3-8-dihydroxy-6h-dibenzo(b-d)pyran-6-one and Prostatic-Neoplasms

Pomegranates slow prostate cancer xenograft growth and prolong prostate-specific antigen (PSA) doubling times in single-arm human studies. Pomegranates' effects on human prostate tissue are understudied. We hypothesized that orally administered pomegranate extract (POMx; Pom Wonderful) would lower tissue 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative stress biomarker. Seventy men were randomized to two tablets, POMx or placebo, daily up to four weeks before radical prostatectomy. Tissue was analyzed for intraprostatic urolithin A, a pomegranate metabolite, benign and malignant 8-OHdG, and cancer pS6 kinase, NF-κB, and Ki67. Primary endpoint was differences in 8-OHdG, and the study was powered to detect 35% reduction. POMx was associated with 16% lower benign tissue 8-OHdG (P = 0.095), which was not statistically significant. POMx was well tolerated with no treatment-related withdrawals. There were no differences in baseline clinicopathological features between arms. Urolithin A was detected in 21 of the 33 patients in the POMx group versus 12 of the 35 in the placebo group (P = 0.031). Cancer pS6 kinase, NF-κB, Ki67, and serum PSA changes were similar between arms. POMx before surgery results in pomegranate metabolite accumulation in prostate tissues. Our primary endpoint in this modest-sized short-term trial was negative. Future larger longer studies are needed to more definitively test whether POMx reduces prostate oxidative stress, as well as further animal testing to better understand the multiple mechanisms through which POMx may alter prostate cancer biology.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Biomarkers, Tumor; Chromatography, Liquid; Combined Modality Therapy; Coumarins; Deoxyguanosine; Double-Blind Method; Humans; Ki-67 Antigen; Lythraceae; Male; Mass Spectrometry; Middle Aged; Neoadjuvant Therapy; NF-kappa B; Oxidative Stress; Plant Extracts; Prostate-Specific Antigen; Prostatectomy; Prostatic Neoplasms; Ribosomal Protein S6 Kinases

Epidemiology supports the important role of nutrition in prostate cancer (PCa) prevention. Pomegranate juice (PJ) exerts protective effects against PCa, mainly attributed to PJ ellagitannins (ETs). Our aim was to assess whether ETs or their metabolites ellagic acid and urolithins reach the human prostate upon consumption of ET-rich foods and to evaluate the effect on the expression of three proliferation biomarkers. Sixty-three patients with BPH or PCa were divided into controls and consumers of walnuts (35 g walnuts/day) or pomegranate (200 mL PJ/day) for 3 days before surgery. Independently of the ETs source, the main metabolite detected was urolithin A glucuronide, (3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one glucuronide) (up to 2 ng/g) together with the traces of urolithin B glucuronide, (3-hydroxy-6H-dibenzo[b,d]pyran-6-one glucuronide) and dimethyl ellagic acid. The small number of prostates containing metabolites was likely caused by clearance of the compounds during the fasting. This was corroborated in a parallel rat study and thus the presence of higher quantities of metabolites at earlier time points cannot be discarded. No apparent changes in the expression of CDKN1A, MKi-67 or c-Myc were found after consumption of the walnuts or PJ. Our results suggest that urolithin glucuronides and dimethyl ellagic acid may be the molecules responsible for the beneficial effects of PJ against PCa.

Topics: Aged; Animals; Beverages; Biomarkers, Tumor; Coumarins; Cyclin-Dependent Kinase Inhibitor p21; Ellagic Acid; Fruit; Gene Expression Regulation, Neoplastic; Glucuronides; Humans; Hydrolyzable Tannins; Intestines; Intracellular Signaling Peptides and Proteins; Juglans; Lythraceae; Male; Middle Aged; Nuclear Proteins; Plant Extracts; Prostate; Prostatic Hyperplasia; Prostatic Neoplasms; Proto-Oncogene Proteins c-myc; Rats; Rats, Sprague-Dawley; RNA, Messenger

Pomegranate and walnuts are widely consumed dietary sources and contain several bioactive compounds, including the ellagitannins (ETs). ETs are polyphenols that are metabolized in the gut microbiota to urolithin A (UA). p53 is a tumor suppressor that lost its activity through MDM2 activation in about half cancers. The purpose of this study was to investigate the influence of UA on the p53-MDM2 interaction pathway in prostate cancer cell lines.. Three human prostate cancer cell lines were used that harbor different p53 genotypes; LNCaP (p53. We found UA inhibited CaP cells' viability and induced apoptosis. For 22RV1 and LNCaP, we found UA increased p53 protein expression and its main target protein, p21, and MDM2, forming an autoregulatory feedback loop. In addition, UA increased the p53 proapoptotic proteins PUMA and NOXA. Moreover, UA inhibited the interaction between p53 and MDM2 and inhibited MDM2-mediated p53 polyubiquitination. UA downregulated MDM2 and XIAP protein expression in PC3 cells and upregulated p21 and p14ARF in a p53-independent manner.. The influencing of UA on p53-MDM2 pathway may partly contribute to its anticancer effect.

