Anticarcinogenic effect of a polyphenolic fraction isolated from grape seeds in human prostate carcinoma DU145 cells: modulation of mitogenic signaling and cell-cycle regulators and induction of G1 arrest and apoptosis

Dissolution Study on Grape Polyphenol Hard Gelatin Capsule Dietary Supplements

Methods for a dissolution study by ultra-high performance liquid chromatography/triple quadrupole mass spectrometry (UHPLC-QqQ/MS) analysis of grape polyphenol dietary supplements, namely, grape seed extract (GSE) and resveratrol (RSV) capsules, were developed following the guidance of United States Pharmacopeia (USP) <2040>. Two dissolution media, 0.1 N hydrochloric acid (pH 1.2) and 0.05 M acetate buffer (pH 4.6), were evaluated with dissolution apparatus (USP 1), 100 rpm rotation speed, and 900 ml dissolution medium volume. Dissolution profiling was performed over 120 min. Major phenolic compounds of gallic acid, catechin, epicatechin, and procyanidin B2 were quantitated to obtain the dissolution profile of GSE capsules, and trans-RSV was used for RSV capsules. Results indicated that the released trans-RSV for RSV capsules in both of the dissolution media meets the USP standards, and that for the GSE capsules, all the four marker compounds passed the dissolution test in the HCl medium but did not reach a 75% release within 60 min in the acetate buffer. These promising results suggest that the general USP dissolution protocols are adequate for the successful release of RSV capsules in HCl medium and acetate buffer and GSE capsules (in HCl medium), but may be inadequate for GSE capsules in acetate buffer. These results showed that under a low pH of 1.2 (simulated stomach environment), bioactive compounds were released on time from the GSE capsules and met the USP guidelines; however, under a higher pH of 4.6 (simulated duodenum environment), the same biomarkers failed, suggesting the need to further improve the dissolution of GSE over a wider range of pH environments to enhance bioavailability and efficacy.

Induced Cell Death as a Possible Pathway of Antimutagenic Action

The existing concepts of antimutagenesis are briefly reviewed. Published reports on antimutagenic and proapoptotic properties of some polyphenols and compounds of other chemical groups obtained in representative in vitro and in vivo experiments on eukaryotic test systems are discussed. The relationships between the antimutagenic and proapoptotic properties of the analyzed compounds (naringin, apigenin, resveratrol, curcumin, N-acetylcysteine, etc.) are considered in favor of the hypothesis on induced cell death as an antimutagenic tool.

Bioactive phenolic components and potential health effects of chestnut shell: A review

Chestnut kernels are often used for direct consumption; or processed to produce marron glacé, chestnut purée, and gluten-free products, while chestnut by-products (inner shell and outer shell) are treated as waste residues. Many in vivo and in vitro studies have proved how chestnut shell extract functions as an antioxidant and exhibits anticancer, anti-inflammatory, antidiabetic, and anti-obesity activities. This review introduces the main components of phenolic compounds in chestnut shells, traditional and modern extraction methods, and reported potential health effects. The aim is to have a better understanding of the functional active ingredients in chestnut shells and their value-added uses, to increase understanding of future applications of this agricultural and sideline product in the food, pharmaceutical, and cosmetic industries. PRACTICAL APPLICATIONS: In recent years, chestnut shells have become a hot research topic because of their rich bioactive ingredients. Due to the large amount of phenolic compounds in chestnut shells and their potential health functions (antioxidant, anticancer, antibacterial, anti-inflammatory, hypoglycemic, and treatment of obesity), extracts of chestnut shells have high biological value in the treatment of diseases. Therefore, this review introduces the main components of phenolic compounds in chestnut shells, traditional and modern extraction methods, and the potential health effects of these compounds. The aim of this review is to better understand the functional, active ingredients in chestnut shells and their value-added uses, and to increase understanding of future applications of this agricultural and sideline product in the food, pharmaceutical, and cosmetic industries.

Identification of a synergistic combination of dimethylaminoparthenolide and shikonin alters metabolism and inhibits proliferation of pediatric precursor-B cell acute lymphoblastic leukemia

Exploiting metabolic vulnerabilities of cancer cells with nontoxic, plant derived compounds constitutes a novel strategy for both chemoprevention and treatment. A high-throughput screening approach was used to evaluate a library of natural products to determine the most synergistic combination in precursor-B cell acute lymphoblast leukemia. Dimethylaminoparthenolide and shikonin effectively inhibited proliferation resulting in cell death in primary and immortalized leukemia cells, while having negligible effects on normal cells. Dimethylaminoparthenolide and shikonin have been shown separately to inhibit cell survival and proliferative signaling and activate tumor suppressors and proapoptotic pathways. Untargeted metabolomics and metabolic flux analysis with stable isotopically labeled glucose and glutamine exhibited a global shift in metabolism following treatment. Pathway analysis indicated significant differences in amino acid, antioxidant, tricarboxylic acid cycle, and nucleotide metabolism. Together, dimethylaminoparthenolide and shikonin reduced the shunting of glycolytic intermediates into the pentose phosphate pathway for biosynthetic purposes. Similarly, the incorporation of glutamine and glutamine-derived metabolites into purine and pyrimidine synthesis was inhibited by the combination of dimethylaminoparthenolide and shikonin, effectively impeding biosynthetic pathways critical for leukemia cell survival. This approach demonstrates that a synergistic pair of compounds with malignant cell specificity can effectively target metabolic pathways crucial to leukemia cell proliferation and induce apoptosis.

Current Perspectives in the Application of Medicinal Plants Against Cancer: Novel Therapeutic Agents

Background:

Cancer is a disease characterized by uncontrolled cell growth and proliferation. It has become a major health problem in the past decades and is now the second leading cause of death globally. Although, there are different types of treatment such as chemotherapy, immune therapy, radiation, hormone therapy and targeted therapy used against cancer, they have possible side effects and significant deficiencies.

Methods:

This review aims to outline the benefits of medicinal plants and plant-derived products and highlight why they should be used as novel anti-cancer therapeutics. Electronic databases, including PubMed, Scopus, ScienceDirect, Cochrane library, and MedlinePlus were searched to summarize in vitro, in vivo and clinical studies on anticancer effects of medicinal plants and their bioactive compounds up-to-date.

