate tumors of transgenic adenocarcinoma mouse prostate (TRAMP) mice. The serum levels of IGFBP-3 were assessed by ELISA. The importance of IGFBP-3 in VES-mediated antitumor effects was confirmed by small interfering RNA knockdown strategy.

RESULTS

We found that VES induced IGFBP-3 mRNA and protein levels in human prostate cancer cell lines. Knockdown of IGFBP-3 by small interfering RNA attenuated VES-induced IGFBP-3 expression and VES-mediated antiproliferative and proapoptotic functions. Furthermore, administration of VES resulted in a significant therapeutic effect on LNCaP and PC3 xenografts and a preventive effect on tumorigenic progression in the TRAMP model without overt toxicity. Notably, the therapeutic and preventive efficacy of VES correlated with increased accumulation of IGFBP-3 in mouse serum as well as in the xenograft tumors and TRAMP prostate samples. Consequently, reduced proliferation and induced apoptosis were witnessed.

CONCLUSIONS

VES mediates its therapeutic and preventive effects against prostate cancer at least partially through up-regulating IGFBP-3, which inhibits cell proliferation and promotes cell apoptosis.

Grape seed proanthocyanidins promote apoptosis in human epidermoid carcinoma A431 cells through alterations in Cdki-Cdk-cyclin cascade, and caspase-3 activation via loss of mitochondrial membrane potential

Dietary grape seed proanthocyanidins (GSPs) prevent photocarcinogenesis in mice. Here, we report that in vitro treatment of human epidermoid carcinoma A431 cells with GSPs inhibited cellular proliferation (13-89%) and induced cell death (1-48%) in a dose (5-100 mug/ml)- and time (24, 48 and 72 h)-dependent manner. GSP-induced inhibition of cell proliferation was associated with an increase in G1-phase arrest at 24 h, which was mediated through the inhibition of cyclin-dependent kinases (Cdk) Cdk2, Cdk4, Cdk6 and cyclins D1, D2 and E and simultaneous increase in protein expression of cyclin-dependent kinase inhibitors (Cdki), Cip1/p21 and Kip1/p27, and enhanced binding of Cdki-Cdk. The treatment of A431 cells with GSPs (20-80 mug/ml) resulted in a dose-dependent increase in apoptotic cell death (26-58%), which was associated with an increased protein expression of proapoptotic Bax, decreased expression of antiapoptotic Bcl-2 and Bcl-xl, loss of mitochondrial membrane potential, and cleavage of caspase-9, caspase-3 and PARP. Pretreatment with the pan-caspase inhibitor (z-VAD-fmk) blocked the GSP-induced apoptosis in A431 cells suggesting that GSP-induced apoptosis is associated primarily with the caspase-3-dependent pathway. Together, our study suggests that GSPs possess chemotherapeutic potential against human epidermoid carcinoma cells in vitro, further in vivo mechanistic studies are required to verify the chemotherapeutic effect of GSPs in skin cancers.

Fractionation of high molecular weight tannins in grape seed extract and identification of procyanidin B2-3,3′-di-O-gallate as a major active constituent causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells

Several studies have documented the anticancer and chemopreventive efficacy of grape seed extract (GSE) against various malignancies including prostate cancer (PCA). GSE is a complex mixture of polyphenols including gallic acid (GA), catechin (Cat), epicatechin (Epi) and procyanidins-oligomers of Cat and Epi, some of which are esterified with GA. Initial studies to identify the GSE components cytotoxic to human prostate carcinoma (DU145) cells demonstrated that GA and several crude chromatographic fractions containing procyanidin dimers and trimers were biologically active. The focus of the present work was to purify 14 procyanidins from the fractions and to identify those with highest activity toward growth inhibition, cell death and apoptosis in DU145 cells. The most active procyanidin was identified by mass spectrometry and enzymatic hydrolysis as the 3,3'-di-O-gallate ester of procyanidin dimer B2 (Epi-Epi). B2-digallate exhibited dose-dependent effects on DU145 cells over the range 25-100 microM, whereas GA exhibited comparable activity at lower doses but was highly lethal at 100 microM. Structure-activity studies demonstrated that all three hydroxyl groups of GA are necessary for activity, but a free carboxylic acid group is not required even though esterification reduced the activity of GA. These data, and the fact that non-esterified B2 exhibited little or no activity, suggest that the galloyl groups of B2-digallate are primarily responsible for its effects on DU145 cells. Taken together, these data identify procyanidin B2-3,3'-di-O-gallate as a novel biologically active agent in GSE that should be studied in greater detail to determine its effects against PCA.

Gallic acid causes inactivating phosphorylation of cdc25A/cdc25C-cdc2 via ATM-Chk2 activation, leading to cell cycle arrest, and induces apoptosis in human prostate carcinoma DU145 cells

We recently reported that gallic acid is a major active agent responsible for grape seed extract activity in DU145 human prostate carcinoma cells. The present study was conducted to examine its efficacy and associated mechanism. Gallic acid treatment of DU145 cells resulted in a strong cell growth inhibition, cell cycle arrest, and apoptotic death in a dose- and time-dependent manner, together with a decrease in cyclin-dependent kinases and cyclins but strong induction in Cip1/p21. Additional mechanistic studies showed that gallic acid induces an early Tyr(15) phosphorylation of cell division cycle 2 (cdc2). Further upstream, gallic acid also induced phosphorylation of both cdc25A and cdc25C via ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 (Chk2) activation as a DNA damage response evidenced by increased phospho-histone 2AX (H2A.X) that is phosphorylated by ATM in response to DNA damage. Time kinetics of ATM phosphorylation, together with those of H2A.X and Chk2, was in accordance with an inactivating phosphorylation of cdc25A and cdc25C phosphatases and cdc2 kinase, suggesting that gallic acid increases cdc25A/C-cdc2 phosphorylation and thereby inactivation via ATM-Chk2 pathway following DNA damage that induces cell cycle arrest. Caffeine, an ATM/ataxia telangiectasia-rad3-related inhibitor, reversed gallic acid-caused ATM and H2A.X phosphorylation and cell cycle arrest, supporting the role of ATM pathway in gallic acid-induced cell cycle arrest. Additionally, gallic acid caused caspase-9, caspase-3, and poly(ADP)ribose polymerase cleavage, but pan-caspase inhibitor did not reverse apoptosis, suggesting an additional caspase-independent apoptotic mechanism. Together, this is the first report identifying gallic acid efficacy and associated mechanisms in an advanced and androgen-independent human prostate carcinoma DU145 cells, suggesting future in vivo efficacy studies with this agent in preclinical prostate cancer models.

