Use of Glycoproteins-Prostate-Specific Membrane Antigen and Galectin-3 as Primary Tumor Markers and Therapeutic Targets in the Management of Metastatic Prostate Cancer.

Galectins and prostate specific membrane antigen (PSMA) are glycoproteins that are functionally implicated in prostate cancer (CaP). We undertook this study to analyze the "PSMA-galectin pattern" of the human CaP microenvironment with the overarching goal of selecting novel-molecular targets for prognostic and therapeutic purposes. We examined CaP cells and biopsy samples representing different stages of the disease and found that PSMA, Gal-1, Gal-3, and Gal-8 are the most abundantly expressed glycoproteins. In contrast, other galectins such as Gal-2, 4-7, 9-13, were uniformly expressed at lower levels across all cell lines. However, biopsy samples showed markedly higher expression of PSMA, Gal-1 and Gal-3. Independently PSA and Gleason score at diagnosis correlated with the expression of PSMA, Gal-3. Additionally, the combined index of PSMA and Gal-3 expression positively correlated with Gleason score and was a better predictor of tumor aggressiveness. Together, our results recognize a tightly regulated "PSMA-galectin- pattern" that accompanies disease in CaP and highlight a major role for the combined PSMA and Gal-3 inhibitors along with standard chemotherapy for prostate cancer treatment. Inhibitor combination studies show enzalutamide (ENZ), 2-phosphonomethyl pentanedioic acid (2-PMPA), and GB1107 as highly cytotoxic for LNCaP and LNCaP-KD cells, while Docetaxel (DOC) + GB1107 show greater efficacy in PC-3 cells. Overall, 2-PMPA and GB1107 demonstrate synergistic cytotoxic effects with ENZ and DOC in various CaP cell lines.

Immunomodulatory activities of curcumin-stabilized silver nanoparticles: Efficacy as an antiretroviral therapeutic.

We synthesized and characterized curcumin-stabilized silver nanoparticles (Cur-AgNP) and found them to be 45 nm by dynamic light scattering with a maximum absorbance at 406 nm. We evaluated Cur-AgNP for immunomodulatory activities and their potential as an antiretroviral agent. The antiretroviral effects of Cur-AgNP were determined in ACH-2 cells latently infected with human immunodeficiency virus (HIV)-1. ACH-2 cells, 200,000/ml, were treated with Cur-AgNP for 24-48 h. Expression of HIV-1 LTR and p24, the pro-inflammatory cytokines, IL-1ß, TNF-α, and NF-κB was quantitated. Treatment of ACH-2 cells latently infected with HIV-1 with Cur-AgNP produced no toxic effects but significantly inhibited the expression of HIV-1 LTR (-73%, P < 0.01) and p24 (-57%, P < 0.05), IL-1ßα (-61%, P < 0.01), TNF-αα (-54%, P < 0.05), IL-6 (-68%, P < 0.01), and NF-κB (-79%, P < 0.0001) as compared to untreated controls. Thus, Cur-AgNP have therapeutic potential as direct antiretroviral agents, as well as having immunomodulatory activities inhibiting the expression of pro-inflammatory mediators induced by infection with HIV-1. Experimental controls, such as curcumin alone, and conventional silver nanoparticles capped with citric acid, produced no similar biological effects. We conclude that treatment of HIV-1 infected cells with Cur-AgNP significantly reduced replication of HIV by inhibition of NF-κB nuclear translocation and the downstream expression of the pro-inflammatory cytokines IL-1ß, TNF-α, and IL-6. Subsequent in vivo studies with Cur-AgNP using a humanized mouse model of HIV infection are underway.

Nanotherapy silencing the interleukin-8 gene produces regression of prostate cancer by inhibition of angiogenesis.