Results:

In recent years, a number of medicinal plants have been administered to cancer patients in order to prevent and treat cancer as an alternative therapy. These plants were used because of their rich anticarcinogenic and chemoprotective potentials. In addition to these remarkable properties, these plants have less toxic anticancer, anti-tumor and anti-proliferation agents than traditional therapeutics. Nevertheless, only a small number of natural anti-tumor products including vinblastine, vincristine, podophyllotoxin, paclitaxel (Taxol) and camptothecin have been tested clinically, while vinflunine ditartrate, anhydrovinblastine, NK-611, tafluposide, paclitaxel poliglumex, combretastatins, salvicine, curcumin, indirubin, triptolide, homoharringtonine are still on trial.

Conclusion:

Consequently, more effective anticancer compounds are identified during the clinical trials; these natural products could be a key source of antitumor agents in modern anticancer therapy. It is expected that novel anticancer phytopharmaceuticals produced from medicinal plants could be effectively used in prevention and therapy for the cancers.

In Vitro Anticancer Properties of Table Grape Powder Extract (GPE) in Prostate Cancer

Although the link between diet and cancer is complex, epidemiological data confirm that diet is a risk factor for prostate cancer and indicate a reduced prostate cancer incidence associated with a diet rich in vegetables and fruits. Because of the known protective effect of grape seed extract (GSE) against prostate cancer, we evaluated the effects of grape powder extract (GPE) on cell viability, proliferation, and metastatic capability. Importantly, we explored the possible novel mechanism of GPE through metastasis-associated protein 1 (MTA1) downregulation in prostate cancer, since our previous studies indicated resveratrol (Res)- and pterostilbene (Pter)-induced MTA1-mediated anticancer activities in prostate cancer. We found that GPE inhibited the cell viability and growth of prostate cancer cells only at high 100 μg/mL concentrations. However, at low 1.5⁻15 μg/mL concentrations, GPE significantly reduced the colony formation and wound healing capabilities of both DU145 and PC3M cells. Moreover, we found that GPE inhibited MTA1 in a dose-dependent manner in these cells, albeit with considerably less potency than Res and Pter. These results indicate that stilbenes such as Res and Pter specifically and potently inhibit MTA1 and MTA1-associated proteins compared to GPE, which contains low concentrations of Res and mainly consists of other flavonoids and anthocyanidins. Our findings support continued interest in GPE as a chemopreventive and anti-cancer agent against prostate cancer but also emphasize the unique and specific properties of stilbenes on MTA1-mediated anticancer effects on prostate cancer.

Procyanidin from peanut skin induces antiproliferative effect in human prostate carcinoma cells DU145

In this study, the antiproliferative activity of peanut skin procyanidins (PSP) and six fractions (PSP-1∼6) isolated from PSP by several chromatographic steps on the human prostate cancer DU145 cells were evaluated. The results showed that PSP and PSP-1∼6 significantly inhibited the proliferation of DU145 cells. PSP-2 was the most effective fraction, which was identified as procyanidin B₃ mainly and procyanidin dimer [(E)C-luteolin or keampferol] secondarily. Moreover, the mechanism of antiproliferative activity of PSP-2 was investigated. It was observed that PSP-2 induced apoptotic cell death and cell cycle arrest at S phase in DU145 cells. PSP-2 caused the increase of intracellular ROS level and the decrease of Bcl-2/Bax ratio, and triggered the activation of p53 and caspases-3 in DU145 cells. Our findings demonstrated that procyanidins from peanut skin have the potential to be developed as an anti-prostate cancer agent.

Synthesis and biological evaluation of sulfur-containing shikonin oxime derivatives as potential antineoplastic agents

As a continuation of our research on developing potent and potentially safe antineoplastic agents, a set of forty five sulfur-containing shikonin oxime derivatives were synthesized and evaluated for their in vitro cytotoxic activity against human colon cancer (HCT-15), gastric carcinoma (MGC-803), liver (Bel7402), breast (MCF-7) cancer cells and human skin fibroblast (HSF) cells. All the synthesized compounds exhibited potent cytotoxic activity selectively towards HCT-15 cells and did not display apparent toxicity to the normal HSF cells, some of which were more or comparatively effective to the parent compound against HCT-15, MGC-803 and Bel7402 cells. The most active agent 9m displayed high potency against human cancer cells with IC₅₀ ranging from 0.27 ± 0.02 to 9.23 ± 0.12 μM. The structure-activity relationships (SARs) studies suggested that the nature of substituent group in the side chain is important for antitumor potency in vitro. Additionally, nitric oxide release studies revealed that the amount of nitric oxide generated from these oxime derivatives was relatively low. Furthermore, cellular mechanism investigations indicated that compound 9m could arrest cell cycle at G1 phase and induce a strong apoptotic response in HCT-15 cells. Moreover, western blot studies revealed that compound 9m induced apoptosis through the down-regulation of Bcl-2 and up-regulation of Bax, caspase 3 and 9. For all these reasons, compound 9m hold promising potential as antineoplastic agent.

Valorisation of softwood bark through extraction of utilizable chemicals. A review

Softwood bark is an important source for producing chemicals and materials as well as bioenergy. Extraction is regarded as a key technology for obtaining chemicals in general, and valorizing bark as a source of such chemicals in particular. In this paper, properties of 237 compounds identified in various studies dealing with extraction of softwood bark were described. Finally, some challenges and perspectives on the production of chemicals from bark are discussed.

Natural Compounds as Modulators of Cell Cycle Arrest: Application for Anticancer Chemotherapies

Natural compounds from various plants, microorganisms and marine species play an important role in the discovery novel components that can be successfully used in numerous biomedical applications, including anticancer therapeutics. Since uncontrolled and rapid cell division is a hallmark of cancer, unraveling the molecular mechanisms underlying mitosis is key to understanding how various natural compounds might function as inhibitors of cell cycle progression. A number of natural compounds that inhibit the cell cycle arrest have proven effective for killing cancer cells in vitro, in vivo and in clinical settings. Significant advances that have been recently made in the understanding of molecular mechanisms underlying the cell cycle regulation using the chemotherapeutic agents is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to anticancer drugs, especially of natural origin, which inhibit the activities of cyclins and cyclin-dependent kinases, as well as other proteins and enzymes involved in proper regulation of cell cycle leading to controlled cell proliferation.

