番茄红素对人前列腺癌细胞生长的影响

目的：观察番茄红素对体外培养的人前列腺癌DU－145和LNCaP细胞存活率、细胞周期和凋亡的影响。方法：用MTT检测番茄红素对DU－145和LNCaP细胞作用的时间效应和剂量效应;流式细胞仪观察番茄红素处理人前列腺癌细胞后细胞周期以及细胞凋亡的改变。结果：番茄红素对DU－145细胞的增殖有明显抑制作用,抑制率可达78％,并有剂量-效应关系。流式细胞仪分析显示,番茄红素可影响该细胞周期并引起细胞凋亡,凋亡率最高达42．42％。而对LNCaP细胞作用不明显。结论：番茄红素对人前列腺癌细胞DU－145具有直接抑制作用,其抑制机理是通过影响人前列腺癌细胞的生长周期和诱导其凋亡而实现。本研究同时也显示番茄红对激素不依赖型细胞DU－145作用较激素依赖型细胞LNCaP敏感。     

Carotenoids affect proliferation of human prostate cancer cells.

We investigated whether various carotenoids present in foodstuffs were potentially involved in cancer-preventing action on human prostate cancer. The effects of 15 kinds of carotenoids on the viability of three lines of human prostate cancer cells, PC-3, DU 145 and LNCaP, were evaluated. When the prostate cancer cells were cultured in a carotenoid-supplemented medium for 72 h at 20 micromol/L, 5,6-monoepoxy carotenoids, namely, neoxanthin from spinach and fucoxanthin from brown algae, significantly reduced cell viability to 10.9 and 14.9% for PC-3, 15.0 and 5.0% for DU 145, and nearly zero and 9.8% for LNCaP, respectively. Acyclic carotenoids such as phytofluene, zeta-carotene and lycopene, all of which are present in tomato, also significantly reduced cell viability. On the other hand, phytoene, canthaxanthin, beta-cryptoxanthin and zeaxanthin did not affect the growth of the prostate cancer cells. DNA fragmentation of nuclei in neoxanthin- and fucoxanthin-treated cells was detected by in situ TdT-mediated dUTP nick end labeling (TUNEL) assay. Neoxanthin and fucoxanthin were found to reduce cell viability through apoptosis induction in the human prostate cancer cells. These results suggest that ingestion of leafy green vegetables and edible brown algae rich in neoxanthin and fucoxanthin might have the potential to reduce the risk of prostate cancer.     

Lycopene differentially induces quiescence and apoptosis in androgen-responsive and -independent prostate cancer cell lines

BACKGROUND & AIMS: Lycopene has been credited with a number of health benefits including a decrease in prostate cancer risk. Our study investigates the molecular mechanism underlying anti-cancer activity of lycopene-based products in androgen-responsive (LNCaP) and androgen-independent (PC3) cells. METHODS: The effect of lycopene-based agents on prostate cancer growth and survival were examined using proliferation assays, bromodeoxyuridine incorporation and flow cytometric analysis of cellular DNA content. Biochemical effects of lycopene treatment were investigated by immunoblotting for changes in the absolute levels and phosphorylation states of cell cycle regulatory and signalling proteins. RESULTS: LNCaP and PC3 cells treated with the lycopene-based agents undergo mitotic arrest, accumulating in G0/G1 phase. Immunoblot screening indicated that lycopene's antiproliferative effects are likely achieved through a block in G1/S transition mediated by decreased levels of cyclins D1 and E and cyclin dependent kinase 4 and suppressed Retinoblastoma phosphorylation. These responses correlated with decreased insulin-like growth factor-I receptor expression and activation, increased insulin-like growth factor binding protein 2 expression and decreased AKT activation. Exposure to lycopene at doses as low as 10 nM for 48 h induced a profound apoptotic response in LNCaP cells. In contrast PC3 cells were resistant to apoptosis at doses up to 1 microM. CONCLUSIONS: Lycopene exposure can suppress phosphatidylinositol 3-kinase-dependent proliferative and survival signalling in androgen-responsive LNCaP and androgen-independent PC3 cells suggesting that the molecular mechanisms for the cytostatic and cytotoxic actions of lycopene involve induction of G0/G1 cell cycle arrest. This study supports further examination of lycopene as a potential agent for both the prevention and treatment of prostate cancer.     

