Estrogen receptor β

Molecular insights into the potential effects of selective estrogen receptor β agonists in Alzheimer's and Parkinson's diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative disorders. Pathologically, AD and PD are characterized by the accumulation of misfolded proteins. Hence, they are also called as proteinopathy diseases. Gender is considered as one of the risk factors in both diseases. Estrogens are widely accepted to be neuroprotective in several neurodegenerative disorders. Estrogens can be produced in the central nervous system, where they are called as neurosteroids. Estrogens mediate their neuroprotective action mainly through their actions on estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). However, ERα is mainly involved in the growth and development of the primary and secondary sexual organs in females. Hence, the activation of ERα is associated with undesired side effects such as gynecomastia and increase in the risk of breast cancer, thromboembolism, and feminization. Therefore, selective activation of ERβ is often considered to be safer. In this review, we explore the role of ERβ in regulating the expression and functions of AD- and PD-associated genes. Additionally, we discuss the association of these genes with the amyloid-beta peptide (Aβ) and α-synuclein mediated toxicity. Ultimately, we established a correlation between the importance of ERβ activation and the process underlying ERβ's neuroprotective mechanisms in AD and PD.

Effects of matcha tea extract on cell viability and estrogen receptor-β expression on MCF-7 breast cancer cells

PURPOSE

In the following work, we investigated the effect of matcha green tea extract (MTE) on MCF-7 breast cancer cell viability and estrogen receptor-beta expression (ERβ).

METHODS

MCF-7 cells were stimulated with MTE at concentrations of 5 and 10 µg/ml. Cell viability was assessed using a water-soluble tetrazolium assay (WST-1 assay) after an incubation time of 72 h. ERβ was quantified at gene level by real-time polymerase chain reaction (PCR). A western blot (WB) was carried out for the qualitative assessment of the expression behavior of on a protein level.

RESULTS

The WST-1 test showed a significant inhibition of viability in MFC-7 cells after 72 h at 10 µg/ml. The WB demonstrated a significant quantitative decrease of ERβ at protein level with MTE concentrations of 10 µg/ml. In contrast, the PCR did not result in significant downregulation of ERβ.

CONCLUSION

MTE decreases the cell viability of MCF-7 cells and furthermore leads to a decrease of ERβ at protein level.

Renal tubular and glomerular estrogen receptor ß levels are lower in lupus nephritis than in familial Mediterranean fever-associated renal amyloidosis

BACKGROUND

Estrogen has been thought to play an essential role in the disease pathogenesis of systemic lupus erythematosus, which is 9-10 times more prevalent in the female population. It has been shown that irregular estrogen/estrogen receptor signaling pathways may contribute to the pathophysiology of various renal diseases. In this study, we compared renal estrogen receptors between lupus nephritis, familial Mediterranean fever-associated renal amyloidosis, ANCA-associated nephritis, and intact kidney to investigate their role in the pathophysiology of renal diseases.

METHODS

This study was designed as a retrospective cohort study. Thirty systemic lupus erythematosus patients with lupus nephritis, 12 familial Mediterranean fever amyloidosis and 10 ANCA-associated glomerulonephrites, and 14 individuals with normal renal histology were included in the study.

RESULTS

Tubular estrogen receptor ß expression score was found to be significantly higher in the familial Mediterranean fever [5 (1-8)] group than in the lupus nephritis [0 (0-1)] (B = 1.385, OR = 3.996, CI %95 = 1.805-8.846, p = .001) and ANCA [4 (1-6.5)] (B = -1.431, OR = 0.239, CI 95% = 0.093-0.614, p = .003) groups. A significant correlation was found between serum creatinine values and tubular estrogen receptor ß expression score (OR = 0.565, CI 95% = 0.622-1.402, p < .0001). In ANCA-associated glomerulonephritis, a significant relationship was found between fibro cellular crescents in renal biopsy and glomerular estrogen receptor ß expression score (OR = 0.247, CI 95% = 0.11-0.999, p = .045) and tubular estrogen receptor ß expression score (OR = 0.282, CI 95% = -0.180-2.812, p = .026).

CONCLUSIONS

This study showed that tubular estrogen receptor ß expression score was elevated in familial Mediterranean fever amyloidosis and correlated with serum creatinine levels and renal crescents.

Crosstalk between ferroptosis and steroid hormone signaling in gynecologic cancers

Ferroptosis is a novel types of regulated cell death and is widely studied in cancers and many other diseases in recent years. It is characterized by iron accumulation and intense lipid peroxidation that ultimately inducing oxidative damage. So far, signaling pathways related to ferroptosis are involved in all aspects of determining cell fate, including oxidative phosphorylation, metal-ion transport, energy metabolism and cholesterol synthesis progress, et al. Recently, accumulated studies have demonstrated that ferroptosis is associated with gynecological oncology related to steroid hormone signaling. This review trends to summarize the mechanisms and applications of ferroptosis in cancers related to estrogen and progesterone, which is expected to provide a theoretical basis for the prevention and treatment of gynecologic cancers.

Selective Estrogen receptor degraders (SERDs) for the treatment of breast cancer: An overview

Discovery of SERDs has changed the direction of anticancer research, as more than 70% of breast cancer cases are estrogen receptor positive (ER+). Therapies such as selective estrogen receptor modulators (SERM) and aromatase inhibitors (AI's) have been effective, but due to endocrine resistance, SERDs are now considered essential therapeutics for the treatment of ER+ breast cancer. The present review deliberates the pathophysiology of SERDs from the literature covering various molecules in clinical trials. Estrogen receptors active sites distinguishing characteristics and interactions with currently available FDA-approved drugs have also been discussed. Designing strategy of previously reported SERDs, their SAR analysis, in silico, and the biological efficacy have also been summarized along with appropriate examples.

TLR4 inhibition suppresses growth in oestrogen-induced prolactinoma models

Prolactinomas have harmful effects on human health. Bromocriptine is the only commercially available drug in China, but about 25% of prolactinoma patients do not respond to it in clinic, its pathogenesis remains unknown. Thus, its pathogenesis needs to be determined to develop new therapeutic methods for prolactinomas. The expression of ERβ, TLR4, and prolactin (PRL) in the pituitary gland of C57BL/6 mice and human prolactinoma specimen was examined by immunofluorescence or immunohistochemistry. The role of TLR4 in prolactinoma was determined using estradiol-induced models of C57BL/6 wild-type and TLR4-/- mice. MMQ cells were treated with estradiol, fulvestrant, and lipopolysaccharide (LPS) or transfected with TLR4 siRNA to study the expression of ERβ, TLR4, and PRL in these cells. Furthermore, the interaction between ERβ and TLR4 was investigated by immunoprecipitation analysis. The expression of PRL and TLR4 was co-located and increased in the pituitary gland of mice and human prolactinoma specimen compared to that in the control specimen. Meanwhile, TLR4 knockout or treatment with the TLR4 inhibitor TAK242 not only significantly inhibited tumor overgrowth but also decreased the expression of PRL in estradiol-treated mice through p38 MAPK pathway regulation. However, MMQ treated with estradiol and LPS enhanced PRL expression than treated with estradiol or LPS alone. Finally, ERβ or TLR4 inhibition prevented the estradiol-induced PRL increase by regulating the TLR4/p38 MAPK pathway in vitro. Estradiol promoted prolactinoma development by activating the TLR4/p38 MAPK pathway through ERβ, and TLR4 is a potential therapeutic target for prolactinoma treatment.

