Certain aspects of molecular endocrinology that relate to the influence of dietary factors on the pathogenesis of prostate cancer

Molecular Mechanism of the Role of Apigenin in the Treatment of Hyperlipidemia: A Network Pharmacology Approach

The therapeutic effect of apigenin (APG) on hyperlipidemia was investigated using network pharmacology combined with molecular docking strategy, and the potential targets of APG in the treatment of hyperlipidemia were explored. Genetic Ontology Biological Process (GOBP) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway enrichment analysis of common targets were performed. Then, molecular docking was used to predict the binding mode of APG to the target. Finally, Sprague Dawley rats were used to establish a hyperlipidemia model. The expression levels of insulin (INS) and vascular endothelial growth factor A (VEGFA) mRNA in each group were detected by quantitative reverse transcription-polymerase chain reaction. Network pharmacological studies revealed that the role of APG in the treatment of hyperlipidemia was through the regulation of INS, VEGFA, tumor necrosis factor, epidermal growth factor receptor, matrix metalloprotein 9, and other targets, as well as through the regulation of the hypoxia-inducible factor 1 (HIF-1) signaling pathway, fluid shear stress, and atherosclerosis signaling pathways, vascular permeability; APG also participated in the regulation of glucose metabolism and lipid metabolism, and acted on vascular endothelial cells, and regulated vascular tone. Molecular docking showed that APG binds to the target with good efficiency. Experiments showed that after APG treatment, the expression levels of INS and VEGFA mRNA in the model group were significantly decreased (p<0.01). In conclusion, APG has multiple targets and affects pathways involved in the treatment of hyperlipidemia by regulating the HIF-1 signaling pathway, fluid shear stress, and the atherosclerosis pathway.

African American Participation in Oncology Clinical Trials--Focus on Prostate Cancer: Implications, Barriers, and Potential Solutions

In the United States, the incidence and mortality rates of many cancers, especially prostate cancer, are disproportionately high among African American men compared with Caucasian men. Recently, mortality rates for prostate cancer have declined more rapidly in African American versus Caucasian men, but prostate cancer is still the most common cancer and the second leading cause of cancer deaths in African American men in the United States. Compared with Caucasian men, prostate cancer occurs at younger ages, has a higher stage at diagnosis, and is more likely to progress after definitive treatments in African American men. Reasons for racial discrepancies in cancer are multifactorial and potentially include socioeconomic, cultural, nutritional, and biologic elements. In addition to improving access to novel therapies, clinical trial participation is essential to adequately establish the risks and benefits of treatments in African American populations. Considering the disproportionately high mortality rates noted in these groups, our understanding of the natural history and responses to therapies is limited. This review will explore African American underrepresentation in clinical trials with a focus on prostate cancer, and potentially effective strategies to engage African American communities in prostate cancer research. Solutions targeting physicians, investigators, the community, and health care systems are identified. Improvement of African American participation in prostate cancer clinical trials will benefit all stakeholders.

Kaempferol and quercetin, components of Ginkgo biloba extract (EGb 761), induce caspase-3-dependent apoptosis in oral cavity cancer cells

EGb 761, extracted from Ginkgo biloba leaves, has been proven to induce caspase-3-dependent apoptosis in oral cavity cancer cells. Since EGb 761 is a composition of various components, it is important to identify which components are responsible for its anticancer effects to reduce the total dosage and to avoid toxicity. Therefore, the study aimed to determine the effective compounds of EGb 761 that induce apoptosis in oral cavity cancer cells and to identify whether caspase-3 was involved in apoptosis of oral cancer cells by EGb 761 components. The results of cell proliferation assays on oral cavity cancer cells showed that kaempferol and quercetin significantly inhibited cellular proliferation at a concentration of 40 microM. Flow cytometry showed that the antiproliferative effects of each component were due to increased apoptosis. Kaempferol and quercetin induced apoptosis in various oral cancer cell lines (SCC-1483, SCC-25 and SCC-QLL1) and showed cleavage of poly (ADP-ribose) polymerase (PARP). Caspase-3 activity assay revealed that induction of apoptosis by kaempferol and quercetin was caspase-3-dependent. In conclusion, the results suggest that kaempferol and quercetin, two components of EGb 761, effectively induce caspase-3-dependent apoptosis of oral cavity cancer cells and can be considered as possible anti-oral cavity cancer agents.

Extract of Ginkgo biloba induces glutathione-S-transferase subunit-P1 in vitro

The extract of Ginkgo biloba (EGb), containing 24% flavone glycosides and 6% terpenoids, is widely used to treat early-stage Alzheimer's disease, vascular dementia, peripheral claudication and vascular tinnitus. Its remarkable antioxidant activity has recently been demonstrated in both cell lines and animals. Glutathione-S-transferases (GSTs) are a class of important detoxification enzymes in the antioxidant system and GST-P1 is the major GST isoform highly expressed in human tissues. Over expression of GST-P1 protected prostate cells from cytotoxicity and DNA damage by the heterocyclic amine carcinogen, while inhibition of expression of GST-P1 by transfecting GST-P1 antisense cDNA or targeted deletion of GST-P1 has been found to sensitize cells to cytotoxic chemicals. It is obvious that induction of GST-P1 expression should be a promising alternative for chemoprevention. The present study aimed to investigate the induction effect of EGb on GST-P1 in HepG2 and Hep1c1c7 cell lines and found that GST-P1 was increased both at the expression and enzyme activity levels.