Indole-3-Carbinol Selectively Uncouples Expression and Activity of Estrogen Receptor Subtypes in Human Breast Cancer Cells

Estrogen-responsive breast cancer cells, such as MCF7 and T47D cells, express both estrogen receptor (ER)-α (ERα) and ERβ. Indole-3-carbinol (I3C) strongly down-regulated ERα protein and transcript levels, without altering the level of ERβ protein, in both cell lines. In cells transfected with the ERα promoter linked to a luciferase gene reporter, I3C ablated ERα promoter activity. Propyl pyrazole triol (PPT) is a highly selective ERα agonist, whereas, 17β-estradiol activates both ERα and ERβ. I3C treatment inhibited the PPT- and 17β-estradiol-induced proliferation of breast cancer cells, disrupted the PPT and 17β-estradiol stimulation of estrogen response element (ERE)-driven reporter plasmid activity as well as of endogenous progesterone receptor transcripts. Using an in vitro ERE binding assay, I3C was shown to inhibit the level of functional ERα and stimulated the level of ERE binding ERβ even though the protein levels of this receptor remained constant. In ERα−/ERβ+ MDA-MB-231 breast cancer cells, I3C treatment stimulated a 6-fold increase in binding of ERβ to the ERE. I3C also induced ERE- and activator protein 1-driven reporter plasmid activities in the absence of an ER agonist, suggesting that ERβ is activated in indole-treated cells. Taken together, our results demonstrate that the expression and function of ERα and ERβ can be uncoupled by I3C with a key cellular consequence being a significantly higher ERβ:ERα ratio that is generally highly associated with antiproliferative status of human breast cancer cells.

Grape seed extract inhibits in vitro and in vivo growth of human colorectal carcinoma cells

PURPOSE

Accumulating evidences suggest the beneficial effects of fruit-and-vegetable consumption in lowering the risk of various cancers, including colorectal cancer. Herein, we investigated the in vitro and in vivo anticancer effects and associated mechanisms of grape seed extract (GSE), a rich source of proanthocyanidins, against colorectal cancer.

EXPERIMENTAL DESIGN

Effects of GSE were examined on human colorectal cancer HT29 and LoVo cells in culture for proliferation, cell cycle progression, and apoptosis. The in vivo effect of oral GSE was examined on HT29 tumor xenograft growth in athymic nude mice. Xenografts were analyzed by immunohistochemistry for proliferation and apoptosis. The molecular changes associated with the biological effects of GSE were analyzed by Western blot analysis.

RESULTS

GSE (25-100 microg/mL) causes a significant dose- and time-dependent inhibition of cell growth with concomitant increase in cell death. GSE induced G1 phase cell cycle arrest along with a marked increase in Cip1/p21 protein level and a decrease in G1 phase-associated cyclins and cyclin-dependent kinases. GSE-induced cell death was apoptotic and accompanied by caspase-3 activation. GSE feeding to mice at 200 mg/kg dose showed time-dependent inhibition of tumor growth without any toxicity and accounted for 44% decrease in tumor volume per mouse after 8 weeks of treatment. GSE inhibited cell proliferation but increased apoptotic cell death in tumors. GSE-treated tumors also showed enhanced Cip1/p21 protein levels and poly(ADP-ribose) polymerase cleavage.

CONCLUSIONS

GSE may be an effective chemopreventive agent against colorectal cancer, and that growth inhibitory and apoptotic effects of GSE against colorectal cancer could be mediated via an up-regulation of Cip1/p21.

Suppression of the tumorigenic phenotype in human oral squamous cell carcinoma cells by an ethanol extract derived from freeze-dried black raspberries

Despite focused efforts to improve therapy, 5-yr survival rates for persons with advanced-stage oral squamous cell carcinoma (SCC) remain discouragingly low. Clearly, early detection combined with strategies for local intervention, such as chemoprevention prior to SCC development, could dramatically improve clinical outcomes. Previously conducted oral cavity human chemoprevention trials, however, have provided mixed results. Although some therapies showed efficacy, they were often accompanied by either significant toxicities or circulating antiadenoviral antibodies. It is clearly apparent that identification of nontoxic, effective treatments is essential to prevent malignant transformation of oral epithelial dysplasias. This study employed cell lines isolated from human oral SCC tumors to investigate the effects of a freeze-dried black raspberry ethanol extract (RO-ET) on cellular growth characteristics often associated with a transformed phenotype such as sustained proliferation, induction of angiogenesis, and production of high levels of reactive species. Our results demonstrate that RO-ET suppresses cell proliferation without perturbing viability, inhibits translation of the complete angiogenic cytokine vascular endothelial growth factor, suppresses nitric oxide synthase activity, and induces both apoptosis and terminal differentiation. These data imply that RO-ET is a promising candidate for use as a chemopreventive agent in persons with oral epithelial dysplasia.

Activity of grape extracts from Greek varieties of Vitis vinifera against mutagenicity induced by bleomycin and hydrogen peroxide in Salmonella typhimurium strain TA102

Several in vivo and in vitro studies have shown that grape extracts could prevent certain steps in carcinogenesis and a few mechanisms have been proposed for this activity. In this study, the potential antimutagenic activity of methanolic and aqueous extracts from two Greek grape varieties of Vitis vinifera against DNA damage induced by reactive oxygen species (ROS) was assessed as a potential novel chemopreventive mechanism, using Salmonella typhimurium strain TA102. The two grape varieties were Assyrtiko (white grapes) and Mandilaria (red grapes), while the oxidant mutagens used were bleomycin (BLM) and hydrogen peroxide (H(2)O(2)). Since it has been considered that polyphenols present in grapes are their most potent biologically active compounds, we also tested the effects of polyphenol-rich fractions as well as some of the more common grape polyphenols on the activity of the two test mutagens. These polyphenols were quercetin, (+)-catechin, (-)-epicatechin, trans-resveratrol, gallic acid and protocatechuic acid. Almost all extracts showed inhibitory activity against both mutagens. On the other hand, polyphenol-rich fractions as well as individual polyphenols at concentrations found in the extracts either did not diminish or did enhance the activity of the mutagens. These results suggest that the protection of DNA from mutations induced by ROS may be one of the mechanisms accounting for the chemopreventive activity of grape extracts. However, it seems that this protective activity may not be attributed to polyphenols but rather to a synergism of many compounds in the grapes.