Oxytocin and microglia in the development of social behaviour

Oxytocin is a well-established regulator of social behaviour. Microglia, the resident immune cells of the central nervous system, regulate brain development and maintenance in health and disease. Oxytocin and microglia interact: microglia appear to regulate the oxytocin system and are, in turn, regulated by oxytocin, which appears to have anti-inflammatory effects. Both microglia and oxytocin are regulated in sex-specific ways. Oxytocin and microglia may work together to promote experience-dependent circuit refinement through multiple developmental-sensitive periods contributing to individual differences in social behaviour. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.

Understanding the Role of Estrogen Receptor Status in PRODH/POX-Dependent Apoptosis/Survival in Breast Cancer Cells

It has been suggested that activation of estrogen receptor α (ER α) stimulates cell proliferation. In contrast, estrogen receptor β (ER β) has anti-proliferative and pro-apoptotic activity. Although the role of estrogens in estrogen receptor-positive breast cancer progression has been well established, the mechanism of their effect on apoptosis is not fully understood. It has been considered that ER status of breast cancer cells and estrogen availability might determine proline dehydrogenase/proline oxidase (PRODH/POX)-dependent apoptosis. PRODH/POX is a mitochondrial enzyme that converts proline into pyrroline-5-carboxylate (P5C). During this process, ATP (adenosine triphosphate) or ROS (reactive oxygen species) are produced, facilitating cell survival or death, respectively. However, the critical factor in driving PRODH/POX-dependent functions is proline availability. The amount of this amino acid is regulated at the level of prolidase (proline releasing enzyme), collagen biosynthesis (proline utilizing process), and glutamine, glutamate, α-ketoglutarate, and ornithine metabolism. Estrogens were found to upregulate prolidase activity and collagen biosynthesis. It seems that in estrogen receptor-positive breast cancer cells, prolidase supports proline for collagen biosynthesis, limiting its availability for PRODH/POX-dependent apoptosis. Moreover, lack of free proline (known to upregulate the transcriptional activity of hypoxia-inducible factor 1, HIF-1) contributes to downregulation of HIF-1-dependent pro-survival activity. The complex regulatory mechanism also involves PRODH/POX expression and activity. It is induced transcriptionally by p53 and post-transcriptionally by AMPK (AMP-activated protein kinase), which is regulated by ERs. The review also discusses the role of interconversion of proline/glutamate/ornithine in supporting proline to PRODH/POX-dependent functions. The data suggest that PRODH/POX-induced apoptosis is dependent on ER status in breast cancer cells.

Estrogen-Receptor-Positive Breast Cancer in Postmenopausal Women: The Role of Body Composition and Physical Exercise

Breast cancer (BC) is the most commonly diagnosed cancer among women worldwide and the most common cause of cancer-related death. To date, it is still a challenge to estimate the magnitude of the clinical impact of physical activity (PA) on those parameters producing significative changes in future BC risk and disease progression. However, studies conducted in recent years highlight the role of PA not only as a protective factor for the development of ER+ breast cancer but, more generally, as a useful tool in the management of BC treatment as an adjuvant to traditional therapies. In this review, we focused our attention on data obtained from human studies analyzing, at each level of disease prevention (i.e., primary, secondary, tertiary and quaternary), the positive impact of PA/exercise in ER+ BC, a subtype representing approximately 70% of all BC diagnoses. Moreover, given the importance of estrogen receptors and body composition (i.e., adipose tissue) in this subtype of BC, an overview of their role will also be made throughout this review.

The flavonoid, kaempferol-3-O-apiofuranosyl-7-O-rhamnopyranosyl, as a potential therapeutic agent for breast cancer with a promoting effect on ovarian function

It is widely known that breast cancer cells eventually develop resistance to hormonal drugs and chemotherapies, which often compromise fertility. This study aimed to investigate the effect of the flavonoid, kaempferol-3-O-apiofuranosyl-7-O-rhamnopyranosyl (KARP), on 1) the viability of MCF-7 breast cancer cells and 2) ovarian function in rats. A dose-dependent decrease in MCF-7 cell survival was observed, and the IC50 value was found to be 48 μg/ml. Cells in the control group or those exposed to increasing concentrations of KARP experienced a similar generation of reactive oxygen species and induction of apoptosis. For the rats, estradiol levels correlated negatively to KARP dosages, although a recovery was obtained at administration of 30 mg/kg per day. Noteworthily, when compared against the control, this dosage led to significant increases in mRNA levels for CYP19, CYP17a, CCND2, GDF9, and INSL3 among the treatment groups, and ER1 and ER2 mRNA levels decreased in a dose-dependent manner. KARP shows great promise as an ideal therapy for breast cancer patients since it induced apoptosis and autophagy in cancerous cells without harming fertility in our animal model. Future investigations on humans are necessary to substantiate these findings and determine its efficacy as a general line of treatment.

Estrogen and estrogen receptors in kidney diseases

Acute kidney injury (AKI) and chronic kidney disease (CKD) are posing great threats to global health within this century. Studies have suggested that estrogen and estrogen receptors (ERs) play important roles in many physiological processes in the kidney. For instance, they are crucial in maintaining mitochondrial homeostasis and modulating endothelin-1 (ET-1) system in the kidney. Estrogen takes part in the kidney repair and regeneration via its receptors. Estrogen also participates in the regulation of phosphorus homeostasis via its receptors in the proximal tubule. The ERα polymorphisms have been associated with the susceptibilities and outcomes of several renal diseases. As a consequence, the altered or dysregulated estrogen/ERs signaling pathways may contribute to a variety of kidney diseases, including various causes-induced AKI, diabetic kidney disease (DKD), lupus nephritis (LN), IgA nephropathy (IgAN), CKD complications, etc. Experimental and clinical studies have shown that targeting estrogen/ERs signaling pathways might have protective effects against certain renal disorders. However, many unsolved problems still exist in knowledge regarding the roles of estrogen and ERs in distinct kidney diseases. Further research is needed to shed light on this area and to enable the discovery of pathway-specific therapies for kidney diseases.

