The role of CBP in estrogen receptor cross-talk with nuclear factor-kappaB in HepG2 cells

PARP2 promotes inflammation in psoriasis by modulating estradiol biosynthesis in keratinocytes

Poly(ADP-ribose) polymerase 2 (PARP2) alongside PARP1 are responsible for the bulk of cellular PARP activity, and they were first described as DNA repair factors. However, research in past decades implicated PARPs in biological functions as diverse as the regulation of cellular energetics, lipid homeostasis, cell death, and inflammation. PARP activation was described in Th2-mediated inflammatory processes, but studies focused on the role of PARP1, while we have little information on PARP2 in inflammatory regulation. In this study, we assessed the role of PARP2 in a Th17-mediated inflammatory skin condition, psoriasis. We found that PARP2 mRNA expression is increased in human psoriatic lesions. Therefore, we studied the functional consequence of decreased PARP2 expression in murine and cellular human models of psoriasis. We observed that the deletion of PARP2 attenuated the imiquimod-induced psoriasis-like dermatitis in mice. Silencing of PARP2 in human keratinocytes prevented their hyperproliferation, maintained their terminal differentiation, and reduced their production of inflammatory mediators after treatment with psoriasis-mimicking cytokines IL17A and TNFα. Underlying these observations, we found that aromatase was induced in the epidermis of PARP2 knock-out mice and in PARP2-deficient human keratinocytes, and the resulting higher estradiol production suppressed NF-κB activation, and hence, inflammation in keratinocytes. Steroidogenic alterations have previously been described in psoriasis, and we extend these observations by showing that aromatase expression is reduced in psoriatic lesions. Collectively, our data identify PARP2 as a modulator of estrogen biosynthesis by epidermal keratinocytes that may be relevant in Th17 type inflammation. KEY MESSAGES : PARP2 mRNA expression is increased in lesional skin of psoriasis patients. PARP2 deletion in mice attenuated IMQ-induced psoriasis-like dermatitis. NF-κB activation is suppressed in PARP2-deficient human keratinocytes. Higher estradiol in PARP2-deficient keratinocytes conveys anti-inflammatory effect.

An In Vivo Screening Model for Investigation of Pathophysiology of Human Implantation Failure

To improve current infertility treatments, it is important to understand the pathophysiology of implantation failure. However, many molecules are involved in the normal biological process of implantation and the roles of each molecule and the molecular mechanism are not fully understood. This review highlights the hemagglutinating virus of Japan (HVJ; Sendai virus) envelope (HVJ-E) vector, which uses inactivated viral particles as a local and transient gene transfer system to the murine uterus during the implantation period in order to investigate the molecular mechanism of implantation. In vivo screening in mice using the HVJ-E vector system suggests that signal transducer and activator of transcription-3 (Stat-3) could be a diagnostic and therapeutic target for women with a history of implantation failure. The HVJ-E vector system hardly induces complete defects in genes; however, it not only suppresses but also transiently overexpresses some genes in the murine uterus. These features may be useful in investigating the pathophysiology of implantation failure in women.

Ultraviolet Radiation and Chronic Inflammation-Molecules and Mechanisms Involved in Skin Carcinogenesis: A Narrative Review

The process of skin carcinogenesis is still not fully understood. Both experimental and epidemiological evidence indicate that chronic inflammation is one of the hallmarks of microenvironmental-agent-mediated skin cancers and contributes to its development. Maintaining an inflammatory microenvironment is a condition leading to tumor formation. Multiple studies focus on the molecular pathways activating tumorigenesis by inflammation and indicate several biomarkers and factors that can improve diagnostic and prognostic processes in oncology and dermatology. Reactive oxygen species produced by ultraviolet radiation, oxidizers, or metabolic processes can damage cells and initiate pro-inflammatory cascades. Considering the potential role of inflammation in cancer development and metastasis, the identification of early mechanisms involved in carcinogenesis is crucial for clinical practice and scientific research. Moreover, it could lead to the progress of advanced skin cancer therapies. We focus on a comprehensive analysis of available evidence and on understanding how chronic inflammation and ultraviolet radiation can result in skin carcinogenesis. We present the inflammatory environment as complex molecular networks triggering tumorigenesis and constituting therapeutic targets.

The impact of CBP expression in estrogen receptor-positive breast cancer

Background

The development of new biomarkers with diagnostic, prognostic and therapeutic prominence will greatly enhance the management of breast cancer (BC). Several reports suggest the involvement of the histone acetyltransferases CREB-binding protein (CBP) and general control non-depressible 5 (GCN5) in tumor formation; however, their clinical significance in BC remains poorly understood. This study aims to investigate the value of CBP and GCN5 as markers and/or targets for BC prognosis and therapy. Expression of CBP, GCN5, estrogen receptor α (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) in BC was analyzed in cell lines by western blot and in patients’ tissues by immunohistochemistry. The gene amplification data were also analyzed for CBP and GCN5 using the publicly available data from BC patients.

