Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have indicated that flavonoids exhibit antiproliferative properties on some hormone-dependent cancer cell lines, such as breast and prostate cancer. In the present study, the effects of some selected flavonoids, genistein, apigenin, luteolin, chrysin, kaempferol, and biochanin A on human thyroid carcinoma cell lines, UCLA NPA-87-1 (NPA) (papillary carcinoma), UCLA RO-82W-1 (WRO) (follicular carcinoma), and UCLA RO-81A-1 (ARO) (anaplastic carcinoma) have been examined. Among the flavonoids tested, apigenin and luteolin are the most potent inhibitors of these cell lines with IC50 (concentration at which cell proliferation was inhibited by 50%) values ranging from 21.7 microM to 32.1 microM. The cells were viable at these concentrations. Using NPA cells known to be estrogen receptor positive (ER+), it was shown that no significant [3H]-E2 displacement occurred with these flavonoids at the IC50 concentration. In WRO cells that are known to have an antiestrogen binding site (AEBS), biochanin A caused a stronger inhibitory growth effect (IC50 = 64.1 microM) than in NPA and ARO cells. In addition, it was observed that biochanin A has an appreciable binding affinity for the AEBS as indicated by the displacement of [3H]-tamoxifen from the WRO cells. In summary, flavonoids have potent antiproliferative activity in vitro against various human thyroid cancer cell lines. The inhibitory activity of certain flavonoid compounds may be mediated via the AEBS and/or type II EBS. The observation that ARO cells that lack both the AEBS and the ER are effectively inhibited by apigenin and luteolin suggest that other mechanisms of action are operative as well. The present study suggests that flavonoids may represent a new class of therapeutic agents in the management of thyroid cancer.
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PMID:Growth inhibitory effects of flavonoids in human thyroid cancer cell lines. 1031 43

Asian men have much lower incidences of prostate cancer and possibly of benign prostatic hyperplasia (BPH) than their Western counterparts. Vegetarian men also have a lower incidence of prostate cancer than omnivorous males. Both Asian and vegetarian men consume low-fat, high-fibre diets which provide a rich supply of weak dietary oestrogens. These plant or phyto-oestrogens have been proposed as chemopreventive agents, particularly for Asian men and to a lesser extent, for vegetarian men also. The three principal classes of phyto-oestrogens are the isoflavonoids, flavonoids and lignans. Many foods of plant origin contain varying amounts of these compounds and hundreds of plants manifest some degree of oestrogenic activity. Soya, a dietary staple in many parts of Asia, is a major source of the isoflavonoids, daidzein and genistein. Flavonoids are present in high concentration in many fruits, vegetables and crop species. In particular, apigenin and kaempferol are regarded as major flavonoids because of their common occurrence in plants, and their significant concentrations when present. Apples, onions and tea-leaves are excellent sources of flavonoids. Plant lignans are present in many cereals, grains, fruits and vegetables, and give rise to the mammalian lignans, enterodiol and enterolactone; however, the richest source is linseed (flaxseed) and other oilseeds. In addition to their oestrogenic activity, many of these plant compounds can interfere with steroid metabolism and bioavailability, and also inhibit enzymes, such as tyrosine kinase and topoisomerase, which are crucial to cellular proliferation.
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PMID:Diet and its preventive role in prostatic disease. 1032 92

Isoflavonoids, flavonoids and lignans are natural oestrogenic compounds derived from soya, tea, fruits and vegetables and they have been proposed as chemopreventive agents in Asian men, in whom the incidence of prostate cancer is much lower than in men from the West. In addition to their weak oestrogenic activity, oestrogen antagonistic activity has also been described for some of these compounds. Furthermore, the lignan, enterolactone and the soya-derived isoflavone genistein are inhibitors of several steroid metabolising enzymes, such as aromatase, 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase. Genistein is a potent inhibitor of tyrosine kinases and along with flavonoids such as kaempferol and apigenin is also an inhibitor of topoisomerases I and II, enzymes which are crucial to cellular proliferation. Genistein is also an inhibitor of angiogenesis and many experimental in vivo and in vitro models, including those for prostate cancer, are growth inhibited by isoflavonoids, flavonoids and lignans. It is estimated that the traditionally eating Japanese male consumes approximately 20 mg of isoflavones per day, whereas for Western men, the daily consumption would be less than 1 mg/day. This is reflected in a high mean plasma concentration of genistein (180 ng/ml, n = 72) in Japanese men, compared to a level of <10 ng/ml for Western males.
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PMID:Certain aspects of molecular endocrinology that relate to the influence of dietary factors on the pathogenesis of prostate cancer. 1032 3