Risk of breast cancer in women after a salivary gland carcinoma or pleomorphic adenoma in the Netherlands

Salivary and mammary gland tumors show morphological similarities and share various characteristics, including frequent overexpression of hormone receptors and female preponderance. Although this may suggest a common etiology, it remains unclear whether patients with a salivary gland tumor carry an increased risk of breast cancer (BC). Our purpose was to determine the risk of BC in women diagnosed with salivary gland carcinoma (SGC) or pleomorphic adenoma (SGPA). BC incidence (invasive and in situ) was assessed in two nationwide cohorts: one comprising 1567 women diagnosed with SGC and one with 2083 women with SGPA. BC incidence was compared with general population rates using standardized incidence ratio (SIR). BC risk was assessed according to age at SGC/SGPA diagnosis, follow‐up time and (for SGC patients) histological subtype. The mean follow‐up was 7.0 years after SGC and 9.9 after SGPA diagnosis. During follow‐up, 52 patients with SGC and 74 patients with SGPA developed BC. The median time to BC was 6 years after SGC and 7 after SGPA. The cumulative risk at 10 years of follow‐up was 3.1% after SGC and 3.5% after SGPA (95% Confidence Interval (95%CI) 2.1%–4.7% and 2.6%–4.6%, respectively). BC incidence was 1.59 times (95%CI 1.19–2.09) higher in the SGC‐cohort than expected based on incidence rates in the general population. SGPA‐patients showed a 1.48 times (95%CI 1.16–1.86) higher incidence. Women with SGC or SGPA have a slightly increased risk of BC. The magnitude of risk justifies raising awareness, but is no reason for BC screening.

Targeting the ERβ/Angiopoietin-2/Tie-2 signaling-mediated angiogenesis with the FDA-approved anti-estrogen Faslodex to increase the Sunitinib sensitivity in RCC

Sunitinib has been used as the main therapy to treat the metastatic clear cell renal cell carcinoma (ccRCC) as it could function via suppressing the tumor growth and angiogenesis. Yet most ccRCC tumors may still regrow due to the development of sunitinib-resistance, and detailed mechanisms remain to be further investigated. The angiopoietin family includes angiopoietin-1 and angiopoietin-2 (ANGPT-1 and -2). It was reported that estradiol regulates expression of ANGPT-1, but not ANGPT-2, through estrogen receptor α (ERα) in an experimental stroke model. To date, there is no finding to link the E2/ER signal on regulating ANGPT-2. Our study is the first to explore (i) how estrogen receptor β (ERβ) can up-regulate ANGPT-2 in RCC cells, and (ii) how ERβ-increased ANGPT-2 can promote the HUVEC tube formation and reduce sunitinib sensitivity. Mechanistic studies revealed that ERβ could function via transcriptional regulation of the cytokine ANGPT-2 in the ccRCC cells. We found the up-regulated ANGPT-2 of RCC cells could then increase the Tie-2 phosphorylation to promote the angiogenesis and increase sunitinib treatment resistance of endothelial cells. In addition to the endothelial cell tube formation and aortic ring assay, preclinical studies with a mouse RCC model also confirmed the finding. Targeting this newly identified ERβ/ANGPT-2/Tie-2 signaling pathway with the FDA-approved anti-estrogen, Faslodex, may help in the development of a novel combined therapy with sunitinib to better suppress the ccRCC progression.

Estrogen receptor β induces autophagy of osteosarcoma through the mTOR signaling pathway

BACKGROUND

Estrogen receptor beta (ERβ) was considered as a tumor-inhibiting factor in estrogen-sensitive malignant tumors. In this study, we intended to investigate whether ERβ was involved in inducing autophagy in osteosarcoma.

METHODS

This is an experimental study. The associations between ERβ and autophagy were detected in osteosarcoma U2-OS cells which were treated with E2, E2 + 2,3-Bis (4-hydroxyphenyl) propionitrile (DPN, ERβ agonists), E2 + DPN + water, E2 + DPN + 3-Methyladenine (3-MA, autophagy inhibitor), respectively. Cell viability and death were detected using cell counting kit 8 assay and flow cytometry, respectively. In addition, the expression of autophagy marker LC3II/I, sequestosome 1 (P62), mammalian target of rapamycin (mTOR), and phosphorylated-mTOR (p-mTOR) was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting.

RESULTS

Cell viability was significantly decreased with DPN treatment, while was reversed with 3-MA treatment. DPN treatment decreased living cells proportion and increased cell apoptosis proportion, while 3-MA treatment reversed those changes. However, there were significant differences between the E2 group and the E2 + DPN + 3-MA group for the living cell proportion and cell apoptosis proportion, suggesting apoptosis and autophagy all were induced. In addition, DPN treatment upregulated the LC3II/I expression level and downregulated P62 and mTOR (mRNA level) and p-mTOR (protein level) expression levels.

CONCLUSION

ERβ inhibited the cell viability and mediated cell death by inducing apoptosis and autophagy in osteosarcoma. ERβ-induced autophagy in osteosarcoma was associated with downregulating the P62 expression level and inhibiting mTOR activation.

Recent advances in the anti-aging effects of phytoestrogens on collagen, water content, and oxidative stress

Skin undergoes degenerative changes as it ages, which include the loss of elasticity, reductions in the epidermal thickness and collagen content, elastic fiber degeneration, and increased wrinkling and dryness. Skin aging can be significantly delayed by the administration of estrogen. Estrogen deficiency following menopause results in atrophic skin changes and the acceleration of skin aging. Estrogen administration has positive effects on human skin by delaying or preventing skin aging manifestations, but the use of estrogen replacement is a risk factor for breast and uterine cancer. Phytoestrogens are a large family of plant‐derived molecules possessing various degrees of estrogen‐like activity; they exhibit agonist or antagonist estrogenic properties depending on the tissue. These molecules could be ideal candidates to combat skin aging and other detrimental effects of hypoestrogenism. In this paper, we review the effects of phytoestrogens on human skin and the mechanisms by which phytoestrogens can alleviate the changes due to aging.

Mojave Yucca (Yucca Schidigera Roezl) Effects on Female Reproduction a Review

Yucca is an important source of biologically active substances such as steroidal saponins and stilbenes providing many beneficial effects when administered to humans and other animals. These substances offer a great potential in the prevention and treatment of current civilized diseases as well as to their: antioxidant, hypocholesterolaemic, anti-inflammatory, phytoestrogenic, pro-apoptotic, anti-proliferative, and anti-carcinogenic properties. This review focuses on the roles of two main yucca constituent groups and their ability to modulate ovarian functions and female reproductive performance. Both the biological activity of yucca substances and the mechanisms of their actions on ovaries are still incompletely understood. Thus, the direct effects of yucca extract on ovarian cells in animal models under in vitro conditions, as well as actions after yucca consumption will be discussed.