Epidemiology, pathology, and genetics of prostate cancer among African Americans compared with other ethnicities

Prostate cancer is the most common cancer affecting men in the Western world. In the United States, it is the second leading cause of cancer related deaths after lung and bronchus carcinoma. No definitive causes of prostate cancer (PCa) have been identified to date but, increasing age, a positive family history, and sub-Saharan African ancestry are strongly linked to its development. African American men (AAM) have the highest reported incidence rates in the United States and their mortality from the disease is markedly higher than that of European American men (EAM). Conversely, Asian American men and Pacific Islanders (API), American Indian and Alaskan Native (AI/AN) men, and Hispanic men all have lower incidence and mortality rates as compared with EAM. The reasons for these differences are unclear. However, it is clear that AAM have more advanced PCa when diagnosed. Several other reasons have been suggested and these include differences in treatments and health seeking behavior among the ethnic groups, cultural beliefs, environmental/lifestyle factors, dietary and genetic factors. In conclusion, there are multiple factors that impact prostate cancer outcome and that may be responsible for ethnic disparity. These factors are discussed in this chapter.

Genistein combined polysaccharide enhances activity of docetaxel, bicalutamide and Src kinase inhibition in androgen-dependent and independent prostate cancer cell lines

OBJECTIVE

To determine the benefit of genistein combined polysaccharide (GCP) in combination with the androgen receptor antagonist bicalutamide, the antimicrotubule taxane docetaxel, and the Src kinase inhibitor pp2 as part of a treatment regimen for advanced prostate cancer (CaP).

MATERIALS AND METHODS

The growth inhibitory and apoptotic effects of GCP in combination with bicalutamide, docetaxel and pp2 were evaluated in both the androgen-dependent LNCaP line, and three androgen-independent lines: CWR22Rv1, PC-3, and LNCaP-R273H. The LNCaP-R273H model is an LNCaP variant expressing a p53(GOF) allele; like CWR22Rv1 and PC-3, it is able to grow in a minimal androgen environment. The effects of GCP treatment in combination with the aforementioned drugs were measured using an MTT assay, Western blotting, flow cytometric analysis, and caspase activation assay. Altered schedules of drug administration were explored using combinations of GCP and docetaxel.

RESULTS

GCP potentiated the activity of docetaxel in all four cell lines, resulting in growth inhibition and increased apoptosis. The combination of GCP and bicalutamide had enhanced activity in both the LNCaP and LNCaP-R273H lines, which may better represent patient tumour cells after progression to androgen independence. Administration of docetaxel followed by GCP resulted in a synergistic interaction in LNCaP cells, with increased apoptosis. By contrast, GCP administered first showed subadditivity, probably resulting from GCP-mediated induction of G1 arrest interfering with docetaxel activity.

CONCLUSION

These data suggest that GCP, an isoflavone-enriched compound with minimal side-effects and far superior intestinal absorption rate of genistein, has significant clinical potential in combination with docetaxel, bicalutamide or targeted agents for the treatment of advanced CaP.

Effect of Genistein on the expression of Akt and phosphorylated Akts in human gastric carcinoma cell line

AIM: To investigate the effects of Genestein on the expression of Akt and its phosphorylated proteins (p-Akts) in human gastric carcinoma cell line SGC-7901.

METHODS: SGC-7901 cells were exposed to 0、5、10、20、40 and 80 μmol/L Genistein for 24 h. The effect of Genistein on cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay, and the apoptosis of SGC-7901 cells was evaluated by Hoechst 33342 staining. The expression of Akt and p-Akts (Ser473 and Thr308) were measured by Western blot.

RESULTS: The inhibitory rate was 6.85% ± 3.71%, 13.19% ± 1.90%, 20.94% ± 1.83%, 29.58% ± 1.19% and 41.75% ± 1.92%, respectively, as SGC-7901 cells were exposed to 5, 10, 20, 40 and 80 μmol/L Genistein for 24 h. Typical morphological changes of apoptosis were induced by Genistein at the concentrations (20-80 μmol/L). Genistein had no marked influences on Akt expression. Both Ser473 and Thr308 were expressed in SGC-7901 cells 24 h after Genistein treatment, and they were decreased with the increasing of Genistein concentrations. The weakest expression appeared as 80 μmol/L Genistein was used.

CONCLUSION: The anti-cancer action of Genistein may be associated with the decreased expression of p-Akt (Ser473) and p-Akt (Thr308).

Epidemiology and pathophysiology of prostate cancer in African-American men

PURPOSE

Along with increasing age and a positive family history subSaharan African ancestry has long been recognized as an important risk factor for prostate cancer. In the United States the incidence of prostate cancer is approximately 60% higher in African-American than in European-American men and the mortality rate from the disease is more than twice as high. The purpose of this review article is to examine specific reports highlighting racial disparity and its possible causes.

MATERIALS AND METHODS

The reports chosen for review of this epidemiology and pathophysiology study were included to demonstrate conditions in which racial differences as well as similarities exist in African-American and European-American men. Reports also include autopsy, biological and clinical studies, and early and late stage prostate cancer.