Interleukin-8 (IL-8) is a pro-angiogenic cytokine associated with aggressive prostate cancer (CaP). We detected high levels of IL-8 in sera from patients with CaP compared with healthy controls and patients with benign prostatic hypertrophy. This study examines the role of IL-8 in the pathogenesis of metastatic prostate cancer. We developed a biocompatible, cationic polylactide (CPLA) nanocarrier to complex with and efficiently deliver IL-8 small interfering RNA (siRNA) to CaP cells in vitro and in vivo. CPLA IL-8 siRNA nanocomplexes (nanoplexes) protect siRNA from rapid degradation, are non-toxic, have a prolonged lifetime in circulation, and their net positive charge facilitates penetration of cell membranes and subsequent intracellular trafficking. Administration of CPLA IL-8 siRNA nanoplexes to immunodeficient mice bearing human CaP tumours produced significant antitumour activities with no adverse effects. Systemic (intravenous) or local intra-tumour administration of IL-8 siRNA nanoplexes resulted in significant inhibition of CaP growth. Magnetic resonance imaging and ultrasonography of experimental animals demonstrated reduction of tumour perfusion in vivo following nanoplex treatment. Staining of tumour sections for CD31 confirmed significant damage to tumour neovasculature after nanoplex therapy. These studies demonstrate the efficacy of IL-8 siRNA nanotherapy for advanced, treatment-resistant human CaP.

Single nucleotide polymorphisms (SNPs) in key cytokines may modulate food allergy phenotypes.

Single nucleotide polymorphisms (SNPs) can play a direct or indirect role in phenotypic expression in food allergy pathogenesis. Our goal was to quantitate the expression of SNPs in relevant cytokines that were expressed in food allergic patients. SNPs in cytokine genes IL-4 and IL-10 are known to be important in IgE generation and regulation. We examined IL-4 (C-590T), IL-4Rα (1652A/G) and IL-10 (C-627A) SNPs using real-time PCR followed by restriction fragment length polymorphism (RFLP) analysis. Our results show that the AA, AG and GG genotypes for IL-4Rα (1652A/G) polymorphisms were statistically different in radioallergosorbent test (RAST) positive versus negative patients, and although no statistically significant differences were observed between genotypes in the IL-4 (C-590T) and IL-10 (C-627A) SNPs, we observed a significant decrease in IL-4 (C-590T) gene expression and increase in IL-4Rα (1652A/G) and IL-10 (C-627A) gene expression between RAST(+) versus RAST(-) patients, respectively. We also observed significant modulation in the protein expression of IL-4 and IL-10 in the serum samples of the RAST(+) patients as compared to the RAST(-) patients indicating that changes in SNP expression resulted in altered phenotypic response in these patients.

Anti-HIV-1 nanotherapeutics: promises and challenges for the future.

The advent of highly active antiretroviral therapy (HAART) has significantly improved the prognosis for human immunodeficiency virus (HIV)-infected patients, however the adverse side effects associated with prolonged HAART therapy use continue. Although systemic viral load can be undetectable, the virus remains sequestered in anatomically privileged sites within the body. Nanotechnology-based delivery systems are being developed to target the virus within different tissue compartments and are being evaluated for their safety and efficacy. The current review outlines the various nanomaterials that are becoming increasingly used in biomedical applications by virtue of their robustness, safety, multimodality, and multifunctionality. Nanotechnology can revolutionize the field of HIV medicine by not only improving diagnosis, but also by improving delivery of antiretrovirals to targeted regions in the body and by significantly enhancing the efficacy of the currently available antiretroviral medications.

Nanoparticle based galectin-1 gene silencing, implications in methamphetamine regulation of HIV-1 infection in monocyte derived macrophages.