Results

Elevated expression of CBP and GCN5 was detected in BC tissues from patients and cell lines more than normal ones. In particular, CBP was more expressed in luminal A and B subtypes. Using chemical and biological inhibitors for CBP, ERα and HER2 showed a strong association between CBP and the expression of ERα and HER2. Moreover, analysis of the CREBBP (for CBP) and KAT2A (for GCN5) genes in a larger number of patients in publicly available databases showed amplification of both genes in BC patients. Amplification of CREBBP gene was observed in luminal A, luminal B and triple-negative but not in HER2 overexpressing subtypes. Furthermore, patients with high CREBBP or KAT2A gene expression had better 5-year disease-free survival than the low gene expression group (p = 0.0018 and p < 0.00001, respectively).

Conclusions

We conclude that the persistent amplification and overexpression of CBP in ERα- and PR-positive BC highlights the significance of CBP as a new diagnostic marker and therapeutic target in hormone-positive BC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01060-2.

Gender differences in UV-induced skin inflammation, skin carcinogenesis and systemic damage

Ultraviolet (UV) radiation-induced chronic inflammation contributes to all stages of skin tumor development. In addition, gender plays an important role in inflammatory diseases or cancer. In this study, histopathology changes, hematology, oxidative stress and inflammatory response were used to evaluate sex differences in UV-induced chronic inflammation-associated cancer development. The results showed that the male and female mice had photoaging damage at the 9th week. However, skin tumors only appeared in male mice at 31st week. Furthermore, UV increased ROS production, p65, p-p65, IL-6 and TNF-α protein expressions in skin, and these factors elevated more in male mouse model. Hematology results showed that the parameters of blood systemic inflammation were changed in different degrees in model groups, while the pathological results showed inflammatory cell infiltration in the internal organs of both model groups in varying degrees. These results indicate that there are gender differences in UV-induced skin inflammation, carcinogenesis and systemic damage. Moreover, male mice are more sensitive to UV irradiation, which may be responsible to greater oxidative stress and inflammatory damage.

Androgen and Androgen Receptors as Regulators of Monocyte and Macrophage Biology in the Healthy and Diseased Lung

Androgens, the predominant male sex hormones, drive the development and maintenance of male characteristics by binding to androgen receptor (AR). As androgens are systemically distributed throughout the whole organism, they affect many tissues and cell types in addition to those in male sexual organs. It is now clear that the immune system is a target of androgen action. In the lungs, many immune cells express ARs and are responsive to androgens. In this review, we describe the effects of androgens and ARs on lung myeloid immune cells-monocytes and macrophages-as they relate to health and disease. In particular, we highlight the effect of androgens on lung diseases, such as asthma, chronic obstructive pulmonary disease and lung fibrosis. We also discuss the therapeutic use of androgens and how circulating androgens correlate with lung disease. In addition to human studies, we also discuss how mouse models have helped to uncover the effect of androgens on monocytes and macrophages in lung disease. Although the role of estrogen and other female hormones has been broadly analyzed in the literature, we focus on the new perspectives of androgens as modulators of the immune system that target myeloid cells during lung inflammation.

Tumor Necrosis Factor α Blockade: An Opportunity to Tackle Breast Cancer

Breast cancer is the most frequently diagnosed cancer and the principal cause of mortality by malignancy in women and represents a main problem for public health worldwide. Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine whose expression is increased in a variety of cancers. In particular, in breast cancer it correlates with augmented tumor cell proliferation, higher malignancy grade, increased occurrence of metastasis and general poor prognosis for the patient. These characteristics highlight TNFα as an attractive therapeutic target, and consequently, the study of soluble and transmembrane TNFα effects and its receptors in breast cancer is an area of active research. In this review we summarize the recent findings on TNFα participation in luminal, HER2-positive and triple negative breast cancer progression and metastasis. Also, we describe TNFα role in immune response against tumors and in chemotherapy, hormone therapy, HER2-targeted therapy and anti-immune checkpoint therapy resistance in breast cancer. Furthermore, we discuss the use of TNFα blocking strategies as potential therapies and their clinical relevance for breast cancer. These TNFα blocking agents have long been used in the clinical setting to treat inflammatory and autoimmune diseases. TNFα blockade can be achieved by monoclonal antibodies (such as infliximab, adalimumab, etc.), fusion proteins (etanercept) and dominant negative proteins (INB03). Here we address the different effects of each compound and also analyze the use of potential biomarkers in the selection of patients who would benefit from a combination of TNFα blocking agents with HER2-targeted treatments to prevent or overcome therapy resistance in breast cancer.