Cytotoxicity of bioactive polymeric fractions from grape cell culture on human hepatocellular carcinoma, murine leukemia and non-cancerous PK15 kidney cells

Previously, we isolated two fractions (TP-4 and TP-6) from grape cell culture that were potent catalytic inhibitors in a human DNA topoisomerase II assay for cancer chemoprevention. The objectives of this study were to further assess cytotoxicity of these fractions on cancerous and non-cancerous cells, and to subfractionate and characterize the composition of TP-6, a fraction that was selectively cytotoxic to carcinoma cell lines. Both TP-4 and TP-6 provided significant cytotoxicity to L1210 mouse leukemia cells. Only TP-6, a procyanidin-rich fraction, significantly reduced viability in HepG2 human liver cancer cells, yet unlike resveratrol, caused no cytotoxicity to non-cancerous PK15 pig kidney cells. After further subfractionation of TP-6 (maximal toxicity = 67.2%; ED(50) = 50.5 microM), the cytotoxicity of subfractions on HepG2 cells was TP-6-5 (maximal toxicity=71.8%; ED(50) = 14.1 microM), TP-6-6 (maximal toxicity=64.3%; ED(50) = 67.0 microM), and TP-6-4 (maximal toxicity = 27.6%; ED(50) = 118.0 microM) in descending order. LC-ESI/MS data suggested that cytotoxicity of these procyanidin mixtures to HepG2 cells was proportional to the degree of polymerization. Because TP-6 and its subfractions were selectively cytotoxic to cancerous cell lines tested, they warrant further investigation as potential natural anticancer agents.

Insulin-like growth factor-binding protein-3 inhibition of prostate cancer growth involves suppression of angiogenesis

Insulin-like growth factor-binding protein-3 (IGFBP-3) is a multifunctional protein that induces apoptosis utilizing both insulin-like growth factor receptor (IGF)-dependent and -independent mechanisms. We investigated the effects of IGFBP-3 on tumor growth and angiogenesis utilizing a human CaP xenograft model in severe-combined immunodeficiency mice. A 16-day course of IGFBP-3 injections reduced tumor size and increased apoptosis and also led to a reduction in the number of vessels stained with CD31. In vitro, IGFBP-3 inhibited both vascular endothelial growth factor- and IGF-stimulated human umbilical vein endothelial cells vascular network formation in a matrigel assay. This action is primarily IGF independent as shown by studies utilizing the non-IGFBP-binding IGF-1 analog Long-R3. Additionally, we used a fibroblast growth factor-enriched matrigel-plug assay and chick allantoic membrane assays to show that IGFBP-3 has potent antiangiogenic actions in vivo. Finally, overexpression of IGFBP-3 or the non-IGF-binding GGG-IGFBP-3 mutant in Zebrafish embryos confirmed that both IGFBP-3 and the non-IGF-binding mutant inhibited vessel formation in vivo, indicating that the antiangiogenic effect of IGFBP-3 is an IGF-independent phenomenon. Together, these studies provide the first evidence that IGFBP-3 has direct, IGF-independent inhibitory effects on angiogenesis providing an additional mechanism by which it exerts its tumor suppressive effects and further supporting its development for clinical use in the therapy of patients with prostate cancer.

Grape Seed Extract Prevents Gentamicin-Induced Nephrotoxicity and Genotoxicity in Bone Marrow Cells of Mice

The protection conferred by grape seed extract against gentamicin-induced nephrotoxicity and bone marrow chromosomal aberrations have been evaluated in adult Swiss albino mice. The activity of reduced glutathione peroxidase (GSH peroxidase), the levels of glutathione (GSH) and lipid peroxidation as malondialdehyde (MDA) in the kidneys homogenates, serum urea and creatinine were measured, and in addition the changes in kidney histology and bone marrow chromosomes were investigated. Gentamicin (80 mg/kg b.wt. intraperitoneally for 2 weeks) induced kidney damage as indicated from a pronounced changes in kidney histology, a significant increase in serum urea and creatinine and MDA content in the kidney homogenate. While the activity of the antioxidant enzyme GSH peroxidase and the level of GSH were significantly decreased. Gentamicin induced genotoxicity indicated by increased the number of aberrant cells and different types of structural chromosomal aberrations (fragment, deletion and ring chromosome) and showed no effect on mitotic activity of the cell. Pretreatment with grape seed extract (7 days) and simultaneously (14 days) with gentamicin significantly protected the kidney tissue by ameliorating its antioxidant activity. Moreover, grape seed extract significantly protected bone marrow chromosomes from gentamicin induced genotoxicity by reducing the total number of aberrant cells, and different types of structural chromosomal aberrations. It could be concluded that grape seed extract acts as a potent antioxidant prevented kidney damage and genotoxicity of bone marrow cells.

Modulation of activator protein-1 (AP-1) and MAPK pathway by flavonoids in human prostate cancer PC3 cells

In last couple of decades the use of natural compounds like flavonoids as chemopreventive agents has gained much attention. Our current study focuses on identifying chemopreventive flavonoids and their mechanism of action on human prostate cancer cells. Human prostate cancer cells (PC3), stably transfected with activator protein 1 (AP-1) luciferase reporter gene were treated with four main classes of flavonoids namely flavonols, flavones, flavonones, and isoflavones. The maximum AP-1 luciferase induction of about 3 fold over control was observed with 20 microM concentrations of quercetin, chrysin and genistein and 50 microM concentration of kaempferol. At higher concentrations, most of the flavonoids demonstrated inhibition of AP-1 activity. The MTS assay for cell viability at 24 h showed that even at a very high concentration (500 microM), cell death was minimal for most of the flavonoids. To determine the role of MAPK pathway in the induction of AP-1 by flavonoids, Western blot of phospho MAPK proteins was performed. Four out of the eight flavonoids namely kaempferol, apigenin, genistein and naringenin were used for the Western Blot analysis. Induction of phospho-JNK and phospho-ERK activity was observed after two hour incubation of PC3-AP1 cells with flavonoids. However no induction of phospho-p38 activity was observed. Furthermore, pretreating the cells with specific inhibitors of JNK reduced the AP-1 luciferase activity that was induced by genistein while pretreatment with MEK inhibitor reduced the AP-1 luciferase activity induced by kaempferol. The pharmacological inhibitors did not affect the AP-1 luciferase activity induced by apigenin and naringenin. These results suggest the possible involvement of JNK pathway in genistein induced AP-1 activity while the ERK pathway seems to play an important role in kaempferol induced AP-1 activity.

