Inhibition of human aromatase by mammalian lignans and isoflavonoid phytoestrogens

In Vitro Effects of Combining Genistein with Aromatase Inhibitors: Concerns Regarding Its Consumption during Breast Cancer Treatment

INTRODUCTION

The third-generation of aromatase inhibitors (AIs)-Exemestane (Exe), Letrozole (Let), and Anastrozole (Ana)-is the main therapeutic approach applied for estrogen receptor-positive (ER+) breast cancer (BC), the most common neoplasm in women worldwide. Despite their success, the development of resistance limits their efficacy. Genistein (G), a phytoestrogen present in soybean, has promising anticancer properties in ER+ BC cells, even when combined with anticancer drugs. Thus, the potential beneficial effects of combining G with AIs were investigated in sensitive (MCF7-aro) and resistant (LTEDaro) BC cells.

METHODS

The effects on cell proliferation and expression of aromatase, ERα/ERβ, and AR receptors were evaluated.

RESULTS

Unlike the combination of G with Ana or Let, which negatively affects the Ais' therapeutic efficacy, G enhanced the anticancer properties of the steroidal AI Exe, increasing the antiproliferative effect and apoptosis relative to Exe. The hormone targets studied were not affected by this combination when compared with Exe.

CONCLUSIONS

This is the first in vitro study that highlights the potential benefit of G as an adjuvant therapy with Exe, emphasizing, however, that soy derivatives widely used in the diet or applied as auxiliary medicines may increase the risk of adverse interactions with nonsteroidal AIs used in therapy.

Dietary Modulation of the Human Gut Microbiota and Metabolome with Flaxseed Preparations

Flaxseeds are typically consumed either as whole flaxseed, ground flaxseed, flaxseed oil, partially defatted flaxseed meal, or as a milk alternative. They are considered a rich source of vitamins, minerals, proteins and peptides, lipids, carbohydrates, lignans, and dietary fiber, which have shown hypolipidemic, antiatherogenic, anticholesterolemic, and anti-inflammatory property activity. Here, an in vitro batch culture model was used to investigate the influence of whole milled flaxseed and partially defatted milled flaxseed press cake on the gut microbiota and the liberation of flaxseed bioactives. Microbial communities were profiled using 16S rRNA gene-based high-throughput sequencing with targeted mass spectrometry measuring lignan, cyclolinopeptide, and bile acid content and HPLC for short-chain fatty acid profiles. Flaxseed supplementation decreased gut microbiota richness with Firmicutes, Proteobacteria, and Bacteroidetes becoming the predominant phyla. Secoisolariciresinol, enterodiol, and enterolactone were rapidly produced with acetic acid, butyric acid, and propionic acid being the predominant acids after 24 h of fermentation. The flaxseed press cake and whole flaxseed were equivalent in microbiota changes and functionality. However, press cake may be superior as a functional additive in a variety of foods in terms of consumer acceptance as it would be more resistant to oxidative changes.

Consumption of flavonoids and risk of hormone-related cancers: a systematic review and meta-analysis of observational studies

BACKGROUND

Flavonoids seem to have hormone-like and anti-hormone properties so that the consumption of flavonoids may have potential effects on hormone-related cancers (HRCs), but the findings have been inconsistent so far. This meta-analysis was aimed to explore the association between flavonoids intake and HRCs risk among observational studies.

METHODS

Qualified articles, published on PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI) from January 1999 to March 2022 and focused on relationships between flavonoids (total, subclass of and individual flavonoids) and HRCs (breast, ovarian, endometrial, thyroid, prostate and testicular cancer), were retrieved for pooled analysis. Random effects models were performed to calculate the pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Funnel plots and Begg's/Egger's test were used to evaluate the publication bias. Subgroup analyses and sensitivity analyses were conducted to explore the origins of heterogeneity.

RESULTS

All included studies were rated as medium or high quality. Higher consumption of flavonols (OR = 0.85, 95% CI: 0.76-0.94), flavones (OR = 0.85, 95% CI: 0.77-0.95) and isoflavones (OR = 0.87, 95% CI: 0.82-0.92) was associated with a decreased risk of women-specific cancers (breast, ovarian and endometrial cancer), while the higher intake of total flavonoids was linked to a significantly elevated risk of prostate cancer (OR = 1.11, 95% CI: 1.02-1.21). A little evidence implied that thyroid cancer risk was augmented with the higher intake of flavones (OR = 1.24, 95% CI: 1.03-1.50) and flavanones (OR = 1.31, 95% CI: 1.09-1.57).

CONCLUSIONS

The present study suggests evidence that intake of total flavonoids, flavonols, flavones, flavanones, flavan-3-ols and isoflavones would be associated with a lower or higher risk of HRCs, which perhaps provides guidance for diet guidelines to a certain extent.

TRIAL REGISTRATION

This protocol has been registered on PROSPERO with registration number CRD42020200720 .

Dietary fiber in the prevention of obesity and obesity-related chronic diseases: From epidemiological evidence to potential molecular mechanisms

Obesity is a mostly preventable diet-related disease and currently a major challenge for human populations worldwide. Obesity is a major risk factor for diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease (CVD) and certain cancers. Dietary fiber is a complex mixture of non-digestible molecules, mostly polysaccharides. Multiple epidemiological studies have demonstrated statistically significant reductions in risks of obesity, T2DM, CVD, colorectal cancer, and pre-menopausal breast cancer with higher dietary fiber intakes. Various direct and indirect mechanisms have been proposed including altered digestion and absorption, stimulation of gut hormones including glucagon-like-peptide-1 (GLP-1) and peptide YY (PYY), reduced appetite, and altered metabolism of bile and cholesterol. These may act via pathways involving G-protein-coupled receptors (GPRs), histone deacetylase (HDAC), and aromatase enzymes. Ultimately, fiber intake contributes to improving glucose levels and insulin sensitivity, lowering risk of T2DM, CVD and certain cancers. Therefore, diets rich in dietary fiber should be encouraged to prevent obesity and associated chronic disease.

The Impact of Macronutrient Intake on Sex Steroids During Onset of Puberty

INTRODUCTION

Increased fiber intake has been associated with decreased breast cancer risk, while increased animal protein intake with increased risk. The objective of this study is to examine the relationship of dietary fiber and protein intake to estrogen and sex hormone-binding globulin (SHBG) concentrations at puberty onset.

METHODS

These analyses were conducted using the Cincinnati puberty cohort of the Breast Cancer and the Environment Research Program, with girls followed every 6 months from ages 6 and 7. The analyses included serum measurements at 6-month intervals for estrogen and SHBG concentrations, from 18 months prior to breast stage 2 (onset of puberty). Dietary intake was documented via 24-hour dietary recalls every 3 months. Dietary factors of interest included total energy intake; total and animal protein; total, soluble, and insoluble fiber; and lignan and flavanol intake.

RESULTS

This study included 260 participants who generated 871 serum specimens and 3,000 days of diet intake. In longitudinal models, estradiol was associated inversely with insoluble fiber intake; estrone positively with animal protein intake; SHBG with greater insoluble fiber and lower total protein intake; and ratio of estrone to SHBG, a measure of bioavailable estrogen, positively with animal protein.

CONCLUSIONS

Greater protein intake, especially animal protein, led to greater estrogen concentrations and lower SHBG; greater animal protein and greater caloric intake led to increased bioavailable estrogen. This relationship may have served an evolutionary advantage in the past for greater fertility with adequate high-quality protein; in contemporary women, a modest decrease in animal protein may be beneficial in reducing breast cancer risk.