Grapes (Vitis vinifera) as a Potential Candidate for the Therapy of the Metabolic Syndrome

Metabolic syndrome is associated with several disorders, including hypertension, diabetes, hyperlipidemia as well as cardiovascular diseases and stroke. Plant-derived polyphenols, compounds found in numerous plant species, play an important role as potential treatments for components of metabolic syndrome. Studies have provided evidence for protective effects of various polyphenol-rich foods against metabolic syndrome. Fruits, vegetables, cereals, nuts, and berries are rich in polyphenolic compounds. Grapes (Vitis vinifera), especially grape seeds, stand out as rich sources of polyphenol potent antioxidants and have been reported helpful for inhibiting the risk factors involved in the metabolic syndrome such as hyperlipidemia, hyperglycemia, and hypertension. There are also many studies about gastroprotective, hepatoprotective, and anti-obesity effects of grape polyphenolic compounds especially proanthocyanidins in the literature. The present study investigates the protective effects of grape seeds in metabolic syndrome. The results of this study show that grape polyphenols have significant effects on the level of blood glucose, lipid profile, blood pressure, as well as beneficial activities in liver and heart with various mechanisms. In addition, the pharmacokinetics of grape polyphenols is discussed. More detailed mechanistic investigations and phytochemical studies for finding the exact bioactive component(s) and molecular signaling pathways are suggested.

Carvacrol induces mitochondria-mediated apoptosis in HL-60 promyelocytic and Jurkat T lymphoma cells

The aim of the present study was to investigate the effect of carvacrol, a phenolic monoterpenoid on the induction of apoptosis in HL-60 (Human acute promyelocytic leukemia cells) and Jurkat (human T lymphocyte cells) cells. Carvacrol showed a potent cytotoxic effect on both cells with dose-dependent increase in the level of free radical formation as measured by an oxidation sensitive fluorescent dye, 2,7-dichlorodihydrofluorescein diacetate (H2DCFDA) levels. The reduction in the level of antioxidants such as catalase (CAT) and superoxide dismutase (SOD) (P<0.05) was observed in carvacrol-treated cells. The major cytotoxic effect appears to be intervened by the induction of apoptotic cell death as assessed by annexin-V labeling assay using flow cytometry. Western blot analysis showed that Bax expression was increased, whereas Bcl-2 expression was significantly decreased in carvacrol exposed HL-60 cells and Jurkat cells. Further studies revealed that the dissipation of mitochondrial membrane potential of intact cells was accompanied by the activation of caspase-3. Our results found that the potential mechanism of cellular apoptosis induced by carvacrol is mediated by caspase-3 and is associated with the collapse of mitochondrial membrane potential, generation of free radicals, and depletion of the intracellular antioxidant pool.

The effect of grape seed extract on estrogen levels of postmenopausal women: a pilot study

The role of estrogens in breast cancer (BC) development is widely accepted, leading to the development of selective estrogen receptor modulators and aromatase inhibitors for BC treatment and prevention. However, because of potential adverse effects, healthy women with high risk of BC are hesitant to take them. Preliminary evidence from animal studies shows that grapes may have an aromatase-inhibiting effect, decreasing estrogen synthesis and increasing androgen precursors. We conducted a randomized, double-blind, dose-finding early-phase trial on the effect of grape seed extract (GSE) on estrogen levels. Postmenopausal women who met study inclusion criteria (N = 46) were randomly assigned to daily GSE at a dose of 200, 400, 600, or 800 mg for 12 weeks. Primary outcome was change in plasma levels of estrogen conjugates from baseline to 12 weeks posttreatment. Thirty-nine participants (84.8%) completed the study. GSE in the 4 daily doses did not significantly decrease estrogen or increase androgen precursors.

Flavonoid-enriched apple fraction AF4 induces cell cycle arrest, DNA topoisomerase II inhibition, and apoptosis in human liver cancer HepG2 cells

Apples are a major source of dietary phytochemicals such as flavonoids in the Western diet. Here we report anticancer properties and possible mechanism of action of apple flavonoid-enriched fraction (AF4) isolated from the peels of Northern Spy apples in human hepatocellular carcinoma cells, HepG2. Treatment with AF4 induced cell growth inhibition in HepG2 cells in time- and dose-dependent manner. Concentration of 50 μg/ml (50 μg total monomeric polyphenols/ml) AF4 was sufficient to induce a significant reduction in cell viability within 6 h of treatment (92%, P < 0.05) but had very low toxicity (minimum 4% to maximum 16%) on primary liver and lung cells, which was significantly lower than currently prescribed chemotherapy drug Sorafenib (minimum 29% to maximum 49%, P < 0.05). AF4 induced apoptosis in HepG2 cells within 6 h of treatment via activation of caspase-3. Cell cycle analysis via flow-cytometer showed that AF4 induced G2/M phase arrest. Further, results showed that AF4 acts as a strong DNA topoisomerase II catalytic inhibitor, which may be a plausible reason to drive the cells to apoptosis. Overall, our data suggests that AF4 possesses a significantly stronger antiproliferative and specific action than Sorafenib in vitro and is a potential natural chemotherapy agent for treatment of liver cancer.

Protective effect of grape seed and skin extract against high-fat diet-induced liver steatosis and zinc depletion in rat

BACKGROUND

Obesity is a tremendous public health problem, characterized by ectopic deposition of fat into non-adipose tissues as liver generating an oxidative stress that could lead to steato-hepatitis. Grape seed and skin extract (GSSE) is a complex mixture of polyphenolics exhibiting robust antioxidative properties.

AIM

We hypothesize that GSSE could protect the liver from fat-induced lipotoxicity and have a beneficial effect on liver function.

METHODS

Hepatoprotective effect of GSSE was measured by using an experimental model of fat-induced rat liver steatosis. Male rats were fed a standard diet or a high-fat diet (HFD) during 6 weeks and treated or not with 500 mg/kg bw GSSE. Lipid deposition into the liver was assessed by triglyceride, cholesterol and phospholipid measurements. Fat-induced lipoperoxidation, carbonylation, depletion of glutathione and of antioxidant enzyme activities were used as oxidative stress markers with a special emphasis on transition metal distribution.