Galectin-1, an adhesion molecule, is expressed in macrophages and implicated in human immunodeficiency virus (HIV-1) viral adsorption. In this study, we investigated the effects of methamphetamine on galectin-1 production in human monocyte derived macrophages (MDM) and the role of galectin-1 in methamphetamine potentiation of HIV-1 infection. Herein we show that levels of galectin-1 gene and protein expression are significantly increased by methamphetamine. Furthermore, concomitant incubation of MDM with galectin-1 and methamphetamine facilitates HIV-1 infection compared to galectin-1 alone or methamphetamine alone. We utilized a nanotechnology approach that uses gold nanorod (GNR)-galectin-1 siRNA complexes (nanoplexes) to inhibit gene expression for galectin-1. Nanoplexes significantly silenced gene expression for galectin-1 and reversed the effects of methamphetamine on galectin-1 gene expression. Moreover, the effects of methamphetamine on HIV-1 infection were attenuated in the presence of the nanoplex in MDM.

Quantum rods as nanocarriers of gene therapy.

Both antisense oligonucleotides (ASODN) and small interfering RNA (siRNA) have enormous potential to selectively silence specific cancer-related genes and could therefore be developed to be important therapeutic anti-cancer drugs. The use of nanotechnology may allow for significant advancement of the therapeutic potential of ASODN and siRNA, due to improved pharmacokinetics, bio-distribution and tissue specific targeted therapy. In this mini-review, we have discussed the advantages of using a nanocarrier such as a multimodal quantum rod (QR) complexed with siRNA for gene delivery. Comparisons are made between ASODN and siRNA therapeutic efficacies in the context of cancer and the enormous application potential of nanotechnology in oncotherapy is discussed. We have shown that a QR-interleukin-8 (IL-8) siRNA nanoplex can effectively silence IL-8 gene expression in the PC-3 prostate cancer cells with no significant toxicity. Thus, nanocarriers such as QRs can help translate the potent effects of ASODN/siRNA into a clinically viable anti-cancer therapy. Drug delivery for cancer therapy, with the aid of nanotechnology is one of the major translational aspects of nanomedicine, and efficient delivery of chemotherapy drugs and gene therapy drugs or their co-delivery continue to be a major focus of nanomedicine research.

Morphine and galectin-1 modulate HIV-1 infection of human monocyte-derived macrophages.

Morphine is a widely abused, addictive drug that modulates immune function. Macrophages are a primary reservoir of HIV-1; therefore, they play a role in the development of this disease, as well as impact the overall course of disease progression. Galectin-1 is a member of a family of ß-galactoside-binding lectins that are soluble adhesion molecules and that mediate direct cell-pathogen interactions during HIV-1 viral adhesion. Because the drug abuse epidemic and the HIV-1 epidemic are closely interrelated, we propose that increased expression of galectin-1 induced by morphine may modulate HIV-1 infection of human monocyte-derived macrophages (MDMs). In this article, we show that galectin-1 gene and protein expression are potentiated by incubation with morphine. Confirming previous studies, morphine alone or galectin-1 alone enhance HIV-1 infection of MDMs. Concomitant incubation with exogenous galectin-1 and morphine potentiated HIV-1 infection of MDMs. We used a nanotechnology approach that uses gold nanorod-galectin-1 small interfering RNA complexes (nanoplexes) to inhibit gene expression for galectin-1. We found that nanoplexes silenced gene expression for galectin-1, and they reversed the effects of morphine on galectin-1 expression. Furthermore, the effects of morphine on HIV-1 infection were reduced in the presence of the nanoplex.

Suppression of MMP-9 expression in brain microvascular endothelial cells (BMVEC) using a gold nanorod (GNR)-siRNA nanoplex.