Expression of estrogen receptor beta isoforms in pancreatic adenocarcinoma

Limited studies have shown that some patients with pancreatic adenocarcinoma (PAC) may benefit from treatment with tamoxifen. PAC has been shown to be largely negative for estrogen receptor alpha (ER-alpha). The aim of this pilot study was to investigate ER-beta expression in human PAC. Sections of tissue microarray with 18 evaluable cases of human PAC were stained by immunohistochemistry (IHC) for ER-beta1, ER-beta2, ER-beta5, and Cyclin A. The levels of ER-beta isoform expression and the S-phase fraction (SPF) were determined using quantitative digital image analysis. Higher mean and median ER-beta2 levels correlated with male sex (p = 0.057 and p = 0.035, respectively), older age (p = 0.005 and p = 0.006, respectively), and lower pT stage (p = 0.008 and p = 0.009). Mean and median ER-beta5 levels correlated negatively with SPF (p = 0.021 and p = 0.047, respectively). Mean ER-beta1 expression did not correlate with any of the above mentioned clinicopathologic factors. The findings in this pilot study, although should be considered preliminary, suggest that some ER-beta isoforms may play a role in the biology of PAC. Additional larger studies are needed to confirm our findings, and to determine whether ER-beta may be considered for future targeted therapy.

Shift from androgen to estrogen action causes abdominal muscle fibrosis, atrophy, and inguinal hernia in a transgenic male mouse model

Inguinal hernia is one of the most common disorders that affect elderly men. A major pathology underlying inguinal hernia is the fibrosis and other degenerative changes that affect the lower abdominal muscle strength adjacent to the inguinal canal. Here we describe a critical role of estrogen and its nuclear receptor that enhance fibroblast proliferation and muscle atrophy, leading to inguinal hernia. Further research may reveal a potential role of estrogen ablation to prevent muscle fibrosis or hernia in a subset of elderly men.

Inguinal hernia develops primarily in elderly men, and more than one in four men will undergo inguinal hernia repair during their lifetime. However, the underlying mechanisms behind hernia formation remain unknown. It is known that testosterone and estradiol can regulate skeletal muscle mass. We herein demonstrate that the conversion of testosterone to estradiol by the aromatase enzyme in lower abdominal muscle (LAM) tissue causes intense fibrosis, leading to muscle atrophy and inguinal hernia; an aromatase inhibitor entirely prevents this phenotype. LAM tissue is uniquely sensitive to estradiol because it expresses very high levels of estrogen receptor-α. Estradiol acts via estrogen receptor-α in LAM fibroblasts to activate pathways for proliferation and fibrosis that replaces atrophied myocytes, resulting in hernia formation. This is accompanied by decreased serum testosterone and decreased expression of the androgen receptor target genes in LAM tissue. These findings provide a mechanism for LAM tissue fibrosis and atrophy and suggest potential roles of future nonsurgical and preventive approaches in a subset of elderly men with a predisposition for hernia development.

Sex hormone allergy: clinical aspects, causes and therapeutic strategies - Update and secondary publication

Sex hormone allergy as a clinical syndrome has been known for almost a century. Due to the diversity of clinical presentation regarding symptoms and disease patterns, the optimal patient care represents an enormous interdisciplinary challenge. Frequently, hypersensitivity reactions affect more than one sex hormone and double positive tests for estrogen and progesterone have been described. Since the menstrual cycle dependent symptoms range from skin afflictions, gynecological problems to non-specific reactions, different pathophysiological mechanisms seem likely.

Various desensitization protocols are described as causal treatment options, but are rarely applied in clinical routine. Consequently, major research efforts with a quick translation of therapeutic interventions into clinical practice will be crucial to help affected patients in the future.

Estrogen receptor β exhibited anti-tumor effects on osteosarcoma cells by regulating integrin, IAP, NF-kB/BCL-2 and PI3K/Akt signal pathway

This study aimed to investigate the effects of Estrogen receptor β (ERβ) on osteosarcoma cells, and explore the regulatory mechanisms involved in this process. Osteosarcoma U2-OS cells consisted four groups, and treated by E2, E2 + LY294002 (ERβ agonists), E2 + ERβ siRNA, E2 + ERβ siRNA + LY294002, respectively. Cell counting kit 8 (CCK-8) assay was performed to detect the cell viability of U2-OS cells in each group. The effects of ERβ on the migration and invasion ability of U2-OS cells were examined by wound healing assay and transwell cell culture chamber, respectively. The expression of Inhibitor of apoptosis protein (IAP) and integrin α5 in U2-OS cells of each group was detected by quantitative RT-PCR, and the expression of phosphorylated p65 (p-p65), p-AKT and Bcl-2 was detected by western blotting. The cell viability, migration and invasion ability of U2-OS cells were significantly increased by ERβ siRNA, but inhibited by ERβ agonists LY294002 (p < 0.05). ERβ siRNA significantly downregulated Integrin α5 and unregulated IAP in U2-OS cells (p < 0.05). The expression of p-p65, p-AKT and Bcl-2 was significantly reduced by LY294002, but increased by ERβ siRNA (p < 0.05). In conclusion, ERβ exhibited obvious anti-tumor effects on osteosarcoma cells by regulating integrin, IAP, NF-kBBCL-2 and PI3K/Akt signal pathway.

Ginseng on Nuclear Hormone Receptors

The first record of ginseng use dates back over two millennia, and ginseng is now popular in more than 35 countries. Ginsenosides are the pharmacological constituents responsible for the beneficial effects of ginseng. There is increasing evidence that ginseng and its bioactive ingredients are involved in the regulation of nuclear receptors, molecules that act in response to the specific binding of hormones, which link to a diverse array of signaling pathways, such as the ERK and PI3K/Akt pathways. Knowledge of the mechanism of how ginseng mediates these complexes is essential for the development of multi-target phytomedicine as possible therapy for different diseases. Here, we discuss the literature on the effects of ginseng and its constituents on estrogen, glucocorticoid, peroxisome proliferator-activated, and androgen nuclear hormone receptors, as well as how ginseng and its constituents exert their biological function in the treatment of cancer, obesity, and cardiovascular and neurological disorders. The accumulated results definitely show that the nuclear receptors are cellular targets of ginsenosides, but more rigorous data are required to establish and provide a scientific basis to confirm the suggested efficacy of ginseng or products with ginsenosides.

