Estrogen receptor beta in the breast: role in estrogen responsiveness and development of breast cancer

Causal relationship between sex hormones and cutaneous melanoma: a two-sample Mendelian randomized study

This study aimed to elucidate the genetic aspects of the relationship between sex hormones and cutaneous melanoma risk, providing valuable insights into this complex association. In this study, we used estradiol, bioavailable testosterone, sex hormone-binding globulin, and total testosterone as the exposure and melanoma as the outcome for two-sample Mendelian randomization analysis. In this study, a random-effects inverse-variance weighting (IVW) model was used as the main analysis model, and the corresponding weighted median, simple mode, weighted mode, and Mendelian randomization‒Egger methods were used as supplementary methods. We assessed both heterogeneity and horizontal pleiotropy in our study, scrutinizing whether the analysis results were affected by any individual single nucleotide polymorphism. The random-effects IVW method indicated that estradiol [odds ratio (OR), 1.000; 95% confidence interval (CI), 0.998-1.003; P  = 0.658], bioavailable testosterone (OR = 1.001, 95% CI, 0.999-1.003; P  = 0.294), sex hormone-binding globulin (IVW: OR, 1.000; 95% CI, 0.998-1.003; P  = 0.658), and total testosterone (IVW: OR, 1.002; 95% CI, 0.999-1.005; P  = 0.135) were not genetically linked to cutaneous melanoma. No analyses exhibited heterogeneity, horizontal pleiotropy, or deviations. We were unable to find genetic evidence for a causal relationship between sex hormones and the occurrence of cutaneous melanoma in this study. These results are limited by sample size and population, so the causal relationship between sex hormones and cutaneous melanoma needs to be further studied.

Cyclopia extracts act as selective estrogen receptor subtype downregulators in estrogen receptor positive breast cancer cell lines: Comparison to standard of care breast cancer endocrine therapies and a selective estrogen receptor agonist and antagonist

Breast cancer is the most diagnosed type of cancer amongst women in economically developing countries and globally. Most breast cancers express estrogen receptor alpha (ERα) and are categorized as positive (ER+) breast cancer. Endocrine therapies such as, selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and selective estrogen receptor downregulators (SERDs) are used to treat ER+ breast cancer. However, despite their effectiveness, severe side-effects and resistance are associated with these endocrine therapies. Thus, it would be highly beneficial to develop breast cancer drugs that are as effective as current therapies, but less toxic with fewer side effects, and less likely to induce resistance. Extracts of Cyclopia species, an indigenous South African fynbos plant, have been shown to possess phenolic compounds that exhibit phytoestrogenic and chemopreventive activities against breast cancer development and progression. In the current study, three well characterized Cyclopia extracts, SM6Met, cup of tea (CoT) and P104, were examined for their abilities to modulate the levels of the estrogen receptor subtypes, estrogen receptor alpha and estrogen receptor beta (ERβ), which have been recognized as crucial to breast cancer prognosis and treatment. We showed that the Cyclopia subternata Vogel (C. subternata Vogel) extracts, SM6Met and cup of tea, but not the C. genistoides extract, P104, reduced estrogen receptor alpha protein levels while elevating estrogen receptor beta protein levels, thereby reducing the ERα:ERβ ratio in a similar manner as standard of care breast cancer endocrine therapies such as fulvestrant (selective estrogen receptor downregulator) and 4-hydroxytamoxifen (elective estrogen receptor modulator). Estrogen receptor alpha expression enhances the proliferation of breast cancer cells while estrogen receptor beta inhibits the proliferative activities of estrogen receptor alpha. We also showed that in terms of the molecular mechanisms involved all the Cyclopia extracts regulated estrogen receptor alpha and estrogen receptor beta protein levels through both transcriptional and translational, and proteasomal degradation mechanisms. Therefore, from our findings, we proffer that the C. subternata Vogel extracts, SM6Met and cup of tea, but not the C. genistoides extract, P104, selectively modulate estrogen receptor subtypes levels in a manner that generally supports inhibition of breast cancer proliferation, thereby demonstrating attributes that could be explored as potential therapeutic agents for breast cancer.

Long-term impact of hypothyroidism during gestation and lactation on the mammary gland

The functional differentiation of the mammary gland (MG) is fundamental for the prevention of mammary pathologies. This process occurs throughout pregnancy and lactation, making these stages key events for the study of pathologies associated with development and differentiation. Many studies have investigated the link between mammary pathologies and thyroid diseases, but most have ignored the role of thyroid hormone (TH) in the functional differentiation of the MG. In this work, we show the long-term impact of hypothyroidism in an animal model whose lactogenic differentiation occurred at low TH levels. We evaluated the ability of the MG to respond to hormonal control and regulate cell cycle progression. We found that a deficit in TH throughout pregnancy and lactation induces a long-term decrease in Rb phosphorylation, increases p53, p21, Cyclin D1 and Ki67 expression, reduces progesterone receptor expression, and induces nonmalignant lesions in mammary tissue. This paper shows the importance of TH level control during mammary differentiation and its long-term impact on mammary function.

Cutaneous Melanoma and Hormones: Focus on Sex Differences and the Testis

Cutaneous melanoma, the most aggressive type of skin cancer, remains one the most represented forms of cancer in the United States and European countries, representing, in Australia, the primary cause of cancer-related deaths. Recently, many studies have shown that sex disparities previously observed in most cancers are particularly accentuated in melanoma, where male sex is consistently associated with an increased risk of disease progression and a higher mortality rate. The causes of these sex differences rely on biological mechanisms related to sex hormones, immune homeostasis and oxidative processes. The development of newer therapies, such as immune checkpoint inhibitors (ICIs) (i.e., anti-PD-1 and anti-CTLA-4 monoclonal antibodies) has dramatically changed the treatment landscape of metastatic melanoma patients, though ICIs can interfere with the immune response and lead to inflammatory immune-related adverse events (irAEs). Recently, some studies have shown a potential adverse influence of this immunotherapy treatment also on male fertility and testicular function. However, while many anticancer drugs are known to cause defects in spermatogenesis, the effects of ICIs therapy remain largely unknown. Notwithstanding the scarce and conflicting information available on this topic, the American Society of Clinical Oncology guidelines recommend sperm cryopreservation in males undergoing ICIs. As investigations regarding the long-term outcomes of anticancer immunotherapy on the male reproductive system are still in their infancy, this review aims to support and spur future research in order to understand a potential gonadotoxic effect of ICIs on testicular function, spermatogenesis and male fertility.