Hormone Therapy and Breast Cancer: Emerging Steroid Receptor Mechanisms

Although hormone therapy is widely used by millions of women to relieve symptoms of menopause, it has been associated with several side-effects such as coronary heart disease, stroke and increased invasive breast cancer risk. These side-effects have caused many women to seek alternatives to conventional hormone therapy, including the controversial custom-compounded bioidentical hormone therapy suggested to not increase breast cancer risk. Historically estrogens and the estrogen receptor were considered the principal factors promoting breast cancer development and progression, however, a role for other members of the steroid receptor family in breast cancer pathogenesis is now evident, with emerging studies revealing an interplay between some steroid receptors. In this review, we discuss examples of hormone therapy used for the relief of menopausal symptoms, highlighting the distinction between conventional hormone therapy and custom-compounded bioidentical hormone therapy. Moreover, we highlight the fact that not all hormones have been evaluated for an association with increased breast cancer risk. We also summarize the current knowledge regarding the role of steroid receptors in mediating the carcinogenic effects of hormones used in menopausal hormone therapy, with special emphasis on the influence of the interplay or crosstalk between steroid receptors. Unraveling the intertwined nature of steroid hormone receptor signaling pathways in breast cancer biology is of utmost importance, considering that breast cancer is the most prevalent cancer among women worldwide. Moreover, understanding these mechanisms may reveal novel prevention or treatment options, and lead to the development of new hormone therapies that does not cause increased breast cancer risk.

The role of NFκB in the three stages of pregnancy - implantation, maintenance, and labour: a review article

The transcription factor nuclear factor kappa B (NFκB) controls the expression of over 400 genes, some of which are associated with reproductive events. During implantation, immune cells accumulate in the maternal-fetal interface; they secrete inflammatory mediators under the control of NFĸB, the level of which also rises. NFĸB is then downregulated to maintain gestation, but its level rises again before birth to manage prostaglandin, cytokine, and chemokine synthesis, and to stimulate uterine contraction. This review summarises the current state of knowledge about NFκB and its role in the molecular regulation of processes related to pregnancy development.

TWEETABLE ABSTRACT

This review examines the current state of knowledge about role of NFκB in the development of pregnancy.

Estrogen-dependent downregulation of hypoxia-inducible factor (HIF)-2α in invasive breast cancer cells

The involvement of estrogen (E2) and hypoxia in tumor progression is well established. Hypoxia has been reported to activate and degrade estrogen receptor alpha (ERα) in breast cancer cells. Furthermore, E2 has been shown to regulate hypoxia-inducible factor (HIF)-1α protein, but its role in HIF-2α regulation remains largely unexplored. In this study, we found that both HIF-2α mRNA and protein were down-regulated in ER positive but not ER negative breast cancer cells upon treatment with E2. The analysis of 690 samples derived from 608 mixed and 82 triple-negative breast cancer patients revealed that high nuclear HIF-2α tumor levels are associated with a worse prognosis specifically in human epidermal growth factor receptor 2 (HER2) and hormone receptor positive patients. Consistently, ERα/HER2 positive breast cancer cells displayed less pronounced downregulation of HIF-2α by E2. Experiments using a histone deacetylase inhibitor indicate that the E2 mediated decrease in HIF-2α mRNA is due to transcriptional repression. A functional estrogen response element (ERE) was identified in the first intron of the gene encoding HIF-2α (EPAS1), suggesting transcriptional co-repressor recruitment by ERα. Our results demonstrate a novel modulation of HIF-2α in breast cancer cells, explaining the opposing regulation between HIF-1α and HIF-2α in hormone-responsive breast cancer.

A comparative characterization of estrogens used in hormone therapy via estrogen receptor (ER)-α and -β