Dietary Management of Skin Health: The Role of Genistein

In women, aging and declining estrogen levels are associated with several cutaneous changes, many of which can be reversed or improved by estrogen supplementation. Two estrogen receptors—α and β—have been cloned and found in various tissue types. Epidermal thinning, declining dermal collagen content, diminished skin moisture, decreased laxity, and impaired wound healing have been reported in postmenopausal women. Experimental and clinical studies in postmenopausal conditions indicate that estrogen deprivation is associated with dryness, atrophy, fine wrinkling, and poor wound healing. The isoflavone genistein binds to estrogen receptor β and has been reported to improve skin changes. This review article will focus on the effects of genistein on skin health.

Utility of 18F-fluoroestradiol (18F-FES) PET/CT imaging as a pharmacodynamic marker in patients with refractory estrogen receptor-positive solid tumors receiving Z-endoxifen therapy

BACKGROUND

Z-endoxifen is the most potent of the metabolites of tamoxifen, and has the potential to be more effective than tamoxifen because it bypasses potential drug resistance mechanisms attributable to patient variability in the expression of the hepatic microsomal enzyme CYP2D6. 18F-FES is a positron emission tomography (PET) imaging agent which selectively binds to estrogen receptor alpha (ER-α) and has been used for non-invasive in vivo assessment of ER activity in tumors. This study utilizes 18F-FES PET imaging as a pharmacodynamic biomarker in patients with ER+ tumors treated with Z-endoxifen.

METHODS

Fifteen patients were recruited from a parent therapeutic trial of Z-endoxifen and underwent imaging with 18F-FES PET at baseline. Eight had positive lesions on the baseline scan and underwent follow-up imaging with 18F-FES 1-5 days post administration of Z-endoxifen.

RESULTS

Statistically significant changes (p = 0.0078) in standard uptake value (SUV)-Max were observed between the baseline and follow-up scans as early as 1 day post drug administration.

CONCLUSION

F-FES PET imaging could serve as a pharmacodynamic biomarker for patients treated with ER-directed therapy.

Dietary supplementation of yucca (Yucca schidigera) affects ovine ovarian functions

Yucca (Yucca schidigera) is a popular medicinal plant due to its many positive effects on animal and human physiology, including their reproductive systems. To examine the effect of supplemental yucca feeding on sheep reproduction, including ovarian functions and their hormonal regulators, ewes were fed (or not fed, control) yucca powder (1.5 g/head/day, 30 days). Macromorphometric indexes of the oviduct, ovary, and ovarian folliculogenesis were measured. Reproductive hormone levels in the blood were measured using a radioimmunoassay. Granulosa cells were aspirated from the ovary, and their proliferation and apoptosis were detected using immunocytochemistry. To assess secretory activity and its response to gonadotropin, ovarian fragments of treated and control ewes were cultured with and without follicle-stimulating hormone (FSH; 0, 0.1, 1, 10, or 100 IU/mL), and the release of reproductive hormones into the culture medium was evaluated. Finally, to examine the direct action of yucca on the ovary, ovarian fragments from control ewes were cultured with and without yucca extract (1, 10, or 100 μg/mL), and the release of reproductive hormones was measured. Yucca supplementation significantly decreased the size of small antral follicles (2 to <5 mm in diameter), increased accumulation of the apoptosis marker bax, and decreased serum progesterone (P4) and estradiol (E2) levels. It inhibited the release of P4 (but not other hormones), to prevent the stimulatory action of FSH on P4 output and promoted insulin-like growth factor I (IGF-I) release by fragments cultured with FSH. However, yucca supplementation did not affect the size of larger follicles and number of follicles, volume and weight of ovaries, length and weight of oviducts, caspase 3 accumulation, cell proliferation, testosterone (T) or IGF-I serum levels, or T or E2 release by cultured ovarian fragments and their response to FSH. Yucca addition to culture medium inhibited P4 and IGF-I, but not T or E2 release at the lowest (1 μg/mL) dose, and stimulated P4, but not T, E2, or IGF-I release at the highest (100 μg/mL) dose. These data suggest that yucca supplementation can reduce small antral ovarian follicle development possibly via the stimulation of apoptosis of their granulosa cells, suppression of ovarian P4 and E2 release, and alteration of ovarian IGF-I output and ovarian response to gonadotropin. Thus, yucca can directly affect P4 and IGF-I release by ovine ovarian cells.

Effects of ginseng on two main sex steroid hormone receptors: estrogen and androgen receptors

Ginseng has been used in China for at least two millennia and is now popular in over 35 countries. It is one of the world's popular herbs for complementary and alternative medicine and has been shown to have helpful effects on cognition and blood circulation, as well as anti-aging, anti-cancer, and anti-diabetic effects, among many others. The pharmacological activities of ginseng are dependent mainly on ginsenosides. Ginsenosides have a cholesterol-like four trans-ring steroid skeleton with a variety of sugar moieties. Nuclear receptors are one of the most important molecular targets of ginseng, and reports have shown that members of the nuclear receptor superfamily are regulated by a variety of ginsenosides. Here, we review the published literature on the effects of ginseng and its constituents on two main sex steroid hormone receptors: estrogen and androgen receptors. Furthermore, we discuss applications for sex steroid hormone receptor modulation and their therapeutic efficacy.

Estrogen receptor β promoter methylation: a potential indicator of malignant changes in breast cancer

INTRODUCTION

Estrogen receptor β (ERβ) always lacks expression in estrogen-dependent tumors, which may result from gene inactivation by methylation. In this study, we aimed to determine whether aberrant methylation of the ERβ promoter is associated with decreased ERβ gene expression in breast cancer.

MATERIAL AND METHODS

ERβ methylation status was determined for 132 pairs of breast cancer and adjacent normal tissues via the MethyLight method. Additionally, mRNA relative expression was quantified by real-time polymerase chain reaction (RT-PCR) to determine whether aberrant methylation had a negative correlation with expression. The correlation of ERβ promoter methylation and clinical parameters is also discussed.

RESULTS

Methylation was observed in 96 (72.7%) breast cancer samples, and the median percentage of fully methylated reference (PMR) among methylated tissues was 0.83. Meanwhile, 94 (71.2%) adjacent normal tissues were methylated and the median PMR was 0.48. Compared to adjacent normal tissues, the methylation level of breast cancer was significantly higher (p < 0.001) and mRNA expression was much lower (p < 0.001). There was a significant correlation between ERβ methylation and mRNA expression in adjacent normal breast tissues (p = 0.004). In addition, the methylation rate of cancer tissues whose maximum diameter < 3 cm was significantly higher than those > 3 cm (p = 0.025).

CONCLUSIONS

ERβ promoter methylation level varies between cancerous and adjacent normal breast tissues. There was significant downregulation of ERβ methylation expression in pre-cancerous stages of breast cancer. Therefore, demethylation drugs may offer a potential strategy for preventing the development of pre-cancerous cells.