The Role of Aromatase Enzyme in Hormone Related Diseases and Plant-Based Aromatase Inhibitors as Therapeutic Regimens

Medicinal plants have a long history of use as food and remedy in traditional and modern societies, as well as have been used as herbal drugs and sources of novel bioactive compounds. They provide a wide array of chemical compounds, many of which can not be synthesized via current synthesis methods. Natural products may provide aromatase inhibitory activity through various pathways and may act clinically effective for treating pathologies associated with excessive aromatase secretion including breast, ovarian and endometrial cancers, endometriosis, uterine fibroid, benign prostatic hyperplasia (BPH), prostate cancer, infertility, and gynecomastia. Recent studies have shown that natural products with aromatase inhibitory activity, could also be good options against secondary recurrence of breast cancer by exhibiting chemopreventive effects. Therefore, screening for new plant-based aromatase inhibitors may provide novel leads for drug discovery and development, particularly with increased clinical efficacy and decreased side effects.

Influence of phytoestrogens on endometrial thickness: a systematic review and meta-analysis

The objective of this systematic review was to evaluate the influence of the use of phytoestrogens on variations in endometrial thickness in postmenopausal women. Randomized controlled trials were searched in the following electronic databases until March 2020: MEDLINE, Embase, Cochrane Library, Web of Science and LILACS. We used the terms 'phytoestrogens' and 'endometrium' or 'endometrial hyperplasia' to search for relevant trials. The data were analyzed using RevMan 5.3 software. A total of 10 studies involving 1476 patients were included. The difference in endometrial thickness was evaluated in 10 studies, with a total of 805 participants in the phytoestrogen group and 761 in the control group. Such a difference was not significant between groups after 3 months (standardized mean difference [SMD] 0.00, 95% confidence interval [CI] - 0.37 to 0.37; I² = 63%), 6 months (SMD -0.30, 95% CI -0.79 to 0.19; I² = 70%), 12 months (SMD -0.02, 95% CI 0.22 to -0.18; I² = 0%) and 24 months (SMD -0.09, 95% CI -0.25, 0.08; I² = 0%) of use. Our meta-analysis shows no changes in endometrial thickness in women using phytoestrogens. Evidence is still uncertain owing to the presence of heterogeneity among the studies currently available, whose reported outcomes cover a period between 3 and 6 months.

Is soy protein effective in reducing cholesterol and improving bone health?

Hyperlipidemia associated with cardiovascular health, and bone loss with regard to osteoporosis contribute to increased morbidity and mortality and are influenced by diet. Soy protein has been shown to reduce cholesterol levels, and its isoflavones may improve bone health. The objective of this study was to determine the effects of soy protein on lipid profiles and biomarkers of bone metabolism and inflammation. Ninety men and women (aged 27-87) were randomly assigned to consume 40 g of soy or casein protein daily for three months. Both soy and casein consumption significantly reduced bone alkaline phosphatase (P = 0.011) and body fat % (P < 0.001), tended to decrease tartrate-resistant acid phosphatase (P = 0.066), and significantly increased serum insulin-like growth factor-I (IGF-1) (P < 0.001), yet soy increased IGF-1 to a greater extent (P = 0.01) than casein. Neither treatment affected total cholesterol, HDL cholesterol, LDL cholesterol, or C-reactive protein. These results demonstrate that daily supplementation of soy and casein protein may have positive effects on indices of bone metabolism and body composition, with soy protein being more effective at increasing IGF-1, an anabolic factor, which may be due to soy isoflavones' role in upregulating Runx2 gene expression, while having little effect on lipid profiles and markers of inflammation.

Dietary isoflavone-induced, estrogen receptor-β-mediated proliferation of Caco-2 cells is modulated by gallic acid

Dietary isoflavones and their biotransformation products (from food fermentation) are estrogen mimics which activate estrogen receptors (ER)α and ERβ. In silico molecular modelling is used to determine theoretical binding energies of genistein, daidzein and hydroxylated biotransformation products, and to investigate structure-binding energy relationships with ERβ. Results suggest that ligand hydroxyl arrangement determines binding energy and influences binding affinity. Caco-2 cells (ERβ expressing) are used to study the proliferative effect of genistein, daidzein and their hydroxylated biotransformation products. Isoflavones/biotransformation products showed weaker enhancement of Caco-2 proliferation than 17β-estradiol. The EC₅₀s of isoflavones/biotransformation products agreed with in silico-predicted binding affinity order. Hydroxylated biotransformation products studied showed greater Caco-2 proliferative effects than the parent isoflavones except 8-hydroxygenistein, probably due to unfavourable ERβ interactions caused by 8-hydroxygenistein's extra hydroxyl. Caco-2 pre-treatment with UDP-glucose dehydrogenase inhibitor gallic acid promoted genistein/8-hydroxygenistein-mediated proliferation. This is probably due to a reduced isoflavone glucuronidation to form low estrogenicity glucuronides. Findings are discussed in the context of dietary isoflavones/gallic acid and effects on proliferation of ERβ-expressing gut cancer cells.

Understanding the Composition, Biosynthesis, Accumulation and Transport of Flavonoids in Crops for the Promotion of Crops as Healthy Sources of Flavonoids for Human Consumption

Flavonoids are a class of polyphenolic compounds that naturally occur in plants. Sub-groups of flavonoids include flavone, flavonol, flavanone, flavanonol, anthocyanidin, flavanol and isoflavone. The various modifications on flavonoid molecules further increase the diversity of flavonoids. Certain crops are famous for being enriched in specific flavonoids. For example, anthocyanins, which give rise to a purplish color, are the characteristic compounds in berries; flavanols are enriched in teas; and isoflavones are uniquely found in several legumes. It is widely accepted that the antioxidative properties of flavonoids are beneficial for human health. In this review, we summarize the classification of the different sub-groups of flavonoids based on their molecular structures. The health benefits of flavonoids are addressed from the perspective of their molecular structures. The flavonoid biosynthesis pathways are compared among different crops to highlight the mechanisms that lead to the differential accumulation of different sub-groups of flavonoids. In addition, the mechanisms and genes involved in the transport and accumulation of flavonoids in crops are discussed. We hope the understanding of flavonoid accumulation in crops will guide the proper balance in their consumption to improve human health.

Impact of lignans in oilseed mix on gut microbiome composition and enterolignan production in younger healthy and premenopausal women: an in vitro pilot study

BACKGROUND

Dietary lignans belong to the group of phytoestrogens together with coumestans, stilbenes and isoflavones, and themselves do not exhibit oestrogen-like properties. Nonetheless, the gut microbiota converts them into enterolignans, which show chemical similarity to the human oestrogen molecule. One of the richest dietary sources of lignans are oilseeds, including flaxseed. The aim of this pilot study was to determine the concentration of the main dietary lignans in an oilseed mix, and explore the gut microbiota-dependent production of enterolignans for oestrogen substitution in young and premenopausal women. The oilseed mix was fermented in a pH-controlled batch culture system inoculated with women's faecal samples. The lignan content and enterolignan production were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and the faecal-derived microbial communities were profiled by 16S rRNA gene-based next-generation sequencing.

RESULTS

In vitro batch culture fermentation of faecal samples inoculated with oilseed mix for 24 h resulted in a substantial increase in enterolactone production in younger women and an increase in enterodiol in the premenopausal group. As for the gut microbiota, different baseline profiles were observed as well as different temporal dynamics, mainly related to Clostridiaceae, and Klebsiella and Collinsella spp.

CONCLUSIONS

Despite the small sample size, our pilot study revealed that lignan-rich oilseeds could strongly influence the faecal microbiota of both younger and premenopausal females, leading to a different enterolignan profile being produced. Further studies in larger cohorts are needed to evaluate the long-term effects of lignan-rich diets on the gut microbiota and find out how enterolactone-producing bacterial species could be increased. Diets rich in lignans could potentially serve as a safe supplement of oestrogen analogues to meet the cellular needs of endogenous oestrogen and deliver numerous health benefits, provided that the premenopausal woman microbiota is capable of converting dietary precursors into enterolignans.