Grape seed extract is an aromatase inhibitor and a suppressor of aromatase expression

Aromatase is the enzyme that converts androgen to estrogen. It is expressed at higher levels in breast cancer tissues than normal breast tissues. Grape seed extract (GSE) contains high levels of procyanidin dimers that have been shown in our laboratory to be potent inhibitors of aromatase. In this study, GSE was found to inhibit aromatase activity in a dose-dependent manner and reduce androgen-dependent tumor growth in an aromatase-transfected MCF-7 (MCF-7aro) breast cancer xenograft model, agreeing with our previous findings. We have also examined the effect of GSE on aromatase expression. Reverse transcription-PCR experiments showed that treatment with 60 mug/mL of GSE suppressed the levels of exon I.3-, exon PII-, and exon I.6-containing aromatase mRNAs in MCF-7 and SK-BR-3 cells. The levels of exon I.1-containing mRNA, however, did not change with GSE treatment. Transient transfection experiments with luciferase-aromatase promoter I.3/II or I.4 reporter vectors showed the suppression of the promoter activity in a dose-dependent manner. The GSE treatment also led to the down-regulation of two transcription factors, cyclic AMP-responsive element binding protein-1 (CREB-1) and glucocorticoid receptor (GR). CREB-1 and GR are known to up-regulate aromatase gene expression through promoters I.3/II and I.4, respectively. We believe that these results are exciting in that they show GSE to be potentially useful in the prevention/treatment of hormone-dependent breast cancer through the inhibition of aromatase activity as well as its expression.

Dietary agents in the chemoprevention of prostate cancer

Nutritional factors have been estimated to contribute 20-60% of cancers around the globe, and almost one-third of deaths are being reported in Western countries. According to estimates by the American Cancer Society, during the year 2005 about 232,090 new cases of prostate cancer will be diagnosed alone in the United States and 30,350 men will die of this disease. The high incidence and long latency period of prostate cancer offer plenty of time to pursue strategies toward prevention and/or treatment to suppress or revert this disease. Epidemiological evidence suggests that plant-based dietary agents decrease the risk of some types of human cancer, including prostate cancer. Intake of 400-600 g/day of fruits and vegetables is associated with reduced risk of several cancers. The use of micronutrients and/or other phenolic agents in the diet or synthetic exogenous supplements to prevent neoplastic transformation of normal cells or to slow the progression of established malignant changes in cancer cells is termed "chemoprevention." Considerable attention has been devoted to identify plant-based dietary agents that may serve as natural inhibitors of prostate carcinogenesis. Much progress has been made in the last decade in this area of investigation through identification of pathways that play important roles in prostate tumorigenesis. This article summarizes epidemiological, clinical, and mechanistic studies and the significance of plant-derived dietary agents such as flavonoids, indoles, isothiocyanates, phenolics, monoterpenes, and complementary and alternative agents in the management of prostate cancer with recommendations for future studies to advance this area of research.

Polyphenol contents in grape-seed extracts correlate with antipica effects in cisplatin-treated rats

BACKGROUND

Grape-seed (Vitis spp.) extract (GSE) is a widely used antioxidant dietary supplement. Chemotherapeutic agents such as cisplatin induce oxidative damage in the gastrointestinal tract and cause nausea and vomiting.

MATERIALS AND METHODS

A rat model of simulated emesis was used to observe that cisplatin significantly increased kaolin consumption (or pica). Three GSEs from different sources were used in this study.

RESULTS

High-performance liquid chromatographic analysis of five major constituents (gallic acid, catechin, epicatechi, procyanidin B2, and epicatechin gallate) revealed that each constituent had different levels in the three GSEs. Extract #1, prepared in the laboratory of the investigators, had the lowest total polyphenol content (27.27 mg/g); Extract #2, obtained from a dietary supplement company in the United States, had a somewhat higher level (35.84 mg/g); and Extract #3, obtained from China, had the highest level (194.21 mg/g). Subsequently these GSEs were intraperitoneally administered in rats to evaluate their ability to decreasing cisplatin induced pica. At 10 mg/kg all three GSEs, with varying degrees of effect, decreased cisplatin-induced pica. The areas under the curves of kaolin intake from time 0 to 72 hours, compared to those in the cisplantin-only group, were reduced 45% for Extract #1 (p < 0.01), 54% for Extract #2 (p < 0.01), and 66% Extract #3 (p < 0.001).

CONCLUSIONS

The study data showed variable polyphenol contents and proportions in the three GSEs correlated to variable pharmacologic effects, indicating the importance of standardization of herbal product preparations. However further increasing of the GSE doses reversed the antipica effects of GSEs, probably because of their pro-oxidant effects. Results from this study suggest that an appropriate dose of GSE has therapeutic value in treating cisplatin-induced emesis.

Targeting angiogenesis with integrative cancer therapies

An integrative approach for managing a patient with cancer should target the multiple biochemical and physiological pathways that support tumor development while minimizing normal tissue toxicity. Angiogenesis is a key process in the promotion of cancer. Many natural health products that inhibit angiogenesis also manifest other anticancer activities. The authors will focus on natural health products (NHPs) that have a high degree of antiangiogenic activity but also describe some of their many other interactions that can inhibit tumor progression and reduce the risk of metastasis. NHPs target various molecular pathways besides angiogenesis, including epidermal growth factor receptor (EGFR), the HER-2/neu gene, the cyclooxygenase-2 enzyme, the NF-kB transcription factor, the protein kinases, Bcl-2 protein, and coagulation pathways. The herbalist has access to hundreds of years of observational data on the anticancer activity of many herbs. Laboratory studies are confirming the knowledge that is already documented in traditional texts. The following herbs are traditionally used for anticancer treatment and are antiangiogenic through multiple interdependent processes that include effects on gene expression, signal processing, and enzyme activities: Artemisia annua (Chinese wormwood), Viscum album (European mistletoe), Curcuma longa (turmeric), Scutellaria baicalensis (Chinese skullcap), resveratrol and proanthocyanidin (grape seed extract), Magnolia officinalis (Chinese magnolia tree), Camellia sinensis (green tea), Ginkgo biloba, quercetin, Poria cocos, Zingiber officinale (ginger), Panax ginseng, Rabdosia rubescens (rabdosia), and Chinese destagnation herbs. Quality assurance of appropriate extracts is essential prior to embarking on clinical trials. More data are required on dose response, appropriate combinations, and potential toxicities. Given the multiple effects of these agents, their future use for cancer therapy probably lies in synergistic combinations. During active cancer therapy, they should generally be evaluated in combination with chemotherapy and radiation. In this role, they act as biological response modifiers and adaptogens, potentially enhancing the efficacy of the so-called conventional therapies. Their effectiveness may be increased when multiple agents are used in optimal combinations. New designs for trials to demonstrate activity in human subjects are required. Although controlled trials might be preferred, smaller studies with appropriate end points and surrogate markers for antiangiogenic response could help prioritize agents for the larger resource-intensive phase 3 trials.