The Estrogen Receptor-β Expression in De Quervain's Disease

Stenosing tenosynovitis of the first dorsal compartment of the wrist (a.k.a. de Quervain’s disease) is common but how estrogen is involved is still unknown. We previously reported that inflammation was involved in the pathogenesis of this ailment. In the present study, we extended our investigation of estrogen receptor (ER)-β expression to determine whether estrogen is involved in the pathogenesis of de Quervain’s. Intraoperative retinaculum samples were collected from 16 patients with the ailment. Specimens were histologically graded by collagen structure and immunohistochemically evaluated by quantifying the expression of ER-β, interleukin (IL)-1β and IL-6 (inflammatory cytokines), cyclooxygenase (COX)-2 (an inflammatory enzyme), and vascular endothelial growth factor (VEGF), and Von Willebrand’s factor (vWF). De Quervain’s occurs primarily in women. The female:male ratio in our study was 7:1. We found that ER-β expression in the retinaculum was positively correlated with disease grade and patient age. Additionally, disease severity was associated with inflammatory factors—IL-1β and IL-6, COX-2, and VEGF and vWF in tenosynovial tissue. The greater the levels of ER-β expression, tissue inflammation, and angiogenesis are, the more severe de Quervain’s disease is. ER-β might be a useful target for novel de Quervain’s disease therapy.

Estrogen receptor β in Alzheimer's disease: From mechanisms to therapeutics

Alzheimer's disease (AD) disproportionally affects women and men. The female susceptibility for AD has been largely associated with the loss of ovarian sex hormones during menopause. This review examines the current understanding of the role of estrogen receptor β (ERβ) in the regulation of neurological health and its implication in the development and intervention of AD. Since its discovery in 1996, research conducted over the last 15-20 years has documented a great deal of evidence indicating that ERβ plays a pivotal role in a broad spectrum of brain activities from development to aging. ERβ genetic polymorphisms have been associated with cognitive impairment and increased risk for AD predominantly in women. The role of ERβ in the intervention of AD has been demonstrated by the alteration of AD pathology in response to treatment with ERβ-selective modulators in transgenic models that display pronounced plaque and tangle histopathological presentations as well as learning and memory deficits. Future studies that explore the potential interactions between ERβ signaling and the genetic isoforms of human apolipoprotein E (APOE) in brain aging and development of AD-risk phenotype are critically needed. The current trend of lost-in-translation in AD drug development that has primarily been based on early-onset familial AD (FAD) models underscores the urgent need for novel models that recapitulate the etiology of late-onset sporadic AD (SAD), the most common form of AD representing more than 95% of the current human AD population. Combining the use of FAD-related models that generally have excellent face validity with SAD-related models that hold more reliable construct validity would together increase the predictive validity of preclinical findings for successful translation into humans.

Urinary enterolactone associated with liver enzyme levels in US adults: National Health and Nutrition Examination Survey (NHANES)

Phyto-oestrogens are a family of plant-derived xeno-oestrogens that appear to have beneficial effects on human health. To date, no data are available about phyto-oestrogen consumption affecting liver health in a population. The present study aimed to explore the relationship of urinary phyto-oestrogen metabolites with serum liver enzymes in US adults. A nationally representative sample of US adults in the National Health and Nutrition Examination Survey (NHANES) 2003–10 was analysed. The cross-sectional study sample consisted of 6438 adults with data on urinary phyto-oestrogen levels, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and γ-glutamyl transaminase (GGT) concentrations and data on other potential confounders. Multivariate logistic regression and linear regression were applied to assess associations between urinary phyto-oestrogen levels and ALT, AST, ALP and GGT concentrations. We found a remarkable association between urinary enterolactone and GGT in both adult males (OR 0·37, 95 % CI 0·22, 0·61; P= 0·003) and females (OR 0·37, 95 % CI 0·26, 0·54; P= 0·009). Moreover, elevated enterolactone levels were inversely associated with ALT and AST levels in adult males. However, no association was present between levels of urinary daidzein, O-desmethylangolensin, equol, enterodiol or genistein with liver enzyme levels in this population. The present study results provide epidemiological evidence that urinary enterolactone levels are associated with liver GGT levels in humans. This suggests a potential protective effect of enterolactone on human liver function. However, the underlying mechanisms still need further investigation.

Overexpression of estrogen receptor beta alleviates the toxic effects of beta-amyloid protein on PC12 cells via non-hormonal ligands

After binding to the estrogen receptor, estrogen can alleviate the toxic effects of beta-amyloid protein, and thereby exert a therapeutic effect on Alzheimer's disease patients. Estrogen can increase the incidence of breast carcinoma and endometrial cancer in post-menopausal women, so it is not suitable for clinical treatment of Alzheimer's disease. There is recent evidence that the estrogen receptor can exert its neuroprotective effects without estrogen dependence. Real-time quantitative PCR and flow cytometry results showed that, compared with non-transfected PC12 cells, adenovirus-mediated estrogen receptor β gene-transfected PC12 cells exhibited lower expression of tumor necrosis factor α and interleukin 1β under stimulation with beta-amyloid protein and stronger protection from apoptosis. The Akt-specific inhibitor Abi-2 decreased the anti-inflammatory and anti-apoptotic effects of estrogen receptor β gene-transfection. These findings suggest that overexpression of estrogen receptor β can alleviate the toxic effect of beta-amyloid protein on PC12 cells, without estrogen dependence. The Akt pathway is one of the potential means for the anti-inflammatory and anti-apoptotic effects of the estrogen receptor.

Intratumoural inflammation and endocrine resistance in breast cancer

It is becoming clear that inflammation-associated mechanisms can affect progression of breast cancer and modulate responses to treatment. Estrogen receptor alpha (ERα (ESR1)) is the principal biomarker and therapeutic target for endocrine therapies in breast cancer. Over 70% of patients are ESR1-positive at diagnosis and are candidates for endocrine therapy. However, ESR1-positive tumours can become resistant to endocrine therapy. Multiple mechanisms of endocrine resistance have been proposed, including suppression of ESR1. This review discusses the relationship between intratumoural inflammation and endocrine resistance with a particular focus on inflammation-mediated suppression of ESR1.

The role of estrogen receptor β in prostate cancer

Although androgen receptor (AR) signaling is the main molecular tool regulating growth and function of the prostate gland, estrogen receptor β (ERβ) is involved in the differentiation of prostatic epithelial cells and numerous antiproliferative actions on prostate cancer cells. However, ERβ splice variants have been associated with prostate cancer initiation and progression mechanisms. ERβ is promising as an anticancer therapy and in the prevention of prostate cancer. Herein, we review the recent experimental findings of ERβ signaling in the prostate.

