The dietary bioflavonoid, quercetin, selectively induces apoptosis of prostate cancer cells by down-regulating the expression of heat shock protein 90

Resveratrol induces antioxidant and heat shock protein mRNA expression in response to heat stress in black-boned chickens

This study investigated the effects of dietary resveratrol at 0, 200, 400, or 600 mg/kg of diet on the performance, immune organ growth index, serum parameters, and expression levels of heat shock protein (Hsp) 27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius, thymus, and spleen of 42-d-old female black-boned chickens exposed to heat stress at 37 ± 2°C for 15 d. The results showed that heat stress reduced daily feed intake and BW gain; decreased serum glutathione (GSH), growth hormone, and insulin-like growth factor-1 levels; and inhibited GSH peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) activities compared with birds subjected to thermo-neutral circumstances. Chickens that were fed diets supplemented with resveratrol exhibited a linear increase in feed intake and BW gain (P < 0.001); serum GSH, growth hormone, and insulin-like growth factor-1 levels (P ≤ 0.01); and GSH-Px, SOD, and CAT activities (P < 0.001) compared with chickens that were fed diets without resveratrol during heat stress. In contrast, serum malonaldehyde concentrations were decreased (P < 0.001) in the chickens fed a resveratrol-supplemented diet. Heat stress also reduced (P < 0.05) the growth index of the bursa of Fabricus and spleen; however, it had no effect on the growth index of the thymus. The growth index of the bursa of Fabricius and spleen increased (P < 0.05) upon heat stress and coincided with an increase in supplemental resveratrol levels. The expression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen were increased (P < 0.01), but those of Hsp27 and Hsp90 mRNA in thymus were decreased (P < 0.01) under heat stress compared with no heat stress. Resveratrol attenuated the heat stress-induced overexpression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen and increased the low expression of Hsp27 and Hsp90 mRNA in thymus upon heat stress. The results suggest that supplemental resveratrol improves growth performance and reduces oxidative stress in heat-stressed black-boned chickens by increasing serum growth hormone concentrations and modulating the expression of heat shock genes in organs of the immune system.

The inhibitory effect of quercetin on asymmetric dimethylarginine-induced apoptosis is mediated by the endoplasmic reticulum stress pathway in glomerular endothelial cells

Asymmetric dimethylarginine (ADMA) is considered an independent mortality and cardiovascular risk factor in chronic kidney disease (CKD) patients, and contributes to the development of renal fibrosis. Quercetin (QC), a natural component of foods, protects against renal injury. Here, we explored the possible mechanisms that are responsible for ADMA-induced renal fibrosis and the protective effect of QC. We found that ADMA treatment activated the endoplasmic reticulum (ER) stress sensor proteins phosphorylated protein kinase RNA-activated-like ER kinase (PERK) and inositol requiring-1α (IRE1), which correspondingly induced C/EBP homologous protein (CHOP) expression and phosphorylated c-Jun N-terminal kinase (JNK) phosphorylation in glomerular endothelial cells (GEnCs). Following this, ADMA promoted ER stress-induced apoptosis and resulted in transforming growth factor β (TGF-β) expression in GEnCs. SP600125, an inhibitor of JNK, and CHOP siRNA protected against ADMA-induced cell apoptosis and TGF-β expression. QC prevented ADMA-induced PERK and IRE1 apoptotic ER stress pathway activation. Also, ADMA-induced GEnCs apoptosis and TGF-β expression was reduced by QC. Overexpression of CHOP blocked QC-mediated protection from apoptosis in ER stressed cells. Overall, these observations indicate that ADMA may induce GEnCs apoptosis and TGF-β expression by targeting the PERK-CHOP and IRE1-JNK pathway. In addition, drugs such as QC targeting ER stress may hold great promise for the development of novel therapies against ADMA-induced renal fibrosis.