A combination of spearmint and flaxseed extract improved endocrine and histomorphology of ovary in experimental PCOS

Background

Polycystic ovary syndrome (PCOS) is a complex reproduction and endocrine disorder of women in the reproductive age. Spearmint (Mentha spicata L.) has anti-androgenic activity and flaxseed (Linum usitatissimum L.) contains phytoestrogen and was reported to improve PCOS conditions. This study aimed to evaluate PCOS conditions following administration of a mixture of these two plants.

Methods

Twenty-four rats with regular cycles were randomly divided into four groups as control (C) and treatment-control (TC) received a combination of spearmint extract (SE) + flaxseed extract (FE). PCOS was induced in PCOS and treatment (T) groups by a single intramuscular injection of estradiol valerate. The treatment group received a combination of SE and FE for 30 days, 7 weeks after injection of estradiol valerate. Estrous cycles were monitored for 10 days and in the last day animals were sacrificed, ovaries were collected for the histomorphometric study and the serum levels of progesterone, testosterone, estradiol, and dehydroepiandrosterone (DHEA) were measured.

Result

Significant rise in progesterone and a decrease in testosterone and estradiol with no significant change of DHEA in the T group, was observed in comparison with the PCOS group (P < 0.05). No significant difference noticed between T and control groups (C &CT) regarding evaluated hormones. A significant increase in primary, pre-antral and antral follicles noticed in the T group compared to the PCOS group. The number of cystic follicles decreased in the T group compared with the PCOS group. Granulosa layer thickness increased while the thickness of theca decreased significantly in the T group compared to the PCOS group (P < 0.05). No significant endocrine or histological differences noticed between C and TC groups.

Conclusion

A combination of flaxseed and spearmint extract improved the endocrine profile and the histomorphometric features of the ovary in the T group compared to the PCOS group.

Beyond Metabolism: The Complex Interplay Between Dietary Phytoestrogens, Gut Bacteria, and Cells of Nervous and Immune Systems

The human body has a large, diverse community of microorganisms which not only coexist with us, but also perform many important physiological functions, including metabolism of dietary compounds that we are unable to process ourselves. Furthermore, these bacterial derived/induced metabolites have the potential to interact and influence not only the local gut environment, but the periphery via interaction with and modulation of cells of the immune and nervous system. This relationship is being further appreciated every day as the gut microbiome is researched as a potential target for immunomodulation. A common feature among inflammatory diseases including relapsing-remitting multiple sclerosis (RRMS) is the presence of gut microbiota dysbiosis when compared to healthy controls. However, the specifics of these microbiota-neuro-immune system interactions remain unclear. Among all factors, diet has emerged as a strongest factor regulating structure and function of gut microbial community. Phytoestrogens are one class of dietary compounds emerging as potentially being of interest in this interaction as numerous studies have identified depletion of phytoestrogen-metabolizing bacteria such as Adlercreutzia, Parabacteroides and Prevotella in RRMS patients. Additionally, phytoestrogens or their metabolites have been reported to show protective effects when compounds are administered in the animal model of MS, Experimental Autoimmune Encephalomyelitis (EAE). In this review, we will illustrate the link between MS and phytoestrogen metabolizing bacteria, characterize the importance of gut bacteria and their mechanisms of action in the production of phytoestrogen metabolites, and discuss what is known about the interactions of specific compounds with cells immune and nervous system. A better understanding of gut bacteria-mediated phytoestrogen metabolism and mechanisms through which these metabolites facilitate their biological actions will help in development of novel therapeutic options for MS as well as other inflammatory diseases.

Effect of hydroalcoholic extract of flaxseed on bone mineral density in Wistar rats using digital radiography

Background:

Given that the world's population is aging, the problems associated with osteoporosis and related fractures are increasing. The aim of the study was to evaluate the effect of flaxseed extract on bone mineral density (BMD) in Wistar rats using digital radiography.

Methods:

In this experimental study, 25 male and 25 female Wistar rats were randomly divided into 5 groups: 1. Control, 2. Calcium and vitamin D (Ca/VitD), 3. 100 mg/kg flaxseed, 4. 200 mg/kg flaxseed, and 5. 400 mg/kg flaxseed. Then, the animals were kept for thirty days. Maxillary and mandibular BMD as well as serum levels of calcium, vitamin D and phosphorus were measured at baseline and after 30 days of keeping the rats.

Results:

The results showed that serum levels of calcium and phosphorus were not significantly different in all five groups before and after 30 days. Serum levels of vitamin D were significantly higher in the group receiving Ca/vit D (with a mean of 61.6±15.8 in the male group and 85±12.9 in the female group) as compared with other groups (P<0.001). The highest level of change in maxillary and mandibular bone density was in 200 mg/kg flaxseed group with a mean difference of 24.5±6.1 and 26.5±3.1, respectively, which was significant in comparison with the control and Ca/vit D groups (p<0.001) .

Conclusion:

Flaxseed extract is more effective in increasing bone density than the group receiving Ca/vit D. The mandibular and maxillary BMD was higher in the group receiving 200 mg/kg flaxseed compared to the group receiving Ca/vit D (p<0.001).

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

The mechanism(s) of action of antioxidants: From scavenging reactive oxygen/nitrogen species to redox signaling and the generation of bioactive secondary metabolites

Small molecule, dietary antioxidants exert a remarkably broad range of bioactivities, and many of these can be explained by the influence of antioxidants on the redox homeostasis. Such compounds help to modulate the levels of harmful reactive oxygen/nitrogen species, and therefore participate in the regulation of various redox signaling pathways. However, upon ingestion, antioxidants usually undergo extensive metabolism that can generate a wide range of bioactive metabolites. This makes it difficult, but otherwise a need, to identify the ones responsible for the different activities of antioxidants. By better understanding their ways of action, the use of antioxidants in therapy can be improved. This review provides a summary on the role of the in vivo metabolic changes and the oxidized metabolites on the mechanisms behind the bioactivity of antioxidants. A special attention is given to metabolites described as products of biomimetic oxidative chemical reactions, which can be considered as models of free radical scavenging. During such reactions a wide variety of metabolites are formed, and they can exert completely different specific bioactivities as compared to their parent antioxidants. This implies that exploring the free radical scavenging-related metabolite fingerprint of each antioxidant molecule, collectively defined here as the scavengome, will lead to a deeper understanding of the bioactivity of these compounds. Furthermore, this paper aims to be a working tool for systematic studies on oxidized metabolic fingerprints of antioxidants, which will certainly reveal an often-neglected segment of chemical space that is a treasury of bioactive compounds.

Soybean isoflavone affects in rabbits: Effects on metabolism, antioxidant capacity, hormonal balance and reproductive performance

Though soybean isoflavones (SBI) have pharmaceutical properties, the compounds also have endocrine disrupting activities that may adversely affect fertility of mammals. The effects of SBI on metabolism, antioxidant capacity, hormonal balance and reproductive performance of male rabbits were investigated. Adult male rabbits (n = 21) fed an isoflavone-free diet were orally treated with 0 (control; CON), 5 (small; LSBI) or 20 (large; HSBI) mg of SBI/kg body weight/day for 12 weeks. Both SBI doses resulted in lesser blood plasma total protein concentrations, while there were no effects on glucose and cholesterol concentrations compared to CON. The HSBI-treated males had the greatest (P <  0.05) blood plasma total antioxidant capacity and least malondialdehyde. Treatment with both SBI doses induced a 43% increase in triiodothyronine concentrations (P < 0.05) and 82% in reaction times (P <  0.001), while decreased sperm concentrations (P =  0.01) and blood plasma testosterone concentrations (P =  0.017) 26% and 19%, respectively. The total functional sperm fraction was less (P <  0.05) in the HSBI group; however, there was no effect of the LSBI treatment as compared to values for the CON group. The kindling rates of females mated to HSBI-treated males tended to be less (P =  0.081) than those of does mated with LSBI or CON males. In conclusion, only the HSBI treatment improved antioxidant status; whereas, treatment with both LSBI and HSBI doses induced a hormonal imbalance which led to an impaired testis function indicating the sensitivity of the adult male reproductive system to SBI actions.