Triple-negative breast cancer drug resistance, durable efficacy, and cure: How advanced biological insights and emerging drug modalities could transform progress

INTRODUCTION

Triple-negative breast cancer (TNBC) is a heterogeneous disease characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2) and often associated with poor survival outcomes. The backbone of current treatments for TNBC relies on chemotherapy; however, resistance to cytotoxic agents is a commonly encountered hurdle to overcome.

AREAS COVERED

: Current understanding on the mechanisms involved in TNBC chemoresistance is evaluated and novel potential actionable targets and recently explored modalities for carrying and delivering chemotherapeutics are highlighted.

EXPERT OPINION

: A comprehensive identification of both genomic and functional TNBC signatures is required for a more definite categorization of the patients in order to prevent insensitivity to chemotherapy and therefore realize the full potential of precision-medicine approaches. In this scenario, cell-line-derived xenografts (CDX), patient-derived xenografts (PDX), patient-derived orthotopic xenografts (PDOX) and patient-derived organoids (PDO) are indispensable experimental models for evaluating the efficacy of drug candidates and predicting the therapeutic response. The combination of increasingly sensitive "omics" technologies, computational algorithms and innovative drug modalities may accelerate the successful translation of novel candidate TNBC targets from basic research to clinical settings, thus contributing to reach optimal clinical output, with lower side effects and reduced resistance.

Use of Radionuclide-Based Imaging Methods in Breast Cancer

Breast cancer is one of the most commonly occurring cancers in women globally and is the primary cause of cancer mortality in females. Thus, early and effective breast cancer diagnosis is crucial for enhancing the survival rate. Current standard diagnostic techniques to assess the hormone receptor status in biopsies include immunohistochemistry and fluorescence in situ hybridization. However, in recent years, there has been an increase in research on noninvasive techniques for molecular imaging of hormone receptors. These methods offer many advantages over conventional imaging, as repeated measurements can be used to capture heterogeneous tumor expression throughout the body, as well as transformations in receptor status during disease progression. Thus, the noninvasive method, as an adjunct to conventional imaging, offers the potential to improve patient selection, optimize dose and schedule, and streamline the assessment of response.

One-pot synthesis and antiproliferative activity of highly functionalized pyrazole derivatives

A series of highly functionalized pyrazole derivatives has been prepared by a one-pot, versatile and regioselective procedure. Pyrazoles 1-29 were tested in cell-based assay to assess their antiproliferative activity against a panel of tumour cells. Additionally, the cytotoxicity of prepared compounds was evaluated against normal human fibroblasts. The antiproliferative activity of the synthesized molecules emerged to be affected by the nature of the substituents of the pyrazole scaffold and derivatives 21-23 proved to inhibit the growth of melanoma and cervical cancer cells. Compound 23 was identified as the most active derivative and docking simulations predicted its ability to interact with estrogen receptors.

Radionuclide-Based Imaging of Breast Cancer: State of the Art

Simple Summary

Breast cancer is one of the most commonly diagnosed malignant tumors, possessing high incidence and mortality rates that threaten women’s health. Thus, early and effective breast cancer diagnosis is crucial for enhancing the survival rate. Radionuclide molecular imaging displays its advantages for detecting breast cancer from a functional perspective. Noninvasive visualization of biological processes with radionuclide-labeled small metabolic compounds helps elucidate the metabolic state of breast cancer, while radionuclide-labeled ligands/antibodies for receptor-targeted radionuclide molecular imaging is sensitive and specific for visualization of the overexpressed molecular markers in breast cancer. This review focuses on the most recent developments of novel radiotracers as promising tools for early breast cancer diagnosis.

Abstract

Breast cancer is a malignant tumor that can affect women worldwide and endanger their health and wellbeing. Early detection of breast cancer can significantly improve the prognosis and survival rate of patients, but with traditional anatomical imagine methods, it is difficult to detect lesions before morphological changes occur. Radionuclide-based molecular imaging based on positron emission tomography (PET) and single-photon emission computed tomography (SPECT) displays its advantages for detecting breast cancer from a functional perspective. Radionuclide labeling of small metabolic compounds can be used for imaging biological processes, while radionuclide labeling of ligands/antibodies can be used for imaging receptors. Noninvasive visualization of biological processes helps elucidate the metabolic state of breast cancer, while receptor-targeted radionuclide molecular imaging is sensitive and specific for visualization of the overexpressed molecular markers in breast cancer, contributing to early diagnosis and better management of cancer patients. The rapid development of radionuclide probes aids the diagnosis of breast cancer in various aspects. These probes target metabolism, amino acid transporters, cell proliferation, hypoxia, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), gastrin-releasing peptide receptor (GRPR) and so on. This article provides an overview of the development of radionuclide molecular imaging techniques present in preclinical or clinical studies, which are used as tools for early breast cancer diagnosis.

Role of estrogen receptor coregulators in endocrine resistant breast cancer

Breast cancer (BC) is the most ubiquitous cancer in women. Approximately 70–80% of BC diagnoses are positive for estrogen receptor (ER) alpha (ERα). The steroid hormone estrogen [17β-estradiol (E2)] plays a vital role both in the initiation and progression of BC. The E2-ERα mediated actions involve genomic signaling and non-genomic signaling. The specificity and magnitude of ERα signaling are mediated by interactions between ERα and several coregulator proteins called coactivators or corepressors. Alterations in the levels of coregulators are common during BC progression and they enhance ligand-dependent and ligand-independent ERα signaling which drives BC growth, progression, and endocrine therapy resistance. Many ERα coregulator proteins function as scaffolding proteins and some have intrinsic or associated enzymatic activities, thus the targeting of coregulators for blocking BC progression is a challenging task. Emerging data from in vitro and in vivo studies suggest that targeting coregulators to inhibit BC progression to therapy resistance is feasible. This review explores the current state of ERα coregulator signaling and the utility of targeting the ERα coregulator axis in treating advanced BC.

Endocrine disrupting chemicals and the mammary gland

Development of the mammary gland requires coordination of hormone signaling pathways including those mediated by estrogen, progesterone, androgen and prolactin receptors. These hormones play important roles at several distinct stages of life including embryonic/fetal development, puberty, pregnancy, lactation, and old age. This also makes the gland sensitive to perturbations from environmental agents including endocrine disrupting chemicals (EDCs). Although there is evidence from human populations of associations between EDCs and disruptions to breast development and lactation, these studies are often complicated by the timing of exposure assessments and the latency to develop breast diseases (e.g., years to decades). Rodents have been instrumental in providing insights-not only to the basic biology and endocrinology of the mammary gland, but to the effects of EDCs on this tissue at different stages of development. Studies, mostly but not exclusively, of estrogenic EDCs have shown that the mammary gland is a sensitive tissue, that exposures during perinatal development can produce abnormal mammary structures (e.g., alveolar buds, typically seen in pregnant females) in adulthood; that exposures during pregnancy can alter milk production; and that EDC exposures can enhance the response of the mammary tissue to hormones and chemical carcinogens. Other studies of persistent organic pollutants have shown that EDC exposures during critical windows of development can delay development of the gland, with lifelong consequences for the individual. Collectively, this work continues to support the conclusion that EDCs can harm the mammary gland, with effects that depend on the period of exposure and the period of evaluation.