Topics: Blotting, Western; Cell Culture Techniques; Cell Death; Coumarins; Flow Cytometry; Humans; Male; Polymerase Chain Reaction; Prostatic Neoplasms; Tumor Suppressor Protein p53

The gut microbiota-derived metabolites of ellagitannins and green tea catechins, urolithin A (uroA) and 5-(3',4',5'-trihydroxyphenyl)-

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Colon; Coumarins; Gastrointestinal Microbiome; Humans; In Vitro Techniques; Lactones; Male; Polyphenols; Prostatic Neoplasms

Walnuts contain several bioactive compounds, including pedunculagin, a polyphenol metabolized by microbiota to form urolithins, namely urolithin A (UA). The aim of this study was to determine gene expression changes in prostate cancer cells after incubation with UA.. We performed a genomic analysis to study the effect of UA on LNCaP prostate cells. Cells were incubated with 40 µM UA for 24 h, and RNA was extracted and hybridized to Affymetrix Human Genome U219 array. Microarray results were analyzed using GeneSpring v13 software. Differentially expressed genes (p < 0.05, fold change > 2) were used to perform biological association networks. Cell cycle was analyzed by flow cytometry and apoptosis measured by the rhodamine method and by caspases 3 and 7 activation. Cell viability was determined by MTT assay.. We identified two nodes, FN-1 and CDKN1A, among the differentially expressed genes upon UA treatment. CDKN1A was validated, its mRNA and protein levels were significantly up-regulated, and the promoter activation measured by luciferase. Cell cycle analysis showed an increase in G1-phase, and we also observed an induction of apoptosis and caspases 3 and 7 activation upon UA treatment.. Our results indicate a potential role of UA as a chemopreventive agent for prostate cancer.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Caspase 7; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Coumarins; Cyclin-Dependent Kinase Inhibitor p21; Fibronectins; Gene Expression Regulation, Neoplastic; Humans; Juglans; Male; Nuts; Polyphenols; Prostatic Neoplasms; RNA, Messenger; Up-Regulation

Urolithins are bioactive ellagic acid-derived metabolites produced by human colonic microflora. Although previous studies have demonstrated the cytotoxicity of urolithins, the effect of urolithins on miRNAs is still unclear. In this study, the suppressing effects of methylated urolithin A (mUA) on cell viability in human prostate cancer DU145 cells was investigated. mUA induced caspase-dependent cell apoptosis, mitochondrial depolarization and down-regulation of Bcl-2/Bax ratio. The results showed that upon exposure to mUA, miR-21 expression was decreased and the expression of PTEN and Pdcd4 protein was elevated. mUA could further suppress Akt phosphorylation and increase protein expression of FOXO3a, and the effects of mUA on Akt phosphorylation and protein expression of FOXO3a were blocked by PTEN silence. Moreover, mUA suppressed the Wnt/β-catenin-mediated transcriptional activation of MMP-7 and c-Myc, and this function of mUA on MMP-7 and c-Myc was attenuated by over-expression of miR-21. In conclusion, our data suggest that mUA can suppress cell viability in DU145 cells through modulating miR-21 and its downstream series-wound targets, including PTEN, Akt and Wnt/β-catenin signaling.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; beta Catenin; Blotting, Western; Cell Proliferation; Coumarins; Forkhead Box Protein O3; Gene Expression Regulation, Neoplastic; Hepatocyte Nuclear Factor 1-alpha; Humans; Lymphoid Enhancer-Binding Factor 1; Male; Methylation; Mice; Mice, Inbred BALB C; Mice, Nude; MicroRNAs; Prostatic Neoplasms; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA-Binding Proteins; RNA, Messenger; Tumor Cells, Cultured; Wnt Signaling Pathway; Xenograft Model Antitumor Assays

Walnuts have been gathering attention for their health-promoting properties. They are rich in polyphenols, mainly ellagitannins (ETs) that after consumption are hydrolyzed to release ellagic acid (EA). EA is further metabolized by microbiota to form urolithins, such as A and B, which are absorbed. ETs, EA and urolithins have shown to slow the proliferation and growth of different types of cancer cells but the mechanisms remain unclear. We investigate the role of urolithins in the regulatory mechanisms in prostate cancer, specifically those related to the androgen receptor (AR), which have been linked to the development of this type of cancer. In our study, urolithins down-regulated the mRNA and protein levels of both prostate specific antigen (PSA) and AR in LNCaP cells. The luciferase assay performed with a construct containing three androgen response elements (AREs) showed that urolithins inhibit AR-mediated PSA expression at the transcriptional level. Electrophoretic mobility shift assays revealed that urolithins decreased AR binding to its consensus response element. Additionally, urolithins induced apoptosis in LNCaP cells, and this effect correlated with a decrease in Bcl-2 protein levels. In summary, urolithins attenuate the function of the AR by repressing its expression, causing a down-regulation of PSA levels and inducing apoptosis. Our results suggest that a diet rich in ET-containing foods, such as walnuts, could contribute to the prevention of prostate cancer.