Grape seed extract induces anoikis and caspase-mediated apoptosis in human prostate carcinoma LNCaP cells: possible role of ataxia telangiectasia mutated–p53 activation

Prostate cancer is the second leading cancer diagnosed in elderly males in the Western world. Epidemiologic studies suggest that dietary modifications could be an effective approach in reducing various cancers, including prostate cancer, and accordingly cancer-preventive efficacy of dietary nutrients has gained increased attention in recent years. We have recently shown that grape seed extract (GSE) inhibits growth and induces apoptotic death of advanced human prostate cancer DU145 cells in culture and xenograft. Because prostate cancer is initially an androgen-dependent malignancy, here we used LNCaP human prostate cancer cells as a model to assess GSE efficacy and associated mechanisms. GSE treatment of cells led to their detachment within 12 hours, as occurs in anoikis, and caused a significant decrease in live cells mostly due to their apoptotic death. GSE-induced anoikis and apoptosis were accompanied by a strong decrease in focal adhesion kinase levels, but an increase in caspase-3, caspase-9, and poly(ADP-ribose) polymerase cleavage; however, GSE caused both caspase-dependent and caspase-independent apoptosis as evidenced by cytochrome c and apoptosis-inducing factor release into cytosol. Additional studies revealed that GSE causes DNA damage-induced activation of ataxia telangiectasia mutated kinase and Chk2, as well as p53 Ser(15) phosphorylation and its translocation to mitochondria, suggesting this to be an additional mechanism for apoptosis induction. GSE-induced apoptosis, cell growth inhibition, and cell death were attenuated by pretreatment with N-acetylcysteine and involved reactive oxygen species generation. Together, these results show GSE effects in LNCaP cells and suggest additional in vivo efficacy studies in prostate cancer animal models.

A long-term investigation of the anti-hepatocarcinogenic potential of an indigenous medicine comprised of Nigella sativa, Hemidesmus indicus and Smilax glabra

BACKGROUND

A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root bark and Smilax glabra rhizome is being recommended for cancer patients by a family of traditional medical practitioners of Sri Lanka. Previous investigations have demonstrated that a short term (10 weeks) treatment with the decoction can significantly inhibit diethylnitrosamine (DEN) mediated expression of Glutathione S-transferase P form (GST-P) in rat liver. The objective of the present investigation was to determine whether long term (16 months) treatment with the decoction would be successful in inhibiting in rat livers, not only DEN- mediated expression of GST-P, but also the carcinogen mediated development of overt tumours (OT) or histopathological changes leading to tumour development (HT).

METHODS

Thirty-six male Wistar rats were divided into 3 groups of 12 each. Groups 1 and 2 were injected intraperitoneally (i.p) with DEN (200 mg/kg) while group 3 was injected normal saline (NS). Twenty-four hours later, decoction (DC; 6 g/kg body weight/day) was orally administered to group 1 rats, while groups 2 and 3 (DEN-control and normal control) were given distilled water (DW). Treatment with DC or DW continued for 16 months. At the end of the 9th month and 16th months (study 1 and study 2 respectively), six rats from each group were sacrificed, and livers observed for OT or HT, both visually and by subjecting liver sections to staining with Haemotoxylin and Eosin (H & E), Sweet's Silver stain (for reticulin fibers), Periodic Acid Schiff (PAS) staining (for glycogen), and immunohistochemical staining (for GST-P).

RESULTS

At the end of 9 months (study 1) a hepatocellular adenoma (HA) developed in one of the rats in the DEN + DW treated group (group 2). At the end of 16 months (study 2), livers of all rats of group 2 developed OT and HT. Large areas of GST-P positive foci were also observed. No OT, HT or GST-P positive foci were detected in any of the other groups.

CONCLUSION

Protection against DEN-mediated carcinogenic changes in rat liver can be achieved by long term treatment with the DC comprised of N. sativa seeds, S. glabra rhizome and H. indicus root bark.

Endocrine regulation of prostate cancer growth

Prostate cancer is one of the most frequently diagnosed malignant neoplasms in the Western world. The focus of this article is on regulation of proliferation, apoptosis, angiogenesis and differentiation by steroid and peptide hormones. Steroid hormones, in particular androgens and estrogens, exert their effects through respective receptors. The androgen receptor is functional in all stages of the disease and it can be activated in a ligand-dependent and -independent manner. In prostate cancer, expression of some androgen receptor coactivators increases during tumor progression. Interleukins and transforming growth factor-β are multifunctional regulators of prostate growth and proliferation. Signal transduction cascades of fibroblast growth factors and insulin-like growth factors are responsible for increased survival and angiogenesis in prostate cancer. In clinical specimens obtained from prostate cancer, there is an increased phosphorylation of mitogen-activated protein kinase and Akt kinase, whose action in the regulation of cell survival is redundant.

Inhibition of sphingosine-1-phosphate- and vascular endothelial growth factor-induced endothelial cell chemotaxis by red grape skin polyphenols correlates with a decrease in early platelet-activating factor synthesis

Vascular endothelial growth factor (VEGF) and platelet-derived lipid sphingosine-1-phosphate (S1P) are two proinflammatory mediators which contribute to angiogenesis, in part through the synthesis of platelet-activating factor (PAF). The red grape skin polyphenolic extract (SGE) both prevents and inhibits angiogenesis in the Matrigel model, decreases the basal motility of endothelial and cancer cells, and reverses the chemotactic effect of S1P and VEGF on bovine aortic endothelial cells (BAECs) as well as the chemotactic effect of conditioned medium on human HT-1080 fibrosarcoma, human U-87 glioblastoma, and human DAOY medulloblastoma cells. Inhibition of VEGF- and S1P-mediated chemotaxis by SGE is associated with a down-regulation of ERK and p38/MAPK phosphorylation and a decreased in acute PAF synthesis. Notably, as do extracellular inhibitors of PAF receptor, SGE prevents S1P-induced PAF synthesis and the resulting activation of the S1P/endothelial differentiation gene-1 cascade. Given the key role of VEGF and S1P in inflammation, angiogenesis, and tumor invasion, SGE may therefore contribute to prevent (or to delay) the development of diseases associated with angiogenesis dysregulation, including cancer. The dual inhibition of S1P- and VEGF-mediated migration of endothelial cell and of serum-stimulated migration of U-87 cells suggests a usefulness of SGE against highly invasive human glioblastoma.