Urinary mycoestrogens and age and height at menarche in New Jersey girls

BACKGROUND

Despite evidence of the endocrine disrupting properties of zearalenone (ZEN) and alpha-zearalanol (zeranol, α-ZAL), they have been minimally studied in human populations. In previous cross-sectional analyses, we demonstrated that 9-10 years old girls with detectable urinary ZEN were of shorter stature and less likely to have reached the onset of breast development than girls with undetectable urinary ZEN. The aim of this study was to examine baseline concentrations of ZEN, (α-ZAL), and their phase-1 metabolites in relation to subsequent growth and timing of menarche using 10 years of longitudinal data.

METHODS

Urine samples were collected from participants in the Jersey Girl Study at age 9-10 (n = 163). Unconjugated ZEN, (α-ZAL), and their metabolites were analyzed using high performance liquid chromatography and tandem mass spectrometry. Information on height, weight, and pubertal development was collected at a baseline visit with annual follow-up by mail thereafter. Cox regression was used to evaluate time to menarche in relation to baseline ZEN, (α-ZAL), and total mycoestrogen exposure. Z-scores for height and weight were used in mixed models to assess growth.

RESULTS

Mycoestrogens were detectable in urine in 78.5% of the girls (median ZEN: 1.02 ng/ml, range 0-22.3). Girls with detectable urinary concentrations of (α-ZAL) and total mycoestrogens (sum of ZEN, (α-ZAL) and their metabolites) at baseline were significantly shorter at menarche than girls with levels below detection (p = 0.04). ZEN and total mycoestrogen concentrations were inversely associated with height- and weight-z-scores at menarche (adjusted β = - 0.18, 95% CI: -0.29, - 0.08, and adjusted β = - 0.10, 95% CI: -0.21, 0.01, respectively).

CONCLUSION

This study supports and extends our previous results suggesting that exposure to ZEN, (α-ZAL), and their metabolites is associated with slower growth and pubertal development in adolescent girls.

Long-Term Whole Grain Wheat and Rye Intake Reflected by Adipose Tissue Alkylresorcinols and Breast Cancer: A Case-Cohort Study

Whole grain rye (WGR) and whole grain wheat (WGW) have been suggested to protect against the development of breast cancer. In this study, we estimated long-term intake of WGR and WGW, using both a food frequency questionnaire (FFQ) and alkylresorcinol concentrations in adipose tissue biopsies, in relation to the risk of developing invasive breast cancer in a case-cohort study (n = 414 in the case group, n = 933 in the subcohort group) on the Danish “Diet, Cancer and Health” cohort. The median follow-up time of the subcohort was 5.3 years. Total WGR and WGW intake estimated with FFQ or reflected by total alkylresorcinol concentration in adipose tissue was not significantly associated with risk of breast cancer. However, after adjustment for total WGR and WGW intake, women in the highest quartile of relative WGR intake, reflected by the alkylresorcinol C17:0/C21:0 ratio, had a higher risk of overall breast cancer and estrogen-receptor-positive (ER+) breast cancer than women in the lowest quartile of relative WGR intake, while the risk of estrogen-receptor-negative (ER-) breast cancer incidence was unaffected. Similar results were obtained with the FFQ data. Based on these data, further investigation of the role of specific grain types in reducing or increasing breast cancer risk, and their overall impact on health, is warranted.

Anticancer and antimetastatic potential of enterolactone: Clinical, preclinical and mechanistic perspectives

Currently cancer is the second leading cause of death globally and worldwide incidence and mortality rates of all cancers of males and females are rising tremendously. In spite of advances in chemotherapy and radiation, metastasis and recurrence are considered as the major causes of cancer related deaths. Hence there is a mounting need to develop new therapeutic modalities to treat metastasis and recurrence in cancers. A significant amount of substantiation from epidemiological, clinical and laboratory research highlights the importance of diet and nutrition in cancer chemoprevention. Enterolactone (EL) is a bioactive phenolic metabolite known as a mammalian lignan derived from dietary lignans. Here in we review the reported anti-cancer properties of EL at preclinical as well as clinical level. Several in-vivo and in-vitro studies have provided strong evidence that EL exhibits potent anti-cancer and/or protective properties against different cancers including breast, prostate, colo-rectal, lung, ovarian, endometrial, cervical cancers and hepatocellular carcinoma. Reported laboratory studies indicate a clear role for EL in preventing cancer progression at various stages including cancer cell proliferation, survival, angiogenesis, inflammation and metastasis. In clinical settings, EL has been reported to reduce risk, decrease mortality rate and improve overall survival particularly in breast, prostate, colon, gastric and lung cancer. Further, the in-vitro human cell culture studies provide strong evidence of the anticancer and antimetastatic mechanisms of EL in several cancers. This comprehensive review supports an idea of projecting EL as a promising candidate for developing anticancer drug or adjunct dietary supplements and nutraceuticals.

Possible role of phytoestrogens in breast cancer via GPER-1/GPR30 signaling

Estrogens generated within endocrine organs and the reproductive system act as ligands for at least three types of estrogen receptors. Estrogen receptors α (ERα) and β (ERβ) belong to the so-called classical family of estrogen receptors, whereas the G protein-coupled receptor GPR30, also known as GPER-1, has been described as a novel estrogen receptor sited in the cell membrane of target cells. Furthermore, these receptors are under stimulation of a family of exogenous estrogens, known as phytoestrogens, which are a diverse group of non-steroidal plant compounds derived from plant food consumed by humans and animals. Because phytoestrogens are omnipresent in our daily diet, they are becoming increasingly important in both human health and disease. Recent evidence indicates that in addition to classical estrogen receptors, phytoestrogens also activate GPER-1 a relevant observation since GPER-1 is involved in several physiopathological disorders and especially in estrogen-dependent diseases such as breast cancer.The first estrogen receptors discovered were the classical ERα and ERβ, but from an evolutionary point of view G protein-coupled receptors trace their origins in history to over a billion years ago suggesting that estrogen receptors like GPER-1 may have been the targets of choice for ancient phytoestrogens and/or estrogens.This review provides a comprehensive and systematic literature search on phytoestrogens and its relationship with classical estrogen receptors and GPER-1 including its role in breast cancer, an issue still under discussion.

The role of endocrine disruptors in ocular surface diseases

Endocrine disruptors are a group of compounds that occur in increasing amounts in the environment. These compounds change the hormone homeostasis of the target organs regulated by those hormones, mostly by binding to their receptors and affecting their signaling pathways. Among the hormones altered by endocrine disruptors are sex hormones, thyroid hormones, and insulin. Studies have documented abnormalities in the reproductive and metabolic systems of various animal species exposed to endocrine disruptors. Endocrine disruptors can play a significant role in ocular diseases once hormone deficiency or excess are involved in the mechanism of that disease. Cataracts, dry eye disease and retinal diseases, such as macular hole and diabetic retinopathy, are some of the frequent problems where hormones have been implicated. We found that some compounds function as endocrine disruptors in the metabolism of body organs and systems. The increasing frequency of dry eye and other ocular diseases indicates the need to better investigate the potential relationships beyond the isolated associations mentioned by patients and documented as rare case reports. The evidence from case-control studies and experimental assays can provide the information necessary to confirm the endocrine effects of these chemicals in the pathophysiology of dry eye disease. We hypothesize that endocrine disruptors may contribute to the increase of ocular diseases, such as dry eye disease, in recent years.