RESULTS

From the 1970s to the current statistical analysis of the National Cancer Institute Surveillance, Epidemiology, and End Results program African-American men have continued to have a significant higher incidence and mortality rate than European-American men. Autopsy studies show a similar prevalence of early small subclinical prostate cancers but a higher prevalence of high grade prostatic intraepithelial neoplasia. Clinical studies show a similarity in prostate cancer outcome when pathological stage is organ confined but a worse outcome when disease is locally advanced and metastatic in African-American vs European-American men. There is increasing genetic evidence that suggest that prostate cancer in African-American vs European-American men may be more aggressive, especially in young men.

CONCLUSIONS

Improving the outcome in African-American men with prostate cancer requires awareness of the epidemiological patterns of the disease and willingness on the part of physicians to implement targeted study initiatives with end points designed to detect the disease early in this population and begin appropriate management. It is proposed that a multi-institutional study should be done to demonstrate the ability to decrease racial outcome disparity by education, aggressive testing and treatment.

A review of the effects and mechanisms of polyphenolics in cancer

This paper is a comprehensive review of the effects of bioactive polyphenolic compounds commonly found in many fruits and vegetables on cancer. These include the pheniolic acids, anthocyanins, catechins, stilbenes and several other flavonoids. We have attempted to compile information from most of the major studies in this area into one source. The review encompasses the occurrence and bioavailability of the polyphenolics, the in vitro and in vivo evidence for their effects on cancer, both positive and negative, and the various mechanisms by which the chemicals may exert their effects. Although most of the work done to date indicates a chemopreventative activity of these compounds, there are some studies that show cancer-inducing or no effects. There are several common mechanisms by which these chemicals exert their effects that could be conducive to additive, synergistic, or antagonistic interactions. These include effects on cellular differentiation, proliferation, and apoptosis, effects on proteins and enzymes that are involved in these processes at a molecular level, and other various effects through altered immune function and chemical metabolism.

Ginkgo biloba extract (EGb 761) induces apoptosis by the activation of caspase-3 in oral cavity cancer cells

We have investigated whether Ginkgo biloba extract (EGb 761) induces apoptosis of oral cavity cancer cells and attempted to characterize the apoptotic pathway activated by EGb 761. The inhibition of SCC 1483 oral cavity cancer cells proliferation was noted from 250 micro/ml of EGb 761. Apoptosis was observed after 24 h of incubation with 250 microg/ml EGb 761 and occurred in a time- and dose-dependent manner. Apoptosis was confirmed by DNA fragmentation and PARP cleavage. Co-treatment with the caspase inhibitor (z-VAD-fmk) inhibited apoptosis and PARP cleavage induced by EGb 761. Caspase-3 activity was upregulated by EGb 761 but reduced to the control level by co-treating with z-VAD-fmk. In summary, EGb 761 induces apoptosis of oral cavity cancer cells and caspase-3 is activated in this apoptosis. Therefore, EGb 761 may be considered as a possible chemopreventive agent against oral cavity cancer.

Modulation of anti-adhesion molecule MUC-1 is associated with arctiin-induced growth inhibition in PC-3 cells

BACKGROUND

Lignans have been reported to possess anti-tumor activity in various cancer cells. However, their anticancer effects in human prostate cancer have not been well established. Here, we examine the effect of arctiin, a lignan compound, on growth regulation in prostate cancer PC-3 cells. We postulated that arctiin modulates the attachment/detachment of PC-3 cells and we investigated the role of arctiin on MUC-1 expression.

METHODS

The effect of arctiin on PC-3 cell growth was examined using an MTT assay method and cell number was calculated by means of a standard regression line. The expressions of MUC-1 and integrins alpha2, alpha5, and beta1 were detected using FACScan flow cytometric analysis. Levels of MUC-1 mRNA were determined using reverse transcriptase PCR (RT-PCR).

RESULTS

Treatment of PC-3 cells with arctiin decreased the cell number in a concentration- and time-dependent manner in serum-containing condition. Arctiin preferentially induced cell detachment, but did not have anti-proliferation or cytotoxic effects in PC-3 cells. The arctiin-induced effect was inhibited by cycloheximide, indicating that protein synthesis was required. FACScan flow cytometric analysis demonstrated that arctiin increased the expression of the anti-adhesion mucin MUC-1, but did not affect integrin expression in PC-3 cells. The arctiin-induced increase in MUC-1 protein expression was due to up-regulation of mRNA, as revealed by RT-PCR analysis.

CONCLUSIONS

Arctiin significantly induces cell detachment and decreases the cell numbers via the up-regulation of MUC-1 mRNA and protein in PC-3 cells.