Site-specific anticancer effects of dietary flavonoid quercetin

Food-derived flavonoid quercetin, widely distributed in onions, apples, and tea, is able to inhibit growth of various cancer cells indicating that this compound can be considered as a good candidate for anticancer therapy. Although the exact mechanism of this action is not thoroughly understood, behaving as antioxidant and/or prooxidant as well as modulating different intracellular signalling cascades may all play a certain role. Such inhibitory activity of quercetin has been shown to depend first of all on cell lines and cancer types; however, no comprehensive site-specific analysis of this effect has been published. In this review article, cytotoxicity constants of quercetin measured in various human malignant cell lines of different origin were compiled from literature and a clear cancer selective action was demonstrated. The most sensitive malignant sites for quercetin revealed to be cancers of blood, brain, lung, uterine, and salivary gland as well as melanoma whereas cytotoxic activity was higher in more aggressive cells compared to the slowly growing cells showing that the most harmful cells for the organism are probably targeted. More research is needed to overcome the issues of poor water solubility and relatively low bioavailability of quercetin as the major obstacles limiting its clinical use.

Quercetin-induced cardioprotection against doxorubicin cytotoxicity

Background

Cancer has continually been the leading cause of death worldwide for decades. Thus, scientists have actively devoted themselves to studying cancer therapeutics. Doxorubicin is an efficient drug used in cancer therapy, but also produces reactive oxygen species (ROS) that induce severe cytotoxicity against heart cells. Quercetin, a plant-derived flavonoid, has been proven to contain potent antioxidant and anti-inflammatory properties. Thus, this in vitro study investigated whether quercetin can decrease doxorubicin-induced cytotoxicity and promote cell repair systems in cardiomyocyte H9C2 cells.

Results

Proteomic analysis and a cell biology assay were performed to investigate the quercetin-induced responses. Our data demonstrated that quercetin treatment protects the cardiomyocytes in a doxorubicin-induced heart damage model. Quercetin significantly facilitated cell survival by inhibiting cell apoptosis and maintaining cell morphology by rearranging the cytoskeleton. Additionally, 2D-DIGE combined with MALDI-TOF MS analysis indicated that quercetin might stimulate cardiomyocytes to repair damage after treating doxorubicin by modulating metabolic activation, protein folding and cytoskeleton rearrangement.

Conclusion

Based on a review of the literature, this study is the first to report detailed protective mechanisms for the action of quercetin against doxorubicin-induced cardiomyocyte toxicity based on in-depth cell biology and proteomic analysis.

Medicinal properties of the Jamaican pepper plant Pimenta dioica and Allspice

The Caribbean tropical tree, Pimenta dioica has been used for a variety of human endeavors, such as in perfumery industry, food spice, as a natural pesticide, and in folk medicine. Discovered in Jamaica during the voyages of Christopher Columbus, the dried unripe berries of P. dioica also known as Allspice can be found in all continents with unique names in over 50 languages. Systematic investigation of aromatic constituents of Pimenta leaves and its unripe berries, Allspice, have resulted in discovery of many and novel aromatic compounds, mostly glycosides and polyphenols that show antibacterial, hypotensive, anti-neuralgic and analgesic properties. Recent studies have shown two of the known compounds isolated from Allspice, Eugenol and Gallic acid have selective antiproliferative and anti-tumor properties on human cancer cells and their animal models. New characterization of novel compounds such as Ericifolin from the aqueous extract of Allspice berries show potent anti-prostate cancer and anti-breast cancer properties that can be verified in vitro as well as in vivo. Considering its purity, mostly available as "organically grown" berries, availability at low cost, wide acceptance in culinary delights of many cultures world-wide, Allspice may have an additional space in most households, in their medicine cabinets.

Inhibition of Hsp90 and 70 sensitizes melanoma cells to hyperthermia using ferromagnetic particles with a low Curie temperature

BACKGROUND

Heat shock protein (Hsp) 90 is a key regulator of various oncogene products and cell-signaling molecules, while Hsp70 protects against heat-induced apoptosis. We previously described a system in which hyperthermia was produced using thermosensitive ferromagnetic particles (FMPs) with a Curie temperature (T c) of 43 °C to mediate automatic temperature control, and demonstrated its antitumor effect in a mouse melanoma model. In the present study, the antitumor effects of combining Hsp90 inhibitor (17DMAG) and Hsp70 inhibitor (quercetin) with FMP-mediated hyperthermia were examined.