Effect of Dietary Flaxseed Intake on Circulating Sex Hormone Levels among Postmenopausal Women: A Randomized Controlled Intervention Trial

Lignan intake, and its richest food source, flaxseed, have been associated with reduced breast cancer risk. Endogenous sex hormones, such as estrogens, play a role in breast cancer development, and lignans may alter these sex hormone levels. To assess the effect of flaxseed on circulating sex hormones, a randomized controlled trial was conducted among 99 postmenopausal women in Toronto, Canada. The intervention arm consumed 2 tablespoons (15 g) of ground flaxseed daily for 7 weeks; the control arm maintained usual diet. Baseline and week 7 concentrations of 14 serum sex hormones were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay, and serum enterolignans (lignan biomarker) using LC-MS/MS. Intervention effects on sex hormone levels were assessed using analysis of covariance. Serum enterolignans increased among the flaxseed arm (+516%). Women consuming flaxseed (vs. controls) had increased serum 2-hydroxyestrone [treatment effect ratio (TER) = 1.54; 95% CI: 1.18-2.00] and 2:16α-hydroxyestrone ratio (TER =1.54; 95% CI: 1.15-2.06); effects on other hormones were not statistically significant. Within the flaxseed arm, change in enterolignan level was positively correlated with changes in 2-hydroxyestrone and 2:16α-hydroxyestrone ratio, and negatively with prolactin. Findings suggest flaxseed affects certain circulating sex hormone levels with possible implications for future breast cancer prevention research.

Fennel induces cytotoxic effects against testicular germ cells in mice; evidences for suppressed pre-implantation embryo development

Foeniculum vulgare (FVE; fennel) is an aromatic plant belonging to Umbelliferae family, which is widely used in traditional societies because of its different pharmaceutical properties. To uncover the fennel-derived essential oil (FVEO)-induced effects on male reproductive potential, 24 mature male albino mice were divided into, control, 0.37, 0.75, and 1.5 mg kg-1 FVEO-received groups. Following 35 days, the animals were euthanized and the testicular tissue and sperm samples were collected. The histological alterations, tubular differentiation (TDI), spermiogenesis (SPI) indices, apoptosis ratio, and RNA damage of germinal cells were analyzed. Moreover, the sperm count, motility, viability, chromatin condensation, and DNA fragmentation were assessed. Finally, the pre-implantation embryo development including; the percentage of zygote, 2-cell embryos and blastocysts were assessed. Observations showed that the FVEO, dose dependently, increased histological damages, resulted in germ cells dissociation, depletion, nuclear shrinkage and significantly (P < .05) decreased tubular differentiation and spermiogenesis ratios. Moreover, the FVEO-received animals (more significantly in 1.5 mg kg-1 -received group) exhibited decreased sperm count, viability, and motility and represented enhanced percentage of sperms with decondensed chromatin and DNA fragmentation. Finally, the animals in FVEO-received group showed diminished zygote formation and represented decreased pre-implantation embryo development compared to control animals. In conclusion, our data showed that, FVEO albeit at higher doses, is able to adversely affect cellular DNA and RNA contents, which in turn is able to negatively affect the sperm count and morphology. All these impairments are able to negatively affect the fertilization potential as well as pre-implantation embryo development.

17α-Ethinylestradiol and 17β-estradiol removal from a secondary urban wastewater using an RBC treatment system

The presence of micropollutants that include endocrine-disrupting compounds (EDC) in aquatic environments is currently one of the most relevant aspects of water quality due to their adverse effects on aquatic organisms and human health. From the several categories of EDC, 17β-estradiol (E2) is a natural hormone, which is prevalent in vertebrates, associated with the female reproductive system and maintenance of the sexual characters. 17α-Ethinylestradiol (EE2) is a synthetic hormone produced from the natural hormone E2 and is an essential component of oral contraceptives. These compounds are susceptible to bioconcentration and have high potential to bioaccumulation. Wastewater treatment plants are the main point source of E2 and EE2 into aquatic environments, but conventional wastewater treatment systems are not specifically designed for steroid removal. To overcome this problem, biological tertiary treatment may be a solution for the removal of emergent pollutants such as E2 and EE2. The main purpose of the present study is to provide a solution based on the optimization of a rotating biological contactor system to remove estrogens, specifically E2 and EE2, and to quantify their removal efficiency on different matrices, namely real wastewater and different synthetic wastewaters. All assays presented viable removal efficiencies for compound E2 with values always above 50%; real wastewater yielded the highest removal efficiencies. EE2 removal had better removal efficiencies with synthetic wastewater as feed solution, with removals above 15%, whereas the removal efficiency with real wastewater was inexistent.

The role of soybean extracts and isoflavones in hormone-dependent breast cancer: aromatase activity and biological effects

Estrogen receptor-positive (ER+) breast cancer is the most common cause of cancer death in women worldwide. Nowadays, the relationship between soya diet and breast cancer is controversial due to the unknown role of its isoflavones, genistein (G) and daidzein (D). In this work, we investigated not only the anti-tumor properties of a soybean extract (NBSE) but also whether the biotransformation of extract (BSE) by the fungus Aspergillus awamori increased its effectiveness. The BSE showed a stronger anti-aromatase activity and anti-proliferative efficacy in ER+ aromatase-overexpressing breast cancer cells. D and G were weak aromatase inhibitors, but inhibited cancer cell growth, being G the isoflavone that contributed to the BSE-induced effects. This work demonstrated that the biotransformation increased the anti-aromatase activity and the anti-tumoral efficacy of soybean extract in breast cancer cells. Moreover, it elucidated the potential use of soya in the prevention and/or treatment of ER+ breast cancer.

Peripubertal dietary flavonol and lignan intake and age at menarche in a longitudinal cohort of girls

BackgroundDietary phytoestrogens may alter hormonal activity in childhood. Flavonols and lignans are the most prevalent phytoestrogens in the Western diet. We examined whether higher intake of flavonols and lignans was associated with later age at menarche in a prospective study of young girls.MethodsIn all, 1,044 girls aged 6-8 years (mean 7.3 years) with two to four 24-h dietary recalls during their baseline year were followed up for 11 years until the attainment of menarche in the Breast Cancer and Environment Research Project (BCERP). Associations of age at menarche with quintiles of phytoestrogens were assessed using hazard ratios (HR) and 95% confidence intervals (CIs) from Cox proportional hazards models, controlling for body mass index and other covariates.ResultsThe highest quintile of flavonol intake was associated with a later age at menarche, compared with the lowest quintile (adjusted HR: 0.80, 95% CI: (0.66-1.00). For lignans, there was a later age in overweight girls (HR: 0.56, 95% CI=0.40-0.80).ConclusionThese dietary bioactives may reflect a healthy diet, and foods high in phytoestrogens may influence the timing of menarche.

Phytoestrogens in Botanical Dietary Supplements: Implications for Cancer

Phytoestrogens are plant constituents that possess either estrogenic or antiestrogenic activity. Although their activities are weak as compared with human endogenous estrogens, the consumption of phytoestrogens may have clinically significant consequences. A number of botanicals, or the compounds contained therein, have been identified as putative estrogenic agents, but consensus in the biomedical community has been hampered by conflicting data from various in vitro and in vivo models of estrogenic activity. Phytoestrogens may serve as chemopreventive agents while at the same time being capable of promoting growth in estrogen receptor positive cancer cell lines. Furthermore, they may exert their estrogenic influence through receptor-dependent and/or receptor-independent mechanisms. These findings have led to speculation that phytoestrogen intake might be ill advised for patients at an increased risk for hormone-dependent cancers, cancer patients, or cancer survivors. This article will attempt to sort out discrepancies between various experimental models and establish whether certain herbs possess estrogenic activity. The review will focus on 5 popular botanical dietary supplements: Trifolium pratense (red clover), Cimicifuga racemosa (black cohosh), Humulus lupulus (hops), Angelica sinensis (dong quai), and Glycyrrhiza glabra (licorice). It will address their mechanisms of action, clinical evidence bases, and implications for use in cancer.