Anti-angiogenesis and angioprevention: mechanisms, problems and perspectives

The recognition that angiogenesis is a key early event in tumor progression and metastasis has led to the development of new strategies for cancer therapy. The generation of a new blood vessel network under physiological conditions is regulated by the concerted action of activators and inhibitors. Perturbation of this balance, as it occurs in solid tumor growth and metastasis, appears to be a critical point in tumorigenesis. This has led to the "angiogenic switch" hypothesis: the point at which a tumor acquires the potential to induce angiogenesis is a critical step towards malignancy. Based on experimental evidence, prevention of blood vessel development appears to be the mechanism of action of many successful chemopreventive drugs of natural or synthetic origin: a novel concept that we termed "angioprevention". The hypothesis that anti-angiogenesis is at the basis of tumor prevention also suggests that many anti-angiogenic drugs could be used for chemoprevention in higher risk populations or in early intervention. There is a growing body of experimental evidence that anti-angiogenic strategies will contribute to the future therapy of cancer, several compounds with anti-angiogenic properties are now under clinical investigation including anti-inflammatory compounds, as inflammation may play a key role in angiogenesis. We must persevere in the development of novel, powerful and safer angiogenesis inhibitors and in the use of anti-angiogenic drugs in combination with other natural or synthetic anti-cancer agents in a biological therapy strategy.

Ginkgo biloba extracts and cancer: a research area in its infancy

Recent studies conducted with various molecular, cellular and whole animal models have revealed that leaf extracts of Ginkgo biloba may have anticancer (chemopreventive) properties that are related to their antioxidant, anti-angiogenic and gene-regulatory actions. The antioxidant and associated anti-lipoperoxidative effects of Ginkgo extracts appear to involve both their flavonoid and terpenoid constituents. The anti-angiogenic activity of the extracts may involve their antioxidant activity and their ability to inhibit both inducible and endothelial forms of nitric oxide synthase. With regard to gene expression, a Ginkgo extract and one of its terpenoid constituents, ginkgolide B, inhibited the proliferation of a highly aggressive human breast cancer cell line and xenografts of this cell line in nude mice. cDNA microarray analyses have shown that exposure of human breast cancer cells to a Ginkgo extract altered the expression of genes that are involved in the regulation of cell proliferation, cell differentiation or apoptosis, and that exposure of human bladder cancer cells to a Ginkgo extract produced an adaptive transcriptional response that augments antioxidant status and inhibits DNA damage. In humans, Ginkgo extracts inhibit the formation of radiation-induced (chromosome-damaging) clastogenic factors and ultraviolet light-induced oxidative stress - effects that may also be associated with anticancer activity. Flavonoid and terpenoid constituents of Ginkgo extracts may act in a complementary manner to inhibit several carcinogenesis-related processes, and therefore the total extracts may be required for producing optimal effects.

[Diet and prostate cancer]

Prostate cancer is the first neoplasia in the United States accounting the second in cancer deaths. With all the treatments strategies in debate because of their side effects, is very important try to elucidate prevention mechanisms that may be implicate in the development of this disease, between these, nutrients have been of mayor importance. In the present review we tried to study the most important nutritional factors implicated in the development and prevention of prostate carcinoma. We focus our attention over the polyphenols of the red wine, which influence over cellular proliferation and apoptosis in LNCaP cells have been studied in our Department.

Dietary flaxseed inhibits human breast cancer growth and metastasis and downregulates expression of insulin-like growth factor and epidermal growth factor receptor

Recent studies indicate that diets rich in phytoestrogens and n-3 fatty acid have anticancer potential. This study determined the effect of flaxseed (FS), the richest source of lignans and alpha-linolenic acid, on growth and metastasis of established human breast cancer in a nude mice model. Estrogen receptor-negative human breast cancer cells, MDA-MB-435, were injected into the mammary fat pad of mice (Ncr nu/nu) fed a basal diet (BD). At Week 8, mice were randomized into two diet groups, such that the groups had similar tumor size and body weight. One continued on the BD, while the other was changed to BD supplemented with 10% FS, until sacrifice at Week 15. A significant reduction (P < 0.05) in tumor growth rate and a 45% reduction (P = 0.08) in total incidence of metastasis were observed in the FS group. Lung metastasis incidence was 55.6% in the BD group and 22.2% in the FS group, while the lymph node metastasis incidence was 88.9% in the BD group and 33.3% in the FS group (P < 0.05). Mean tumor number (tumor load) of total and lymph node metastasis was significantly lower in the FS than in the BD group (P < 0.05). Metastatic lung tumor number was reduced by 82%, and a significantly lower tumor trend (P < 0.01) was observed in the FS group. Lung weight, which also reflects metastatic tumor load, in the FS group was reduced by 20% (P < 0.05) compared with the BD group. Immunohistochemical study showed that Ki-67 labeling index and expression of insulin-like growth factor I and epithelial growth factor receptor in the primary tumor were lower in the FS (P < 0.05) than in the BD group. In conclusion, flaxseed inhibited the established human breast cancer growth and metastasis in a nude mice model, and this effect is partly due to its downregulation of insulin-like growth factor I and epidermal growth factor receptor expression.

The experience of Japan as a clue to the etiology of testicular and prostatic cancers

In Japan dramatic lifestyle changes occurred after World War 2. To examine the experience of Japan as a clue to the etiology, trends in the mortality rates of testicular and prostatic cancers from 1947 to 1998 were related to changes in dietary practices. The male population born before 1945 had a peak in death from testicular cancer in their thirties or forties, whereas those born after 1946 had a peak in their twenties. The death rate of prostatic cancer increased 25-fold almost linearly after the war. The intake of milk, meat, and eggs increased 20-, 9-, and 7-fold, respectively, after the war. In connection with the development and growth of testicular and prostatic cancers in Japan, particular attention should be paid to milk, because the increase in its consumption in this country is a recent occurrence and because milk contains considerable amounts of estrogens plus saturated fats.