Pomegranate extracts potently suppress proliferation, xenograft growth, and invasion of human prostate cancer cells

We completed a multicenter study of the effects of pomegranate cold-pressed (Oil) or supercritical CO(2)-extracted (S) seed oil, fermented juice polyphenols (W), and pericarp polyphenols (P) on human prostate cancer cell xenograft growth in vivo, and/or proliferation, cell cycle distribution, apoptosis, gene expression, and invasion across Matrigel, in vitro. Oil, W, and P each acutely inhibited in vitro proliferation of LNCaP, PC-3, and DU 145 human cancer cell lines. The dose of P required to inhibit cell proliferation of the prostate cancer cell line LNCaP by 50% (ED(50)) was 70 microg/mL, whereas normal prostate epithelial cells (hPrEC) were significantly less affected (ED(50) = 250 g/mL). These effects were mediated by changes in both cell cycle distribution and induction of apoptosis. For example, the androgen-independent cell line DU 145 showed a significant increase from 11% to 22% in G(2)/M cells (P <.05) by treatment with Oil (35 microg/mL) with a modest induction of apoptosis. In other cell lines/treatments, the apoptotic response predominated, for example, in PC-3 cells treated with P, at least partially through a caspase 3-mediated pathway. These cellular effects coincided with rapid changes in mRNA levels of gene targets. Thus, 4-hour treatment of DU 145 cells with Oil (35 microg/mL) resulted in significant 2.3 +/- 0.001-fold (mean +/- SEM) up-regulation of the cyclin-dependent kinase inhibitor p21((waf1/cip1)) (P <.01) and 0.6 +/- 0.14-fold down-regulation of c-myc (P <.05). In parallel, all agents potently suppressed PC-3 invasion through Matrigel, and furthermore P and S demonstrated potent inhibition of PC-3 xenograft growth in athymic mice. Overall, this study demonstrates significant antitumor activity of pomegranate-derived materials against human prostate cancer.     

The use of fetal bovine serum as delivery vehicle to improve the uptake and stability of lycopene in cell culture studies

Tetrahydrofuran (THF) has commonly been used to deliver carotenoids to cells but the use of THF is associated with cytotoxicity and low uptake efficiency of carotenoids. Here, we used fetal bovine serum (FBS) as the delivery vehicle for lycopene in comparison with THF, THF containing 0.0025 % butylated hydroxytoluene (THF/BHT), methyl-beta-cyclodextrin (M-beta-CD) and micelles in two human prostate cancer cell lines, DU145 and PC-3. Lycopene (10 mM) solubilized in THF/BHT and then diluted in FBS at ratios of 5 and 10 gave the highest lycopene uptake in DU145 cells. Using a dilution factor of 10, we found that lycopene (10 microm) carried in FBS in a cell-free system led to significantly less loss of lycopene than in THF, THF/BHT and M-beta-CD within 24 h of incubation. Lycopene solubilized in micelles was more stable than that in FBS within 24 h, but the micelle itself led to marked cytotoxicity to DU145 cells. Lycopene at 10 microm in FBS led to significantly higher uptake of lycopene in both cell lines than that in THF, THF/BHT or M-beta-CD within 24 h of incubation. When FBS was replaced with lipoprotein-deficient serum, the uptake of lycopene by DU145 cells was markedly decreased and was not significantly different from that of THF or THF/BHT. These results demonstrate that FBS is superior to THF, THF/BHT, M-beta-CD and micelles as a delivery vehicle for lycopene in prostate cell lines and that the lipoprotein of FBS is likely responsible for the improved stability and cellular uptake of lycopene.     

Soybean phytochemicals inhibit the growth of transplantable human prostate carcinoma and tumor angiogenesis in mice.