Inhibition of Matrix metalloproteinase-9 (MMP-9) activity using delivery of short interfering RNA (siRNA) molecules to brain microvascular endothelial cells (BMVECs) that constitute the BBB may have a significant impact on reducing the BBB permeability. Gold nano rods (GNRs) can electrostatically bind with MMP-9 siRNA to form a nanoplex and the uptake of this nanoplex by BMVEC cells can result in suppression of MMP-9 expression. The current study explores if this GNR-MMP-9 siRNA nanoplex gene silencing modulates the expression of tight junction (TJ) proteins in the BMVEC. The endothelial TJ's of the BBB play a critical role in controlling cellular traffic into the central nervous system. We hypothesize that silencing of the MMP-9 gene expression in BMVEC will increase the expression of TJ proteins thereby decrease endothelial permeability. Our results showed a significant increase in the gene and protein expression of TJ proteins: ZO-1, Occludin and Claudin-5 in BMVEC cells that were transfected with the GNRs-siRNA-MMP-9 nanoplex suggesting that BBB disruption, which results from loss of TJ function due to MMP-9 activation during neuroinflammation can be prevented by silencing MMP-9 expression.

Proteomic Approach to Evaluate Mechanisms That Contribute to Food Allergenicity: Comparative 2D-DIGE Analysis of Radioallergosorbent Test Positive and Negative Patients.

Proteomic profiles of RAST(+) subjects with severe food allergies and RAST(-) subjects were compared using 2D-DIGE analysis to obtain candidate biomarkers specific to food allergies. Our analysis highlighted 52 proteins that were differentially expressed between the RAST(+) and RAST(-) groups of which 37 were successfully identified that include chondroitin sulfates, zinc finger proteins, C-type lectins, retinoic acid binding proteins, heat shock proteins, myosin, cytokines, mast cell expressed proteins, and MAP kinases. Biological network analysis tool Metacore revealed that most of these regulated proteins play a role in immune tolerance, hypersensitivity and modulate cytokine patterns inducing a Th2 response that typically results in IgE-mediated allergic response which has a direct or indirect biological link to food allergy. Identifying unique biomarkers associated with certain allergic phenotypes and potentially cross-reactive proteins through bioinformatics analyses will provide enormous insight into the mechanisms that underlie allergic response in patients with food allergies.

Nanotherapeutics Using an HIV-1 Poly A and Transactivator of the HIV-1 LTR-(TAR-) Specific siRNA.

HIV-1 replication can be efficiently inhibited by intracellular expression of an siRNA targeting the viral RNA. We used a well-validated siRNA (si510) which targets the poly A/TAR (transactivator of the HIV-1 LTR) site and suppresses viral replication. Nanotechnology holds much potential for impact in the field of HIV-1 therapeutics, and nanoparticles such as quantum rods (QRs) can be easily functionalized to incorporate siRNA forming stable nanoplexes that can be used for gene silencing. We evaluated the efficacy of the QR-si510 HIV-1 siRNA nanoplex in suppressing viral replication in the HIV-1-infected monocytic cell line THP-1 by measuring p24 antigen levels and gene expression levels of HIV-1 LTR. Our results suggest that the QR-si510 HIV-1 siRNA nanoplex is not only effective in delivering siRNA, but also in suppressing HIV-1 viral replication for a longer time period. HIV-1 nanotherapeutics can thus enhance systemic bioavailability and offer multifunctionality.

Overexpression of MMP-9 contributes to invasiveness of prostate cancer cell line LNCaP.

Matrix metallaprotinase-9 (MMP-9) is zinc-containing proteinase whose expression and trafficking are frequently altered in cancer. MMP-9 in the plasma membrane and the secreted forms are thought to contribute to the invasive and metastatic properties of malignant tumors. We have manipulated the expression of MMP-9 in prostate tumor cell line LNCaP and measured their capacity to invade through a basement membrane matrix. Stable expression of human MMP-9 in a poorly metastatic LNCaP prostate cancer cell line produced a 2-3-fold increase in MMP-9 activity and a comparable increase in invasiveness. Transient transfection of LNCaP stable clone expressing MMP-9 with MMP-9 antisense oligonucleotide (ASODN) produced 55-90% less MMP-9 than control cells and were proportionately less invasive. In contrast, manipulating MMP-9 levels had no effect on cell migration across an uncoated membrane. A standard MMP-9 inhibitor at a concentration ranging from 1-10 nM, caused a nearly quantitative inhibition of extracellular MMP-9 activity and had significant effect on basement membrane invasion. Collectively, these results confirm the role of MMP-9 in tissue remodeling associated with prostate tumor invasion.