Genistein inhibits vitamin D hydroxylases CYP24 and CYP27B1 expression in prostate cells

In human prostate cancer cells, the availability of the steroid hormone 1,25-dihydroxyvitamin D(3) for antimitotic action is determined through the activity of the two enzymes CYP24 and CYP27B1, viz. 25-hydroxyvitamin D-24-hydroxylase and 25-hydroxyvitamin D-1alpha-hydroxylase. High performance liquid chromatography (HPLC) analysis of [(3)H]25(OH)D(3) metabolism in human prostate cancer DU-145 cells revealed that genistein and other isoflavonoids, such as dihydrogenistein and daidzein, as well as the antiestrogenic compound ICI 182,780, inhibited Vitamin D-metabolizing enzyme activities. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that only in case of genistein this was due to transcriptional inhibition of CYP24 and CYP27B1 gene expressions. In case of CYP27B1, reduction of gene activity involves histone deacetylation because genistein was inactive in the presence of the histone deactylase inhibitor trichostatin A. In contrast, under the same condition, CYP24 gene activity was largely suppressed. In summary, our results suggest that a combined effect of genistein and trichostatin A could increase the responsiveness of human prostate cancer cells to the antiproliferative action of 1,25-dihydroxyvitamin D(3).

Steroid hormone genotypes ARStuI and ER325 are linked to the progression of human prostate cancer

Steroid hormones and their receptors are involved as initiators or promoters in prostate carcinogenesis. The intrauterine-perinatal period and maternal estrogen and testosterone levels have been proposed to be of etiologic importance in prostate tumorigenesis and cancer progression. The objective of this study was to analyze genetic polymorphisms in the androgen receptor ARStuI by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and in the estrogen receptor ER325 by PCR-single-strand conformational polymorphism (PCR-SSCP). In our study of 170 prostate cancer patients, ARStuI and ER325 genotypes and their association with disease progression and metastasis were analyzed. Age-adjusted logistic regression analysis indicates the association of ARStuI S1 allele with high-grade tumor (P = 0.033; OR = 3.0, 95% CI = 1.1-8.3) and the association of ER325 with high-grade tumor (P = 0.003; OR = 3.0, 95% CI = 1.4-6.4), advanced disease (P = 0.020; OR = 2.4, 95% CI = 1.1-5.1), risk of progression (P = 0.027; OR = 2.5, 95% CI = 1.1-5.7) and the presence of metastatic disease (P = 0.006; OR = 3.1, 95% CI = 1.4-6.8). In summary, this study has demonstrated androgen receptor (ARStuI) and estrogen receptor (ER325) genetic polymorphisms in prostate cancer patients and its association with disease progression and metastasis. Our results support the hypothesis that genetic factors related to steroid hormone receptors may influence the behavior of human prostate cancer.

Non-nutrient bioactive substances of pulses

Pulses supply many bioactive substances found in minor amounts in food, but which may have significant metabolic and/or physiological effects. These compounds have long been classified as antinutritional factors, but many studies have reconsidered their impact on health. Some could play a role in the prevention of the major diseases of affluent societies. As these compounds can be beneficial or adverse, depending on conditions, an assessment of their various physiological effects is necessary to determine whether they should be preserved or eliminated in each main nutritional situation.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

Phytoestrogens regulate vitamin D metabolism in the mouse colon: relevance for colon tumor prevention and therapy

Soybean products are highly represented in the traditional Asian diet. Major components of soy proteins are phytoestrogens, such as isoflavones. They may be responsible for the extremely low incidence of prostate and mammary tumors and possibly also of colon cancer in countries such as China and Japan. Serum 1,25-dihydroxyvitamin D3 level is inversely related to incidence of some cancers. Levels are determined by skin exposure to ultraviolet light or, to a minor extent, nutritional uptake and by subsequent conversion of the precursor vitamin D to the active hormone by the cytochrome P450 hydroxylases CYP27A1, CYP27B1 (responsible for synthesis) and CYP24 (responsible for catabolism) in liver and kidney. However, vitamin D synthesis is also found in colonocytes and is enhanced during incipient malignancy. This may indicate an autocrine/paracrine role for this differentiation-inducing hormone in defense against progression. We were able to demonstrate that either a single large oral dose of genistein or feeding soy protein for 4 mo elevated CYP27B1 and decreased CYP24 expression in the mouse colon. Our data therefore suggest that an inverse correlation of soy product consumption with colon tumor incidence may be consequent to enhanced colonic synthesis of the antimitotic hormone 1,25-dihydroxyvitamin D3.

Enterolignans

A review with 114 references about mammalian lignans (enterolignans). Several aspects have been reviewed: the precursors of mammalian lignans and their biosynthesis, biological activities and health effects, metabolism (in vivo and in vitro) in human and animals, some synthetic strategies to obtain enterolignan skeleton types, including the synthesis of haptens and deuterated lignans, and finally an overview of the analytical methods to detect and quantify lignans in biological matrices and foods.