METHODS

Expressions of Hsp90/70 and Akt were evaluated using Western blotting in vitro. In an in vivo study, melanoma cells were subcutaneously injected into the backs of C57BL/6 mice. FMPs were then injected into the resultant tumors, and the mice were divided into groups treated with quercetin and/or 17DMAG with/without hyperthermia. When exposed to a magnetic field, the temperature of tissues containing FMPs increased and stabilized at the T c. The TUNEL method was used to determine whether hyperthermia induced apoptosis within tumors.

RESULTS

In the group pretreated with hyperthermia + quercetin + 17DMAG, Akt expression was reduced in vitro, the incidence of apoptosis within tumors was greater, and tumor growth was significantly suppressed 20 days after FMP injection in vivo, compared with other treatment groups. The survival rates among tumor-bearing mice observed for a period of 40 days were significantly higher in the hyperthermia + quercetin + 17DMAG group.

CONCLUSION

Combining Hsp90/70 inhibition with hyperthermia appears to increase their antitumor effects. Thus, the combination of FMP-mediated, self-regulating hyperthermia with Hsp90/70 inhibition has important implications for cancer treatment.

Modulation of protein quality control systems by food phytochemicals

There is compelling evidence showing that dietary phytochemicals have exhibited pronounced bioactivities in a number of experimental models. In addition, a variety of epidemiological surveys have demonstrated that frequent ingestion of vegetables and fruits, which contain abundant phytochemicals, lowers the risk of onset of some diseases. However, the action mechanisms by which dietary phytochemicals show bioactivity remain to be fully elucidated and a fundamental question is why this class of chemicals has great potential for regulating health. Meanwhile, maintenance and repair of biological proteins by molecular chaperones, such as heat shock proteins, and clearance of abnormal proteins by the ubiquitin-proteasome system and autophagy play central roles in health, some disease prevention, and longevity. Interestingly, several recent studies have revealed that phytochemicals, including curcumin (yellow pigment in turmeric), resveratrol (phytoalexin in grapes), quercetin (general flavonol in onions and others), and isothiocyanates (preferentially present in cruciferous vegetables, such as broccoli and cabbage), are remarkable regulators of protein quality control systems, suggesting that their physiological and biological functions are exerted, at least in part, through activation of such unique mechanisms. This review article highlights recent findings regarding the effects of representative phytochemicals on protein quality control systems and their possible molecular mechanisms.

Synthesis and biological evaluation of novel flavonols as potential anti-prostate cancer agents

A library of flavonol analogues was synthesised and evaluated as potential anticancer agents against a human prostate cancer cell line, 22rν1. Compounds 3, 8 and 11 (IC(50) 2.6, 3.3 and 4.0 μM respectively) showed potent cancer cell growth inhibition, comparable to the lead compound 3',4',5'-trimethoxyflavonol (1) (IC(50) 3.1 μM) and superior to the naturally occurring flavonols quercetin (16) and fisetin (22) (both >15 μM). Results indicate that the 3',4',5'- arrangement of either hydroxy (OH) or methoxy (OMe) residues is important for growth arrest of these cells and that the OMe analogues may be superior to their OH counterparts. Compounds 1, 3, 8 and 11 warrant further investigation as potential agents for the management of prostate cancer.

Opportunities and challenges for nutritional proteomics in cancer prevention

Knowledge gaps persist about the efficacy of cancer prevention strategies based on dietary food components. Adaptations to nutrient supply are executed through tuning of multiple protein networks that include transcription factors, histones, modifying enzymes, translation factors, membrane and nuclear receptors, and secreted proteins. However, the simultaneous quantitative and qualitative measurement of all proteins that regulate cancer processes is not practical using traditional protein methodologies. Proteomics offers an attractive opportunity to fill this knowledge gap and unravel the effects of dietary components on protein networks that impinge on cancer. The articles presented in this supplement are from talks proffered in the "Nutrition Proteomics and Cancer Prevention" session at the American Institute for Cancer Research Annual Research Conference on Food, Nutrition, Physical Activity and Cancer held in Washington, DC on October 21 and 22, 2010. Recent advances in MS technologies suggest that studies in nutrition and cancer prevention may benefit from the adoption of proteomic tools to elucidate the impact on biological processes that govern the transition from normal to malignant phenotype; to identify protein changes that determine both positive and negative responses to food components; to assess how protein networks mediate dose-, time-, and tissue-dependent responses to food components; and, finally, for predicting responders and nonresponders. However, both the limited accessibility to proteomic technologies and research funding appear to be hampering the routine adoption of proteomic tools in nutrition and cancer prevention research.