Selective degradation of the estrogen receptor in the treatment of cancers

Estrogen receptor subtype α (ERα) plays key roles in breast cancers, and has been a target for endocrine therapy for a long time. Unfortunately, long-term treatment by Aromatase Inhibitors (AIs) or Selective Estrogen Receptor Modulators (SERMs) could cause drug resistance and also would increase the risk for uterine cancer. Therefore, novel anti-breast cancer drugs based on different mechanisms of action have received significant attention, especially through the strategies of selective degradation of ER. In this article, the latest research progress of selective targeting ER for degradation, including Selective ER Downregulators (SERDs), Proteolysis Targeting Chimaeras (PROTACs) and other techniques, was reviewed, and the applications and problems to be solved were prospected.

Beer and its non-alcoholic compounds in health and disease

Moderate alcohol consumption has been associated with beneficial effects on human health. Specifically, consumption of red wine and beer has shown a J-shape relation with many important diseases. While a role of ethanol cannot be excluded, the high content of polyphenols in both beverages has been proposed to contribute to these effects, with beer having the advantage over wine that it is lower in alcohol. In addition to ethanol, beer contains a wide variety of compounds with known medicinal potential such as kaempferol, quercetin, tyrosol and phenolic acids, and it is the main dietary source for the flavones xanthohumol and 8-prenylnaringenin, and bitter acids such as humulones and lupulones. Clinical and pre-clinical evidence for the protective effects of moderate beer consumption against cardiovascular disease and other diseases has been accumulating since the 1990s, and the non-alcoholic compounds of beer likely exert most of the observed beneficial effects. In this review, we summarize and discuss the effects of beer consumption in health and disease as well as the clinical potential of its non-alcoholic compounds which may be promising candidates for new therapies against common chronic diseases.

Insight Analysis of Promiscuous Estrogen Receptor α-Ligand Binding by a Novel Machine Learning Scheme

Estrogen receptor α (ERα) plays a significant role in occurrence of breast cancer and may cause various adverse side-effects when ERα is an off-target protein. A theoretical model was derived to predict the binding affinity of ERα using the pharmacophore ensemble/support vector machine (PhE/SVM) scheme to consider the promiscuous characteristic of ERα. The estimations by PhE/SVM were discovered to be in good agreement with the observed values for those training molecules ( n = 31, r² = 0.80, q_CV² = 0.77, RMSE = 0.57, s = 0.58), test molecules ( n = 179, q² = 0.91-0.96, RMSE = 0.33, s = 0.26) and outliers ( n = 15, q² = 0.80-0.86, RMSE = 0.56, s = 0.49). When subjected to various statistical validations, the PhE/SVM model consistently fulfilled the strictest criteria. A mock test also asserted its predictivity. When compared with crystal structures, the calculated results are consistent with the reported ERα-ligand co-complex structure, and the plasticity nature of ERα is also disclosed. Consequently, this precise, fast, and robust model can be adopted to predict ERα-ligand binding affinities and to design safer non-ERα-targeted pharmaceuticals in the process of drug discovery and development.

Oxybenzone Alters Mammary Gland Morphology in Mice Exposed During Pregnancy and Lactation

Hormones and endocrine-disrupting chemicals are generally thought to have permanent “organizational” effects when exposures occur during development but not adulthood. Yet, an increasing number of studies have shown that pregnant females are disrupted by endocrine-disrupting chemical exposures, with some effects that are permanent. Here, we examined the long-term effects of exposure to oxybenzone, an estrogenic chemical found in sunscreen and personal care products, on the morphology of the mammary gland in mice exposed during pregnancy and lactation. Female mice were exposed to vehicle or 30, 212, or 3000 µg oxybenzone/kg/d, from pregnancy day 0 until weaning. A nulliparous group, receiving vehicle treatment, was also evaluated. Mammary glands were collected 5 weeks after involution for whole-mount, histological, immunohistochemical, and molecular analyses. Exposure to 3000 µg oxybenzone/kg/d induced permanent changes to ductal density that was significantly different from both the nulliparous and vehicle groups. The two highest doses of oxybenzone similarly induced an intermediate phenotype for expression of progesterone receptor. A monotonic, dose-dependent increase in cell proliferation was also observed in the oxybenzone-treated females, becoming statistically significant at the highest dose. Finally, oxybenzone exposure induced an intermediate phenotype for Esr1 expression in all oxybenzone-treated groups. These data suggest that oxybenzone, at doses relevant to human exposures, produces long-lasting alterations to mammary gland morphology and function. Further studies are needed to determine if exposure to this chemical during pregnancy and lactation will interfere with the known protection that pregnancy provides against breast cancer.

Bisphenol S Alters the Lactating Mammary Gland and Nursing Behaviors in Mice Exposed During Pregnancy and Lactation

High doses of estrogenic pharmaceuticals were once prescribed to women to halt lactation. Yet, the effects of low-level xenoestrogens on lactation remain poorly studied. We investigated the effects of bisphenol S (BPS), an estrogen receptor (ER) agonist, on the lactating mammary gland; the arcuate nucleus, a region of the hypothalamus important for neuroendocrine control of lactational behaviors; and nursing behavior in CD-1 mice. Female mice were exposed to vehicle, 2 or 200 µg BPS/kg/d from pregnancy day 9 until lactational day (LD) 20, and tissues were collected on LD21. Tissues were also collected from a second group at LD2. BPS exposure significantly reduced the fraction of the mammary gland comprised of lobules, the milk-producing units, on LD21, but not LD2. BPS also altered expression of Esr1 and ERα in the mammary gland at LD21, consistent with early involution. In the arcuate nucleus, no changes were observed in expression of signal transducer and activator of transcription 5, a marker of prolactin signaling, or ERα, suggesting that BPS may act directly on the mammary gland. However, observations of nursing behavior collected during the lactational period revealed stage-specific effects on both pup and maternal nursing behaviors; BPS-treated dams spent significantly more time nursing later in the lactational period, and BPS-treated pups were less likely to initiate nursing. Pup growth and development were also stunted. These data indicate that low doses of BPS can alter lactational behaviors and the maternal mammary gland. Together, they support the hypothesis that pregnancy and lactation are sensitive to low-dose xenoestrogen exposures.