Comparison of the effects of mesquite pod and Leucaena extracts with phytoestrogens on the reproductive physiology and sexual behavior in the male rat

Mesquite (Prosopis sp.) and Leucaena leucocephala are widespread legumes, widely used to feed several livestock species and as food source for human populations in several countries. Both mesquite and Leucaena contain several phytoestrogens which might have potential estrogenic effects. Thus, the aim of this study was to evaluate the effects of mesquite pod and Leucaena extracts on several aspects of behavior and reproductive physiology of the male rat. The effects of the extracts were compared with those of estradiol (E2) and of two isoflavones: daidzein (DAI) and genistein (GEN). The following treatments were given to groups of intact male rats: vehicle; mesquite pod extract; Leucaena extract; E2; DAI; GEN. The results indicate that mesquite pod and Leucaena extracts disrupt male sexual behavior in a similar way to DAI and GEN, but less than E2. The main disruptor of sexual behavior was E2, however after 40 and 50days of administration, both extracts and phytoestrogens disrupted sexual behavior in a similar way to E2. The extracts also increased testicular germ cell apoptosis, decreased sperm quality, testicular weight, and testosterone levels, as phytoestrogens did, although these effects were less than those caused by estradiol. The number of seminiferous tubules with TUNEL-positive germ cells increased in extracts treated groups in a similar way to phytoestrogens groups, and E2 caused the greatest effect. The number of TUNEL-positive cells per tubule increased only in Leucaena extract and E2 groups, but not in mesquite- and phytoestrogens-treated groups. Spermatocytes and round spermatids were the TUNEL-positive cells observed in all experimental groups. This effect was associated with smaller testicular weights without atrophy in experimental groups compared with control. Testicular atrophy was only observed in estradiol-treated males. Testosterone decreased in males of all experimental groups, compared with control, this androgen was undetectable in E2 treated males. These results suggest that mesquite pod and Leucaena extracts cause effects similar to those of phytoestrogens in male rat reproduction, these effects were lower than those caused by E2.

Chemopreventive Metabolites Are Correlated with a Change in Intestinal Microbiota Measured in A-T Mice and Decreased Carcinogenesis

Intestinal microbiota play a significant role in nutrient metabolism, modulation of the immune system, obesity, and possibly in carcinogenesis, although the underlying mechanisms resulting in disease or impacts on longevity caused by different intestinal microbiota are mostly unknown. Herein we use isogenic Atm-deficient and wild type mice as models to interrogate changes in the metabolic profiles of urine and feces of these mice, which are differing in their intestinal microbiota. Using high resolution mass spectrometry approach we show that the composition of intestinal microbiota modulates specific metabolic perturbations resulting in a possible alleviation of a glycolytic phenotype. Metabolites including 3-methylbutyrolactone, kyneurenic acid and 3-methyladenine known to be onco-protective are elevated in Atm-deficient and wild type mice with restricted intestinal microbiota. Thus our approach has broad applicability to study the direct influence of gut microbiome on host metabolism and resultant phenotype. These results for the first time suggest a possible correlation of metabolic alterations and carcinogenesis, modulated by intestinal microbiota in A-T mice.

Modulation of Aromatase by Phytoestrogens

The aromatase enzyme catalyzes the conversion of androgens to estrogens in many human tissues. Estrogens are known to stimulate cellular proliferation associated with certain cancers and protect against adverse symptoms during the peri- and postmenopausal intervals. Phytoestrogens are a group of plant derived naturally occurring compounds that have chemical structures similar to estrogen. Since phytoestrogens are known to be constituents of animal/human food sources, these compounds have received increased research attention. Phytoestrogens may contribute to decreased cancer risk by the inhibition of aromatase enzyme activity and CYP19 gene expression in human tissues. This review covers (a) the aromatase enzyme (historical descriptions on function, activity, and gene characteristics), (b) phytoestrogens in their classifications and applications to human health, and (c) a chronological coverage of aromatase activity modulated by phytoestrogens from the early 1980s to 2015. In general, phytoestrogens act as aromatase inhibitors by (a) decreasing aromatase gene expression, (b) inhibiting the aromatase enzyme itself, or (c) in some cases acting at both levels of regulation. The findings presented herein are consistent with estrogen's impact on health and phytoestrogen's potential as anticancer treatments, but well-controlled, large-scale studies are warranted to determine the effectiveness of phytoestrogens on breast cancer and age-related diseases.

Isoflavones: chemistry, analysis, functions and effects on health and cancer

Isoflavones are phytoestrogens and natural plant compounds which are similar to 17-β-estradiol in chemical structure. It is known that they can act as estrogen agonists or antagonists, depending on endocrine estrogenic levels, but actions of isoflavones are rather complex due to large number of variables such as chemical structures and mechanisms. Some hypotheses on biological mechanisms have not satisfactorily been confirmed to date and human epidemiological and experimental studies have been relatively limited. Nevertheless, isoflavones and isoflavone rich foods have become a focus on interest due to positive health benefits on many diseases, especially prevention of hormone-related cancers, cardiovascular disease, osteoporosis, and adverse postmenopausal symptoms, and improvement of physiological condition such as maintaining cognitive function. This review provides an overview of chemistry, analytical techniques (focused on human biospecimens), functions including biological mechanisms, and effects of isoflavones, on the basis of the available meta-analysis and review articles and some original articles, on health and cancer.

Flaxseed-a potential functional food source

There is currently much interest in phytochemicals as bioactive molecules of food. Functional foods are an emerging field in food science due to their increasing popularity among health conscious consumers. Flaxseed is cultivated in many parts of world for fiber, oil as well as for medicinal purposes and also as nutritional product. In this review, nutrients, anti-nutrients, functional properties, processing, metabolism and health benefits of bioactive molecules viz., essential fatty acids, lignans and dietary fiber of flaxseed are discussed.

A systematic review of non-hormonal treatments of vasomotor symptoms in climacteric and cancer patients

The cardinal climacteric symptoms of hot flushes and night sweats affect 24-93% of all women during the physiological transition from reproductive to post-reproductive life. Though efficacious, hormonal therapy and partial oestrogenic compounds are linked to a significant increase in breast cancer. Non-hormonal treatments are thus greatly appreciated.

This systematic review of published hormonal and non-hormonal treatments for climacteric, and breast and prostate cancer-associated hot flushes, examines clinical efficacy and therapy-related cancer risk modulation.

A PubMed search included literature up to June 19, 2014 without limits for initial dates or language, with the search terms, (hot flush* OR hot flash*) AND (clinical trial* OR clinical stud*) AND (randomi* OR observational) NOT review). Retrieved references identified further papers. The focus was on hot flushes; other symptoms (night sweats, irritability, etc.) were not specifically screened. Included were some 610 clinical studies where a measured effect of the intervention, intensity and severity were documented, and where patients received treatment of pharmaceutical quality. Only 147 of these references described studies with alternative non-hormonal treatments in post-menopausal women and in breast and prostate cancer survivors; these results are presented in Additional file 1.

The most effective hot flush treatment is oestrogenic hormones, or a combination of oestrogen and progestins, though benefits are partially outweighed by a significantly increased risk for breast cancer development.

This review illustrates that certain non-hormonal treatments, including selective serotonin reuptake inhibitors, gabapentin/pregabalin, and Cimicifuga racemosa extracts, show a positive risk-benefit ratio.

Key points

Several non-hormonal alternatives to hormonal therapy have been established and registered for the treatment of vasomotor climacteric symptoms in peri- and post-menopausal women.

There are indications that non-hormonal treatments are useful alternatives in patients with a history of breast and prostate cancer. However, confirmation by larger clinical trials is required.