RESULTS

HFD induced liver hypertrophy and inflammation as assessed by high liver transaminases. HFD also induced an oxidative stress characterized by increased lipid and protein oxidation, a drop in glutathione and antioxidant enzyme activities as glutathione peroxidase and superoxide dismutase and a drastic depletion in liver zinc. Importantly, GSSE prevented all the deleterious effects of HFD treatment.

CONCLUSIONS

Data suggest that GSSE could be used as a safe preventive agent against fat-induced liver lipotoxicity which could also have potential applications in other non-alcoholic liver diseases.

Anticarcinogenic activity of polyphenolic extracts from grape stems against breast, colon, renal and thyroid cancer cells

A major part of the wineries' wastes is composed of grape stems which are discarded mainly in open fields and cause environmental problems due mainly to their high polyphenolic content. The grape stem extracts' use as a source of high added value polyphenols presents great interest because this combines a profitable venture with environmental protection close to wine-producing zones. In the present study, at first, the Total Polyphenolic Content (TPC) and the polyphenolic composition of grape stem extracts from four different Greek Vitis vinifera varieties were determined by HPLC methods. Afterwards, the grape stem extracts were examined for their ability to inhibit growth of colon (HT29), breast (MCF-7 and MDA-MB-23), renal (786-0 and Caki-1) and thyroid (K1) cancer cells. The cancer cells were exposed to the extracts for 72 h and the effects on cell growth were evaluated using the SRB assay. The results indicated that all extracts inhibited cell proliferation, with IC₅₀ values of 121-230 μg/ml (MCF-7), 121-184 μg/ml (MDA-MD-23), 175-309 μg/ml (HT29), 159-314 μg/ml (K1), 180-225 μg/ml (786-0) and 134->400 μg/ml (Caki-1). This is the first study presenting the inhibitory activity of grape stem extracts against growth of colon, breast, renal and thyroid cancer cells.

The strategies to control prostate cancer by chemoprevention approaches

Prostate cancer (PCA) is the most commonly diagnosed cancer in men in the United States with growing worldwide incidence. Despite intensive investment in improving early detection, PCA often escapes timely detection and mortality remains high; this malignancy being the second highest cancer-associated mortality in American men. Collectively, health care costs of PCA results in an immense financial burden that is only expected to grow. Additionally, even in cases of successful treatment, PCA is associated with long-term and pervasive effects on patients. A proactive alternative to treat PCA is to prevent its occurrence and progression prior to symptomatic malignancy. This may serve to address the issue of burgeoning healthcare costs and increasing number of sufferers. One potential regimen in service of this alternative is PCA chemoprevention. Here, chemical compounds with cancer preventive efficacy are identified on the basis of their potential in a host of categories: their historical medicinal use, correlation with reduced risk in population studies, non-toxicity, their unique chemical properties, or their role in biological systems. PCA chemopreventive agents are drawn from multiple broad classes of chemicals, themselves further subdivided based on source or potential effect, with most derived from natural products. Many such compounds have shown efficacy, varying from inhibiting deregulated PCA cell signaling, proliferation, epithelial to mesenchymal transition (EMT), invasion, metastasis, tumor growth and angiogenesis and inducing apoptosis. Overall, these chemopreventive agents show great promise in PCA pre-clinical models, though additional work remains to be done in effectively translating these findings into clinical use.

(-)-Epigallocatechin-3-gallate induces apoptosis and inhibits invasion and migration of human cervical cancer cells

Invasion and metastasis are the major causes of cancer-related death. Pharmacological or therapeutic interventions such as chemoprevention of the progression stages of neoplastic development could result in substantial reduction in the incidence of cancer mortality. (-)-Epigallocatechin-3-gallate (EGCG), a promising chemopreventive agent, has attracted extensive interest for cancer therapy utilizing its antioxidant, anti- proliferative and inhibitory effects on angiogenesis and tumor cell invasion. In this study, we assessed the influence of EGCG on the proliferative potential of HeLa cells by cell viability assay and authenticated the results by nuclear morphological examination, DNA laddering assay and cell cycle analysis. Further we analyzed the anti-invasive properties of EGCG by wound migration assay and gene expression of MMP-9 and TIMP-1 in HeLa cells. Our results indicated that EGCG induced growth inhibition of HeLa cells in a dose- and time- dependent manner. It was observed that cell death mediated by EGCG was through apoptosis. Interestingly, EGCG effectively inhibited invasion and migration of HeLa cells and modulated the expression of related genes (MMP-9 and TIMP-1) . These results indicate that EGCG may effectively suppress promotion and progression stages of cervical cancer development.

Resveratrol reduces prostate cancer growth and metastasis by inhibiting the Akt/MicroRNA-21 pathway

The consumption of foods containing resveratrol produces significant health benefits. Resveratrol inhibits cancer by reducing cell proliferation and metastasis and by inducing apoptosis. These actions could be explained by its ability to inhibit (ERK-1/2), Akt and suppressing the levels of estrogen and insulin growth factor -1 (IGF-1) receptor. How these processes are manifested into the antitumor actions of resveratrol is not clear. Using microarray studies, we show that resveratrol reduced the expression of various prostate-tumor associated microRNAs (miRs) including miR-21 in androgen-receptor negative and highly aggressive human prostate cancer cells, PC-3M-MM2. This effect of resveratrol was associated with reduced cell viability, migration and invasiveness. Additionally, resveratrol increased the expression of tumor suppressors, PDCD4 and maspin, which are negatively regulated by miR-21. Short interfering (si) RNA against PDCD4 attenuated resveratrol’s effect on prostate cancer cells, and similar effects were observed following over expression of miR-21 with pre-miR-21 oligonucleotides. PC-3M-MM2 cells also exhibited high levels of phospho-Akt (pAkt), which were reduced by both resveratrol and LY294002 (a PI3-kinase inhibitor). MiR-21 expression in these cells appeared to be dependent on Akt, as LY294002 reduced the levels of miR-21 along with a concurrent increase in PDCD4 expression. These in vitro findings were further corroborated in a severe combined immunodeficient (SCID) mouse xenograft model of prostate cancer. Oral administration of resveratrol not only inhibited the tumor growth but also decreased the incidence and number of metastatic lung lesions. These tumor- and metastatic-suppressive effects of resveratrol were associated with reduced miR-21 and pAkt, and elevated PDCD4 levels. Similar anti-tumor effects of resveratrol were observed in DU145 and LNCaP prostate cancer cells which were associated with suppression of Akt and PDCD4, but independent of miR-21.These data suggest that resveratrol’s anti-tumor actions in prostate cancer could be explained, in part, through inhibition of Akt/miR-21 signaling pathway.