Quercetin increased the antiproliferative activity of green tea polyphenol (-)-epigallocatechin gallate in prostate cancer cells

We previously demonstrated that 50% of (-)-epigallocatechin gallate (EGCG) was present in methylated form (4″-MeEGCG) in human prostate tissue, which is less bioactive. We therefore investigated whether quercetin, a natural inhibitor of catechol-O-methyl transferase (COMT), will inhibit EGCG methylation leading to enhanced antiproliferative activity of EGCG in prostate cancer cells. Incubation with both quercetin and EGCG for 2 h increased the cellular concentrations of EGCG by 4- to 8-fold and 6- to 10-fold in androgen-independent PC-3 cells and androgen-dependent LNCaP cells, respectively. Concurrently, the percent of 4″-MeEGCG in the total EGCG was decreased from 39% to 15% in PC-3 cells and from 61% to 38% in LNCaP cells. Quercetin and EGCG in combination synergistically inhibited cell proliferation, caused cell cycle arrest, and induced apoptosis in PC-3 cells. In LNCaP cells, EGCG and quercetin exhibited a stronger antiproliferative activity leading to an additive effect. The synergistic effect of these 2 agents in PC-3 cells could be based on the fact that EGCG primarily inhibited COMT activity, whereas quercetin reduced the amount of COMT protein. In summary, quercetin combined with EGCG in vitro demonstrated enhanced inhibition of cell proliferation by increasing the intracellular concentration of EGCG and decreasing EGCG methylation.

Regulation of inflammatory cytokines in lipopolysaccharide-stimulated RAW 264.7 murine macrophage by 7-O-methyl-naringenin

7-O-Methylnaringenin, extracted from Rhododendron speciferum, belongs to the flavanone class of polyphenols. In the present study, we investigated the anti-inflammatory effects of 7-O-methylnaringenin on cytokine production by lipopoly-saccharide (LPS)-stimulated RAW 264.7 macrophages in vitro. The results showed that pretreatment with 10, 20 or 40 μg/mL of 7-O-methylnaringenin could downregulate tumour necrosis factor (TNF-α), interleukin (IL-6) and interleukin (IL-1β) in a dose-dependent manner. Furthermore, we investigated the signal transduction mechanisms to determine how 7-O-methylnaringenin affects RAW 264.7 macrophages. The activation of mitogen-activated protein kinases (MAPK) and IκBα were measured by Western blotting. The data showed that 7-O-methylnaringenin could downregulate LPS-induced levels of phosphorylation of ERK1/2, JNK and IκBα. These observations indicated that 7-O-methylnaringenin modulated inflammatory cytokine responses by blocking NF-қB, ERK1/2 and JNK/MAPKs activation.

Impact of butyrate on PKM2 and HSP90β expression in human colon tissues of different transformation stages: a comparison of gene and protein data