Antiangiogenic mechanisms of diet-derived polyphenols

Accumulating evidence demonstrates that polyphenols in natural products are beneficial against human lethal diseases such as cancer and metastasis. The underlying mechanisms of anti-cancer effects are complex. Recent studies show that several polyphenols, including epigallocatechin-3-gallate (EGCG) in green tea and resveratrol in red wine, inhibit angiogenesis when administrated orally. These polyphenols have direct effects on suppression of angiogenesis in several standard animal angiogenesis models. Because angiogenesis is involved in many diseases such as cancer, diabetic retinopathy and chronic inflammations, the discovery of these polyphenols as angiogenesis inhibitors has shed light on the health beneficial mechanisms of natural products, which are rich in these molecules. At the molecular level, recent studies have provided important information on how these molecules inhibit endothelial cell growth. Perhaps the greatest therapeutic advantage of these small natural molecules over large protein compounds is that they can be administrated orally without causing severe side effects. It is anticipated that more polyphenols in natural products will be discovered as angiogenesis inhibitors and that these natural polyphenols could serve as leading structures in the discovery of more potent, synthetic angiogenesis inhibitors.

Incidence and mortality of testicular and prostatic cancers in relation to world dietary practices

The incidence and mortality rates of testicular and prostatic cancers in 42 countries were correlated with the dietary practices in these countries using the cancer rates (1988-92) provided by the International Agency for Research on Cancer (IARC) and the food supply data (1961-90) provided by the Food and Agriculture Organization (FAO). Among the food items we examined, cheese was most closely correlated with the incidence of testicular cancer at ages 20-39, followed by animal fats and milk. The correlation coefficient (r) was highest (r = 0.804) when calculated for cheese consumed during the period 1961-65 (maternal or prepubertal consumption). Stepwise-multiple-regression analysis revealed that milk + cheese (1961-65) made a significant contribution to the incidence of testicular cancer (standardized regression coefficient [R] = 0.654). Concerning prostatic cancer, milk (1961-90) was most closely correlated (r = 0.711) with its incidence, followed by meat and coffee. Stepwise-multiple-regression analysis identified milk + cheese as a factor contributing to the incidence of prostatic cancer (R = 0.525). The food that was most closely correlated with the mortality rate of prostatic cancer was milk (r = 0.766), followed by coffee, cheese and animal fats. Stepwise-multiple-regression analysis revealed that milk + cheese was a factor contributing to mortality from prostatic cancer (R = 0.580). The results of our study suggest a role of milk and dairy products in the development and growth of testicular and prostatic cancers. The close correlation between cheese and testicular cancer and between milk and prostatic cancer suggests that further mechanistic studies should be undertaken concerning the development of male genital organ cancers.

The role of soy phytoestrogens in prostate cancer

Epidemiological data of phytoestrogens and prostate cancer strongly supports the cancer protective effects of isoflavones found in soy products. Inhibition of cell proliferation via hormone-dependent and hormone-independent mechanisms by soy phytochemicals has been studied extensively in cell culture and animal studies. Herein, we review the current literature on the epidemiology and effects of two soy phytoestrogens, genistein and daidzein, and would stress the need for controlled human trials to assess the true preventive and therapeutic effects of these compounds.

Green tea and prostate cancer

Many laboratory studies and human epidemiological data suggest that most prostate cancer deaths are attributable to lifestyle, including nutritional factors where diet plays a major role in initiation as well as subsequent progression of the disease. Under these circumstances, chemoprevention seems to be a logical and obvious strategy. Because of its long latency and high incidence, prostate cancer is an ideal disease for chemoprevention. The suitable agent(s) for prostate cancer chemoprevention should be the one(s) that has efficacy in the laboratory experiments on one hand, and also possesses proven epidemiological basis on the other hand. In this article, we address the use of green tea for prostate cancer chemoprevention. Experimental as well as the epidemiological basis for this possibility is provided.

The effect of isoflavone extract ingestion, as Trinovin, on plasma steroids in normal men

Plasma testosterone, dihydrotestosterone, androstenedione, dehydroepiandrosterone sulfate, androsterone and epiandrosterone sulfates, cortisol and sex hormone binding globulin were measured in six adult men before and during daily isoflavone extract ingestion (40 mg) in the form of Trinovin tablets. Although modest plasma genistein levels were achieved following three weeks of Trinovin ingestion (106-356 nmol/l) there were no significant changes in most of the analytes tested. However plasma levels of dihydrotestosterone showed an increase that reached significance when combined basal levels were compared to levels following Trinovin treatment. The results suggest that the daily ingestion of isoflavones in the form of Trinovin (1 tablet/day), over a short term, does not alter most plasma steroid levels. We therefore question the value of Trinovin, at the recommended dosage, as offering protective effects against prostate disease by mechanisms involving either significant modulation of plasma steroid or SHBG levels. In contrast the increase in dihydrotestosterone plasma levels could be seen as possibly detrimental.