From Pregnancy to Preeclampsia: A Key Role for Estrogens

Preeclampsia (PE) results in placental dysfunction and is one of the primary causes of maternal and fetal mortality and morbidity. During pregnancy, estrogen is produced primarily in the placenta by conversion of androgen precursors originating from maternal and fetal adrenal glands. These processes lead to increased plasma estrogen concentrations compared with levels in nonpregnant women. Aberrant production of estrogens could play a key role in PE symptoms because they are exclusively produced by the placenta and they promote angiogenesis and vasodilation. Previous assessments of estrogen synthesis during PE yielded conflicting results, possibly because of the lack of specificity of the assays. However, with the introduction of reliable analytical protocols using liquid chromatography/mass spectrometry or gas chromatography/mass spectrometry, more recent studies suggest a marked decrease in estradiol levels in PE. The aim of this review is to summarize current knowledge of estrogen synthesis, regulation in the placenta, and biological effects during pregnancy and PE. Moreover, this review highlights the links among the occurrence of PE, estrogen biosynthesis, angiogenic factors, and cardiovascular risk factors. A close link between estrogen dysregulation and PE occurrence might validate estrogen levels as a biomarker but could also reveal a potential approach for prevention or cure of PE.

Variants of estrogen receptor alpha and beta genes modify the severity of sporadic breast cancer

INTRODUCTION

Reproductive factors pose a risk for sporadic breast cancer (BC) development owing to the lifetime exposure to estrogen, a hormone responsible for cell proliferation in the breast. Because variants of the estrogen receptor (ER) alpha and beta genes have been associated with BC risk in numerous populations, the objective of the study was to determine whether the risk and severity of sporadic BC was associated with the rs2228480 (ESR1) and rs4986938 (ESR2) variants in a Brazilian population.

METHODS

A total of 253 DNA samples from sporadic BC patients and 257 DNA samples from healthy controls were studied. The samples were genotyped by PCR-RFLP. Epidemiological, clinical, and reproductive factors were analyzed. Statistical tests conducted included the χ² test, Fisher's exact test, and Mann-Whitney and Kruskal-Wallis tests or their parametric equivalents.

RESULTS

There was a high frequency of the rs2228480*GG genotype among the ER-positive tumors (OR=2.13; 95% CI=1.189-3.816) and it showed minor association with clinical stage 0 (OR=0.324; 95% CI=0.116-0.904). The rs2228480*GA genotype was associated with minor ER expression, whereas rs2228480*GG was associated with high expression of the progesterone receptor (PR). The frequency of rs4986938*GA was high among women who breastfed (OR=2.11; 95% CI=1.203-3.702), and it showed high association with clinical stage 0 (OR=4.383; 95% CI=1.606-11.96) whereas it had minor association with systemic arterial hypertension (OR=0.53; 95% CI=0.319-0.880). The rs2228480*GG/rs4986938*GG haplotype occurred at a low frequency among women who breastfed (OR=0.525; 95% CI=0.298-0.924) but it was associated with a high expression of PR.

CONCLUSION

The rs2228480 and rs4986938 variants did not alter sporadic BC risk, but they did modulate the BC severity.

Estrogen and its role in thyroid cancer

Proliferative thyroid diseases are more prevalent in females than in males. Upon the onset of puberty, the incidence of thyroid cancer increases in females only and declines again after menopause. Estrogen is a potent growth factor both for benign and malignant thyroid cells that may explain the sex difference in the prevalence of thyroid nodules and thyroid cancer. It exerts its growth-promoting effect through a classical genomic and a non-genomic pathway, mediated via a membrane-bound estrogen receptor. This receptor is linked to the tyrosine kinase signaling pathways MAPK and PI3K. In papillary thyroid carcinomas, these pathways may be activated either by a chromosomal rearrangement of the tyrosine receptor kinase TRKA, by RET/PTC genes, or by a BRAF mutation and, in addition, in females they may be stimulated by high levels of estrogen. Furthermore, estrogen is involved in the regulation of angiogenesis and metastasis that are critical for the outcome of thyroid cancer. In contrast to other carcinomas, however, detailed knowledge on this regulation is still missing for thyroid cancer.

Estrogen as Jekyll and Hyde: regulation of cell death

Sustained estrogenic exposure increases the risk and/or the progression of various cancers, including those of the breast, endometrium and ovary. Unexpectedly, physiological level of estrogen together with a novel IKKα inhibitor BAY11-7082 could effectively induce cell apoptosis in ER-positive breast cancer cells, suggesting combining estrogen with IKKα inhibition may be beneficial for breast cancer patients. This opinion article touches upon the dual role estrogen played in inducing cancer cell death and asks whether use of estrogen in combination with IKKα-targeted therapy would be possible reconsider the newly identified crosstalk between ER and NFκB pathway which can be utilized to switch the effects of estrogen on cell death.

Ritonavir binds to and downregulates estrogen receptors: molecular mechanism of promoting early atherosclerosis

Estrogenic actions are closely related to cardiovascular disease. Ritonavir (RTV), a human immunodeficiency virus (HIV) protease inhibitor, induces atherosclerosis in an estrogen-related manner. However, how RTV induce pathological phenotypes through estrogen pathway remains unclear. In this study, we found that RTV increases thickness of coronary artery walls of Sprague Dawley rats and plasma free fatty acids (FFA) levels. In addition, RTV could induce foam cell formation, downregulate both estrogen receptor α (ERα) and ERβ expression, upregulate G protein-coupled estrogen receptor (GPER) expression, and all of them could be partially blocked by 17β-estradiol (E2), suggesting RTV acts as an antagonist for E2. Computational modeling shows a similar interaction with ERα between RTV and 2-aryl indoles, which are highly subtype-selective ligands for ERα. We also found that RTV directly bound to ERα and selectively inhibited the nuclear localization of ERα, and residue Leu536 in the hydrophobic core of ligand binding domain (LBD) was essential for the interaction with RTV. In addition, RTV did not change the secondary structure of ERα-LBD like E2, which explained how ERα lost the capacity of nuclear translocation under the treatment of RTV. All of the evidences suggest that ritonavir acts as an antagonist for 17β-estradiol in regulating α subtype estrogen receptor function and early events of atherosclerosis.