Conventional hormone therapy (HT) containing estrogens such as ethinylestradiol (EE) have been associated with an increased risk of breast cancer and cardiovascular disease resulting in women seeking safer alternatives that are claimed to have fewer health risks. One such alternative gaining popularity, is custom-compounded bioidentical (b)HT formulations containing bioidentical estradiol (bE₂) and estriol (bE₃). However, the preparation of these custom-compounded estrogens is not regulated, and depending on the route of synthesis, steroid mixtures with differing activities may be produced. Thus, an investigation into the activities of estrogens prepared by custom-compounded pharmacies is warranted. The aim of this study was therefore to directly compare the pharmacological properties of bE₂ and bE₃ of unknown purity relative to commercially available, pure E₂, E₃ and estrone (E₁) standards as well as synthetic EE used in conventional HT via the human estrogen receptor (ER)-α and -β. We determined precise equilibrium dissociation constants (K_d or K_i values) and showed that bE₂ and bE₃ display similar binding affinities to the E₂ and E₃ standards, while EE had a higher affinity for ERα, and E₁ a lower affinity for ERβ. Furthermore, all the estrogens display similar agonist efficacies, but not potencies, for transactivation on a minimal ERE-containing promoter via the individual ER subtypes. Although E₂ and E₃ were equally efficacious and potent on the endogenous ERE-containing pS2 promoter in the MCF-7 BUS breast cancer cell line co-expressing ERα and ERβ, E₁ was less efficacious and potent than E₂. This study is the first to demonstrate that the bioidentical estrogens, commercially available estrogen standards and synthetic EE are full agonists for transrepression on both minimal and endogenous NFκB-containing promoters. Moreover, we showed that these estrogens all increase proliferation and anchorage-independent growth of MCF-7 BUS cells to a similar extent, suggesting that custom-compounded bHT may in fact not be a safer alternative to conventional HT. Furthermore, our results showing that E₃ and E₁ are not weak estrogens, and that E₃ does not antagonize the activity of E₂, suggest that the rationale behind the use of E₃ and E₁ in custom-compounded bHT formulations should be readdressed. Taken together, the results indicating that there is mostly no difference between the custom-compounded bioidentical estrogens, commercially available estrogen standards and synthetic EE, at concentrations reflecting serum levels in women using estrogen-containing HT, suggest that there is no clear advantage in choosing bHT above conventional HT.

RelB/NF-κB links cell cycle transition and apoptosis to endometrioid adenocarcinoma tumorigenesis

Dysfunction of nuclear factor-κB (NF-κB) signaling has been causally associated with numerous human malignancies. Although the NF-κB family of genes has been implicated in endometrial carcinogenesis, information regarding the involvement of central regulators of NF-κB signaling in human endometrial cancer (EC) is limited. Here, we investigated the specific roles of canonical and noncanonical NF-κB signaling in endometrial tumorigenesis. We found that NF-κB RelB protein, but not RelA, displayed high expression in EC samples and cell lines, with predominant elevation in endometrioid adenocarcinoma (EEC). Moreover, tumor cell-intrinsic RelB was responsible for the abundant levels of c-Myc, cyclin D1, Bcl-2 and Bcl-xL, which are key regulators of cell cycle transition, apoptosis and proliferation in EEC. In contrast, p27 expression was enhanced by RelB depletion. Thus, increased RelB in human EC is associated with enhanced EEC cell growth, leading to endometrial cell tumorigenicity. Our results reveal that regulatory RelB in noncanonical NF-κB signaling may serve as a therapeutic target to block EC initiation.

Sex-Based Differences in Smgc Expression in the Submandibular Gland of C57BL/6 Mice

OBJECTIVE

The decrease in female hormone levels at menopause affects whole-body homeostasis. Various therapies including hormone therapy and treatment with herbal supplements are available to improve menopausal symptoms. However, a method for evaluating their effectiveness has not been established. We sought to identify useful biomarkers to assess therapy efficacy.

METHODS

We searched for salivary proteins affected by changes in female hormone levels in mouse submandibular glands.

RESULTS

The expression of submandibular gland protein C (Smgc) was decreased following ovariectomy, while the expression of the alternative splicing transcript t-Smgc was increased. Notably, Smgc expression increased following β-estradiol administration, and was barely detectable in the submandibular glands of male mice.

CONCLUSION

The results suggest that Smgc expression may be estrogen dependent. Moreover, changes in the SMGC protein amount in the saliva were in accordance with those in mRNA expression in the submandibular gland. Our findings suggest that salivary proteins have potential as markers for evaluating therapies for menopausal symptoms.

Estrogen receptor alpha-36 (ER-α36): A new player in human breast cancer

Prevailing wisdom is that estrogen receptor (ER)-α mediated genomic estrogen signaling is responsible for estrogen-stimulated cell proliferation and development of ER-positive breast cancer. However, accumulating evidence indicates that another estrogen signaling pathway, non-genomic or rapid estrogen signaling, also plays an important role in mitogenic estrogen signaling. Previously, our laboratory cloned a 36 kDa variant of ER-α, ER-α36, and found that ER-α36 is mainly expressed in the cytoplasm and at the plasma membrane. ER-α36 mediates rapid estrogen signaling and inhibits genomic estrogen signaling. In this review, we review and update the biological function of ER-α36 in ER-positive and -negative breast cancer, breast cancer stem/progenitor cells and tamoxifen resistance, potential interaction and cross-talk of ER-α36 with other ERs and growth factor receptors, and intracellular pathways of ER-α36-mediated rapid estrogen signaling. The potential function and underlying mechanism of ER-α in development of ER-positive breast cancer will also be discussed.