The objectives of our studies are to characterize the ability of dietary soybean components to inhibit the growth of prostate cancer in mice and alter tumor biomarkers associated with angiogenesis. Soy isoflavones (genistein or daidzein) or soy phytochemical concentrate inhibit the growth of prostate cancer cells LNCaP, DU 145 and PC-3 in vitro, but only at supraphysiologic concentrations, i.e., 50% inhibitory concentration (IC(50)) > 50 micromol/L. G2-M arrest and DNA fragmentation consistent with apoptosis of prostate cancer cells are also observed at concentrations causing growth inhibition. In contrast, the in vitro proliferation of vascular endothelial cells was inhibited by soy phytochemcials at much lower concentrations. We evaluated the ability of dietary soy phytochemical concentrate and soy protein isolate to inhibit the growth of the LNCaP human prostate cancer in severe combined immune-deficient mice. Mice inoculated subcutaneously with LNCaP cells (2 x 10(6)) were randomly assigned to one of the six dietary groups based on the AIN-76A formulation for 3 wk. A 2 x 3 factorial design was employed with two protein sources (20%, casein vs. soy protein) and three levels of soy phytochemical concentrate (0, 0.2 and 1.0% of the diet). Soy components did not alter body weight gain or food intake. Compared with casein-fed controls, the tumor volumes after 3 wk were reduced by 11% (P = 0.45) by soy protein, 19% (P = 0.17) by 0.2% soy phytochemical concentrate, 28% by soy protein with 0.2% soy phytochemical concentrate (P < 0.05), 30% by 1.0% soy phytochemical concentrate (P < 0.05) and 40% by soy protein with 1.0% soy phytochemical concentrate (P < 0.005). Histologic examination of tumor tissue showed that consumption of soy products significantly reduced tumor cell proliferation, increased apoptosis and reduced microvessel density. The angiogenic protein insulin-like growth factor-I was reduced in the circulation of mice fed soy protein and phytochemical concentrate. Our data suggest that dietary soy products may inhibit experimental prostate tumor growth through a combination of direct effects on tumor cells and indirect effects on tumor neovasculature.     

Molecular mechanisms of cell cycle block by methionine restriction in human prostate cancer cells

Previous studies have shown that dietary or pharmacological methionine restriction inhibits growth of human prostate cancer cells in vitro or as xenografts in mice. We undertook the present studies to clarify the molecular mechanisms by which methionine restriction inhibits prostate cancer cell growth. We found that PC-3 and DU 145 cells stopped proliferating within six days in growth medium containing homocysteine in place of methionine. In contrast, proliferation of LNCaP cells was only partially inhibited by the absence of methionine. Using flow cytometry, we found that methionine restriction caused PC-3 cells to arrest in all phases of the cell cycle, but predominantly in the G2/M phase, whereas LNCaP cells accumulated exclusively in the G1 phase. Methionine restriction led to accumulation of the cyclin-dependent kinase inhibitors p21 and p27, as determined by Western blot analysis, and inhibited the enzymatic activities of the cyclin-dependent kinases CDK2 and cdc2, as determined by an in vitro kinase assay: However, methionine restriction had little or no effect on CDK2 or cdc2 protein levels. Methionine restriction also induced PC-3 cells to undergo apoptosis, as indicated by the appearance of a typical nucleosomal ladder on gel electrophoresis of genomic DNA. We conclude that methionine restriction has potential as a novel treatment strategy for prostate cancer.     

Lycopene and Apo-12′-Lycopenal Reduce Cell Proliferation and Alter Cell Cycle Progression in Human Prostate Cancer Cells

Lycopene is associated with a reduced risk of prostate cancer. However, lycopene may not be wholly responsible for the effects seen in vivo or in cell culture systems. Apo-lycopenals or other lycopene metabolites, whether produced by cleavage enzymes within the body or consumed with tomato products, can be found in tissues at concentrations equivalent to physiological retinoid concentrations. Therefore, it is plausible that lycopenoids, like retinoids, are bioactive within tissues. Androgen-independent DU145 prostate cancer cells were treated with lycopene, apo-8′-lycopenal, or apo-12′-lycopenal. DU145 cell proliferation was significantly reduced by supra-physiological levels of lycopene and apo-12′-lycopenal, in part, through alteration of the normal cell cycle. Levels of the gap junction protein, connexin 43, were unaltered by lycopene or apo-lycopenal treatment while cell apoptosis rates significantly decreased. We further confirmed that connexin 43 protein levels were unaltered by lycopene treatment in mouse embryonic fibroblasts, or in Dunning R3327-H rat prostate tumor. The present data indicate that lycopene and apo-12′-lycopenal reduce the proliferation of prostate cancer cells, in part, by inhibiting normal cell cycle progression.     