Fractionation of grape seed extract and identification of gallic acid as one of the major active constituents causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells

The anti-cancer efficacy of grape seed extract (GSE) against prostate cancer (PCA) via its anti-proliferative, pro-apoptotic and anti-angiogenic activities in both cell culture and animal models have recently been described by us. GSE is a complex mixture containing gallic acid (GA), catechin (C), epicatechin (EC) and several oligomers (procyanidins) of C and/or EC, some of which are esterified to GA. To determine which components are most active against PCA, an ethyl acetate extract of GSE was separated by reverse-phase high-performance liquid chromatography (HPLC) into three fractions. Fraction 1 was far more effective than others in causing growth inhibition and apoptotic death of human PCA DU145 cells. Of the components in this fraction, GA showed a very strong dose- and time-dependent growth inhibition and apoptotic death of DU145 cells, but C and procyanidins B1 (EC-C dimer), B2 (EC-EC dimer) and B3 (C-C dimer) were nearly ineffective. Mechanistic studies demonstrated a strong caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavages by GA in DU145 cells. Procyanidin oligomers eluting in HPLC Fractions 2 and 3 were obtained in larger quantities by separating GSE into eight fractions (I-VIII) on a gel filtration column. All fractions were analyzed by HPLC-UV and negative-ion electrospray mass spectrometry. Fractions I-III contained the active compound GA and inactive components C, EC, B1 and B2. Fraction IV contained other dimers and a dimer-GA ester and was also less active than GSE in DU145 cells. Fractions V-VIII, however, caused significant growth inhibition and apoptosis with the highest activity present in the later fractions that contained procyanidin trimers and GA esters of dimers and trimers. Together, these observations identify GA as one of the major active constituents in GSE. Several procyanidins, however, and especially the gallate esters of dimers and trimers also may be efficacious against PCA and merit further investigation.

Effects of herbal extracts on the function of human organic anion-transporting polypeptide OATP-B

Most known interactions between herbal extracts and drugs involve the inhibition of drug-metabolizing enzymes, but little is yet known about the possible role of transporters in these interactions. In this study, we have examined the effects of herbal extracts used in dietary supplements on the function of organic anion-transporting polypeptide B (OATP-B; OATP2B1), which is expressed on human intestinal epithelial cells and is considered to be involved in the intestinal absorption of various drugs. Specifically, the effects of 15 herbal extracts on uptake of estrone-3-sulfate, a typical OATP-B substrate, by human embryonic kidney 293 cells stably expressing OATP-B were evaluated. At concentration levels considered likely to be attainable in the human intestine, extracts of bilberry, echinacea, green tea, banaba, grape seed, ginkgo, and soybean potently inhibited estrone-3-sulfate uptake by 75.5, 55.5, 82.1, 61.1, 64.5, 85.4, and 66.8%, respectively (P < 0.01). The inhibitory effect of ginkgo leaf extract was concentration-dependent (IC(50) = 11.2 +/- 3.3 microg/ml) and reversible. Moreover, flavonol glycosides and catechins significantly inhibited the function of OATP-B, suggesting that the inhibitory effects of the herbal extracts on OATP-B may be primarily attributable to flavonoids. The extracts of mulberry, black cohosh, and Siberian ginseng moderately (but significantly) inhibited estrone-3-sulfate uptake by 39.1, 47.2, and 49.2%, respectively (P < 0.05). Extracts of barley, Job's tears, rutin, rafuma, and passionflower were ineffective. These results suggest that coadministration of some dietary supplements may decrease the absorption of orally administered substrates of OATP-B.

Differential effects of blueberry proanthocyanidins on androgen sensitive and insensitive human prostate cancer cell lines

Blueberries are rich in health-promoting polyphenolic compounds including proanthocyanidins. The purpose of this study was to determine if proanthocyanidin-rich fractions from both wild and cultivated blueberry fruit have the same inhibitory effects on the proliferation of LNCaP, an androgen-sensitive prostate cancer cell line, and DU145, a more aggressive androgen insensitive prostate cancer cell line. When 20 microg/ml of a wild blueberry proanthocyanidin fraction (fraction 5) was added to LNCaP media, growth was inhibited to 11% of control with an IC50 of 13.3 microg/ml. Two similar proanthocyanidin-rich fractions from cultivated blueberries (fractions 4 and 5) at the same concentration inhibited LNCaP growth to 57 and 26% of control with an IC50 of 22.7 and 5.8 microg/ml, respectively. In DU145 cells, the only fraction that significantly reduced growth compared to control was fraction 4 from cultivated blueberries with an IC50 value of 74.4 microg/ml, indicating only minor inhibitory activity. Differences in cell growth inhibition of LNCaP and DU145 cell lines by blueberry fractions rich in proanthocyanidins indicate that blueberry proanthocyanidins have an effect primarily on androgen-dependant growth of prostate cancer cells. Possible molecular mechanisms for growth inhibition are reviewed.

Combination therapy of insulin-like growth factor binding protein-3 and retinoid X receptor ligands synergize on prostate cancer cell apoptosis in vitro and in vivo

We have previously identified the retinoid X receptor-alpha (RXRalpha) as an insulin-like growth factor binding protein-3 (IGFBP-3) nuclear binding partner, which is required for IGFBP-3-induced apoptosis. In the current study, we investigated the biological interactions of the RXR ligand, VTP194204 and rhIGFBP-3, in vitro and in vivo. In vitro, IGFBP-3 and VTP194204 individually induced apoptosis, and suppressed cell growth in prostate cancer cell lines in an additive manner. In vivo, LAPC-4 xenograft-bearing severe combined immunodeficiency mice treated daily with saline, IGFBP-3, and/or VTP194204 for 3 weeks showed no effect of individual treatments with IGFBP-3 or VTP194204 on tumor growth. However, the combination of IGFBP-3 and VTP194204 treatments inhibited tumor growth by 50% and induced a significant reduction in serum prostate-specific antigen levels. In terminal nucleotidyl transferase-mediated nick end labeling immunohistochemistry of LAPC-4 xenografts, there was modest induction of apoptosis with either IGFBP-3 or VTP194204 individual treatment, but combination therapy resulted in massive cell death, indicating that IGFBP-3 and VTP194204 have a synergistic effect in preventing tumor growth by apoptosis induction. In summary, this is an initial description of the successful therapeutic use of IGFBP-3 as a cancer therapy in vivo, and shows that combination treatment of IGFBP-3 and RXR ligand has a synergistic effect on apoptosis induction leading to substantial inhibition of prostate cancer xenograft growth. Taken together, these observations suggest that combination therapy with IGFBP-3 and RXR ligands may have therapeutic potential for prostate cancer treatment.