The cholesterol metabolite 27-hydroxycholesterol promotes atherosclerosis via proinflammatory processes mediated by estrogen receptor alpha

Oxysterols are cholesterol metabolites that serve multiple functions in lipid metabolism, including as liver X receptor (LXR) ligands. 27-hydroxycholesterol (27HC) is an abundant oxysterol metabolized by CYP7B1. How 27HC impacts vascular health is unknown. We show that elevations in 27HC via cyp7b1 deletion promote atherosclerosis in apoe(-/-) mice without altering lipid status; furthermore, estrogen-related atheroprotection is attenuated. In wild-type mice, leukocyte-endothelial cell adhesion is increased by 27HC via estrogen receptor (ER)-dependent processes. In monocytes/macrophages, 27HC upregulates proinflammatory genes and increases adhesion via ERα. In endothelial cells, 27HC is also proadhesive via ERα, and in contrast to estrogen, which blunts NF-κB activation, 27HC stimulates NF-κB activation via Erk1,2 and JNK-dependent IκBα degradation. Whereas 27HC administration to apoe(-/-) mice increases atherosclerosis, apoe(-/-);erα(-/-) are unaffected. Thus, 27HC promotes atherosclerosis via proinflammatory processes mediated by ERα, and it attenuates estrogen-related atheroprotection. Strategies to lower 27HC may complement approaches targeting cholesterol to prevent vascular disease.

Estrogen signalling in the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) is a multifactorial eye disease that is associated with aging, family history, smoking, obesity, cataract surgery, arteriosclerosis, hypertension, hypercholesterolemia and unhealthy diet. Gender has commonly been classified as a weak or inconsistent risk factor for AMD. This disease is characterized by degeneration of retinal pigment epithelial (RPE) cells, Bruch's membrane, and choriocapillaris, which secondarily lead to damage and death of photoreceptor cells and central visual loss. Pathogenesis of AMD involves constant oxidative stress, chronic inflammation, and increased accumulation of lipofuscin and drusen. Estrogen has both anti-oxidative and anti-inflammatory capacity and it regulates signaling pathways that are involved in the pathogenesis of AMD. In this review, we discuss potential cellular signaling targets of estrogen in retinal cells and AMD pathology.

Role of estrogen in hepatocellular carcinoma: is inflammation the key?

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and accounts for the third-leading cause of cancer-related deaths. Over the past decades, advances have been made in the field of surgery, but effective treatment of HCC is lacking. Due to a marked male predominance in morbidity and mortality in HCC patients, it has long been considered that sex hormones play a role in HCC development. Recently estrogen has been proven to exert protective effects against HCC through IL-6 restrictions, STAT3 inactivation and tumour-associated macrophage inhibition. While IL-6-dependent STAT3 activation is considered a key event in inflammation-induced liver cancer, the anti-inflammation effect of estrogen is well documented. The roles of the estrogen receptor and aromatase and interactions between microRNAs and estrogen in HCC have been investigated. In this review, we present a novel model to elucidate the mechanism of estrogen-mediated inhibition of HCC development through an anti-inflammation effect and provide new insights into the roles of estrogen in liver disease.

Estradiol reduces ferrous citrate complex-induced NOS2 up-regulation in cerebral endothelial cells by interfering the nuclear factor kappa B transactivation through an estrogen receptor β-mediated pathway

Hemorrhagic stroke caused leakage of red blood cells which converts to hemoglobin, heme, and iron accumulated at the lesions. High concentration of ferrous iron from subarachnoid hemorrhage (SAH) induced cerebral vasospasm. Using the two-hemorrhage SAH model in rats, we previously demonstrated that estradiol (E2) significantly attenuated the SAH-induced vasospasm by inhibiting the NOS2 expression. Adding ferrous citrate (FC) complexes to the primary cultured mouse cerebral endothelial cells (CEC) to mimic the SAH conditions, we also showed that FC up-regulates NOS2 through nuclear translocation of NFκB induced by free radicals generation. Here, we further studied the molecular mechanism underlying E2-mediated reduction of the FC-induced up-regulation of NOS2. Treatment with E2 (100 nM) reduced the FC (100 µM)-induced increases of free radical generation and the levels of NOS2 mRNA and protein in the CEC. Moreover, E2 also prevented the FC-induced increases of IκBα phosphorylation, NFκB nuclear translocation, NFκB binding onto the NOS2 promoter, and the NOS2 promoter luciferase activity. However, knock-down the estrogen receptor β (ERβ), but not ERα, abolished the E2-mediated prevention on the FC-induced increases of NOS2 mRNA and protein. The data from the present study suggest that E2 inhibited NOS2 gene expression by interfering with NFκB nuclear translocation and NFκB binding onto the NOS2 through an ERβ-mediated pathway. Our results provide the molecular basis for designing the applicable therapeutic or preventive strategies in the treatment SAH patients.

Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo

Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.

Minireview: Inflammation: an instigator of more aggressive estrogen receptor (ER) positive breast cancers

Approximately 75% of breast tumors express the estrogen receptor (ER), and women with these tumors will receive endocrine therapy. Unfortunately, up to 50% of these patients will fail ER-targeted therapies due to either de novo or acquired resistance. ER-positive tumors can be classified based on gene expression profiles into Luminal A- and Luminal B-intrinsic subtypes, with distinctly different responses to endocrine therapy and overall patient outcome. However, the underlying biology causing this tumor heterogeneity has yet to become clear. This review will explore the role of inflammation as a risk factor in breast cancer as well as a player in the development of more aggressive, therapy-resistant ER-positive breast cancers. First, breast cancer risk factors, such as obesity and mammary gland involution after pregnancy, which can foster an inflammatory microenvironment within the breast, will be described. Second, inflammatory components of the tumor microenvironment, including tumor-associated macrophages and proinflammatory cytokines, which can act on nearby breast cancer cells and modulate tumor phenotype, will be explored. Finally, activation of the nuclear factor κB (NF-κB) pathway and its cross talk with ER in the regulation of key genes in the promotion of more aggressive breast cancers will be reviewed. From these multiple lines of evidence, we propose that inflammation may promote more aggressive ER-positive tumors and that combination therapy targeting both inflammation and estrogen production or actions could benefit a significant portion of women whose ER-positive breast tumors fail to respond to endocrine therapy.

CBP mediates NF-κB-dependent histone acetylation and estrogen receptor recruitment to an estrogen response element in the BIRC3 promoter

Estrogen receptor (ER) and NF-κB are transcription factors with profound effects on breast cancer cell proliferation and survival. While many studies demonstrate that ER and NF-κB can repress each other, we previously identified a gene signature that is synergistically upregulated by these two factors in more aggressive luminal B breast tumors. Herein, we examine a novel mechanism of cross talk between ER and NF-κB that results in the upregulation of the antiapoptotic gene BIRC3 (also known as cIAP2). We demonstrate that NF-κB, acting through two response elements, is required for ER recruitment to an adjacent estrogen response element (ERE) in the BIRC3 promoter. This effect is accompanied by a major increase in NF-κB-dependent histone acetylation around the ERE. Interestingly, CBP, a histone acetyltransferase previously implicated in repressive interactions between ER and NF-κB, plays a permissive role by promoting histone acetylation and ER recruitment, as well as enhanced expression of BIRC3. These findings suggest a new gene regulatory mechanism by which inflammation and NF-κB activation can influence ER recruitment to inherently inactive ER binding sites. This fine-tuning mechanism may explain how two factors that generally repress each other's activity may work together on certain genes to promote breast cancer cell survival and tumor progression.

Inhibition of Bcl3 gene expression mediates the anti-proliferative action of estrogen in pituitary lactotrophs in primary culture

In addition to their well-known stimulatory action, estrogens have an anti-proliferative effect. The present study was undertaken to investigate the mechanism by which 17β-estradiol (E2) inhibits insulin-like growth factor-1 (IGF-1)-induced proliferation in vitro in the rat pituitary lactotroph, a typical estrogen-responsive cell. E2 treatment of pituitary cells did not change levels of IGF-1-induced phosphorylation of proliferation-related protein kinases such as Erk1/2 and Akt. We performed global gene expression profiling by DNA microarray analysis and identified 177 genes regulated by E2 in the presence of IGF-1. These results were verified by quantitative real time PCR. The estrogen-regulated genes included several NFκB family related genes. As pharmacological inhibition of the NFκB pathway blocked IGF-1-induced lactotroph proliferation, we chose to investigate whether one NFκB pathway gene, Bcl3, was involved in the anti-proliferative action of E2. RNA interference-mediated knockdown of Bcl3 expression attenuated IGF-1-induced lactotroph proliferation. Even minimal induced overexpression of Bcl3 blocked the anti-proliferative action of E2. In contrast, Nfkb2, another E2-downregulated protein, required maximal overexpression to block the anti-proliferative action of E2. These results suggest that inhibition of Bcl3 expression is involved in the anti-proliferative action of estrogens in pituitary lactotrophs in culture.