Lycopene and apo-12'-lycopenal reduce cell proliferation and alter cell cycle progression in human prostate cancer cells

Lycopene is associated with a reduced risk of prostate cancer. However, lycopene may not be wholly responsible for the effects seen in vivo or in cell culture systems. Apo-lycopenals or other lycopene metabolites, whether produced by cleavage enzymes within the body or consumed with tomato products, can be found in tissues at concentrations equivalent to physiological retinoid concentrations. Therefore, it is plausible that lycopenoids, like retinoids, are bioactive within tissues. Androgen-independent DU145 prostate cancer cells were treated with lycopene, apo-8'-lycopenal, or apo-12'-lycopenal. DU145 cell proliferation was significantly reduced by supra-physiological levels of lycopene and apo-12'-lycopenal, in part, through alteration of the normal cell cycle. Levels of the gap junction protein, connexin 43, were unaltered by lycopene or apo-lycopenal treatment while cell apoptosis rates significantly decreased. We further confirmed that connexin 43 protein levels were unaltered by lycopene treatment in mouse embryonic fibroblasts, or in Dunning R3327-H rat prostate tumor. The present data indicate that lycopene and apo-12'-lycopenal reduce the proliferation of prostate cancer cells, in part, by inhibiting normal cell cycle progression.     

Specific amino acid dependency regulates invasiveness and viability of androgen-independent prostate cancer cells

Androgen-independent prostate cancer is resistant to therapy and is often metastatic. Here we studied the effect of deprivation of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), or methionine (Met), in vitro on human DU145 and PC3 androgen-independent prostate cancer cells, and on nontumorigenic human infant foreskin fibroblasts and human prostate epithelial cells. Deprivation of the amino acids similarly inhibited growth of DU145 and PC3 cells, arresting the cell cycle at G0/G1. Met and Tyr/Phe deprivation induces apoptosis in DU145, but only Met deprivation induces apoptosis in PC3 cells. The growth of normal cells is inhibited, but no apoptosis is induced by amino acid deprivation. Tyr/Phe deprivation inhibits expression and phosphorylation of focal adhesion kinase (FAK) and extracellular-regulated kinase (ERK) in DU145 but not PC3 or normal cells. Met deprivation inhibits phosphorylation but not protein expression of FAK and ERK in PC3. Therefore, apoptosis of DU145 and PC3 cells by amino acid restriction is FAK and ERK dependent. Tyr/Phe and Met deprivation inhibits invasion of DU145 and PC3, but Gln deprivation only inhibits invasion of DU145 cells. This indicates that the inhibition of invasion is not dependent on induction of apoptosis. The inhibition of invasion by Tyr/Phe restriction in DU145 and Met restriction in PC3 is consistent with the inhibition on FAK/ERK signaling. The inhibition of Tyr/Phe restriction in PC3 and Gln restriction in DU145 is not associated with inhibition of FAK/ERK. This indicates that FAK/ERK-dependent and independent pathways are modulated by specific amino acid restriction. This study shows the potential for specific amino acid restriction to treat prostate cancer.     

Effect of lycopene on prostate LNCaP cancer cells in culture

Epidemiological studies have shown an inverse relationship between serum lycopene levels and the risk of prostate cancer. The objective of this study was to measure the effect of lycopene on the proliferation of LNCaP human prostate cancer cells in culture. A new, water-dispersible lycopene in an appropriate vehicle was used. The stock solution was diluted in the medium to obtain lycopene concentrations of 10(-6), 10(-5), and 10(-4) M; their corresponding vehicles were similarly diluted to be used as controls. Cells were grown for 48 hours in RPMI-1640 medium supplemented with 10% fetal bovine serum and antibiotics. Lycopene was then added at different concentrations, and the cells were allowed to grow for 24, 48, 72, and 96 hours. Lycopene at concentrations of 10(-6) and 10(-5) M significantly reduced the growth of LNCaP cells after 48, 72, and 96 hours of incubation, by 24.4% to 42.8% (P <.05). The inhibitory effect of lycopene was significantly higher than that of the corresponding vehicle controls. In a follow-up experiment, a lower range of lycopene concentrations (10(-9) to 10(-7) M) was used to determine whether there was a dose-response effect. Lycopene significantly decreased the growth of cells in a dose-dependent manner when cells were incubated for 24, 48, 72, or 96 hours (F = 3.150, 11.27, 54.51, and 297.5, respectively; P <.05). The growth inhibitory effect of lycopene on human prostate cancer cells observed in this study suggests a possibly important role for lycopene as an antioxidant in human prostate cancer; however, investigations of other mechanisms are warranted.     