Effect of androgens on different breast cancer cells co-cultured with or without breast adipose fibroblasts

About 70% of breast tumors express androgen receptors. In addition, there is clinical evidence suggesting that androgens can inhibit mammary epithelial proliferation. Vice versa, there is also significant evidence indicating that androgens can increase the risk of breast cancer via multiple mechanisms, e.g. direct conversion to estrogens that can bind to the estrogen receptor and thereby stimulate cell proliferation. We examined the effect of testosterone (T) and dihydroxytestosterone (DHT) on cell proliferation, pS2 and Ki-67 expression in three different breast cancer cell lines alone or in co-culture with primary human breast adipose fibroblasts (BAFs) obtained from breast cancer patients. In the co-cultures, T induced cell proliferation, pS2 and Ki-67 expression in the estrogen receptor positive (ER(+)) MCF-7 and T47D cells. This was not observed in the (ER(-)) MDA-MB-231 cells. The differences might be explained by the high expression of aromatase, which converts androgens to estrogens in BAFs followed by ER-mediated cell proliferation. In line with this absence of increased cell proliferation, pS2 and Ki-67 expression was observed in the presence of DHT, which is not a substrate for aromatase. In contrast, DHT caused a significant suppression of cell proliferation (68% and 38%), pS2 and Ki-67 expression in the (ER(+)) MCF-7 and T47D cells. More importantly, DHT decreased cell proliferation in (ER(-)) MDA-MB-231 cells by 38%. The results suggest that androgens that cannot be aromatized, like DHT, may provide a perspective for treatment of breast cancer patients, especially those with triple negative breast cancer.

Loss of estrogen receptor Beta expression in follicular thyroid carcinoma predicts poor outcome

BACKGROUND

Well-differentiated follicular thyroid carcinomas (FTCs) usually act indolently, while aggressively acting tumors are difficult to detect early enough. Estrogen receptors (ERs) have prognostic significance in many cancers. Thyroid diseases, including neoplasms, are associated with the female sex. The prognostic significance of ERs in FTCs has not been reported previously.

METHODS

We studied the role of ERα and ERβ in 83 cases of follicular thyroid adenoma (FTA) and 43 FTC cases, including seven cases of poorly differentiated FTC, obtained from the Department of Surgery, Helsinki University Central Hospital between 1990 and 2009. Patient follow-up was conducted until March 2011. Expression of ERα, ERβ, and MIB-1/Ki-67 was investigated by immunohistochemistry and correlated with clinicopathological characteristics, including survival.

RESULTS

Two major observations were apparent. First, ERβ expression was significantly higher in FTA than in FTC, and it was a stronger differential diagnostic marker than MIB-1/Ki-67. Second, low ERβ expression correlated with poor survival in FTC. All cancer-specific deaths due to FTC were among low ERβ-score patients.

CONCLUSION

ERβ is a differential marker for malignancy and could thus be used as a preoperative tool. FTC patients with a low ERβ score need more thorough follow-up and may benefit from more aggressive treatment.

Estrogens and melanoma: an important clinical question

"Estrogen receptors may be of significance in melanoma development and progression. Estrogen receptors can become important pharmacological targets in melanoma management."

Molecular markers in peripheral blood of Iranian women with breast cancer

A biomarker is a quantifiable laboratory measure of a disease specific biologically relevant molecule that can act as an indicator of a current or future disease state. The purpose of this study is to detect the expression of RNA biomarkers using Cytokeratin 19 (CK-19), Mammaglobin (MAM), Carcinoembryonic antigen (CEA), Mucin (MUC), C-Myc, erb-B2, a proliferation marker (Ki-67), Epidermal growth factor receptor (Her2/neu) and Estrogen receptor (ER) in Iranian women who were diagnosed with breast cancer. In this study, 90 samples; 60 cancer patients and 30 healthy controls were considered. 73.4 % patients were in stage I/II and 26.6 % were in stage III/IV. Patients were selected prior to the administration of any adjuvant systemic therapy. Total RNA extraction was obtained from peripheral blood of each patient and healthy control. Reverse transcription polymerase chain reaction (RT-PCR) method was used for detection of mRNA of the selected biomarkers of circulating breast cancer cells in blood. Molecular characterization is assessed as a method for early detection of breast cancer. For this purpose, eleven specific primers were selected and RT-PCR was used. The data of RT-PCR revealed that expression of MUC1, CK19, CEA, MAM, erbB-2, Ki67 and C-Myc biomarkers were significantly different between breast cancer patients and healthy controls. On the other hand, ERα, ERβ and Her2 markers were not significantly different between the two mentioned groups. Biomarkers detection of breast cancer patients could be assessed as a diagnostic factor and its potential for conveying as a prognostic factor require further studies, with a larger number of patients.

Androgens inhibit the stimulatory action of 17β-estradiol on normal human breast tissue in explant cultures

BACKGROUND

The data concerning the effects and safety of androgen in human breast tissue are conflicting.

OBJECTIVE

Our aim was to analyze the effects of androgens on normal human breast tissue (HBT).

APPROACH

We cultured explants of HBT (obtained from reduction mammoplasty operations of postmenopausal women) with or without testosterone (T) and 5α-dihydrotestosterone (DHT) or in combination with 17β-estradiol (E(2)) for 7 and 14 d to study the effects of androgens on proliferation, apoptosis, target gene expression, and steroid receptors. The androgen receptor (AR) and estrogen receptor (ER) dependences of the effects were studied with the antihormones bicalutamide and fulvestrant, respectively.

RESULTS

The hormone responsiveness of cultured breast tissue was assessed by assaying apolipoprotein-D and prostate-specific antigen expression increased by androgens and amphiregulin and trefoil factor-1 expression induced by E(2) treatment. T and DHT reduced proliferation and increased apoptosis in breast epithelium, the effects of which were reversed by bicalutamide. In combination with E(2), they suppressed E(2)-stimulated proliferation and cell survival. DHT also inhibited basal (P < 0.05) and E(2)-induced expression of cyclin-D1 mRNA (P < 0.05). Immunohistochemistry showed that T (P < 0.05) and DHT (P < 0.05) increased the relative number of AR-positive cells, whereas ERα-positive (P < 0.001) cell numbers were strongly decreased. The percentage of ERβ-positive cells remained unchanged. E(2) treatment increased ERα-positive (P < 0.01) cells, whereas AR- (P < 0.05) and ERβ-expressing (P < 0.001) cells diminished. These effects were repressed in combination cultures of E(2) with T and DHT.

CONCLUSION

T and DHT inhibited proliferation and increased apoptosis in the epithelium of cultured normal HBT and opposed E(2)-stimulated proliferation and cell survival in an AR-dependent manner. These effects were associated with changes in the proportions of ERα- and AR-positive epithelial cells.