The enzyme steroid 5 alpha-reductase (EC 1.3.99.5) catalyzes the NADPH-dependent reduction of the double bond of a variety of 3-oxo-Delta(4) steroids including the conversion of testosterone to 5 alpha-dihydrotestosterone. In humans, 5 alpha-reductase activity is critical for certain aspects of male sexual differentiation, and may be involved in the development of benign prostatic hyperplasia, alopecia, hirsutism, and prostate cancer. Certain natural products contain components that are inhibitors of 5 alpha-reductase, such as the green tea catechin (-)-epigallocatechin gallate (EGCG). EGCG shows potent inhibition in cell-free but not in whole-cell assays of 5 alpha-reductase. Replacement of the gallate ester in EGCG with long-chain fatty acids produced potent 5 alpha-reductase inhibitors that were active in both cell-free and whole-cell assay systems. Other flavonoids that were potent inhibitors of the type 1 5alpha-reductase include myricetin, quercitin, baicalein, and fisetin. Biochanin A, daidzein, genistein, and kaempferol were much better inhibitors of the type 2 than the type 1 isozyme. Several other natural and synthetic polyphenolic compounds were more effective inhibitors of the type 1 than the type 2 isozyme, including alizarin, anthrarobin, gossypol, nordihydroguaiaretic acid, caffeic acid phenethyl ester, and octyl and dodecyl gallates. The presence of a catechol group was characteristic of almost all inhibitors that showed selectivity for the type 1 isozyme of 5 alpha-reductase. Since some of these compounds are consumed as part of the normal diet or in supplements, they have the potential to inhibit 5 alpha-reductase activity, which may be useful for the prevention or treatment of androgen-dependent disorders. However, these compounds also may adversely affect male sexual differentiation.
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PMID:Structure-activity relationships for inhibition of human 5alpha-reductases by polyphenols. 1193 50

We examined the ability of polyphenols from tomatoes and soy (genistein, quercetin, kaempferol, biochanin A, daidzein and rutin) to modulate insulin-like growth factor-I (IGF-I)-induced in vitro proliferation and apoptotic resistance in the AT6.3 rat prostate cancer cell line. IGF-I at 50 micro g/L in serum-free medium produced maximum proliferation and minimized apoptosis. Polyphenols exhibited different abilities to modulate IGF-I-induced proliferation, cell cycle progression (flow cytometry) and apoptosis (Annexin V/propidium iodide and terminal deoxynucleotidyltransferase-mediated deoxyuridine 5'-triphosphate nick end labeling). Genistein, quercetin, kaempferol and biochanin A exhibited dose-dependent inhibition of growth with a 50% inhibitory concentration (IC(50)) between 25 and 40 micro mol/L, whereas rutin and daidzein were less potent with an IC(50) of >60 micro mol/L. Genistein and kaempferol potently induced G(2)/M cell cycle arrest. Genistein, quercetin, kaempferol and biochanin A, but not daidzein and rutin, counteracted the antiapoptotic effects of IGF-I. Human prostate epithelial cells grown in growth factor-supplemented medium were also sensitive to growth inhibition by polyphenols. Genistein, biochanin A, quercetin and kaempferol reduced the insulin receptor substrate-1 (IRS-1) content of AT6.3 cells and prevented the down-regulation of IGF-I receptor beta in response to IGF-I binding. IGF-I-stimulated proliferation was dependent on activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) and phosphatidylinositide 3-kinase pathways. Western blotting demonstrated that ERK1/2 was constitutively phosphorylated in AT6.3 cells with no change in response to IGF-I, whereas IRS-1 and AKT were rapidly and sensitively phosphorylated after IGF-I stimulation. Several polyphenols suppressed phosphorylation of AKT and ERK1/2, and more potently inhibited IRS-1 tyrosyl phosphorylation after IGF-I exposure. In summary, polyphenols from soy and tomato products may counteract the ability of IGF-I to stimulate proliferation and prevent apoptosis via inhibition of multiple intracellular signaling pathways involving tyrosine kinase activity.
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PMID:Tomato and soy polyphenols reduce insulin-like growth factor-I-stimulated rat prostate cancer cell proliferation and apoptotic resistance in vitro via inhibition of intracellular signaling pathways involving tyrosine kinase. 1284 Feb 8