Soy food and isoflavone intake and endometrial cancer risk: the Japan Public Health Center-based prospective study

OBJECTIVE

Compared with western populations, the consumption of soy foods among Japanese is very high and the incidence of endometrial cancer very low. We evaluated the association of soy food and isoflavone intake with endometrial cancer risk in Japanese women.

DESIGN

Prospective cohort study.

SETTING

Ten public health centre areas in Japan.

POPULATION

Forty nine thousand one hundred and twenty-one women of age 45-74 years who responded to a 5-year follow-up survey questionnaire.

METHODS

Intakes of soy foods as well as other covariates were assessed in 1995-1998 by a self-administered food frequency questionnaire. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI).

MAIN OUTCOME MEASURE

Incidence of endometrial cancer.

RESULTS

During an average of 12.1 years of follow up, 112 newly diagnosed endometrial cancer cases were identified. Energy-adjusted intakes of soy food and isoflavone were not associated with the risk of endometrial cancer. The multivariate-adjusted HR per 25 g/day increase in the intake of soy food was 1.02 (95% CI 0.94-1.10), and the corresponding value for isoflavone intake per 15 mg/day was 1.01 (95% CI 0.84-1.22).

CONCLUSION

In this population-based prospective cohort study of Japanese women, we observed no evidence of a protective association between soy food or isoflavone intake and endometrial cancer risk.

Dietary lignan intake and androgen receptor expression in breast tumors

PURPOSE

Lignans, a class of phytoestrogen commonly found in the Western diet, have been linked to decreased breast cancer risks in epidemiologic studies. Similar to estrogen receptors, the androgen receptor (AR), a prognostic factor in breast tumors, may be affected by lignans. However, few studies have investigated this link in the context of breast cancer etiology. We evaluated the relationship between dietary lignan intake and AR expression in incident breast tumors.

METHODS

Tumor tissue, epidemiological, and clinical data were collected from 216 women with incident, primary, histologically confirmed breast cancer enrolled in the Roswell Park Cancer Institute (RPCI) Data Bank and BioRepository (DBBR). On average, three tumor cores from each participant were assembled into a tissue micro array. After immunohistochemical staining, a trained RPCI pathologist determined AR status of each core. Lignan intake was calculated from a food frequency questionnaire collected upon enrollment into the DBBR.

RESULTS

We observed a weak positive association between dietary lignans and AR expression [β (SE) 27.6 (17.0), p 0.10], and there was no significant difference in lignan intake across categories of AR expression (p = 0.09, R (2) = 0.35).

CONCLUSION

Our results do not support a clear relationship between dietary lignan intake and AR expression. This investigation is the first, to our knowledge, to examine dietary lignan intake and AR expression in breast tumors. Further research is needed within a larger, more representative sample to determine whether lignan intake is truly associated with AR expression.

The anti-proliferative effects of enterolactone in prostate cancer cells: evidence for the role of DNA licencing genes, mi-R106b cluster expression, and PTEN dosage

The mammalian lignan, enterolactone, has been shown to reduce the proliferation of the earlier stages of prostate cancer at physiological concentrations in vitro. However, efficacy in the later stages of the disease occurs at concentrations difficult to achieve through dietary modification. We have therefore investigated what concentration(s) of enterolactone can restrict proliferation in multiple stages of prostate cancer using an in vitro model system of prostate disease. We determined that enterolactone at 20 μM significantly restricted the proliferation of mid and late stage models of prostate disease. These effects were strongly associated with changes in the expression of the DNA licencing genes (GMNN, CDT1, MCM2 and 7), in reduced expression of the miR-106b cluster (miR-106b, miR-93, and miR-25), and in increased expression of the PTEN tumour suppressor gene. We have shown anti-proliferative effects of enterolactone in earlier stages of prostate disease than previously reported and that these effects are mediated, in part, by microRNA-mediated regulation.

Excessive levels of diverse phytoestrogens can modulate steroidogenesis and cell migration of KGN human granulosa-derived tumor cells

Phytoestrogens are plant-derived estrogen-like compounds that are increasingly used for their suggested health promoting properties, even by healthy, young women. However, scientific concerns exist regarding potential adverse effects on female reproduction. In this study, naringenin (NAR), 8-prenylnaringenin (8-PN), genistein (GEN), coumestrol (COU), quercetin (QUE) and resveratrol (RSV) up-regulated steroidogenic acute regulatory protein (StaR) mRNA levels in KGN human granulosa-like tumor cells. Most of the phytoestrogens tested also increased CYP19A1 (aromatase) mRNA levels via activation of ovary-specific I.3 and II promoters. Yet, only NAR (3 and 10 μM), COU (10 and 30 μM) and QUE (10 μM) also statistically significantly induced aromatase activity in KGN cells after 24 h. 8-PN, aromatase inhibitor letrozole and estrogen receptor antagonist ICI 182,780 concentration-dependently inhibited aromatase activity with IC₅₀ values of 8 nM, 10 nM and 72 nM, respectively. Co-exposure with ICI 182,780 (0.1 μM) statistically significantly attenuated the induction of aromatase activity by QUE and COU, but not NAR. Cell cycle status and proliferation of KGN cells were not affected by any of the phytoestrogens tested. Nonetheless, the migration of KGN cells was significantly reduced with approximately 30% by COU, RSV and QUE and 46% by GEN at 10 μM, but not NAR and 8-PN. Our results indicate that phytoestrogens can affect various pathways in granulosa-like cells in vitro at concentrations that can be found in plasma upon supplement intake. This implies that phytoestrogens may interfere with ovarian function and caution is in place regarding the use of supplements with high contents of phytoestrogens.

Sources, concentrations, and exposure effects of environmental gestagens on fish and other aquatic wildlife, with an emphasis on reproduction

Fish and other aquatic wildlife, including frogs, turtles, and alligators, have been used as vertebrate sentinels for the effects of endocrine disrupting and other emerging chemicals of concern found in aquatic ecosystems. Research has focused on the effects of estrogenic, androgenic, and thyroidogenic compounds, but there is a growing body of literature on the reproductive health exposure effects of environmental gestagens on aquatic wildlife. Gestagens include native progestogens, such as progesterone, and synthetic progestins, such as gestodene and levonorgestrel, which bind progesterone receptors and have critically important roles in vertebrate physiology, especially reproduction. Roles for progestogen include regulating gamete maturation and orchestrating reproductive behavior, both as circulating hormones and as secreted pheromones. Gestagens enter the aquatic environment through paper mill effluent, wastewater treatment plant effluent, and agricultural runoff. A number of gestagens have been shown to negatively affect reproduction, development, and behavior of exposed fish and other aquatic wildlife at ng/L concentrations, and these compounds have been measured in the environment at single to 375 ng/L. Given the importance of endogenous progestogens in the regulation of gametogenesis, secondary sex characteristics, and reproductive behavior in vertebrates and the documented exposure effects of pharmaceutical progestins and progesterone, environmental gestagens are an emerging class of contaminants that deserve increased attention from researchers and regulators alike. The potential for environmental gestagens to affect the reproductive health of aquatic vertebrates seems evident, but there are a number of important questions for researchers to address in this nascent field. These include identifying biomarkers of gestagen exposure; testing the effects of environmentally relevant mixtures; and determining what other physiological endpoints and taxa might be affected by exposure to environmental gestagens.