Due to protection of oncogenic proteins from degradation and enhancement of glycolytic phosphometabolites for synthetic processes, respectively, heat shock protein 90 (HSP90) and pyruvate kinase type M2 (PKM2) are important proteins for tumor growth. The present study was undertaken to investigate the susceptibility of both proteins and their encoding genes to the chemopreventive agent butyrate in human colon cells. Matched tissue of different transformation stages derived from 20 individual colon cancer patients was used for the experiments. The results of quantitative real-time PCR revealed a moderate increase of HSP90β and PKM2 mRNA in colon tumors (P < 0.01) compared to normal tissues without relation to clinical parameters. The expression pattern could be confirmed for PKM2 protein by Western blot but not for HSP90β. During culturing with butyrate, the amount of PKM2 transcripts decreased in all three tissue types with the strongest effects observed in tumors (median fold decrease 45%, P < 0.05). The protein data have not reflected this influence supposing a more gradual degradation rate due to a longer half-life of PKM2. In contrast, the mRNA expression of HSP90β in normal tissue was found 1.38-fold increased by butyrate (P < 0.05), but not the corresponding protein level. HSP90β expression in adenomas and tumors remained generally insensitive. Only in malignant tissue, however, a significant correlation was found between the individual effects observed on gene and protein expression level. In conclusion, the present study identified PKM2 as a potential direct target of butyrate in neoplastic colon tissue, whereas HSP90β is none of it.

Biotinylated quercetin as an intrinsic photoaffinity proteomics probe for the identification of quercetin target proteins

Quercetin is a flavonoid natural product, that is, found in many foods and has been found to have a wide range of medicinal effects. Though a number of quercetin binding proteins have been identified, there has been no systematic approach to identifying all potential targets of quercetin. We describe an O7-biotinylated derivative of quercetin (BioQ) that can act as a photoaffinity proteomics reagent for capturing quercetin binding proteins, which can then be identified by LC-MS/MS. BioQ was shown to inhibit heat induction of HSP70 with almost the same efficiency as quercetin, and to both inhibit and photocrosslink to CK2 kinase, a known target of quercetin involved in activation of the heat shock transcription factor. BioQ was also able to pull down a number of proteins from unheated and heated Jurkat cells following UV irradiation that could be detected by both silver staining and Western blot analysis with an anti-biotin antibody. Analysis of the protein bands by trypsinization and LC-MS/MS led to the identification of heat shock proteins HSP70 and HSP90 as possible quercetin target proteins, along with ubiquitin-activating enzyme, a spliceosomal protein, RuvB-like 2 ATPases, and eukaryotic translation initiation factor 3. In addition, a mitochondrial ATPase was identified that has been previously shown to be a target of quercetin. Most of the proteins identified have also been previously suggested to be potential anticancer targets, suggesting that quercetin's antitumor activity may be due to its ability to inhibit multiple target proteins.

HDAC pharmacological inhibition promotes cell death through the eIF2α kinases PKR and GCN2

Histone deacetylase inhibitors (HDACi) comprise a family of chemotherapeutic agents used in the clinic to treat cutaneous T-cell lymphoma and tested for the therapy of other malignancies. Previous reports have shown that eIF2α phosphorylation is induced upon treatment with HDACi. However the kinase responsible for this phosphorylation or the biological significance of this finding is not yet established. Herein, we show that eIF2α phosphorylation is not attributed to a specific eIF2α kinase, but rather different eIF2α kinases contribute to its upregulation in response to the HDACi, vorinostat. More importantly our data indicate that eIF2α phosphorylation acts in a cytoprotective manner, whereas the eIF2α kinases PKR and GCN2 promote vorinostat-induced apoptosis. These results reveal a dual nature for eIF2α kinases with potential implications in the treatment with histone deacetylase inhibitors.

Meta-analysis of heat- and chemically upregulated chaperone genes in plant and human cells

Molecular chaperones are central to cellular protein homeostasis. In mammals, protein misfolding diseases and aging cause inflammation and progressive tissue loss, in correlation with the accumulation of toxic protein aggregates and the defective expression of chaperone genes. Bacteria and non-diseased, non-aged eukaryotic cells effectively respond to heat shock by inducing the accumulation of heat-shock proteins (HSPs), many of which molecular chaperones involved in protein homeostasis, in reducing stress damages and promoting cellular recovery and thermotolerance. We performed a meta-analysis of published microarray data and compared expression profiles of HSP genes from mammalian and plant cells in response to heat or isothermal treatments with drugs. The differences and overlaps between HSP and chaperone genes were analyzed, and expression patterns were clustered and organized in a network. HSPs and chaperones only partly overlapped. Heat-shock induced a subset of chaperones primarily targeted to the cytoplasm and organelles but not to the endoplasmic reticulum, which organized into a network with a central core of Hsp90s, Hsp70s, and sHSPs. Heat was best mimicked by isothermal treatments with Hsp90 inhibitors, whereas less toxic drugs, some of which non-steroidal anti-inflammatory drugs, weakly expressed different subsets of Hsp chaperones. This type of analysis may uncover new HSP-inducing drugs to improve protein homeostasis in misfolding and aging diseases.