Estrogens, estrogen receptors and melanoma

The skin is the largest nonreproductive target tissue on which estrogen plays many beneficial and protective roles. Although neither exogenous hormones nor pregnancy represent significant risk factors for melanoma, epidemiological data suggest a higher survival rate in women with metastatic disease versus men and in premenopausal versus postmenopausal patients. Despite the fact that hyperestrogenic signaling has long been implicated in the initiation and progression of several tumors, the role of estrogens in malignant melanoma is still unclear. The cellular effects of estrogens are mediated by two subtypes of estrogen receptors (ERs). Estrogen receptor β (ERβ), the predominant ER in the skin, antagonizes the proliferative action mediated by estrogen receptor α. According to recent immunohistochemical studies, ERβ protein expression decreases progressively with increased Breslow thickness and results in more invasive melanomas; thus, ERβ immunophenotype may distinguish melanomas linked to poor prognosis from those with a favorable course and lead to melanoma unresponsiveness to both estrogen and anti-estrogen treatment. Therefore, if future large-scale immunohistochemical and molecular studies point towards ERβ as an important factor in malignant melanoma progression, they will open up novel and targeted prognostic and therapeutic perspectives.

Celastrol inhibits the growth of estrogen positive human breast cancer cells through modulation of estrogen receptor α

Human estrogen receptor α (ERα) is a nuclear transcription factor that displays a major therapeutic target for breast cancer. The transcriptional activity of ERα can be regulated by particular estrogen receptor modulators. Celastrol, a quinine methide triterpene extracted from a Chinese medicine (Trypterygium wilfordii Hook F.), has been reported to have therapeutic efficacy against various cancer cells, including prostate cancer, leukemia, and melanoma cells. However, ERα regulation by Celastrol has not been reported. In this study, we investigated the effects of Celastrol on the growth of breast cancer cells. We observed that Celastrol decreased expression of ERα at both the mRNA and the protein levels in MCF7 and T47D human breast cancer cells. Results from a luciferase assay showed that Celastrol decreased the transcriptional activity of ERα. Also, Celastrol treatment inhibited ERα target gene expression, including expressions of cyclin D(1), progesterone receptor (PR), and c-Myb leading to cell cycle arrest and growth inhibition of breast cancer cells. We propose that Celastrol, an anti-cancer drug extracted from natural sources, induces inhibition of cell growth through modulation of ERα in estrogen positive breast cancer cells and is a candidate for use in cancer chemotherapy for human breast cancer.

Oestrogens and spermatogenesis

The role of oestrogens in male reproductive tract physiology has for a long time been a subject of debate. The testis produces significant amounts of oestrogenic hormones, via aromatase, and oestrogen receptors (ERs)alpha (ESR1) and ERbeta (ESR2) are selectively expressed in cells of the testis as well as the epididymal epithelium, depending upon species. This review summarizes the current knowledge concerning the presence and activity of aromatase and ERs in testis and sperm and the potential roles that oestrogens may have in mammalian spermatogenesis. Data show that physiology of the male gonad is in part under the control of a balance of androgens and oestrogens, with aromatase serving as a modulator.

Biomarkers of the metabolic syndrome and breast cancer prognosis

In spite of its public health importance, our understanding of the mechanisms of breast carcinogenesis and progress is still evolving. The metabolic syndrome (MS) is a constellation of biochemical abnormalities including visceral adiposity, hyperglycemia, hyperinsulinemia, dyslipidemia and high blood pressure. The components of the MS have all been related to late-stage disease and even to a poor prognosis of breast cancer through multiple interacting mechanisms. In this review, we aim to present a summary of recent advances in the understanding of the contribution of the MS to breast cancer with the emphasis on the role of biomarkers of the MS in the prognosis of breast cancer.

Effects of triptolide from Tripterygium wilfordii on ERalpha and p53 expression in two human breast cancer cell lines

The aim of the study was to discover possible differential cytotoxicity of triptolide towards estrogen-sensitive MCF-7 versus estrogen-insensitive MDA-MB-231 human breast cancer cells. Considering that MCF-7 cells express functional Estrogen receptor alpha (ERalpha) and wild-type p53, whereas MDA-MB-231 cells which are ERalpha-negative express mutant p53, the anti-proliferation effect of triptolide on MCF-7 and MDA-MB-231 cells were examined, the apoptotic effect and cell cycle arrest caused by triptolide were investigated, ERalpha and p53 expression were also observed in this paper. The results showed that the anti-proliferation effects were induced by triptolide in both cell lines. But the value of IC(50) in MCF-7 cells for its anti-proliferation effect was about one tenth of that in MDA-MB-231 cells, which indicated that the effect is more potent in MCF-7 cells. Condensed chromatin or fragmented nuclei could be found in MCF-7 cells treated with only 40nM triptolide but in MDA-MB-231 cells they couldn't be observed until the concentration reached to 400nM. Triptolide induced significant S cell cycle arrest along with the presence of sub-G0/G1 peak in MDA-MB-231 cells, whereas there was only slightly S cell cycle arrest on cell cycle distribution in MCF-7 cells. The role of p53 in two breast cancer cells was examined, the results showed that the mutant p53 in MDA-MB-231 cells was suppressed and the wild-type p53 in MCF-7 was increased. Moreover, triptolide could down regulate the expression of ERalpha in MCF-7 cells. The results showed that triptolide is much more sensitive to ERalpha-positive MCF-7 cells than to ERalpha-negative MDA-MB-231 cells, and the sensitivity is significantly associated with the ERalpha and p53 status.

Underlying causes of the black-white racial disparity in breast cancer mortality: a population-based analysis

BACKGROUND

In the United States, a black-to-white disparity in age-standardized breast cancer mortality rates emerged in the 1980s and has widened since then.

METHODS

To further explore this racial disparity, black-to-white rate ratios (RRs(BW)) for mortality, incidence, hazard of breast cancer death, and incidence-based mortality (IBM) were investigated using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program on 244 786 women who were diagnosed with breast cancer from January 1990 through December 2003 and followed through December 2004. A counterfactual approach was used to examine the expected IBM RRs(BW), assuming equal distributions for estrogen receptor (ER) expression, and/or equal hazard rates of breast cancer death, among black and white women.

RESULTS

From 1990 through 2004, mortality RR(BW) was greater than 1.0 and widened over time (age-standardized breast cancer mortality rates fell from 36 to 29 per 100 000 for blacks and from 30 to 22 per 100 000 for whites). In contrast, incidence RR(BW) was generally less than 1.0. Absolute hazard rates of breast cancer death declined substantially for ER-positive tumors and modestly for ER-negative tumors but were persistently higher for blacks than whites. Equalizing the distributions of ER expression in blacks and whites decreased the IBM RR(BW) slightly. Interestingly, the black-to-white disparity in IBM RR(BW) was essentially eliminated when hazard rates of breast cancer death were matched within each ER category.

CONCLUSIONS

The black-to-white disparity in age-standardized breast cancer mortality was largely driven by the higher hazard rates of breast cancer death among black women, diagnosed with the disease, irrespective of ER expression, and especially in the first few years following diagnosis. Greater emphasis should be placed on identifying the etiology of these excess hazards and developing therapeutic strategies to address them.