Angioprevention': angiogenesis is a common and key target for cancer chemopreventive agents

The potential to block tumor growth by inhibition of the neoangiogenic process represents an intriguing approach to the treatment of solid tumors. The high proliferation rate in the tumor deprived of proper vascularization would be balanced by cell death due to lack of diffusion of nutrients and oxygen. Matrix metalloproteinases (MMPs), angiogenic growth factors, and their receptors are the main targets of an increasing number of clinical trials approved to test the tolerance and therapeutic efficacy of antiangiogenic agents. We observed that a series of substances proposed as possible cancer chemopreventive agents show antiangiogenic properties when tested in in vitro and in vivo angiogenesis models. We demonstrated that N-acetyl-l-cysteine is able to reduce the invasive and metastatic potential of melanoma cells, and to inhibit endothelial cell invasion by direct inhibition of MMP activity. We also showed that epigallocatechin gallate (EGCG), a flavonoid from green tea that possesses chemopreventive activity in experimental and epidemiological studies, is a potent inhibitor of MMP-2 and MMP-9. Angiogenesis has also been demonstrated to be a target for nonsteroidal anti-inflammatory drug chemopreventive activity. Based on these data, we hypothesize that other chemopreventive agents, including natural or synthetic retinoids, steroid hormone antagonists, peroxisome proliferator-activated receptor gamma ligands, vitamin D, and protease inhibitors, might have antiangiogenesis as an important mechanism of action, a novel concept we will term 'angioprevention'. We analyze the mechanisms on how and why chemopreventive agents could exert antiangiogenic effects aimed at controlling tumor growth, and their potential use in the clinic.

Aromatase inhibitors: past, present and future

For the cellular physiology of sex steroid sensitive cells, the androgen/estrogen ratio may be more important than only one hormone action per se, in both sexes. This ratio is controlled in vertebrates by aromatase; its gene expression can be inhibited in different ways, and this is crucial for the treatment of estrogen-dependent diseases such as breast cancer, or gynecomastia in males for instance. To reach this goal, new steroidal and non-steroidal inhibitors are continuously being developed, and some of them are used as first or second line agents. Aromatase inhibition is also an essential tool for studying the role of estrogens in the adult, or during development. Aromatase inhibitors have shown in particular that estrogens are essential also in males for skeletal maturation and bone mineralization, development of masculine dendritic morphology in male brain linked to mating behaviour, and testicular function. Testosterone is often the prohormone converted in situ in active estrogens, at these levels. Several strategies can be used for aromatase inhibition. The first ones employed were blind screening or deductions from in vivo observations, which led for instance to the discovery of the role of aminoglutethimide in aromatase inhibition. Subsequently, in the years 1975-1990, the molecular modeling of compounds to mimic the substrate shape of the enzyme constituted the major idea. Hundreds of chemicals were synthesized by numerous authors, ranging from the well-known and very efficient 4-OHA to complicated imidazole or indane derivatives tested by sophisticated comparative molecular field analyses. Reticulum-bound active aromatase has not as yet been X-ray analyzed. Thus, aromatase inhibitors were also used more recently to probe and understand the active site conformation of the enzyme and its modelization was obtained from comparisons with bacterial-related cytochromes. We developed a mammalian model considerably closer to human aromatase in order to study the active site shape with new potent aromatase non-steroidal inhibitors. This model is equine aromatase. This enzyme was biochemically characterized, purified, and cloned by our group. It allowed testing, by site-directed mutagenesis, predictive hypotheses in human aromatase which contributed to designing of new inhibitors. The understanding of the functioning of an essential member of the cytochrome P450 family, which is necessary for cellular detoxification, was also facilitated. Inhibition of aromatase activity has also been carried out with antibodies directed to the catalytic site and at the gene level by knock-out or by control of factor-specific promoters. This may result in different mRNA synthesized by alternative splicing. We have also obtained specific inhibition of aromatase activity in human cells with antisense stable phosphorothioate oligodeoxynucleotides directed against aromatase mRNA tertiary structures. Besides known steroidal and non-steroidal inhibitors, the antiaromatase effects of compounds found in our daily environment such as dietary flavonoids or xenobiotic pollutants have also been described. Finally, we underline that all these aromatase inhibitors, or methods of aromatase inhibition, can modulate the estrogenic balance essential not only for female, but also for male physiology, including gonadal function.

Therapeutic potential of curcumin in human prostate cancer. III. Curcumin inhibits proliferation, induces apoptosis, and inhibits angiogenesis of LNCaP prostate cancer cells in vivo

BACKGROUND

Earlier work from our laboratory highlighted the therapeutic potential of curcumin (turmeric), used as a dietary ingredient and as a natural anti-inflammatory agent in India and other Southeast Asian countries. This agent was shown to decrease the proliferative potential and induce the apoptosis potential of both androgen-dependent and androgen-independent prostate cancer cells in vitro, largely by modulating the apoptosis suppressor proteins and by interfering with the growth factor receptor signaling pathways as exemplified by the EGF-receptor. To extend these observations made in vitro and to study the efficacy of this potential anti-cancer agent in vivo, the growth of LNCaP cells as heterotopically implanted tumors in nude mice was followed.

METHODS

The androgen-dependent LNCaP prostate cancer cells were grown, mixed with Matrigel and injected subcutaneously into nude mice. Experimental group received a synthetic diet containing 2% curcumin for up to 6 weeks. At the end point, sections taken from the excised tumors were evaluated for pathology, cell proliferation, apoptosis, and vascularity.