Oestrogen treatment enhances the sensitivity of hormone-resistant breast cancer cells to doxorubicin

Recently, it was shown that the resistance of breast cancer cells to growth-stimulating oestrogen action may be accompanied with the paradoxical tumour sensitization to oestrogen apoptotic action. In the present paper, we studied the influence of oestrogens on the sensitivity of resistant breast tumours to cytostatic drugs, and to evaluate the role of NF-κB (nuclear factor κB) signalling in the regulation of the apoptotic response of the resistant cells. The experiments were carried out on the oestrogen-dependent MCF-7 breast cancer cells and resistant MCF-7/LS subline generated through long-term cultivation of the parental cells in the absence of oestrogen. The cell treatment with the combination of oestradiol and Dox (doxorubicin) was found to enhance the apoptotic action of Dox in MCF-7/LS cells but not in the parent cells. MCF-7/LS cells were characterized by the increased level of ROS (reactive oxygen species) and decreased NF-κB activity. Oestradiol in combination with Dox leads to significant NF-κB stimulation and its accumulation in the nucleus of MCF-7/LS cells. The knockdown of NF-κB with siRNA (small interfering RNA) increased the apoptotic response of the MCF-7/LS cells to both Dox and oestradiol demonstrating the important role of NF-κB in the protection of the MCF-7/LS cells against apoptosis. In general, the results obtained show that: (i) oestradiol enhances the apoptotic action of Dox in the resistant breast cancer cells; and (ii) suppression of NF-κB signalling amplifies the apoptotic response of the resistant cells to both oestrogen and Dox, demonstrating that NF-κB may serve as a potential target in the therapy of the resistant breast cancer.

In situ proteomic analysis of human breast cancer epithelial cells using laser capture microdissection: annotation by protein set enrichment analysis and gene ontology

Identification of molecular signatures that allow detection of the transition from normal breast epithelial cells to malignant invasive cells is a critical component in the development of diagnostic, therapeutic, and preventative strategies for human breast cancer. Substantial efforts have been devoted to deciphering breast cancer etiology at the genome level, but only a limited number of studies have appeared at the proteome level. In this work, we compared individual in situ proteome profiles of nonpatient matched nine noncancerous, normal breast epithelial (NBE) samples with nine estrogen receptor (ER)-positive (luminal subtype), invasive malignant breast epithelial (MBE) samples by combining laser capture microdissection (LCM) and quantitative shotgun proteomics. A total of 12,970 unique peptides were identified from the 18 samples, and 1623 proteins were selected for quantitative analysis using spectral index (SpI) as a measure of protein abundance. A total of 298 proteins were differentially expressed between NBE and MBE at 95% confidence level, and this differential expression correlated well with immunohistochemistry (IHC) results reported in the Human Protein Atlas (HPA) database. To assess pathway level patterns in the observed expression changes, we developed protein set enrichment analysis (PSEA), a modification of a well-known approach in gene expression analysis, Gene Set Enrichment Analysis (GSEA). Unlike single gene-based functional term enrichment analyses that only examines pathway overrepresentation of proteins above a given significance threshold, PSEA applies a weighted running sum statistic to the entire expression data to discover significantly enriched protein groups. Application of PSEA to the expression data in this study revealed not only well-known ER-dependent and cellular morphology-dependent protein abundance changes, but also significant alterations of downstream targets for multiple transcription factors (TFs), suggesting a role for specific gene regulatory pathways in breast tumorigenesis. A parallel GOMiner analysis revealed both confirmatory and complementary data to PSEA. The combination of the two annotation approaches yielded extensive biological feature mapping for in depth analysis of the quantitative proteomic data.

Proinflammatory cytokines enhance estrogen-dependent expression of the multidrug transporter gene ABCG2 through estrogen receptor and NF{kappa}B cooperativity at adjacent response elements

Constitutive activation of NFκB in estrogen receptor (ER)-positive breast cancer is associated with tumor recurrence and development of anti-estrogen resistance. Furthermore, a gene expression signature containing common targets for ER and NFκB has been identified and found to be associated with the more aggressive luminal B intrinsic subtype of ER-positive breast tumors. Here, we describe a novel mechanism by which ER and NFκB cooperate to up-regulate expression of one important gene from this signature, ABCG2, which encodes a transporter protein associated with the development of drug-resistant breast cancer. We and others have confirmed that this gene is regulated primarily by estrogen in an ER- and estrogen response element (ERE)-dependent manner. We found that whereas proinflammatory cytokines have little effect on this gene in the absence of 17β-estradiol, they can potentiate ER activity in an NFκB-dependent manner. ER allows the NFκB family member p65 to access a latent NFκB response element located near the ERE in the gene promoter. NFκB recruitment to the gene is, in turn, required to stabilize ER occupancy at the functional ERE. The result of this cooperative binding of ER and p65 at adjacent response elements leads to a major increase in both ABCG2 mRNA and protein expression. These findings indicate that estrogen and inflammatory factors can modify each other's activity through modulation of transcription factor accessibility and/or occupancy at adjacent response elements. This novel transcriptional mechanism could have important implications in breast cancer, where both inflammation and estrogen can promote cancer progression.