Methamphetamine and HIV-1 gp120 effects on lipopolysaccharide stimulated matrix metalloproteinase-9 production by human monocyte-derived macrophages.

Monocytes/macrophages are a primary source of human immunodeficiency virus (HIV-1) in the central nervous system (CNS). Macrophages infected with HIV-1 produce a plethora of factors, including matrix metalloproteinase-9 (MMP-9) that may contribute to the development of HIV-1-associated neurocognitive disorders (HAND). MMP-9 plays a pivotal role in the turnover of the extracellular matrix (ECM) and functions to remodel cellular architecture. We have investigated the role of methamphetamine and HIV-1 gp120 in the regulation of lipopolysaccaride (LPS) induced-MMP-9 production in monocyte-derived macrophages (MDM). Here, we show that LPS-induced MMP-9 gene expression and protein secretion are potentiated by incubation with methamphetamine alone and gp120 alone. Further, concomitant incubation with gp120 and methamphetamine potentiated LPS-induced MMP-9 expression and biological activity in MDM. Collectively methamphetamine and gp120 effects on MMPs may modulate remodeling of the extracellular environment enhancing migration of monocytes/macrophages to the CNS.

Role of chemokine and cytokine polymorphisms in the progression of HIV-1 disease.

Allelic variants of the genes for chemokine receptors and their natural ligands, the chemokines, and cytokines can affect HIV-1 disease progression. This study investigates the level of expression of the CCR5-Delta32, CCR2b-641, RANTES In1.1C, SDF-1 3'A, IL-10-5'-592A and IL-4-589T alleles in two unique HIV-1 infected patient cohorts that represent the two distinct stages of disease progression, namely rapid progressors (RPs) and long term non-progressors (LTNPs) (n=12/group) were recruited. Quantitation of the gene expression of CCR5-Delta32, CCR2b-641, RANTES In1.1C, SDF-1 3'A, IL-10-5'-592A and IL-4-589T in peripheral blood mononuclear leukocytes (PBML) isolated from patients was performed by real time, quantitative (Q)-PCR using DNA was isolated from PBML. We observed that expression of these HIV-protective alleles was generally greater in the LTNP cohort than the RP cohort. LTNPs expressed more of the protective chemokine, SDF-1alpha than RPs, and no statistically significant difference was observed in RANTES production between the LTNPs and RPs. The LTNPs expressed significantly less amounts of cytokines IL-10 and IL-4 as compared to the RPs. Our results demonstrate that gene polymorphisms for CCR5-Delta32, CCR2b-641, RANTES In1.1C, SDF-1 3'A, IL-10-5'-592A and IL-4-589T may be used as clinical markers to predict progression of HIV-1 infections.

Genomic Analysis Highlights the Role of the JAK-STAT Signaling in the Anti-proliferative Effects of Dietary Flavonoid-'Ashwagandha' in Prostate Cancer Cells.