Estrogen receptor beta treats Alzheimer's disease

In vitro studies have shown that estrogen receptor β can attenuate the cytotoxic effect of amyloid β protein on PC12 cells through the Akt pathway without estrogen stimulation. In this study, we aimed to observe the effect of estrogen receptor β in Alzheimer's disease rat models established by intraventricular injection of amyloid β protein. Estrogen receptor β lentiviral particles delivered via intraventricular injection increased Akt content in the hippocampus, decreased interleukin-1β mRNA, tumor necrosis factor α mRNA and amyloid β protein levels in the hippocampus, and improved the learning and memory capacities in Alzheimer's disease rats. Estrogen receptor β short hairpin RNA lentiviral particles delivered via intraventricular injection had none of the above impacts on Alzheimer's disease rats. These experimental findings indicate that estrogen receptor β, independent from estrogen, can reduce inflammatory reactions and amyloid β deposition in the hippocampus of Alzheimer's disease rats, and improve learning and memory capacities. This effect may be mediated through activation of the Akt pathway.

Prognostic significance of interactions between ER alpha and ER beta and lymph node status in breast cancer cases

OBJECTIVE

Both estrogen receptors, ER alpha (ERα) and ER beta (ERβ), are expressed in 50-70% of breast cancer cases. The role of ERα as a prognostic marker in breast cancer has been well established as its expression is negative correlated with tumor size and lymph node metastasis. ERβ is also a favorable prognostic predictor although this is less well documented than for ERα.

MATERIALS AND METHODS

To explore whether ERs independently or together might influence clinical outcome in breast cancer, the correlation between the ERs with the clinicopathological features was analyzed in 84 patients.

RESULTS

ERα expression negatively correlated with tumor stage (r=-0.246, p=0.028) and tended to be negatively correlated with lymph node status (r=-0.156, p=0.168) and tumor size (r=-0.246, p=0.099). Also, ERβ was negatively correlated with nodal status (r=-0.243, p=0.028), as was coexpression of ERα and ERβ (p=0.043, OR=0.194, 95% CI= 0.040- 0.953).

CONCLUSION

Coexpression of ERs might serve as an indicator of good prognosis in breast cancer patients.

Genistein versus ICI 182, 780: an ally or enemy in metastatic progression of prostate cancer

BACKGROUND

Androgen signalling through the androgen receptor (AR) plays a critical role in prostate cancer (PCa) initiation and progression. Estrogen in synergy with androgen is essential for cell growth of the normal and malignant prostate. However, the exact role that estrogen and the estrogen receptor play in prostate carcinogenesis remains unclear. We have previously demonstrated the metastasis-promoting effect of an estrogen receptor beta (ERβ) agonist (genistein) in a patient-derived PCa xenograft model mimicking localized and metastatic disease.

METHODS

To test the hypothesis that the tumor-promoting activity of genistein was due to its estrogenic properties, we treated the xenograft-bearing mice with genistein and an anti-estrogen compound (ICI 182, 780) and compared the differential gene expression using microarrays.

RESULTS

Using a second xenograft model which was derived from another patient, we showed that genistein promoted disease progression in vivo and ICI 182, 780 inhibited metastatic spread. The microarray analysis revealed that the metallothionein (MT) gene family was differentially expressed in tumors treated by these compounds. Using qRT-PCR, the differences in expression levels were validated in the metastatic and non-metastatic LTL313 PCa xenograft tumor lines, both of which were originally derived from the same PCa patient.

CONCLUSIONS

Together our data provide evidence that genistein stimulates and ICI 182, 780 inhibits metastatic progression, suggesting that these effects may be mediated by ERβ signalling.

PET imaging of oestrogen receptors in patients with breast cancer

Oestrogen receptors are overexpressed in around 70% of all breast cancers, and are a target for endocrine therapy. These receptors can be visualised on PET with use of 16α-[(18)F]-fluoro-17β-oestradiol ((18)F-FES) as a tracer. Compared with biopsy, which enables assessment of individual sites, whole-body (18)F-FES-PET enables quantification of oestrogen-receptor expression in all metastases. In several studies, measurement of tumour protein expression in oestrogen receptors by (18)F-FES-PET, concurrent with biopsy, detected oestrogen-receptor-positive tumour lesions with a sensitivity of 84% and specificity of 98%. Roughly 45% of patients with metastatic breast cancer have discordant oestrogen-receptor expression across lesions (ie, (18)F-FES-positive and (18)F-FES-negative metastases). Low tumour (18)F-FES uptake in metastases can predict failure of hormonal therapy in patients with oestrogen-receptor-positive primary tumours. Finally, (18)F-FES-PET has shown that oestrogen-receptor binding capacity changes after intervention with hormonal drugs, but findings need to be confirmed. Factors other than oestrogen-receptor expression, including menopausal status and concomitant therapies, that can affect tumour (18)F-FES uptake must be taken into account.

The expression of estrogen receptors β2, 5 identifies and is associated with prognosis in non-small cell lung cancer

Estrogens play a pivotal role in the development and progression of non-small lung cancer (NSCLC). With the discovery of estrogen receptor β (ERβ) isoforms, some controversial roles of ERβ were explained adequately in NSCLC. In this study, our aim is to elucidate expression, distribution, and prognostic significance of ERβ 1, 2, 5 in NSCLC. Estrogen receptors β1, 2, 5 protein expression were confirmed by Western-blot analysis in all frozen tissues, and immunohistochemistry (IHC). Nuclear and cytoplasmic staining was evaluated and correlated with histopathologic characteristics, overall survival (OS) and disease-free survival (DFS) via Pearson χ (2) square, Kaplan-Meier plots and Cox proportional hazard models. ERβ1 was commonly found in the cytoplasm and was the most abundant isofroms followed by ERβ2 and ERβ5 which were localized in the cytoplasm and nucleus. In contrast to BPL, both in nucleus and cytoplasm, ERβ1, ERβ2, and ERβ5 were over expressed all in NSCLC (P < 0.05). IHC results were correlated with pathological and clinical follow-up data to delineate the distinct roles of ERβ1, ERβ2, and ERβ5 in NSCLC. nERβ1 "nuclear", cERβ2 and cERβ5 "cytoplasm" were in a negative correlation with the pathological stage and lymph node metastasis. In a Kaplan-Meier analysis, the expression cERβ2 and cERβ5 identified a group of patients with the longest DFS and OS. Cox proportional hazard models revealed that cERβ2 and cERβ5 predicted long time to DFS and OS. This is the first study to uncover the expression of ERβ1, ERβ2, and ERβ5, and show that they were over expressed in NSCLC. Meantime, we find that positive expression of cERβ2 and cERβ5 were in a positive correlation with DFS, and have prognostic values for the progression of NSCLC.