Antiproliferative and pro-apoptotic effects of quercetin on human pancreatic carcinoma cell lines EPP85-181P and EPP85-181RDB

Polyphenols are present in several edible plants and for many years induce high interest mainly due to their antioxidative and anti-inflammatory influence. At present, numerous studies are conducted on antineoplastic effects of the compounds. One of most effective biopolyphenols involves the flavonol quercetin. Our studies aimed at evaluation of antiproliferative and pro-apoptotic effects of quercetin alone and in combinations with daunorubicin on cells of human pancreatic carcinoma lines. The experiments were conducted on two cell lines, sensitive to daunorubicin EPP85-181P line, and its resistant variant EPP85-181RDB. Effect of studied substances on cell proliferation was detected using sulphorhodamine B (SRB) protein staining method. Apoptotic damage was estimated using comet and TUNEL techniques. Our data demonstrated that quercetin exerted cytotoxic action on cells of the both neoplastic cell lines in concentration-dependent manner. In the case of EPP85-181RDB cell line, quercetin seemed to sensitize resistant cells to daunorubicin. In parallel, the effect of both substances on the sensitive cell line was synergistic. Results of the studies confirmed that quercetin may probably break resistance of neoplastic cells to chemotherapy. On the other side, studied flavonol augmented action of cytostatic drug in case of sensitive tumour cells what suggest, that it might allow to decrease dosage of cytostatic drugs and reduce negative side effects of the treatment.

Synergistic chemoprotective mechanisms of dietary phytoestrogens in a select combination against prostate cancer

Combination of dietary phytoestrogens with diverse molecular mechanisms may enhance their anticancer efficacy at physiological concentrations, as evidenced in epidemiological studies. A select combination of three dietary phytoestrogens containing 8.33 μM each of genistein (G), quercetin (Q) and biochanin A (B) was found to be more potent in inhibiting the growth of androgen-responsive prostate cancer cells (LNCaP) as well as DU-145 and PC-3 prostate cancer cells in vitro than either 25 μM of G, B or Q or 12.5+12.5 μM of G+Q, Q+B or G+B. Subsequent mechanistic studies in PC-3 cells indicated that the action of phytoestrogens was mediated both through estrogen receptor (ER)-dependent and ER-independent pathways as potent estrogen antagonist ICI-182780 (ICI, 5 μM) could not completely mask the synergistic anticancer effects, which were sustained appreciably in presence of ICI. G+Q+B combination was significantly more effective than individual compounds or their double combinations in increasing ER-β, bax (mRNA expression); phospho-JNK, bax (protein levels); and in decreasing bcl-2, cyclin E, c-myc (mRNA expression); phospho-AKT, phospho-ERK, bcl-2, proliferating cell nuclear antigen (protein levels) in PC-3 cells. Phytoestrogens also synergistically stimulated caspase-3 activity. Our findings suggest that selectively combining anticancer phytoestrogens could significantly increase the efficacy of individual components resulting in improved efficacy at physiologically achievable concentrations. The combination mechanism of multiple anticancer phytochemicals may be indicative of the potential of some vegetarian diet components to elicit chemopreventive effects against prostate cancer at their physiologically achievable concentrations, in vivo.

Hormesis and synergy: pathways and mechanisms of quercetin in cancer prevention and management

Quercetin is a unique dietary polyphenol because it can exert biphasic dose-responses on cells depending on its concentration. Cancer preventative effects of quercetin are observed at concentrations of approximately 1-40 microM and are likely mediated by quercetin's antioxidant properties. Pro-oxidant effects are present at cellular concentrations of 40-100 microM. However, at higher concentrations, many novel pathways in addition to ROS contribute to its effects. The potent bioactivity of quercetin has led to vigorous study of this compound and revealed numerous pathways that could interact synergistically to prevent or treat cancer. The effect of intake and concentration on emerging pathways and how they may interact are discussed in this review.