Grape seed procyanidin extract modulates proliferation and apoptosis of pancreatic beta-cells

Grape seed procyanidin extract (GSPE) modulates glucose homeostasis and insulinemia in several animal models. Under pathological conditions, insulin levels are dependent on pancreatic beta-cell functionality, as well as on the beta-cell mass expansion or apoptosis in the pancreas. In this study, we analysed the effects of GSPE on modulating apoptosis and proliferation in beta-cells. We tested the effects of GSPE in the INS-1E pancreatic beta-cell line, either under basal or altered conditions with high glucose, insulin or palmitate levels. GSPE enhanced the pro-apoptotic effect of high glucose and showed clear antiproliferative effects under high glucose, insulin and palmitate conditions. These antiproliferative effects are likely due to high molecular weight compounds contained in the extract. GSPE also modulated pro- and anti-apoptotic markers in the pancreas of rats fed a cafeteria diet, with the effect depending on the dose of GSPE and duration of treatment. Thus, GSPE is able to modulate apoptosis and proliferation of beta-cells under altered, but not basal, conditions.

Grape-seed procyanidins inhibit the in vitro growth and invasion of pancreatic carcinoma cells

OBJECTIVES

Grape-seed procyanidins (GSPs) can inhibit cell proliferation and invasiveness in various human cancers. However, the effect of GSP on pancreatic carcinoma cells has not been investigated.

METHODS

Pancreatic carcinoma cell lines MIA PaCa-2 and BxPC-3 treated with GSP were assessed for viability by trypan blue exclusion, for cell cycle distribution by flow cytometry, for increased apoptosis by annexin V labeling, for their adhesion and invasion potential by evaluating their ability to penetrate through a matrix gel-coated Boyden chamber, and for changes in the levels of proteins involved in cellular events by immunoblotting.

RESULTS

Grape-seed procyanidin inhibited MIA PaCa-2 and BxPC-3 proliferation in a dose-dependent manner and induced G1-phase arrest of the cell cycle in BxPC-3 or mitochondria-mediated apoptosis in MIA PaCa-2. Grape-seed procyanidin also inhibited the adhesion and invasion potential of both cell lines in a dose-dependent manner, which are associated with the suppression of metalloproteases matrix metalloproteinase 9 or 2 (MMP-9 or -2) expression.

CONCLUSIONS

Grape-seed procyanidin inhibited the proliferation of pancreatic carcinoma cells by cell cycle blockage or apoptotic induction. The invasiveness was also suppressed by GSP through down-regulation of MMP-2 or MMP-9 in pancreatic carcinoma cells. Grape-seed procyanidin is a potential chemotherapeutic or preventive agent for pancreatic carcinoma.

miR-34a regulates mouse neural stem cell differentiation

Background

MicroRNAs (miRNAs or miRs) participate in the regulation of several biological processes, including cell differentiation. Recently, miR-34a has been implicated in the differentiation of monocyte-derived dendritic cells, human erythroleukemia cells, and mouse embryonic stem cells. In addition, members of the miR-34 family have been identified as direct p53 targets. However, the function of miR-34a in the control of the differentiation program of specific neural cell types remains largely unknown. Here, we investigated the role of miR-34a in regulating mouse neural stem (NS) cell differentiation.

Methodology/Principal Findings

miR-34a overexpression increased postmitotic neurons and neurite elongation of mouse NS cells, whereas anti-miR-34a had the opposite effect. SIRT1 was identified as a target of miR-34a, which may mediate the effect of miR-34a on neurite elongation. In addition, acetylation of p53 (Lys 379) and p53-DNA binding activity were increased and cell death unchanged after miR-34a overexpression, thus reinforcing the role of p53 during neural differentiation. Interestingly, in conditions where SIRT1 was activated by pharmacologic treatment with resveratrol, miR-34a promoted astrocytic differentiation, through a SIRT1-independent mechanism.

Conclusions

Our results provide new insight into the molecular mechanisms by which miR-34a modulates neural differentiation, suggesting that miR-34a is required for proper neuronal differentiation, in part, by targeting SIRT1 and modulating p53 activity.

Grape seed extract regulates androgen receptor-mediated transcription in prostate cancer cells through potent anti-histone acetyltransferase activity

Histone acetylation, which is regulated by histone acetyltransferases (HATs) and deacetylases, is an epigenetic mechanism that influences eukaryotic transcription. Significant changes in histone acetylation are associated with cancer; therefore, manipulating the acetylation status of key gene targets is likely crucial for effective cancer therapy. Grape seed extract (GSE) has a known protective effect against prostate cancer. Here, we showed that GSE significantly inhibited HAT activity by 30-80% in vitro (P < .05). Furthermore, we demonstrated significant repression of androgen receptor (AR)-mediated transcription by GSE in prostate cancer cells by measuring luciferase activity using a pGL3-PSA construct bearing the AR element in the human prostate cancer cell line LNCaP (P < .05). GSE treatment also decreased the mRNA level of the AR-regulated genes PSA and NKX 3.1. Finally, GSE inhibited growth of LNCaP cells. These results indicate that GSE potently inhibits HAT, leading to decreased AR-mediated transcription and cancer cell growth, and implicate GSE as a novel candidate for therapeutic activity against prostate cancer.

The phenomenon of resveratrol: redefining the virtues of promiscuity

Cancer chemoprevention entails the ingestion of dietary or pharmaceutical agents that can prevent, delay, or reverse the process of carcinogenesis. With support provided by the National Cancer Institute, we have been actively engaged in the systematic discovery and characterization of natural chemopreventive agents. The typical approach involves identifying active crude substances such as extracts derived from terrestrial plants or marine organisms, utilizing in vitro bioassay systems, followed by the isolation of pure active components. As part of this project, an extract obtained from a nonedible Peruvian legume, Cassia quinquangulata Rich. (Leguminosae), was evaluated and found to be active as an inhibitor of cyclooxygenase. The active component was identified as resveratrol. Surprisingly broad spectrum activity was observed, indicative of potential to inhibit carcinogenesis at the stages of initiation, promotion, and progression. This discovery has led to many additional research efforts. There are now around 3,500 papers concerning some aspect of resveratrol action, yet the molecule is unusually promiscuous and specific mechanisms remain elusive. Considering the structural simplicity of this stilbene, the intensity of interest is phenomenal.