The consumption of food products containing high amounts of flavonoids has been reported to lower the risk of various cancers. The mechanisms underlying the cancer-protective effects of these naturally occurring polyphenolic compounds, however, remain elusive. Based on our previous finding that the cytotoxic effect of the flavanol epigallocatechin-3-gallate on prostate cancer cells correlates with its ability to inhibit fatty acid synthase (FAS, a key lipogenic enzyme overexpressed in many human cancers), we examined the anti-lipogenic effects of a panel of 18 naturally occurring polyphenolic compounds. In addition to epigallocatechin-3-gallate, five other flavonoids, more particularly luteolin, quercetin, kaempferol, apigenin, and taxifolin, also markedly inhibited cancer cell lipogenesis. Interestingly, in both prostate and breast cancer cells, a remarkable dose-response parallelism was observed between flavonoid-induced inhibition of fatty acid synthesis, inhibition of cell growth, and induction of apoptosis. In support for a role of fatty acid synthesis in these effects, the addition of exogenous palmitate, the end product of FAS, markedly suppressed the cytotoxic effects of flavonoids. Taken together, these findings indicate that the potential of flavonoids to induce apoptosis in cancer cells is strongly associated with their FAS inhibitory properties, thereby providing a new mechanism by which polyphenolic compounds may exert their cancer-preventive and antineoplastic effects.
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PMID:Induction of cancer cell apoptosis by flavonoids is associated with their ability to inhibit fatty acid synthase activity. 1553 29

CYP 1B1 is involved in metabolizing both polycyclic aromatic hydrocarbons and estradiol to potentially carcinogenic intermediates, and it is also over-expressed in human cancer cells. In order to investigate whether flavonoids could specifically inhibit CYP 1B1, seven flavonoids in St. John's wort and apigenin were screened for their inhibition of recombinant human CYP 1B1 and CYP 1A1. While seven flavonoids (myricetin, apigenin, kaempferol, quercetin, amentoflavone, quercitrin and rutin) were slightly more selective for CYP 1B1 EROD inhibition (K(i)s 0.06-5.96 microM) compared to CYP 1A1 (K(i)s 0.20-1.6 microM) the difference in K(i)s for the P450s were not significantly different. Rutin did not inhibit CYP 1A1 at concentrations up to 10 microM. Kinetic analyses determined that apigenin and amentoflavone were competitive inhibitors of CYP 1B1, while quercetin showed mixed type inhibition. To characterize the inhibition potential of these flavonoids, five were studied further for their ability to inhibit TCDD-induced EROD activity in 22Rv1 human prostate cancer cells. 22Rv1 cells express constitutive and TCDD-inducible CYP 1A1 and CYP 1B1 mRNA. In the cells, the IC(50)s were similar to those measured for the recombinant CYP 1A1 except for amentoflavone. Quercetin (IC(50): 4.1 microM), kaempferol (3.8 microM), myricetin (3.0 microM) and apigenin (3.1 microM) caused significant inhibition of EROD activity whereas amentoflavone did not cause inhibition. Depending on their bioavailability, flavonoids that can selectively inhibit CYP1 enzymes may be useful as chemoprotective agents in prostate cancer prevention.
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PMID:Inhibition of human cytochrome CYP 1 enzymes by flavonoids of St. John's wort. 1627 22