Heat shock proteins in prostate cancer: from tumorigenesis to the clinic

The heat shock proteins (HSP) constitute a superfamily of chaperone proteins present in all cells and in all cell compartments, operating in a complex interplay with synergistic/overlapping multiplicity of functions, even though the common effect is cell protection. Several reasons explain the need for investigating HSP in prostate cancer: (1) these molecules function as chaperones of tumorigenesis accompanying the emergence of prostate cancer cells, (2) they appear as useful molecular markers associated with disease aggressiveness and with resistance to anticancer therapies including hormone therapy, radiotherapy, chemotherapy and hyperthermia, and (3) they can be used as targets for therapies. The latter can be accomplished by: (i) interrupting the interaction of HSP (mainly HSPC1) with various client proteins that are protected from degradation when chaperoned by the HSP; (ii) using the chaperone and adjuvant capabilities of certain HSP to present antigenic peptides to the immune system, so this system can recognise the prostate tumour cells as foreign to mount an effective antitumoral response; and (iii) using treatment planning models taking into account the HSP expression levels to obtain more effective therapies. In summary, the study of the HSP during tumorigenesis as well as during cancer progression, and the inclusion of treatment designs targeting HSP combined with other treatment modalities, should improve prostate cancer survival in the near future.

Activation of PI3K/Akt/IKK-alpha/NF-kappaB signaling pathway is required for the apoptosis-evasion in human salivary adenoid cystic carcinoma: its inhibition by quercetin

Quercetin, one of the most common natural flavonoids, has been reported to possess significant anti-tumor activities both in vitro and in vivo. The present study was to investigate the effects of quercetin on growth and apoptosis in human salivary adenoid cystic carcinoma (ACC). The result from MTT assay showed that quercetin decreased cell viability of both low metastatic cell line ACC-2 and high metastatic cell line ACC-M in a concentration- and time-dependent manner. Moreover, treatment with quercetin resulted in significantly increased apoptosis in ACC cells. Our data also revealed that the apoptosis induced by quercetin treatment was through a mitochondria-dependent pathway which showed close correlation with the down-regulation of the PI3K/Akt/IKK-alpha/NF-kappaB pathway. Most importantly, quercetin significantly prevented in vivo growth of ACC xenografts in nude mice, accompanied by induction of tumor cell apoptosis, suppression of NF-kappaB nuclear translocation, as well as down-regulation of Akt and IKK-alpha activation. In addition, we explored the clinical significance of the PI3K/Akt/IKK-alpha/NF-kappaB signaling axis in ACC by immunohistochemical analysis of tissue specimens followed by the clustering analyses. We determined that the PI3K/Akt/IKK-alpha/NF-kappaB pathway is ubiquitously activated in ACC and plays an essential role in the evasion of apoptosis. Taken together, the results from our study implicated that quercetin would be a promising chemotherapeutic agent against ACC through its function of down-regulating the PI3K/Akt/IKK-alpha/NF-kappaB signaling pathway.

Interfering with ROS Metabolism in Cancer Cells: The Potential Role of Quercetin

A main feature of cancer cells, when compared to normal ones, is a persistent pro-oxidative state that leads to an intrinsic oxidative stress. Cancer cells have higher levels of reactive oxygen species (ROS) than normal cells, and ROS are, in turn, responsible for the maintenance of the cancer phenotype. Persistent ROS stress may induce adaptive stress responses, enabling cancer cells to survive with high levels of ROS and maintain cellular viability. However, excessive ROS levels render cancer cells highly susceptible to quercetin, one of the main dietary flavonoids. Quercetin depletes intracellular glutathione and increases intracellular ROS to a level that can cause cell death.