Phytochemicals are dietary phytoestrogens that may play a role in prostate cancer prevention. Forty percent of Americans use complementary and alternative medicines (CAM) for disease prevention and therapy. Ashwagandha (Withania somnifera) contains flavonoids and active ingredients like alkaloids and steroidal lactones which are called 'Withanolides'. We hypothesize that the immunomodulatory and anti-inflammatory properties of Ashwagandha might contribute to its overall effectiveness as an anti-carcinogenic agent. The goal of our study was gain insight into the general biological and molecular functions and immunomodulatory processes that are altered as a result of Ashwagandha treatment in prostate cancer cells, and to identify the key signaling mechanisms that are involved in the regulation of these physiological effects using genomic microarray analysis in conjunction with quantitative real-time PCR and western blot analysis. Ashwagandha treatment significantly downregulated the gene and protein expression of proinflammatory cytokines IL-6, IL-1ß, chemokine IL-8, Hsp70 and STAT-2, while a reciprocal upregulation was observed in gene and protein expression of p38 MAPK, PI3K, caspase 6, Cyclin D and c-myc. Furthermore, Ashwagandha treatment significantly modulated the JAK-STAT pathway which regulates both the apoptosis process as well as the MAP kinase signaling. These studies outline several functionally important classes of genes, which are associated with immune response, signal transduction, cell signaling, transcriptional regulation, apoptosis and cell cycle regulation and provide insight into the molecular signaling mechanisms that are modulated by Ashwagandha, thereby highlighting the use of this bioflavanoid as effective chemopreventive agent relevant to prostate cancer progression.

Therapeutic targeting of "DARPP-32": a key signaling molecule in the dopiminergic pathway for the treatment of opiate addiction.

The 32-kDa dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein (DARPP-32) is recognized to be critical to the pathogenesis of drug addiction. Opiates via the mu-receptor act on the dopaminergic system in the brain and modulates the expression of DARPP-32 phosphoprotein which is an important mediator of the activity of the extracellular signal-regulated kinase (ERK) signaling cascades, the activation of which represents an exciting nexus for drug-induced changes in neural long-term synaptic plasticity. Silencing of DARPP-32 using an siRNA against DARPP-32 may provide a novel gene therapy strategy to overcome drug addiction. In this study, we investigated the effect of the opiate (heroin) on D1 receptor (D1R) and DARPP-32 expression and additionally, evaluated the effects of DARPP-32-siRNA gene silencing on protein phosphatase-1 (PP-1), ERK, and cAMP response element-binding (CREB) gene expression in primary normal human astrocytes (NHA) cells in vitro. Our results indicate that heroin significantly upregulated both D1R and DARPP-32 gene expression, and that DARPP-32 silencing in the NHA cells resulted in the significant modulation of the activity of downstream effector molecules such as PP-1, ERK, and CREB which are known to play an important role in opiate abuse-induced changes in long-term neural plasticity. These findings have the potential to facilitate the development of DARPP32 siRNA-based therapeutics against drug addiction.

Proteomic analyses of the effects of drugs of abuse on monocyte-derived mature dendritic cells.

Drug abuse has become a global health concern. Understanding how drug abuse modulates the immune system and how the immune system responds to pathogens associated with drug abuse, such hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1), can be assessed by an integrated approach comparing proteomic analyses and quantitation of gene expression. Two-dimensional (2D) difference gel electrophoresis was used to determine the molecular mechanisms underlying the proteomic changes that alter normal biological processes when monocyte-derived mature dendritic cells were treated with cocaine or methamphetamine. Both drugs differentially regulated the expression of several functional classes of proteins including those that modulate apoptosis, protein folding, protein kinase activity, and metabolism and proteins that function as intracellular signal transduction molecules. Proteomic data were validated using a combination of quantitative, real-time PCR and Western blot analyses. These studies will help to identify the molecular mechanisms, including the expression of several functionally important classes of proteins that have emerged as potential mediators of pathogenesis. These proteins may predispose immunocompetent cells, including dendritic cells, to infection with viruses such as HCV and HIV-1, which are associated with drug abuse.

Modulation of the proteome of peripheral blood mononuclear cells from HIV-1-infected patients by drugs of abuse.