Annexin-1 regulates growth arrest induced by high levels of estrogen in MCF-7 breast cancer cells

Estrogen, a naturally occurring female steroid growth hormone, has been implicated as a major risk factor for the development of breast cancer. Recent research into this disease has also correlated Annexin-1 (ANXA1), a glucocorticoid-inducible protein, with the development of breast tumorigenesis. ANXA1 is lost in many cancers, including breast cancer, and this may result in a functional promotion of tumor growth. In this study, we investigated the expression of ANXA1 in MCF-7 cells treated with estrogen and the regulation of estrogen functions by ANXA1. Exposure of MCF-7 breast cancer cells to high physiologic levels (up to 100 nmol/L) of estrogen leads to an up-regulation of ANXA1 expression partially through the activation of cyclic AMP-responsive element binding protein and dependency on activation of the estrogen receptor. In addition, treatment of MCF-7 cells with physiologic levels of estrogen (1 nmol/L) induced proliferation, whereas high pregnancy levels of estrogen (100 nmol/L) induced a growth arrest of MCF-7 cells, associated with constitutive activation of extracellular signal-regulated kinase 1/2 and up-regulation of cell cycle arrest proteins such as p21(waf/cip). Silencing of ANXA1 with specific small interfering RNA reverses the estrogen-dependent proliferation as well as growth arrest and concomitantly modulates extracellular signal-regulated kinase 1/2 phosphorylation. We confirm that ANXA1 is lost in clinical breast cancer, indicating that the antiproliferative protective function of ANXA1 against high levels of estrogen may be lost. Finally, we show that ANXA1-deficient mice exhibit faster carcinogen-induced tumor growth. Our data suggest that ANXA1 may act as a tumor suppressor gene and modulate the proliferative functions of estrogens.

[Anatomy of the breast]

The human breast consists of lobes with a luminal glandular and a basal myoepithelial layer. Immunofluorescence studies have shown that the breast epithelium contains cytokeratin (CK)5/14-positive precursor cells which give rise to CK8/18-positive glandular or sm-actin-positive myoepithelial cells. Only some of the glandular cells contain estrogen receptors. The luminal epithelium of the lobules shows a much higher glandular differentiation than the ductal system. Diagnostically important cytokeratins of normal breast epithelium and its proliferative epithelial processes include luminal cytokeratins (CK7, CK8 and CK18) as markers of glandular differentiation and basal cytokeratins (CK5, CK14 and CK17) as markers of progenitor cells and early cells of the glandular and myoepithelial differentiation pathway. The most important myoepithelial markers are currently CD10, SMA, SMM-HC and Calponin.

Molecular mechanisms of endocrine resistance and their implication in the therapy of breast cancer

The use of endocrine agents is a safe and effective treatment in the management of hormone-sensitive breast cancer. Unfortunately, sooner or later, tumor cells develop resistance to endocrine manipulation making useless this approach. During the last decade, new molecules and intracellular signaling pathways involved in endocrine resistance have been identified. Several studies have documented that estrogen receptor signaling may maintain a pivotal role in the tumor growth despite the failure of a previous hormonal treatment. In this review we will discuss the general principles for optimizing the choice of endocrine therapy based on an understanding of the molecular mechanisms responsible for resistance to the different anti-hormonal agents.

Estradiol-estrogen receptor: a key interplay of the expression of syndecan-2 and metalloproteinase-9 in breast cancer cells

Estrogens are related with the growth and development of target tissues and play a critical role in breast cancer progression. The effects of estrogens are mediated by the estrogen receptors ERalpha and ERbeta, which are members of the nuclear steroid receptor superfamily. To date, it is not known how these hormones elicit many of their effects on extracellular matrix molecules and how these effects can be connected with ER expression. For this purpose, the effect of estradiol on ER expression as well as on proteoglycan and metalloproteinase expression was studied. The effect of E2 on extracellular matrix molecule expression has been studied using ERalpha suppression in breast cancer cells. Our studies using ERalpha-positive MCF-7 cells show that estradiol affects the expression of syndecan-2, but not of syndecan-4, through ERalpha. Furthermore, the ability of estradiol to affect MMP-9 and TIMP-1 expression is connected with ERalpha status. Together, these data demonstrate the significant role of ERalpha on mediating the effect of estradiol on extracellular matrix molecules.

Prepubertal physical activity up-regulates estrogen receptor beta, BRCA1 and p53 mRNA expression in the rat mammary gland

Findings in BRCA1 mutation carriers suggest that physical activity, particularly during childhood, may be linked to a reduced risk of developing breast cancer. We investigated whether physical activity at puberty alters the expression of BRCA1 and two other tumor suppressor genes--p53 and estrogen receptor (ER)-beta--in rats. In addition, the effects on ER-alpha expression, mammary proliferation and functional epithelial differentiation were investigated as markers of altered mammary cancer risk in rats exposed to regular physical activity at puberty. Female Sprague Dawley rat pups were randomized to voluntary exercise, sham-exercise control and non-manipulated control groups. Treadmill training (20-25 m/min, 15% grade, 30 min/day, 5 days/week) started on postnatal day 14 and continued through day 32. Third thoracic mammary glands (n = 5 per group and age) were obtained at days 32, 48 and 100 and assessed for changes in morphology through wholemounts, and at 100 days cell proliferation by using Ki67 staining, protein levels of ER-alpha and ER-beta by immunohistochemistry, and mRNA expression levels of BRCA1, p53, ER-alpha and ER-beta by real-time PCR. Mammary glands of rats exposed to exercise during puberty contained fewer terminal end buds (TEBs) and a higher number of differentiated alveolar buds and lobules than the sham controls. However, cell proliferation was not significantly altered among the groups. ER-alpha protein levels were significantly reduced, while ER-beta levels were increased in the mammary ducts and lobular epithelial structures of 100-day old rays which were voluntarily exercised at puberty, compared to sham controls. ER-beta, BRCA1 and p53 mRNA levels were significantly higher in the mammary glands of 100-day-old exercised versus sham control rats. Pubertal physical activity reduced mammary epithelial targets for neoplastic transformation through epithelial differentiation and it also up-regulated tumor suppressor genes BRCA1, p53 and ER-beta, and reduced ER-alpha/ER-beta ratio in the mammary gland. It remains to be determined whether the up-regulation of BRCA1, and perhaps p53, explains the protective effect of childhood physical activity against breast cancer in women who carry a germline mutation in one of the BRCA1 alleles.

Targeting synuclein-gamma to counteract drug resistance in cancer

BACKGROUND

Expression of synuclein-gamma (SNCG) protein is elevated in the advanced stages of many types of cancers, including ovarian, lung, liver, esophagus, colon, prostate and, in particular, breast. In breast carcinoma, SNCG is causatively linked to stimulated proliferation, metastasis and drug resistance.