Estrogen receptor beta 2 is associated with poor prognosis in estrogen receptor alpha-negative breast carcinoma

PURPOSE

Our aim was to examine the prognostic significance of ERbeta1 and ERbeta2 expression in ERalpha-negative breast carcinomas.

MATERIALS AND METHODS

We evaluated nuclear and cytoplasmic expression of ERbeta1 and ERbeta2 by immunohistochemistry in a group of 95 patients with long follow-up. ERbeta1 and ERbeta2 status was correlated with clinicopathological parameters and disease outcome. Univariate and multivariate analyses of ERbeta1 and ERbeta2 as independent markers of disease-free survival (DFS) were carried out using the Cox proportional hazards model.

RESULTS

Nuclear ERbeta1 (nERbeta1) and nERbeta2 status was positively correlated (p = 0.01). nERbeta1 positivity was associated with low histological grade (p = 0.01) in all patients and in the nERbeta2-positive subgroup (p = 0.03) but not in the nERbeta2-negative (p = 0.27). nERbeta2 positivity was associated with lymph node involvement and tumor relapse in all cases (p < 0.00 and p < 0.00, respectively) and in the nERbeta1-negative subgroup (p < 0.00 and p < 0.00, respectively) but not in the nERbeta1-positive (p = 0.09 and p = 0.20, respectively). nERbeta2 positivity was associated with poor DFS in all patients (log-rank p <0.00), in the post-menopausal patient subgroup (log-rank p = 0.02) and in the HER2-negative (triple-negative) subgroup (log-rank p = 0.04). Cox multivariate analysis including ERbeta1, ERbeta2 and established clinicopathological variables highlighted ERbeta2 as an independent marker of early disease recurrence (hazard ratio 4.87; 95 % confidence interval 1.07-22.3; p = 0.04).

CONCLUSION

High nERbeta2 is an independent marker of early relapse in ERalpha-negative breast carcinoma, and in particular, in the nERbeta1-negative, the post-menopausal patient and the triple-negative subgroups. These findings suggest that inhibition of expression and/or function of ERbeta2 could improve disease outcome.

Estrogen receptor β agonists affect growth and gene expression of human breast cancer cell lines

Expression of estrogen receptor β (ERβ) has been described to reduce growth of cancer cell lines derived from hormone-dependent tumors, like breast cancer. In this study we tested to what extent two ERβ agonists, androgen derivative 3β-Adiol and flavonoid Liquiritigenin, would affect growth and gene expression of different ERβ-positive human breast cancer cell lines. Under standard cell culture conditions, we observed 3β-Adiol to inhibit growth of MCF-7 cells in a dose-dependent manner, whereas growth of BT-474 and MCF-10A cells was suppressed by the maximum concentration (100 nM) only. When treated in serum-free medium, all cell lines except of MDA-MB-231 were responsive to 1 nM 3β-Adiol, and ZR75-1 cells exhibited a dose-dependent antiproliferative response. Providing putative mechanisms underlying the observed growth-inhibitory effect, expression of Ki-67 or cyclins A2 and B1 was downregulated after 3β-Adiol treatment in all responsive lines. In contrast, treatment with lower doses of Liquiritigenin did not affect growth. In MCF-7 cells, the highest dose of this flavonoid exerted proliferative effects accompanied by increased expression of cyclin B1, PR and PS2, indicating unspecific activation of ERα. In conclusion, the ERβ agonists tested exerted distinct concentration-dependent and cell line-specific effects on growth and gene expression. The observed inhibitory effects of 3β-Adiol on breast cancer cell growth encourage further studies on the potential of this and other ERβ agonists as targeted drugs for breast cancer therapy.

Synthesis and biological evaluation of two agents for imaging estrogen receptor β by positron emission tomography: challenges in PET imaging of a low abundance target

INTRODUCTION

Independent measurement of the levels of both the estrogen receptors, ERα and ERβ, in breast cancer could improve prediction of benefit from endocrine therapies. While ERα levels can be measured by positron emission tomography (PET) using 16α-[(18)F]fluoroestradiol (FES), no effective agent for imaging ERβ by PET has yet been reported.

METHODS

We have prepared the fluorine-18 labeled form of 8β-(2-fluoroethyl)estradiol (8BFEE(2)), an analog of an ERβ-selective steroidal estrogen, 8β-vinylestradiol; efficient incorporation of fluorine-18 was achieved, but required very vigorous conditions. We have examined the biodistribution of this compound, as well as of Br-041, an analog of a known non-steroidal ERβ-selective ligand (ERB-041), labeled with bromine-76. Studies were done in immature female rodents, with various pharmacological and endocrine perturbations to assess ERβ selectivity of uptake.

RESULTS

Little evidence of ERβ-mediated uptake was observed with either [(18)F]8BFEE(2) or [(76)Br]Br-041. Attempts to increase the ERβ content of target tissues were not effective and failed to improve biodistribution selectivity.

CONCLUSIONS

Because on an absolute basis level, ERβ levels are low in all target tissues, these studies have highlighted the need to develop improved in vivo models for evaluating ERβ-selective radiopharmaceuticals for use in PET imaging. Genetically engineered breast cancer cells that are being developed to express either ERα or ERβ in a regulated manner, grown as xenografts in immune-compromised mice, could prove useful for future studies to develop ER subtype-selective radiopharmaceuticals.

Influence of berry polyphenols on receptor signaling and cell-death pathways: implications for breast cancer prevention

Breast cancer is the most commonly diagnosed cancer among women worldwide. Many women have become more aware of the benefits of increasing fruit consumption, as part of a healthy lifestyle, for the prevention of cancer. The mechanisms by which fruits, including berries, prevent breast cancer can be partially explained by exploring their interactions with pathways known to influence cell proliferation and evasion of cell-death. Two receptor pathways, estrogen receptor (ER) and tyrosine kinase receptors, especially the epidermal growth factor receptor (EGFR) family, are drivers of cell proliferation and play a significant role in the development of both primary and recurrent breast cancer. There is strong evidence to show that several phytochemicals present in berries such as cyanidin, delphinidin, quercetin, kaempferol, ellagic acid, resveratrol, and pterostilbene interact with and alter the effects of these pathways. Furthermore, they also induce cell death (apoptosis and autophagy) via their influence on kinase signaling. This review summarizes in vitro data regarding the interaction of berry polyphenols with the specific receptors and the mechanisms by which they induce cell death. This paper also presents in vivo data of primary breast cancer prevention by individual compounds and whole berries. Finally, a possible role for berries and berry compounds in the prevention of breast cancer and a perspective on the areas that require further research are presented.