Vitamin E succinate induces apoptosis in human prostate cancer cells: role for Fas in vitamin E succinate-triggered apoptosis

The apoptosis-triggering properties of vitamin E succinate (VES, RRR-alpha-tocopheryl succinate) for human LNCaP and PC-3 prostate carcinoma cells and normal PrEC human prostate epithelial cells were investigated. LNCaP and PC-3 cells were sensitive to VES-induced apoptosis, with 100% and 60% of cells undergoing apoptosis after three days of treatment with 10 micrograms of VES/ml, respectively. PrEC cells were resistant to VES-induced apoptosis. Treatment of prostate cells with agonistic anti-Fas antibody triggered apoptosis in approximately 50% of PC-3 cells within 48 hours, whereas LNCaP and PrEC cells were resistant. Prostate cells simultaneously treated with VES and agonistic anti-Fas antibodies revealed 1) no effect on PrEC cells, 2) an additive effect on Fas-sensitive PC-3 cells, and 3) a synergistic effect on LNCaP cells. VES treatment of LNCaP cells caused depletion of cytosolic 43-kDa Fas, enhanced membrane levels of 43-kDa Fas, and induced Fas sensitivity. PC-3 cells expressed high levels of membrane 43-kDa Fas that were enhanced by VES treatments. Fas ligand expression by LNCaP cells was enhanced by VES treatments. In summary, VES triggers apoptosis in human prostate carcinoma cells but not normal prostate cells in vitro, and VES modulates Fas signaling.     

番茄红素对前列腺癌细胞PC-3增殖和细胞周期的影响

目的研究番茄红素对体外培养的雄激素非依赖性前列腺癌细胞PC-3的抑制作用及其可能的作用机制。方法采用MTT法和H3-TdR掺入法观察番茄红素对癌细胞增殖的影响,流式细胞仪观察同步化的细胞经番茄红素作用后细胞周期及凋亡的变化,RT-PCR检测cyclin D1、bcl-2、bax的mRNA的表达的变化。结果番茄红素抑制PC-3细胞的增殖和DNA合成、诱导其凋亡、改变细胞周期分布(使G0/G1期细胞增多、而S期和G2/M期细胞减少)。RT-PCR结果显示,cyclin D1和bcl-2的mRNA表达水平下调,而bax的mRNA表达水平上调。上述作用呈剂量效应关系。结论番茄红素可诱导PC-3细胞凋亡、改变细胞周期分布、影响cyclin D1、bcl-2、bax的mRNA的表达,从而抑制肿瘤细胞增殖。     

Wine antioxidant polyphenols inhibit the proliferation of human prostate cancer cell lines