OBJECTIVE

To establish SNCG as a potential therapeutic target and to discuss clinical use of SNCG inhibiting peptide.

METHODS

This review focuses on the plausible mechanisms of SNCG activity, SNCG mediated drug resistance and its inhibition.

RESULTS/CONCLUSION

Evidence based research shows that the aberrant expression of SNCG has a strong correlation with breast cancer progression and poor clinical outcome. A peptide based inhibitor counters activity of SNCG, which may be developed as an adjuvant therapy.

Decursin and decursinol angelate inhibit estrogen-stimulated and estrogen-independent growth and survival of breast cancer cells

Introduction

Estrogen and estrogen receptor (ER)-mediated signaling are crucial for the etiology and progression of human breast cancer. Attenuating ER activities by natural products is a promising strategy to decrease breast cancer risk. We recently discovered that the pyranocoumarin compound decursin and its isomer decursinol angelate (DA) have potent novel antiandrogen receptor signaling activities. Because the ER and the androgen receptor belong to the steroid receptor superfamily, we examined whether these compounds affected ER expression and signaling in breast cancer cells.

Methods

We treated estrogen-dependent MCF-7 and estrogen-independent MDA MB-231 human breast cancer cells with decursin and DA, and examined cell growth, apoptosis, and ERα and ERβ expression in both cell lines – and, in particular, estrogen-stimulated signaling in the MCF-7 cells. We compared these compounds with decursinol to determine their structure-activity relationship.

Results

Decursin and DA exerted growth inhibitory effects on MCF-7 cells through G₁ arrest and caspase-mediated apoptosis. These compounds decreased ERα in MCF-7 cells at both mRNA and protein levels, and suppressed estrogen-stimulated genes. Decursin and the pure antiestrogen Faslodex™ exerted an additive growth inhibitory effect on MCF-7 cells. In MDA MB-231 cells, these compounds induced cell-cycle arrests in the G₁ and G₂ phases as well as inducing apoptosis, accompanied by an increased expression of ERβ. In contrast, decursinol, which lacks the side chain of decursin and DA, did not have these cellular and molecular activities at comparable concentrations.

Conclusion

The side chain of decursin and DA is crucial for their anti-ER signaling and breast cancer growth inhibitory activities. These data provide mechanistic rationales for validating the chemopreventive and therapeutic efficacy of decursin and its derivatives in preclinical animal models of breast cancer.

Evaluation of estrogen receptor alpha and beta and progesterone receptor expression and correlation with clinicopathologic factors and proliferative marker Ki-67 in breast cancers

To elucidate the molecular profile of hormonal steroid receptor status, we analyzed ER-alpha, ER-beta, and PGR mRNA and protein expression in 80 breast carcinomas using reverse transcriptase polymerase chain reaction (RT-PCR), quantitative RT-PCR, and immunohistochemical analysis. Qualitative analysis revealed positive expression of ER-alpha, ER-beta, and PGR mRNA in 48%, 59%, and 48% of the breast carcinomas, respectively. ER-alpha, ER-beta, and PGR transcript overexpression was observed in 51%, 0%, and 12% of the cases, respectively, whereas moderate or strong protein expression was detected in 68%, 78%, and 49% of the cases, respectively. Tumor grade was negatively correlated with transcript and protein levels of ER-alpha (P = .0169 and P = .0006, respectively) and PGR (P = .0034 and P = .0005, respectively). Similarly, proliferative index Ki-67 was negatively associated with transcript and protein levels of ER-alpha (P = .0006 and P < .0001, respectively) and PGR (P = .0258 and P = .0005, respectively). These findings suggest that ER-alpha and PGR expression are associated with well-differentiated breast tumors and less directly related to cell proliferation. A significant statistical difference was observed between lymph node status and ER-beta protein expression (P = .0208). In ER-alpha-negative tumors, we detected a correlation between ER-beta protein expression and high levels of Ki-67. These data suggest that ER-beta could be a prognostic marker in human breast cancer.

17β-Estradiol Up-regulates the Insulin-like Growth Factor Receptor through a Nongenotropic Pathway in Prostate Cancer Cells

Prostate carcinomas frequently express estrogen receptors (ER), irrespective of androgen receptor (AR) expression; however, the role of ERs and estrogens in prostate cancer is controversial. We found that 17beta-estradiol (E(2)) is able to markedly up-regulate insulin-like growth factor (IGF)-I receptor (IGF-IR) mRNA and protein expression in both AR-positive (LNCaP cells) and AR-negative (PC-3 cells) prostate cancer cells. This effect occurs not only via ERalpha but also via ERbeta stimulation and is specific for IGF-IR because it does not involve the cognate insulin receptor. IGF-IR up-regulation is associated with increased IGF-IR phosphorylation and with increased mitogenic and motogenic activities in response to IGF-I. IGF-IR up-regulation by E(2) does not require ER binding to DNA and is poorly sensitive to antiestrogen blockade, whereas it is associated with the activation of cytosolic kinase cascades involving Src, extracellular signal-regulated kinase (ERK)-1/2, and, to a lesser extent, phosphatidylinositol 3-kinase and is sensitive to the inhibition of these kinases. In conclusion, our data indicate that estrogens may contribute to IGF system deregulation in prostate cancer through the activation of a nongenotropic pathway. Estrogens may have a role, therefore, in tumor progression to androgen independence. Inhibition of the IGF-IR or the Src-ERK pathway should be considered, therefore, as an adjuvant therapy in prostate cancer.

Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence

Incidences of breast cancer, type 2 diabetes, and metabolic syndrome have increased over the past decades with the obesity epidemic, especially in industrialized countries. Insulin resistance, hyperinsulinemia, and changes in the signaling of growth hormones and steroid hormones associated with diabetes may affect the risk of breast cancer. We reviewed epidemiologic studies of the association between type 2 diabetes and risk of breast cancer and the available evidence on the role of hormonal mediators of an association between diabetes and breast cancer. The combined evidence supports a modest association between type 2 diabetes and the risk of breast cancer, which appears to be more consistent among postmenopausal than among premenopausal women. Despite many proposed potential pathways, the mechanisms underlying an association between diabetes and breast cancer risk remain unclear, particularly because the 2 diseases share several risk factors, including obesity, a sedentary lifestyle, and possibly intake of saturated fat and refined carbohydrates, that may confound this association. Although the metabolic syndrome is closely related to diabetes and embraces additional components that might influence breast cancer risk, the role of the metabolic syndrome in breast carcinogenesis has not been studied and thus remains unknown.