Procyanidin B2 has anti- and pro-oxidant effects on metal-mediated DNA damage

Procyanidin B2 (epicatechin-(4beta-8)-epicatechin), which is present in grape seeds, apples, and cacao beans, has antioxidant properties. We investigated the mechanism of preventive action of procyanidin B2 against oxidative DNA damage in human cultured cells and isolated DNA. Procyanidin B2 inhibited the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in the human leukemia cell line HL-60 treated with an H2O2-generating system. In contrast, a high concentration of procyanidin B2 increased the formation of 8-oxodG in HL-60 cells. Experiments with calf thymus DNA also revealed that procyanidin B2 decreased 8-oxodG formation by Fe(II)/H2O2, whereas procyanidin B2 induced DNA damage in the presence of Cu(II), and H2O2 extensively enhanced it. An electron spin resonance spin trapping study utilizing 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) demonstrated that procyanidin B2 decreased the signal of M4PO-OH from H2O2 and Fe(II), whereas procyanidin B2 enhanced the signal from H2O2 and Cu(II). As an antioxidant mechanism, UV-visible spectroscopy showed that procyanidin B2 chelated Fe(II) at equivalent concentrations. As a pro-oxidant property, we examined DNA damage induced by procyanidin B2, using 32P-labeled DNA fragments obtained from genes relevant to human cancer. Our results raise the possibility that procyanidin B2 exerts both antioxidant and pro-oxidant properties by interacting with H2O2 and metal ions.

Proanthocyanidin from grape seeds enhances doxorubicin-induced antitumor effect and reverses drug resistance in doxorubicin-resistant K562/DOX cells

With the aim of enhancing the efficacy of chemotherapeutic agents, we investigated the antitumor actions and reversal effect on drug resistance of proanthocyanidin plus doxorubicin. The results showed that proanthocyanidin 12.5-200 mg/L significantly inhibited proliferation of K562, K562/DOX, SPC-A-1, and Lewis cells in vitro in a time- and concentration-dependent manner, as determined by microculture tetrazolium assay. A combination of proanthocyani din 12.5, or 25 mg/L and doxorubicin treatment synergistically inhibited cell proliferation with decreased IC50 values. Proanthocyanidin reverses drug resistance in doxorubicin-resistant K562/DOX cells, and IC50 values were decreased by 9.19 (3.64-23.19), 2.56 (1.48-.44), and 0.94 (0.81-1.09) mg/L, respectively, after 24 h treatment with doxorubicin 0.1-9.0 mg/L alone or in combination with proanthocyanidin 12.5 or 25 mg/L; the proanthocyanidin reversal fold was 3.6 and 9.8, respectively. Under confocal laser scanning microscope, the combination of proanthocyanidin 25 or 50 mg/L with doxorubicin 3 mg/L significantly increased the accumulation of intracellular doxorubicin, Ca2+, and Mg2+, and reduced the pH value and mitochondrial membrane potential in K562/DOX cells as compared with doxorubicin alone (p < 0.01). Additionally, the apoptosis rate was increased by 11.3% +/- 3.3%, 14.2% +/- 5.4%, and 23.8% +/- 2.8%, respectively, for doxorubicin 3 mg/L alone or with proanthocyanidin 12.5 or 25 mg/L, as compared with controls (3.0% +/- 1.4%), as demonstrated by flow cytometry. In vivo experiments demonstrated that i.p. administration of proanthocyanidin 10 mg/kg with doxorubicin 2 mg/kg had an inhibitory effect on the growth of transplantation tumor sarcoma 180 and hepatoma 22 in mice as compared with doxorubicin alone (p < 0.05). These results suggest that proanthocyanidin enhances doxorubicin-induced antitumor effect and reverses drug resistance, and its mechanism is attributed partially to the promotion of doxorubicin-induced apoptosis through an elevation of intracellular doxorubicin, and Ca2+, Mg2+ concentration, and a reduction of pH value and mitochondrial membrane potential.

Proanthocyanidin from grape seeds potentiates anti-tumor activity of doxorubicin via immunomodulatory mechanism

The purpose of this study was to investigate the anti-tumor activities of proanthocyanidin (PA) from grape seeds and doxorubicin (DOX) in vitro as well as in vivo, either alone or in combination and to explore the immunomodulatory mechanism in tumor-bearing mice. PA (12.5 approximately 200 mg/l) or DOX (0.01 approximately 1 mg/l) for 24 h significantly inhibited YAC-1 cell proliferation (IC(50) 57.53 or 0.198 mg/l, respectively) in a concentration-dependent manner using microculture tetrazolium (MTT) assay. Meanwhile, a combination of PA (12.5, 25 mg/l) with DOX strongly inhibited cell proliferation with IC(50) values of DOX decreasing by 0.09 and 0.045 mg/l, respectively. In mouse tumor xenograft models, intraperitoneal administrations of PA (10 mg/kg) daily or DOX (2 mg/kg) every other day for 9 days significantly inhibited the growth of sarcoma 180, whereas a combination of the two strongly inhibited tumor growth as compared with PA or DOX alone (p<0.01). In contrast to PA treatment, DOX inhibited Con A-stimulated lymphocyte proliferation, IL-2 and IFN-gamma productions, NK cell cytotoxicity and CD4+/CD8+ ratio, while the administration of PA combined with DOX significantly enhanced the above immune responses as compared with the tumor-bearing control (p<0.01). Taken together, these results suggest that PA has anti-tumor activity and increases the anti-tumor activity of DOX, and the mechanism might be related partially to immunopotentiating activities through the enhancements of lymphocyte proliferation, NK cell cytotoxicity, CD4+/CD8+ ratio, IL-2 and IFN-gamma productions.

Effects of cyclosporine on oxidant/antioxidant status in rat ovary tissues: Protective role of black grape extract

OBJECTIVES

It has been demonstrated that immunosuppressive drug cyclosporine A (CsA) increases the synthesis of reactive oxygen species (ROS) and lipid peroxidation products in vitro and in vivo studies, but its possible toxic effects in ovary tissue have not been defined yet. This study was designed to elucidate possible relation between CsA treatment and oxidant/antioxidant status in rat ovary tissue and, to determine if antioxidant supplementation is beneficial.

METHODS

CsA and black grape extracts were given to rats orally for 10 days. In each group (control, CsA, CsA plus black grape and black grape alone), there were 7 animals (28 rats in total). After the animals were sacrificed, their ovaries were removed to be used in the measurement of malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), catalase (CAT) and xanthine oxidase (XO) enzymes.

RESULTS

In the control, CsA plus black grape and black grape alone groups, MDA levels were significantly lower than CsA group. Xanthine oxidase activities were significantly higher in CsA and CsA plus black grape groups than control group. In addition, XO activity was significantly lower in black grape alone group than all the other groups including control group. There were no significant differences in the activities of SOD and CAT enzymes between the groups.