Topics: Apoptosis; bcl-2-Associated X Protein; Cell Line, Tumor; Coumarins; Down-Regulation; Ellagic Acid; Gene Expression Regulation, Neoplastic; Humans; Hydrolyzable Tannins; Juglans; Male; Nuts; Plant Extracts; Polyphenols; Prostate-Specific Antigen; Prostatic Neoplasms; Receptors, Androgen; Response Elements; RNA, Messenger

The cytochrome P450 enzyme, CYP1B1, is an established target in prostate cancer chemoprevention. Compounds inhibiting CYP1B1 activity are contemplated to exert beneficial effects at three stages of prostate cancer development, that is, initiation, progression, and development of drug resistance. Pomegranate ellagitannins/microbial metabolites were examined for their CYP1B1 inhibitory activity in a recombinant CYP1B1-mediated ethoxyresorufin-O-deethylase (EROD) assay. Urolithin A, a microbial metabolite, was the most potent uncompetitive inhibitor of CYP1B1-mediated EROD activity, exhibiting 2-fold selectivity over CYP1A1, while urolithin B was a noncompetitive inhibitor with 3-fold selectivity. The punicalins and punicalagins exhibited potent CYP1A1 inhibition with 5-10-fold selectivity over CYP1B1. Urolithins, punicalins, and punicalagins were tested for their 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1 inhibitory activity in the 22Rv1 prostate cancer cell line. Urolithins A and B showed a decrease in their CYP1-mediated EROD inhibitory IC50 values upon increasing their treatment times from 30 min to 24 h. Urolithin C, 8-O-methylurolithin A, and 8,9-di-O-methylurolithin C caused a potent CYP1-mediated EROD inhibition in 22Rv1 cells upon 24 h of incubation. Neutral red uptake assay results indicated that urolithin C, 8-O-methylurolithin A, and 8,9-di-O-methylurolithin C induced profound cytotoxicity in the proximity of their CYP1 inhibitory IC50 values. Urolithins A and B were studied for their cellular uptake and inhibition of TCDD-induced CYP1B1 expression. Cellular uptake experiments demonstrated a 5-fold increase in urolithin uptake by 22Rv1 cells. Western blots of the CYP1B1 protein indicated that the urolithins interfered with the expression of CYP1B1 protein. Thus, urolithins were found to display a dual mode mechanism by decreasing CYP1B1 activity and expression.

Topics: Anticarcinogenic Agents; Aryl Hydrocarbon Hydroxylases; Colon; Coumarins; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP1B1; Enzyme Inhibitors; Fruit; Humans; Hydrolyzable Tannins; Lythraceae; Male; Prostatic Neoplasms; Recombinant Proteins

Our group has shown in a phase II clinical trial that pomegranate juice (PJ) increases prostate specific antigen (PSA) doubling time in prostate cancer (CaP) patients with a rising PSA. Ellagitannins (ETs) are the most abundant polyphenols present in PJ and contribute greatly towards its reported biological properties. On consumption, ETs hydrolyze to release ellagic acid (EA), which is then converted by gut microflora to 3,8-dihydroxy-6H-dibenzo[b, d]pyran-6-one (urolithin A, UA) derivatives. Despite the accumulating knowledge of ET metabolism in animals and humans, there is no available data on the pharmacokinetics and tissue disposition of urolithins. Using a standardized ET-enriched pomegranate extract (PE), we sought to further define the metabolism and tissue distribution of ET metabolites. PE and UA (synthesized in our laboratory) were administered to C57BL/6 wild-type male mice, and metabolite levels in plasma and tissues were determined over 24 h. ET metabolites were concentrated at higher levels in mouse prostate, colon, and intestinal tissues as compared to other tissues after administration of PE or UA. We also evaluated the effects of PE on CaP growth in severe combined immunodeficient (SCID) mice injected subcutaneously with human CaP cells (LAPC-4). PE significantly inhibited LAPC-4 xenograft growth in SCID mice as compared to vehicle control. Finally, EA and several synthesized urolithins were shown to inhibit the growth of human CaP cells in vitro. The chemopreventive potential of pomegranate ETs and localization of their bioactive metabolites in mouse prostate tissue suggest that pomegranate may play a role in CaP treatment and chemoprevention. This warrants future human tissue bioavailability studies and further clinical studies in men with CaP.

Topics: Animals; Cell Division; Coumarins; Fruit; Humans; Hydrolyzable Tannins; Lythraceae; Male; Mice; Mice, Inbred C57BL; Mice, SCID; Neoplasm Transplantation; Plant Extracts; Prostate; Prostatic Neoplasms