A number of epidemiological studies have suggested that diet may affect the etiology of prostate cancer, but few have investigated the impact of phytochemical intakes on this cancer. We conducted a case-control study of diet and prostate cancer in western New York involving 433 men with primary, histologically confirmed prostate cancer and 538 population-based controls, frequency matched to cases on age and county of residence. Diet was assessed with a detailed food-frequency questionnaire. We calculated daily intakes of nutrients and the phytochemicals beta-sitosterol, campesterol, stigmasterol, total phytosterols, total lignan precursors, quercetin, and kaempferol based on published food composition data. Odds ratios (ORs) and 95% confidence intervals (CIs) describing the association of prostate cancer risk with selected nutrients, phytochemicals, and food groups were estimated with unconditional logistic regression. Compared with men in the lowest quartile of intake, reduced risks were observed for men in the highest quartile of intake of vitamin C (OR = 0.49; 95% CI = 0.33-0.74), beta-carotene (OR = 0.53; 95% CI = 0.36-0.79), alpha-carotene (OR = 0.67; 95% CI = 0.47-0.97), lutein (OR = 0.55; 95% CI = 0.37-0.81), lycopene (OR = 0.62; 95% CI = 0.42-0.92), total lignan precursors (OR = 0.66; 95% CI = 0.47-0.94), quercetin (OR = 0.64; 95% CI = 0.44-0.92), and total vegetables (OR = 0.53; 95% CI = 0.36-0.79), but weak increased risks were observed for snacks and sweets (OR = 1.46; 95% CI = 0.95-2.23). Estimates associated with nutrients and phytochemicals were attenuated after adjustment for total vegetable intake. Nevertheless, our results support the hypothesis that a phytochemical-rich, plant-based diet is of importance in reducing risks of hormone-related neoplasms.
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PMID:Intakes of selected nutrients, foods, and phytochemicals and prostate cancer risk in western New York. 1635 4

In the United States, the primary cancer in elderly men is prostate cancer (33% of newly diagnosed malignancies), but the prevalence is 75% lower in some Mediterranean countries. A possible explanation for the large difference in prostate cancer cases is that in Mediterranean countries the diet includes fish, olive oil and high amounts of nuts, fruits, vegetables, along with a regular intake of wine with meals several times per week. The LNCaP prostate cancer cells represent the nonaggressive androgen-dependent cell model that expresses moderate levels of cyclooxygenase-2 (COX-2). Epidemiological evidence indicates that polyphenolic compounds in diets are protective against cancer, and cyanidin and kaempferol are abundant in wine and plants. Therefore, the objective of the investigation was to determine the effects of cyanidin and kaempferol on prostaglandin E2 (PGE2) and COX-2 protein levels, and if peroxisome proliferator-activated receptor gamma (PPARgamma) and nuclear factor kappaB (NFkappaB) are involved in the expression of COX-2 in prostate cancer cells. Cyanidin and kaempferol at 1 microM reduced the level of PGE2 in LNCaP cell cultures and also attenuated the effect of arachidonic acid on increasing the amount of PGE2. Cyanidin reduced the levels of COX-2 protein in a dose- and time-dependent fashion. PPARgamma mRNA levels were lower in cells treated after 24 h with kaempferol (0.1 and 1 microM) and cyanidin (1 microM). The reduction of COX-2 mRNA by kaempferol and cyanidin may be mediated through the actions of NFkappaB and PPARgamma as nuclear factors that bind to the COX-2 gene promoter.
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PMID:Cyanidin attenuates PGE2 production and cyclooxygenase-2 expression in LNCaP human prostate cancer cells. 1644 60

In this work we describe the chemical composition of Pteleopsis suberosa (Combretaceae) leaf extract and its biological activity against androgen-insensitive human prostate cancer cells (DU-145). The methanol extract of the plant leaves exhibited activity against tumor cell growth. Fractionation of this active extract led to the isolation and identification of sixteen flavonoids, including gallocatechin and flavonols having kaempferol, quercetin, and myricetin as aglycones. Among the myricetin derivatives, myricetin 3-O-(3''-acetyl)-alpha-L-arabinopyranoside (1) and myricetin 3-O-(4''-acetyl)-alpha- L-arabinopyranoside (2) are now reported for the first time. Six compounds, myricetin 3-O-alpha- L-rhamnopyranoside (4), myricetin 3-O-beta-D-galactopyranoside (7), myricetin 3-O-(6''-galloyl)-beta-D-galactopyranoside (9), myricetin 3-O-beta-D-xylopyranoside (10), myricetin 3-O-alpha-L-arabinofuranoside (12), and gallocatechin (14), exhibited significant activity, reducing cell vitality and inducing apoptosis via the caspase-dependent pathway in DU-145 cells that can be, in part, correlated to modulation of redox-sensitive mechanisms.
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PMID:Antiproliferative activity of Pteleopsis suberosa leaf extract and its flavonoid components in human prostate carcinoma cells. 1663 67


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