The effect of different wine antioxidant polyphenols (catechin, epicatechin, quercetin, and resveratrol) on the growth of three prostate cancer cell lines (LNCaP, PC3, and DU145) was investigated. A dose- and time-dependent inhibition of cell growth by polyphenols was found at nanomolar concentrations. The proliferation of LNCaP and PC3 cells was preferentially inhibited by flavonoids (catechin, epicatechin, and quercetin), whereas resveratrol was the most potent inhibitor of DU145 cell growth. Possible mechanisms of action were investigated: 1) The competition of polyphenols for androgen binding in LNCaP cells revealed significant interaction only in the case of high concentrations of quercetin, at least at five orders of magnitude higher than the concentrations needed for cell growth inhibition. All other phenols showed low interactions. 2) Oxygen species production after mitogen stimulation and H2O2 sensitivity of these cell lines did not correlate with the observed antiproliferative effects, ruling out such a mode of action. 3) NO production revealed two different patterns: LNCaP and DU145 cells produced high concentrations of NO, whereas PC3 cells produced low concentrations. Phorbol ester stimulation of cells did not reveal any additional effect in LNCaP and DU145 cells, whereas it enhanced the secretion of NO in PC3 cells. Polyphenols decreased NO secretion. This effect correlates with their antiproliferative action and the inhibition of inducible NO synthase. It is therefore proposed that the antiproliferative effect of polyphenols is mediated through the modulation of NO production. In conclusion, our data show a direct inhibitory effect of low concentrations of antioxidant wine phenols on the proliferation of human prostate cancer cell lines mediated by the production of NO, further suggesting potential beneficial effects of wine and other phenol-containing foods or drinks for the control of prostate cancer cell growth.     

Modulation of dietary fat‐enhanced colorectal carcinogenesis in N‐methyl‐N‘‐nitro‐N‐nitrosoguanidine‐treated rats by a vegetables‐fruit mixture

The apoptosis-triggering properties of vitamin E succinate (VES, RRR-α-tocopheryl succinate) for human LNCaP and PC-3 prostate carcinoma cells and normal PrEC human prostate epithelial cells were investigated. LNCaP and PC-3 cells were sensitive to VES-induced apoptosis, with 100% and 60% of cells undergoing apoptosis after three days of treatment with 10 μg of VES/ml, respectively. PrEC cells were resistant to VES-induced apoptosis. Treatment of prostate cells with agonistic anti-Fas antibody triggered apoptosis in approximately 50% of PC-3 cells within 48 hours, whereas LNCaP and PrEC cells were resistant. Prostate cells simultaneously treated with VES and agonistic anti-Fas antibodies revealed 1) no effect on PrEC cells, 2) an additive effect on Fas-sensitive PC-3 cells, and 3) a synergistic effect on LNCaP cells. VES treatment of LNCaP cells caused depletion of cytosolic 43-kDa Fas, enhanced membrane levels of 43-kDa Fas, and induced Fas sensitivity. PC-3 cells expressed high levels of membrane 43-kDa Fas that were enhanced by VES treatments. Fas ligand expression by LNCaP cells was enhanced by VES treatments. In summary, VES triggers apoptosis in human prostate carcinoma cells but not normal prostate cells in vitro, and VES modulates Fas signaling.     

Lycopene inhibits the growth of normal human prostate epithelial cells in vitro

Lycopene has repeatedly been shown to inhibit the growth of human prostate cells in vitro. However, previous studies with lycopene have focused on cancer specimens, and it is still unclear whether this carotenoid affects the growth of normal human prostate cells as well. Therefore, we investigated the effects of lycopene on normal human prostate epithelial cells (PrEC) by treating them with synthetic all-E-lycopene (up to 5 micromol/L) and assessing proliferation via [3H]thymidine incorporation. The effects of lycopene on cell cycle progression were investigated via flow cytometry. To elucidate whether lycopene modulates cyclins involved in cell cycle progression, protein expressions of cyclins D1 and E were analyzed. The results show that lycopene significantly inhibited the growth of PrEC in a dose-dependent fashion. Flow cytometry revealed a significant cell cycle arrest in the G0/G1 phase. This effect was confirmed by inhibition of cyclin D1 protein expression, whereas cyclin E levels remained unchanged. The results demonstrate that lycopene inhibits growth of nonneoplastic PrEC in vitro. We hypothesize that lycopene might likewise inhibit the growth of prostatic epithelial cells in vivo. This might have an effect on prostate development and/or on enlargement of prostate tissue as found in benign prostate hyperplasia, a potential precursor of prostate cancer.     