Induction of G(1)/S phase arrest and apoptosis by quercetin in human osteosarcoma cells

Quercetin (3,3',4',5,7-pentahydroxyflavone) is a polyphenolic flavonoid compound and is found in a variety of plants. Potential biological activities including antioxidant and anticarcinogenesis have been reported. The antiproliferative effect and apoptosis inducing effect of quercetin in human osteosarcoma cells was evaluated in this study. The IC(50) values were 290 microM and 160 microM at 24 h and 48 h incubation, respectively. Antiproliferative action of quercetin appeared to be linked to apoptotic cell death based on increase in the sub-G(1) apoptotic cell population analyzed by flow cytometric analysis. Prior to apoptosis induction, quercetin caused cell cycle arrest at G(1)/S phase. The G(1)/S phase arrest was accompanied by down regulation of cyclin D1, one of the cyclins required for advance from G(1) to S. Subsequent apoptosis was induced by the gradual activation of caspase-3 and the cleavage of PARP.

Flavonol quantification and stability of phenolics in fermented extracts from fresh Betula pendula leaves

An HPLC method, which allows reliable quantitation of flavonols and other phenolics in birch leaf extracts, was developed and validated. The method was applied to study the bioconversion of flavonols in fermented aqueous extracts. Almost 100% of the flavonols were converted during the 12 months observation period. The generated phenolics as well as consecutive conversion products were identified by HPLC-DAD, LC-MS and GC-MS techniques.

Stimulus-specific regulation of CD63 and CD203c membrane expression in human basophils by the flavonoid quercetin

BACKGROUND

Flavonoids, such as quercetin, were reported to inhibit histamine release and cytokine production by basophils, but there is no evidence describing their action on membrane markers and intracellular biochemical pathways.

OBJECTIVE

The aim of the study was to examine the effect of several quercetin doses on an in vitro human basophil activation system that evaluates up-regulation of membrane markers in response to agonists.

METHODS

Leukocyte buffy coats from K(2)-EDTA anti-coagulated blood were treated with different concentrations of quercetin and triggered with anti-IgE ("allergy model") and with N-formyl-Met-Leu-Phe (fMLP) ("inflammation model"). Basophils were captured as CD123(bright)/HLA-DR(non-expressing) cells in a flow cytometry analysis and fluorescence values of CD63-FITC, CD203c-PE and CD123-PECy5 were used to produce dose response curves.

RESULTS

Quercetin at a dose of 10 microg/ml strongly inhibited CD63 and CD203c membrane up-regulation triggered by both agonists, but it neither affected cell viability nor changed the expression of the phenotypic marker CD123. The anti-IgE model appeared highly sensitive to the effect of quercetin: a dose as low as 0.01 microg/ml was able to significantly decrease CD63 and CD203c membrane expression. In the fMLP model the dose response was different: quercetin doses from 0.01 to 0.1 microg/ml significantly increased up-regulation of membrane markers, achieving the highest effect with CD63.

CONCLUSION

Very low doses of quercetin, within the pharmacological range, inhibit IgE-mediated membrane marker's up-regulation but prime the response to the chemotactic peptide fMLP; this stimulus specificity may have implications on the possible therapeutic action of the flavonoid in different pathologies.

Not gene therapy, but genetic surgery-the right strategy to attack cancer

In this review, I will suggest to divide all the approaches united now under common term "gene therapy" into two broad strategies of which the first one uses the methodology of targeted therapy with all its characteristics, but with genes in the role of agents targeted at a certain molecular component(s) presumably crucial for cancer maintenance. In contrast, the techniques of the other strategy are aimed at the destruction of tumors as a whole using the features shared by all cancers, for example relatively fast mitotic cell division or active angiogenesis. While the first strategy is "true" gene therapy, the second one is more like genetic surgery when a surgeon just cuts off a tumor with his scalpel and has no interest in knowing delicate mechanisms of cancer emergence and progression. I will try to substantiate the idea that the last strategy is the only right one, and its simplicity is paradoxically adequate to the super-complexity of tumors that originates from general complexity of cell regulation, strongly disturbed in tumor cells, and especially from the complexity of tumors as evolving cell populations, affecting also their ecological niche formed by neighboring normal cells and tissues. An analysis of the most widely used for such a "surgery" suicide gene/prodrug combinations will be presented in some more details.