CONCLUSION

The results suggest that CsA leads to oxidant stress and peroxidation in rat ovary tissues mainly due to increased XO activity. It has been suggested that this oxidant stress and peroxidation reactions can be prevented by antioxidant food supplementation like black grape.

Targeting multiple signaling pathways as a strategy for managing prostate cancer: multifocal signal modulation therapy

The aberrant behavior of cancer reflects upregulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Theoretically, it should be feasible to decrease the activity of these pathways-or increase the activity of pathways that oppose them-with noncytotoxic agents. Since multiple pathways are dysfunctional in most cancers, and cancers accumulate new oncogenic mutations as they progress, the greatest and most durable therapeutic benefit will likely be achieved with combination regimens that address several targets. Thus, a multifocal signal modulation therapy (MSMT) of cancer is proposed. This concept has already been documented by researchers who have shown that certain combinations of signal modulators-of limited utility when administered individually-can achieve dramatic suppression of tumor growth in rodent xenograft models. The present essay attempts to guide development of MSMTs for prostate cancer. Androgen ablation is a signal-modulating measure already in standard use in the management of delocalized prostate cancer. The additional molecular targets considered here include the type 1 insulin-like growth factor receptor, the epidermal growth factor receptor, mammalian target of rapamycin, NF-kappaB, hypoxia-inducible factor-1alpha, hsp90, cyclooxygenase-2, protein kinase A type I, vascular endothelial growth factor, 5-lipoxygenase, 12-lipoxygenase, angiotensin II receptor type 1, bradykinin receptor type 1, c-Src, interleukin-6, ras, MDM2, bcl-2/bclxL, vitamin D receptor, estrogen receptor-beta, and PPAR-. Various nutrients and phytochemicals suspected to have potential utility in prostate cancer prevention and therapy, but whose key molecular targets are still unknown, might reasonably be incorporated into MSMTs for prostate cancer; these include lycopene, selenium, green tea polyphenols, genistein, and silibinin. MSMTs can be developed systematically by testing various combinations of signal-modulating agents, in concentrations that can feasibly be achieved and maintained clinically, on human prostate cancer cell lines; combinations that appear promising can then be tested in xenograft models and, ultimately, in the clinic. Some signal modulators can increase response to cytotoxic drugs by upregulating effectors of apoptosis. When MSMTs fail to raise the spontaneous apoptosis rate sufficiently to achieve tumor stasis or regression, incorporation of appropriate cytotoxic agents into the regimen may improve the clinical outcome.

Effects of black grape extract on activities of DNA turn-over enzymes in cancerous and non cancerous human colon tissues

Effects of extract of dried whole black grape including seed on adenosine deaminase (ADA), 5' nucleotidase (5'NT) and xanthine oxidase (XO) enzymes were investigated in cancerous and non-cancerous human colon tissues. Enzyme activities were measured in 20 colon tissues, 10 from cancerous region and 10 from non cancerous region with and without pre incubation with black grape extract. ADA and 5'NT activities were found increased and that of the XO decreased in the cancerous tissues relative to non cancerous ones. After incubation period with black grape extract for 12 h, ADA and 5'NT activities were found to be significantly lowered but that of XO unchanged in both cancerous and non cancerous tissues. Results suggest that ADA and 5'NT activities increase but XO activity decreases in cancerous human colon tissues, which may provide advantage to the cancerous tissues in obtaining new nucleotides for rapid DNA synthesis through accelerated salvage pathway activity. Black grape extract makes significant inhibition on the ADA and 5'NT activities of cancerous and non cancerous colon tissues, thereby eliminating this advantage of cancer cells, which might be the basis for the beneficial effect of black grape in some kinds of human cancers.

Grape seed proanthocyanidins induce apoptosis through p53, Bax, and caspase 3 pathways

Grape seed proanthocyanidins (GSP) have been shown to inhibit skin chemical carcinogenesis and photocarcinogenesis in mice. The mechanisms responsible for the anticarcinogenic effects of GSP are not clearly understood. Here, we report that treatment of JB6 C141 cells (a well-developed cell culture model for studying tumor promotion in keratinocytes) and p53+/+ fibroblasts with GSP resulted in a dose-dependent induction of apoptosis. GSP-induced (20-80 g/ml) apoptosis was observed by using immunofluorescence (27-90% apoptosis) and flow cytometry (18-87% apoptosis). The induction of apoptosis by GSP was p53-dependent because it occurred mainly in cells expressing wild-type p53 (p53+/+; 15-80%) to a much greater extent than in p53-deficient cells (p53-/-; 6-20%). GSP-induced apoptosis in JB6 C141 cells was associated with increased expression of the tumor-suppressor protein, p53, and its phosphorylation at Ser15. The antiapoptotic proteins, Bcl-2 and Bcl-xl, were downregulated by GSP, whereas the expression of the pro-apoptotic protein, Bax, and the levels of cytochrome c release, Apaf-1, caspase-9, and cleaved caspase 3 (p19 and p17) were markedly increased in JB6 C141 cells. The downregulation of Bcl-2 and upregulation of Bax were also observed in wild-type p53 (p53+/+) fibroblasts but was not observed in their p53-deficient counterparts. These data clearly demonstrate that GSP-induced apoptosis is p53-dependent and mediated through the Bcl-2, Bax, and caspase 3 pathways.

Protective Effects of Oligomers of Grape Seed Polyphenols Against β-Amyloid-Induced Oxidative Cell Death

beta-Amyloid (Abeta) is considered to be responsible for the formation of senile plaques that accumulate in the brains of patients with Alzheimer's disease (AD). There is compelling evidence supporting the notion that Abeta-induced cytotoxicity is mediated through the generation of reactive oxygen species (ROS). Recently, considerable attention has been focused on a wide array of non-vitamin antioxidants present in edible plants that are able to scavenge ROS, thereby protecting against oxidative damage. In this study, we have investigated the possible protective effects of formulated polyphenol oligomers (Oligonol) derived from grape seed extracts on Abeta-induced oxidative cell death. Rat pheochromocytoma (PC12) cells treated with Abeta exhibited increased accumulation of intracellular ROS and underwent apoptosis, as determined by positive in situ terminal end labeling, decreased mitochondrial membrane potential, and the cleavage of poly(ADP-ribose)polymerase. Oligonal attenuated Abeta-induced cytotoxicity, apoptotic features, intracellular ROS accumulation, and lipid peroxidation and increased the cellular glutathione pool. Moreover, Abeta transiently induced the activation of nuclear factor kappaB in PC12 cells, which was suppressed by pretreatment with Oligonol.