RESULTS

Curcumin causes a marked decrease in the extent of cell proliferation as measured by the BrdU incorporation assay and a significant increase in the extent of apoptosis as measured by an in situ cell death assay. Moreover, a significant decrease in the microvessel density as measured by the CD31 antigen staining was also seen.

CONCLUSIONS

Curcumin could be a potentially therapeutic anti-cancer agent, as it significantly inhibits prostate cancer growth, as exemplified by LNCaP in vivo, and has the potential to prevent the progression of this cancer to its hormone refractory state.

Preprostatectomy: A clinical model to study stromal-epithelial interactions

The preprostatectomy setting serves as a valuable clinical model for early developmental clinical trials for evaluating promising agents for chemoprevention. In the preprostatectomy model, study agents are administered between the diagnostic biopsy for prostate cancer and definitive therapy. The prostatic tissue that is available after prostatectomy allows for biomarker evaluation of all the components of the prostate, including the glandular epithelium, blood vessels, and the stroma. This provides an opportunity to study the reciprocal interactions between the stroma and the epithelium. Morphologic studies suggest that prostatic stromal cells play a critical role in affecting the growth and maturation of prostatic epithelium. Experimental studies in tissue culture show that carcinoma-associated stromal cells can promote prostatic carcinogenesis, and normal stromal cells may be able to inhibit prostatic carcinogenesis by inducing differentiation and decreasing the proliferation of the epithelium. Although the complex molecular mechanisms through which stroma modulates the epithelial cell phenotype remain to be elucidated, there are several well-characterized signaling pathways, such as for growth factors and steroid hormones, that are likely to contribute to the modulation of transformed epithelial cells. There is evidence of an association between increased serum levels of IGF-I and an increased risk of prostate cancer. The IGF system appears to play an important role in the development of prostate cancer by modulation of paracrine pathways, and also by modulation of the concentrations of different stromal and epithelial IGFBP, which are differentially expressed in the epithelium and stroma. Nerve growth factor is capable of stimulating a proliferative response via a high affinity Trk receptor present in normal and malignant prostate epithelia, and alternatively can mediate apoptosis via the low affinity p75NTR receptor that is progressively lost from the malignant prostate. As the role of each stromal element involved in carcinogenesis becomes further defined, these elements offer promising targets for new chemopreventive strategies.

Comparison of plasma and urinary phytoestrogens in Japanese and Finnish women by time-resolved fluoroimmunoassay

Time-resolved fluoroimmunoassays (TR-FIA), with europium labeled phytoestrogens as tracers, were developed for the quantitative measurement of genistein, daidzein and enterolactone in plasma and urine for the purpose of screening large populations and studies on possible correlation between the values in biological fluids and the risk of western diseases. The mean values of the three phytoestrogens in plasma as determined by TR-FIA were similar to those obtained by gas chromatography-mass spectrometry (GC-MS). The urinary excretion levels of total individual phytoestrogens were higher than those obtained by GC-MS, with the exception of the daidzein values. However, comparing the assay results obtained by the present method and those obtained by GC-MS, a strong correlation was evident (r = 0.87 - 0.99, p < 0.001). We measured plasma levels of genistein, daidzein and enterolactone in 111 healthy Japanese women The mean and median levels of genistein were 406.8 and 306.3 nmol/l, respectively, and those of daidzein were 118.4 and 76.8 nmol/l, respectively. These levels are higher than those reported for Americans and Western Europeans. Isoflavone intake as calculated from dietary records (genistein: mean, 86.5 mircomol/day and daidzein: mean, 57.4 micromol/day) was correlated with the plasma concentrations observed (genistein: r = 0.287, p < 0.01 and daidzein: r = 0.313, p < 0.01). Plasma enterolactone levels were low in Japanese women (mean, about 10 nmol/l). The levels of urinary excretions of genistein, daidzein were also measured and it was found that, in the majority, the levels ranged between 5-25 and 5-50 micromol/24 h, respectively. In contrast, healthy Finnish women showed very low values of isoflavones (below 10 nmol/l in plasma (n = 87) and below 0.6 micromol/24 h in urine (n = 126) for both compounds) and high levels of enterolactone in both plasma and urine (plasma: mean, 25 nmol/l and urine: majority range, 1-7 micromol/24 h).

Promotion of health by soy isoflavones: efficacy, benefit and safety concerns

Cardiovascular diseases, osteoporosis-related hip fractures, and various cancers of the colon, prostate, uterus, and breast are remarkably less prevalent in Asia than in other industrialized countries. It is believed that the large consumption of soy products in Asian countries is contributory to the reduction of these chronic disorders. Genistein is a major isoflavone found in most soy products and plays an important role in the promotion of human health. Extensive epidemiological, in vitro, and animal studies have been performed, and most studies indicate that genistein has beneficial effects on a multitude of human disorders, including cancers, cardiovascular diseases, osteoporosis, and postmenopausal symptoms. To date, there is an abundance of promising studies supporting genistein's potential uses, but further research is still needed to validate its preventative and therapeutic efficacy. In addition, the adverse effects of genistein have drawn public attention. More studies are required to assess the potential detrimental effect of genistein, and a benefit-risk ratio should be considered before future clinical studies are performed.