INTRODUCTION: We used proteomic analyses to assess how drug abuse modulates immunologic responses to infections with the human immunodeficiency virus type 1 (HIV-1). METHODS: Two-dimensional difference gel electrophoresis was utilized to determine changes in the proteome of peripheral blood mononuclear cells (PBMC) isolated from HIV-1-positive donors that occurred after treatment with cocaine or methamphetamine. Both drugs differentially regulated the expression of several functional classes of proteins. We further isolated specific subpopulations of PBMC to determine which subpopulations were selectively affected by treatment with drugs of abuse. Monocytes, B cells, and T cells were positively or negatively selected from PBMC isolated from HIV-1-positive donors. RESULTS: Our results demonstrate that cocaine and methamphetamine modulate gene expression primarily in monocytes and T cells, the primary targets of HIV-1 infection. Proteomic data were validated with quantitative, real-time polymerase chain reaction. These studies elucidate the molecular mechanisms underlying the effects of drugs of abuse on HIV-1 infections. Several functionally relevant classes of proteins were identified as potential mediators of HIV-1 pathogenesis and disease progression associated with drug abuse.

MMP-9 gene silencing by a quantum dot-siRNA nanoplex delivery to maintain the integrity of the blood brain barrier.

The matrix-degrading metalloproteinases (MMPs), particularly MMP-9, are involved in the neuroinflammation processes leading to disrupting of the blood brain barrier (BBB), thereby exacerbating neurological diseases such as HIV-1 AIDS dementia and cerebral ischemia. Nanoparticles have been proposed to act as non-viral gene delivery vectors and have great potential for therapeutic applications in several disease states. In this study, we evaluated the specificity and efficiency of quantum dot (QD) complexed with MMP-9-siRNA (nanoplex) in downregulating the expression of MMP-9 gene in brain microvascular endothelial cells (BMVEC) that constitute the BBB. We hypothesize that silencing MMP-9 gene expression in BMVECs and other cells such as leukocytes may help prevent breakdown of the BBB and inhibit subsequent invasion of the central nervous system (CNS) by infected and inflammatory cells. Our results show that silencing of MMP-9 gene expression resulted in the up-regulation of extracellular matrix (ECM) proteins like collagen I, IV, V and a decrease in endothelial permeability, as reflected by reduction of transendothelial resistance across the BBB in a well validated in-vitro BBB model. MMP-9 gene silencing also resulted in an increase in expression of the gene tissue inhibitor of metalloproteinase-1 (TIMP-1). This indicates the importance of a balance between the levels of MMP-9 and its natural inhibitor TIMP-1 in maintaining the basement membrane integrity. These studies promise the application of a novel nanoparticle based siRNA delivery system in modulating the MMP-9 activity in BMVECs and other MMP-9 producing cells. This will prevent neuroinflammation and maintain the integrity of the BBB.

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

BACKGROUND: Human and animal studies have suggested that diet-derived flavonoids, in particular quercetin may play a beneficial role by preventing or inhibiting oncogenesis, but the underlying mechanism remains unclear. The aim of this study is to evaluate the effect(s) of quercetin on normal and malignant prostate cells and to identify the target(s) of quercetin's action. METHODOLOGY: We addressed this question using cells in culture and investigated whether quercetin affects key biological processes responsible for tumor cell properties such as cell proliferation and apoptosis and also studied the effect of quercetin on the proteome of prostate cancer cells using difference gel electrophoresis (DIGE) to assess changes in the expression of relevant proteins. RESULTS: Our findings demonstrate that quercetin treatment of prostate cancer cells results in decreased cell proliferation and viability. Furthermore, we demonstrate that quercetin promotes cancer cell apoptosis by down-regulating the levels of heat shock protein (Hsp) 90. Depletion of Hsp90 by quercetin results in decreased cell viability, levels of surrogate markers of Hsp90 inhibition (intracellular and secreted), induced apoptosis and activation of caspases in cancer cells but not in normal prostate epithelial cells. Knockdown of Hsp90 by short interfering RNA also resulted in induction apoptosis similar to quercetin in cancer cells as indicated by annexin V staining. CONCLUSION: Our results demonstrate that quercetin down-regulates the expression of Hsp90 which, in turn, induces inhibition of growth and cell death in prostate cancer cells while exerting no quantifiable effect on normal prostate epithelial cells.