Beta-carotene modulates human prostate cancer cell growth and may undergo intracellular metabolism to retinol

Epidemiologic and animal studies provide support for a relationship between high intakes of carotenoids from fruits and vegetables with reduced risk of several malignancies including prostate cancer. The highly controlled environments of in vitro systems provide an opportunity to investigate the cellular and molecular effects of carotenoids. The effects of beta-carotene (BC) on in vitro growth rates, p21(WAF1) and p53 gene expression, as well as the conversion of BC to retinol were investigated in three human prostate adenocarcinoma cell lines: PC-3, DU 145 and LNCaP. In these experiments, media concentrations of 30 micromol BC/L for 72 h significantly (P < 0.05) slowed in vitro growth rates in all three cell lines, independently of p53 or p21(WAF1) status or expression. (14)C-labeled retinol was detected in prostate tumor cells incubated with (14)C-labeled BC, suggesting metabolic conversion of BC to retinol. Conversely, no (14)C-labeled retinol was detected in media incubated without prostate cancer cells. These studies support a hypothesis that in vitro biological effects of BC on prostate cells may result in part from the conversion of BC to retinol or other metabolites. The possibility that prostate cancer cells in vivo locally metabolize provitamin A carotenoids to retinol and other related metabolites may have implications for our understanding of prostate cancer etiology and the design of future prevention studies.     

Wine Antioxidant Polyphenols Inhibit the Proliferation of Human Prostate Cancer Cell Lines

The effect of different wine antioxidant polyphenols (catechin, epicatechin, quercetin, and resveratrol) on the growth of three prostate cancer cell lines (LNCaP, PC3, and DU145) was investigated. A dose- and time-dependent inhibition of cell growth by polyphenols was found at nanomolar concentrations. The proliferation of LNCaP and PC3 cells was preferentially inhibited by flavonoids (catechin, epicatechin, and quercetin), whereas resveratrol was the most potent inhibitor of DU145 cell growth. Possible mechanisms of action were investigated: 1) The competition of polyphenols for androgen binding in LNCaP cells revealed significant interaction only in the case of high concentrations of quercetin, at least at five orders of magnitude higher than the concentrations needed for cell growth inhibition. All other phenols showed low interactions. 2) Oxygen species production after mitogen stimulation and H²O²2 sensitivity of these cell lines did not correlate with the observed antiproliferative effects, ruling out such a mode of action. 3) NO production revealed two different patterns: LNCaP and DU145 cells produced high concentrations of NO, whereas PC3 cells produced low concentrations. Phorbol ester stimulation of cells did not reveal any additional effect in LNCaP and DU145 cells, whereas it enhanced the secretion of NO in PC3 cells. Polyphenols decreased NO secretion. This effect correlates with their antiproliferative action and the inhibition of inducible NO synthase. It is therefore proposed that the antiproliferative effect of polyphenols is mediated through the modulation of NO production. In conclusion, our data show a direct inhibitory effect of low concentrations of antioxidant wine phenols on the proliferation of human prostate cancer cell lines mediated by the production of NO, further suggesting potential beneficial effects of wine and other phenol-containing foods or drinks for the control of prostate cancer cell growth.     

Reduced growth and integrin expression of prostate cells cultured with lycopene, vitamin E and fish oil in vitro

Integrins are transmembrane proteins that facilitate the interaction of cells with the extracellular environment. They have also been implicated in cancer progression. The effects of nutrients thought to be involved in the prevention of prostate cancer on integrin expression have not been determined. Prostate cancer cell lines representing a range of malignancy from normal (RWPE-1) to highly invasive phenotypes (22Rv1 < LNCaP < PC-3) were cultured with or without lycopene (10 nM), vitamin E (5 microm) or fish oil (100 microm) for 48 h. Growth and integrin (alpha2beta1, alphavbeta3 and alphavbeta5) expression were assessed using Trypan Blue exclusion and monoclonal antibodies combined with flow cytometry. Vitamin E enhanced (P < 0.001) whereas fish oil reduced the growth of all the cell lines tested (P < 0.001). Lycopene had no effect on growth. All the malignant cell lines exhibited lower expression of alpha2beta1 with the addition of lycopene to culture media. Supplemental fish oil reduced alpha2beta1 in most invasive cell lines (LNCaP and PC-3). Each nutrient at physiological levels reduced integrins alphavbeta3 and alphavbeta5 in most invasive cell lines (PC-3). The results suggest that integrins may represent an additional target of bioactive nutrients and that the effects of nutrients may be dependent on the type of cell line used.