NFkappaB-dependent regulation of urokinase plasminogen activator by proanthocyanidin-rich grape seed extract: effect on invasion by prostate cancer cells

Tumor invasion and metastasis present major obstacles to successful control of androgen-independent prostate cancer. Cell migration is a fundamental aspect of cancer cell metastasis. Urokinase plasminogen activator (uPA) system is implicated in cell migration and cancer metastasis and has potential to be developed as therapeutic target. In recent years, efficacy of dietary nutrients in preventing and curing cancer has gained increasing attention. One such promising candidate is proanthocyanidin-rich grape seed extract (GSE). We investigated the efficacy of GSE in regulating uPA expression and cell migration using highly metastatic androgen-independent PC3 prostate cancer cells as a model. GSE down-regulated uPA as a function of concentration. Additional studies showed that GSE inhibited DNA-binding activity of the transcription factor nuclear factor kappa B (NFkappaB), which in turn decreased NFkappaB-dependent uPA transcription. Invasion assays revealed the inhibitory effect of GSE on PC3 cell migration. These in-vitro experiments demonstrate the therapeutic property of GSE as an antimetastatic agent by targeting uPA.

Procyanidin B3, an inhibitor of histone acetyltransferase, enhances the action of antagonist for prostate cancer cells via inhibition of p300-dependent acetylation of androgen receptor

Increasing evidence suggests that AR (androgen receptor) acetylation is critical for prostate cancer cell growth. In the present study, we identified Pro-B3 (procyanidin B3) as a specific HAT (histone acetyltransferase) inhibitor. Pro-B3 selectively inhibited the activity of HATs, but not other epigenetic enzymes. Pro-B3 substantially inhibited the p300-mediated AR acetylation, both in vitro and in vivo. Pro-B3 inhibited both p300-dependent and agonist-induced AR transcription. We demonstrate that the p300-mediated AR acetylation is critical for the hormone responsiveness of AR. Interestingly, B3 treatment efficiently enhanced the antagonist activity of flutamide through suppression of p300 HAT activity, demonstrating that relative p300 activity is critical for the antagonist action. Finally, Pro-B3 treatment inhibited acetylation-dependent prostate cell proliferation and expression of cell-cycle control genes, subsequently increasing cell death, indicating the functional importance of AR acetylation for prostate cancer cell growth.

Clinical pharmacology of isoflavones and its relevance for potential prevention of prostate cancer

Isoflavones are phytoestrogens that have pleiotropic effects in a wide variety of cancer cell lines. Many of these biological effects involve key components of signal transduction pathways within cancer cells, including prostate cancer cells. Epidemiological studies have raised the hypothesis that isoflavones may play an important role in the prevention and modulation of prostate cancer growth. Since randomized phase III trials of isoflavones in prostate cancer prevention are currently lacking, the best evidence for this concept is presently provided by case control studies. However, in vitro data are much more convincing in regard to the activity of a number of isoflavones, and have led to the development of genistein and phenoxodiol in the clinic as potential treatments for cancer. In addition, the potential activity of isoflavones in combination with cytotoxics or radiotherapy warrants further investigation. This review focuses on the clinical pharmacology of isoflavones and its relevance to their development for use in the prevention of prostate cancer, and it evaluates some of the conflicting data in the literature.

Identification of components of grape powder with anti-apoptotic effects

This study is to investigate the mechanism underlying the anti-apoptotic effects of freeze-dried grape powder (FDGP) and identify the polyphenolic compounds involved. We examined apoptotic signaling pathways affected by FDGP and by its active components, including epicatechin, cyanidin, quercetin, and resveratrol, in human Huh7 hepatoma cells by assaying cell viability assays, the activities of caspase 3 and caspase 7, and the expression of endoplasmic reticulum stress-associated proteins. FDGP dramatically decreased taurodeoxycholic acid (TDCA)-induced production of reactive oxygen species (ROS). Assessment of individual active components revealed that at concentrations corresponding to 300 μg/mL FDGP, only quercetin demonstrated cytoprotective effects against mitochondrial-mediated apoptosis. In contrast, increased concentrations of other individual polyphenolic compounds were required to produce measurable cytoprotective effect. Only combinations of all four polyphenolic compounds (epicatechin, cyanidin, quercetin, and resveratrol) restored a degree of the anti-apoptotic effects seen with FDGP. The pretreatment of FDGP at 30 μg/mL concentration could reverse the thapsigargin-induced effects on the expression of endoplasmic reticulum stress-associated proteins. In conclusion, FDGP reduced oxidative stress, endoplasmic reticulum stress, and apoptosis. The mechanisms involved in the anti-apoptotic effects of FDGP included reduced generation of ROS, and reduced processing of certain caspases. We demonstrated that quercetin, epicatechin, and cyanidin are active compounds within FDGP that attenuate apoptosis. These findings contribute to our understanding of the molecular mechanisms of anti-apoptotic and anti-oxidant effects of grape and are expected to assist in developing clinical protocols to treat a variety of stress-mediated conditions.