Current concepts in neuroendocrine disruption

In the last few years, it has become clear that a wide variety of environmental contaminants have specific effects on neuroendocrine systems in fish, amphibians, birds and mammals. While it is beyond the scope of this review to provide a comprehensive examination of all of these neuroendocrine disruptors, we will focus on select representative examples. Organochlorine pesticides bioaccumulate in neuroendocrine areas of the brain that directly regulate GnRH neurons, thereby altering the expression of genes downstream of GnRH signaling. Organochlorine pesticides can also agonize or antagonize hormone receptors, adversely affecting crosstalk between neurotransmitter systems. The impacts of polychlorinated biphenyls are varied and in many cases subtle. This is particularly true for neuroedocrine and behavioral effects of exposure. These effects impact sexual differentiation of the hypothalamic-pituitary-gonadal axis, and other neuroendocrine systems regulating the thyroid, metabolic, and stress axes and their physiological responses. Weakly estrogenic and anti-androgenic pollutants such as bisphenol A, phthalates, phytochemicals, and the fungicide vinclozolin can lead to severe and widespread neuroendocrine disruptions in discrete brain regions, including the hippocampus, amygdala, and hypothalamus, resulting in behavioral changes in a wide range of species. Behavioral features that have been shown to be affected by one or more these chemicals include cognitive deficits, heightened anxiety or anxiety-like, sociosexual, locomotor, and appetitive behaviors. Neuroactive pharmaceuticals are now widely detected in aquatic environments and water supplies through the release of wastewater treatment plant effluents. The antidepressant fluoxetine is one such pharmaceutical neuroendocrine disruptor. Fluoxetine is a selective serotonin reuptake inhibitor that can affect multiple neuroendocrine pathways and behavioral circuits, including disruptive effects on reproduction and feeding in fish. There is growing evidence for the association between environmental contaminant exposures and diseases with strong neuroendocrine components, for example decreased fecundity, neurodegeneration, and cardiac disease. It is critical to consider the timing of exposures of neuroendocrine disruptors because embryonic stages of central nervous system development are exquisitely sensitive to adverse effects. There is also evidence for epigenetic and transgenerational neuroendocrine disrupting effects of some pollutants. We must now consider the impacts of neuroendocrine disruptors on reproduction, development, growth and behaviors, and the population consequences for evolutionary change in an increasingly contaminated world. This review examines the evidence to date that various so-called neuroendocrine disruptors can induce such effects often at environmentally-relevant concentrations.

Flaxseed and its lignan and oil components: can they play a role in reducing the risk of and improving the treatment of breast cancer?

Flaxseed (FS), rich in the phytoestrogen lignans and α-linolenic acid-rich oil, has been suggested to have an anticancer effect. Questions remain whether FS and its lignan and oil components are effective in reducing breast cancer risk and tumour growth, and can interact beneficially with breast cancer drugs. To find answers, in vitro, animal, observational, and clinical studies on FS and its lignan and oil components were reviewed. The majority of studies in various rodent models show that 2.5%–10% FS diet or the equivalent amount of lignan or oil reduces tumour growth. Ten percent FS and equivalent lignans do not interfere with but rather increase the effectiveness of tamoxifen (80 mg/day) while the 4% FS oil increases trastuzumab/Herceptin (2.5 mg/kg) effectiveness. Observational studies show that FS and lignan intake, urinary excretion, or serum levels are associated with reduced risk, particularly in postmenopausal women. Lignans reduce breast cancer and all-cause mortality by 33%–70% and 40%–53%, respectively, without reducing tamoxifen effectiveness. Clinical trials show that FS (25 g/day with 50 mg lignans; 32 days) reduces tumour growth in breast cancer patients and lignans (50 mg/day; 1 year) reduces risk in premenopausal women. Mechanisms include decreased cell proliferation and angiogenesis and increased apoptosis through modulation of estrogen metabolism and estrogen receptor and growth factor receptor signalling pathways. More clinical trials are needed but current overall evidence indicates that FS and its components are effective in the risk reduction and treatment of breast cancer and safe for consumption by breast cancer patients.

Two natural products, trans-phytol and (22E)-ergosta-6,9,22-triene-3β,5α,8α-triol, inhibit the biosynthesis of estrogen in human ovarian granulosa cells by aromatase (CYP19)

Aromatase is the only enzyme in vertebrates to catalyze the biosynthesis of estrogens. Although inhibitors of aromatase have been developed for the treatment of estrogen-dependent breast cancer, the whole-body inhibition of aromatase causes severe adverse effects. Thus, tissue-selective aromatase inhibitors are important for the treatment of estrogen-dependent cancers. In this study, 63 natural products with diverse structures were examined for their effects on estrogen biosynthesis in human ovarian granulosa-like KGN cells. Two compounds-trans-phytol (SA-20) and (22E)-ergosta-6,9,22-triene-3β,5α,8α-triol (SA-48)-were found to potently inhibit estrogen biosynthesis (IC50: 1μM and 0.5μM, respectively). Both compounds decreased aromatase mRNA and protein expression levels in KGN cells, but had no effect on the aromatase catalytic activity in aromatase-overexpressing HEK293A cells and recombinant expressed aromatase. The two compounds decreased the expression of aromatase promoter I.3/II. Neither compound affected intracellular cyclic AMP (cAMP) levels, but they inhibited the phosphorylation or protein expression of cAMP response element-binding protein (CREB). The effects of these two compounds on extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinases (MAPKs), and AKT/phosphoinositide 3-kinase (PI3K) pathway were examined. Inhibition of p38 MAPK could be the mechanism underpinning the actions of these compounds. Our results suggests that natural products structurally similar to SA-20 and SA-48 may be a new source of tissue-selective aromatase modulators, and that p38 MAPK is important in the basal control of aromatase in ovarian granulosa cells. SA-20 and SA-48 warrant further investigation as new pharmaceutical tools for the prevention and treatment of estrogen-dependent cancers.

A pilot study comparing the effect of flaxseed, aromatase inhibitor, and the combination on breast tumor biomarkers

Use of complementary approaches is common among breast cancer survivors. Potential interactions between aromatase inhibitors (AI) and high phytoestrogen foods, such as flaxseed (FS), are not often described. We conducted a pilot 2 × 2 factorial, randomized intervention study between tumor biopsy and resection, in 24 postmenopausal women with estrogen receptor positive (ER+) breast cancer, to assess the effects of FS and anastrozole, and possible interactions between them, on serum steroid hormone and tumor-related characteristics associated with long-term survival (Roswell Park Cancer Institute, 2007-2010). The effect of each treatment vs. placebo on outcomes was determined by linear regression adjusting for pretreatment measure, stage, and grade. Although not statistically significant, mean ERβ expression was approximately 40% lower from pre- to postintervention in the FS + AI group only. We observed a statistically significant negative association (β ± SE -0.3 ± 0.1; P = 0.03) for androstenedione in the FS + AI group vs. placebo and for DHEA with AI treatment (β ± SE -1.6 ± 0.6; P = 0.009). Enterolactone excretion was much lower in the FS + AI group compared to the FS group. Our results do not support strong effects of FS on AI activity for selected breast tumor characteristics or serum steroid hormone levels but suggest AI therapy might reduce the production of circulating mammalian lignans from FS.

Estrogenic endocrine-disrupting chemicals: molecular mechanisms of actions on putative human diseases

Endocrine-disrupting chemicals (EDC), including phthalates, bisphenol A (BPA), phytoestrogens such as genistein and daidzein, dichlorodiphenyltrichloroethane (DDT), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are associated with a variety of adverse health effects in organisms or progeny by altering the endocrine system. Environmental estrogens, including BPA, phthalates, and phytoestrogens, are the most extensively studied and are considered to mimic the actions of endogenous estrogen, 17β-estradiol (E2). Diverse modes of action of estrogen and estrogen receptors (ERα and ERβ) have been described, but the mode of action of estrogenic EDC is postulated to be more complex and needs to be more clearly elucidated. This review examines the adverse effects of estrogenic EDC on male or female reproductive systems and molecular mechanisms underlying EDC effects that modulate ER-mediated signaling. Mechanisms of action for estrogenic EDC may involve both ER-dependent and ER-independent pathways. Recent findings from systems toxicology of examining estrogenic EDC are also discussed.