Dietary-feeding of grape seed extract prevents azoxymethane-induced colonic aberrant crypt foci formation in fischer 344 rats

Chemoprevention by dietary agents/supplements has emerged as a novel approach to control various malignancies, including colorectal cancer (CRC). This study assessed dietary grape seed extract (GSE) effectiveness in preventing azoxymethane (AOM)-induced aberrant crypt foci (ACF) formation and associated mechanisms in Fischer 344 rats. Six-week-old rats were injected with AOM, and fed control diet or the one supplemented with 0.25% or 0.5% (w/w) GSE in pre- and post-AOM or only post-AOM experimental protocols. At 16 wk of age, rats were sacrificed and colons were evaluated for ACF formation followed by cell proliferation, apoptosis, and molecular analyses by immunohistochemistry. GSE-feeding caused strong chemopreventive efficacy against AOM-induced ACF formation in terms of up to 60% (P < 0.001) reduction in number of ACF and 66% (P < 0.001) reduction in crypt multiplicity. Mechanistic studies showed that GSE-feeding inhibited AOM-induced cell proliferation but enhanced apoptosis in colon including ACF, together with a strong decrease in cyclin D1, COX-2, iNOS, and survivin levels. Additional studies showed that GSE-feeding also decreased AOM-caused increase in beta-catenin and NF-kappaB levels in colon tissues. Compared to control animals, GSE alone treatment did not show any considerable change in these biological and molecular events in colon, and was nontoxic. Together, these findings show the chemopreventive efficacy of GSE against the early steps of colon carcinogenesis in rats via likely targeting of beta-catenin and NF-kappaB signaling, and suggest its potential usefulness for the prevention of human CRC.

Inhibition of U-87 human glioblastoma cell proliferation and formyl peptide receptor function by oligomer procyanidins (F2) isolated from grape seeds

Gliomas are the most common and lethal tumor type in the brain. The present study investigated the effect of oligomer procyanidins (F2) (F2, degree of polymerization 2-15), a natural fraction isolated from grape seeds on the biological behavior of glioblastoma cells. We found that F2 significantly inhibited the glioblastoma growth, with little cytotoxicity on normal cells, induced G2/M arrest and decreased mitochondrial membrane potential in U-87 cells. It also induced a non-apoptotic cell death phenotype resembling paraptosis in U-87 cells. In addition, it was found for the first time that F2 in non-cytotoxic concentrations selectively inhibited U-87 cell chemotaxis mediated by a G-protein coupled receptor formyl peptide receptor FPR, which is implicated in tumor cell invasion and metastasis. Further experiments indicated that F2 inhibited fMLF-induced U-87 cell calcium mobilization and MAP kinases ERK1/2 phosphorylation. Moreover, F2 attenuated the glioblastoma FPR expression, a new molecular target for glioma therapeutics, which has been shown to play important roles in glioma cells chemotaxis, proliferation and angiogenesis in addition to its promotion to tumor progression, but did not affect FPR mRNA expression in U-87 cells. Taken together, our results suggest that F2 may be a promising candidate for the development of novel anti-tumor therapeutics.

Apple phytochemical extracts inhibit proliferation of estrogen-dependent and estrogen-independent human breast cancer cells through cell cycle modulation

Breast cancer is the most commonly diagnosed cancer in women in the United States. Dietary modification, particularly increased intake of fruits and vegetables, has been consistently associated with a reduced risk of various cancers, including breast cancer. Apples are a major source of dietary phytochemicals and flavonoids and possess potent antioxidant activity and antiproliferative activity in vitro. However, the molecular mechanisms of the anticancer properties of apple phytochemical extracts are not completely understood. In this study a possible mechanism by which apple extracts could inhibit cancer cell growth in vitro using estrogen-dependent MCF-7 and estrogen-independent MDA-MB-231 human breast cancer cell lines was analyzed. The data showed that apple phytochemical extracts significantly inhibited human breast cancer MCF-7 and MDA-MB-231 cell proliferation at concentrations of 10-80 mg/mL (p < 0.05). DNA flow cytometric analysis showed that apple extracts significantly induced G1 arrest in MCF-7 cells in a dose-dependent manner at concentrations >20 mg/mL (p < 0.05). At concentrations of 15, 30, and 50 mg/mL, apple extracts caused a greater increase in the G1/S ratio in MDA-MB-231 cells when compared with MCF-7 cells (p < 0.05). Cyclin D1 and Cdk4 proteins, the two major G1/S transit regulators, decreased in a dose-dependent manner after exposure to apple extracts. These results suggest that the antiproliferative activities of apple phytochemical extracts toward human breast cancer cells might be due to the modulation effects on cell cycle machinery.

Critical role of glutathione in melatonin enhancement of tumor necrosis factor and ionizing radiation-induced apoptosis in prostate cancer cells in vitro

The role of antioxidants in reducing cancer initiation and progression has been highlighted in recent years. Not only antioxidants limit cancer cell growth but also, in some situations, they promote the effectiveness of conventional treatments. Melatonin, an endogenously synthesized antioxidant, reduces cell growth of several tumor types both in vivo and in vitro. Additionally, the indole limits the collateral damage induced by many chemotherapeutic agents. By using a cellular model of human prostate cancer, we studied the ability of melatonin to enhance apoptosis induced by tumor necrosis factor or gamma radiation. It has been reported that melatonin reduces prostate cancer cell growth and, more recently, it promotes cell differentiation. In this work, we also show that melatonin elevates p21 protein levels and increases antioxidant capacity of prostate cancer cells. In addition, melatonin significantly enhances hrTNFalpha induced cell death by decreasing NFkappaB activation. Bcl-2 and survivin down-regulation appears to be associated to apoptosis stimulation under NFkappaB inhibition. On the contrary, melatonin does not promote irradiation-induced cell death due to an increment in intracellular glutathione content. In conclusion, prevention of NFkappaB activation by melatonin enhances the effectiveness of cytokine treatment in prostate cancer cells but it is not sufficient to enhance cell death triggered by other therapies which generate free radicals. A crucial role of glutathione in survival mechanisms of prostate cancer cells should be carefully considered.

Inhibition of cell-cycle progression in human colorectal carcinoma Lovo cells by andrographolide

In recent years, attention has been focused on the anti-cancer properties of pure components, an important role in the prevention of disease. Andrographolide (Andro), the major constituent of Andrographis paniculata (Burm. F.) Nees plant, is implicated towards its pharmacological activity. To investigate the mechanism basis for the anti-tumor properties of Andro, Andro was used to examine its effect on cell-cycle progression in human colorectal carcinoma Lovo cells. The data from cell growth experiment showed that Andro exhibited the anti-proliferation effect on Lovo cells in a time- and dose-dependent manner. This event was accompanied the arrest of the cells at the G1-S phase by Andro at the tested concentrations of 0-30 microM. Cellular uptake of Andro and Andro was confirmed by capillary electrophoresis analysis and the intracellular accumulation of Andro (0.61+/-0.07 microM/mg protein) was observed when treatment of Lovo cells with Andro for 12h. In addition, an accumulation of the cells in G1 phase (15% increase for 10 microM of Andro) was observed as well as by the association with a marked decrease in the protein expression of Cyclin A, Cyclin D1, Cdk2 and Cdk4. Andro also inducted the content of Cdk inhibitor p21 and p16, and the phosphorylation of p53. Further immunoprecipitation studies found that, in response to the treatment, the formation of Cyclin D1/Cdk4 and Cyclin A/Cdk2 complexes had declined, preventing the phosphorylation of Rb and the subsequent dissociation of Rb/E2F complex. These results suggested Andro can inhibit Lovo cell growth by G1-S phase arrest, and was exerted by inducing the expression of p53, p21 and p16 that, in turn, repressed the activity of Cyclin D1/Cdk4 and/or Cyclin A/Cdk2, as well as Rb phosphorylation.

Flavan-3-ols: nature, occurrence and biological activity

Representing the most common flavonoid consumed in the American diet, the flavan-3-ols and their polymeric condensation products, the proanthocyanidins, are regarded as functional ingredients in various beverages, whole and processed foods, herbal remedies and supplements. Their presence in food affects food quality parameters such as astringency, bitterness, sourness, sweetness, salivary viscosity, aroma, and color formation. The ability of flavan-3-ols to aid food functionality has also been established in terms of microbial stability, foamability, oxidative stability, and heat stability. While some foods only contain monomeric flavan-3-ols [(-)-epicatechin predominates] and dimeric proanthocyanidins, most foods contain oligomers of degree of polymerization values ranging from 1-10 or greater than 10. Flavan-3-ols have been reported to exhibit several health beneficial effects by acting as antioxidant, anticarcinogen, cardiopreventive, antimicrobial, anti-viral, and neuro-protective agents. This review summarizes the distribution and health effects of these compounds.

Inhibition of prostate cancer growth by muscadine grape skin extract and resveratrol through distinct mechanisms

The phytochemical resveratrol contained in red grapes has been shown to inhibit prostate cancer cell growth, in part, through its antioxidant activity. Muscadine grapes contain unique phytochemical constituents compared with other grapes and are potentially a source for novel compounds with antitumor activities. We compared the antitumor activities of muscadine grape skin extract (MSKE), which we show contains no resveratrol, with that of resveratrol using primary cultures of normal prostate epithelial cells (PrEC) and the prostate cancer cell lines RWPE-1, WPE1-NA22, WPE1-NB14, and WPE1-NB26, representing different stages of prostate cancer progression. MSKE significantly inhibited tumor cell growth in all transformed prostate cancer cell lines but not PrEC cells. Prostate tumor cell lines, but not PrEC cells, exhibited high rates of apoptosis in response to MSKE through targeting of the phosphatidylinositol 3-kinase-Akt and mitogen-activated protein kinase survival pathways. The reduction in Akt activity by MSKE is mediated through a reduction in Akt transcription, enhanced proteosome degradation of Akt, and altered levels of DJ-1, a known regulator of PTEN. In contrast to MSKE, resveratrol did not induce apoptosis in this model but arrested cells at the G(1)-S phase transition of the cell cycle associated with increased expression of p21 and decreased expression of cyclin D1 and cyclin-dependent kinase 4 proteins. These results show that MSKE and resveratrol target distinct pathways to inhibit prostate cancer cell growth in this system and that the unique properties of MSKE suggest that it may be an important source for further development of chemopreventive or therapeutic agents against prostate cancer.

Oral grape seed extract inhibits prostate tumor growth and progression in TRAMP mice

Prostate cancer chemoprevention is an alternative and potential strategy to control this malignancy. Herein, we evaluated the chemopreventive efficacy of grape seed extract (GSE) against prostate cancer in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice where animals were fed with GSE by oral gavage at 200 mg/kg body weight dose during 4 to 28 weeks of age. Our results showed a significant reduction (46%, P < 0.01) in the weight of genitourinary tract organs in the GSE-fed mice. The GSE-fed group of mice had a higher incidence of prostatic intraepithelial neoplasia but showed strong reduction in the incidence of adenocarcinoma compared with mice in control group. Prostate tissue from the GSE group showed approximately 50% (P < 0.001) decrease in proliferating cell nuclear antigen (PCNA)-positive cells and 64% (P < 0.01) reduction in total PCNA protein level compared with the control group; however, GSE increased apoptotic cells by 8-fold. Furthermore, GSE strongly decreased the protein levels of cyclin B1, cyclin A, and cyclin E by 84% (P < 0.05), 96% (P < 0.05), and 89% (P < 0.001), respectively. The protein expression of cyclin-dependent kinases 2 and 6 and Cdc2 was also decreased by more than 90% (P < 0.05) in the prostate from the GSE-fed group. Together, for the first time, we identified that oral GSE inhibits prostate cancer growth and progression in TRAMP mice, which could be mediated via a strong suppression of cell cycle progression and cell proliferation and an increase in apoptosis.

Induction of apoptosis in MCF-7 and MDA-MB-231 breast cancer cells by Oligonol is mediated by Bcl-2 family regulation and MEK/ERK signaling

Oligonol is a novel catechin-rich biotechnology product. The role of oligonol in modulating intracellular signaling mechanisms was investigated with the view of demonstrating its potential chemopreventive effect and the ability to inhibit cell proliferation using the estrogen-responsive MCF-7 and the estrogen-unresponsive MDA-MB-231 human breast cancer cell lines. Cell survival assay indicated that Oligonol was cytotoxic to both cells. Oligonol triggered apoptosis as revealed by the morphological features typical of nucleus staining and the accumulation of sub-G1 peak. Treatment with 25 microg/ml Oligonol resulted in an activation of caspase-7 and up-regulation of Bad on MCF-7 cells, while the Oligonol (20 microg/ml) induced up-regulation of Bcl-2 protein in a time-response manner on MDA-MB-231 cells. ERK1/2 in both cells were inactivated after Oligonol treatment in a time-dependent manner, and also inactivated upstream MEK1/2. Oligonol triggers apoptosis in MCF-7 and MDA-MB-231 cells through the modulation of pro-apoptotic Bcl-2 family proteins and MEK/ERK signaling pathway.