Suppression of the inflammatory response in experimental arthritis is mediated via estrogen receptor alpha but not estrogen receptor beta

Introduction

The immune modulatory role of estrogens in inflammation is complex. Both pro- and anti-inflammatory effects of estrogens have been described. Estrogens bind both estrogen receptor (ER)α and β. The contribution of ERα and ERβ to ER-mediated immune modulation was studied in delayed type hypersensitivity (DTH) and in experimental arthritis

Methods

ER-mediated suppression of rat adjuvant arthritis (AA) was studied using ethinyl-estradiol (EE) and a selective ERβ agonist (ERB-79). Arthritis was followed for 2 weeks. Next, effects of ER agonists (ethinyl-estradiol, an ERα selective agonist (ERA-63) and a selective ERβ agonist (ERB-79) on the development of a tetanus toxoid (TT)-specific delayed type hypersensitivity response in wild type (WT) and in ERα - or ERβ-deficient mice were investigated. Finally, EE and ERA-63 were tested for their immune modulating potential in established collagen induced arthritis in DBA/1J mice. Arthritis was followed for three weeks. Joint pathology was examined by histology and radiology. Local synovial cytokine production was analyzed using Luminex technology. Sera were assessed for COMP as a biomarker of cartilage destruction.

Results

EE was found to suppress clinical signs and symptoms in rat AA. The selective ERβ agonist ERB-79 had no effect on arthritis symptoms in this model. In the TT-specific DTH model, EE and the selective ERα agonist ERA-63 suppressed the TT-specific swelling response in WT and ERβKO mice but not in ERαKO mice. As seen in the AA model, the selective ERβ agonist ERB-79 did not suppress inflammation. Treatment with EE or ERA-63 suppressed clinical signs in collagen induced arthritis (CIA) in WT mice. This was associated with reduced inflammatory infiltrates and decreased levels of proinflammatory cytokines in CIA joints.

Conclusions

ERα, but not ERβ, is key in ER-mediated suppression of experimental arthritis. It remains to be investigated how these findings translate to human autoimmune disease.

Abrogation of glucocorticoid receptor dimerization correlates with dissociated glucocorticoid behavior of compound a

Compound A (CpdA), a dissociated glucocorticoid receptor modulator, decreases corticosteroid-binding globulin (CBG), adrenocorticotropic hormone (ACTH), and luteneinizing hormone levels in rats. Whether this is due to transcriptional regulation by CpdA is not known. Using promoter reporter assays we show that CpdA, like dexamethasone (Dex), directly transrepresses these genes. Results using a rat Cbg proximal-promoter reporter construct in BWTG3 and HepG2 cell lines support a glucocorticoid receptor (GR)-dependent transrepression mechanism for CpdA. However, CpdA, unlike Dex, does not result in transactivation via glucocorticoid-responsive elements within a promoter reporter construct even when GR is co-transfected. The inability of CpdA to result in transactivation via glucocorticoid-responsive elements is confirmed on the endogenous tyrosine aminotransferase gene, whereas transrepression ability is confirmed on the endogenous CBG gene. Consistent with a role for CpdA in modulating GR activity, whole cell binding assays revealed that CpdA binds reversibly to the GR, but with lower affinity than Dex, and influences association of [(3)H]Dex, but has no effect on dissociation. In addition, like Dex, CpdA causes nuclear translocation of the GR, albeit to a lesser degree. Several lines of evidence, including fluorescence resonance energy transfer, co-immunoprecipitation, and nuclear immunofluorescence studies of nuclear localization-deficient GR show that CpdA, unlike Dex, does not elicit ligand-induced GR dimerization. Comparison of the behavior of CpdA in the presence of wild type GR to that of Dex with a dimerization-deficient GR mutant (GR(dim)) strongly supports the conclusion that loss of dimerization is responsible for the dissociated behavior of CpdA.

An additive interaction between the NFkappaB and estrogen receptor signalling pathways in human endometrial epithelial cells

BACKGROUND

Human embryo implantation is regulated by estradiol (E2), progesterone and locally produced mediators including interleukin-1beta (IL-1beta). Interactions between the estrogen receptor (ER) and NF kappa B (NFkappaB) signalling pathways have been reported in other systems but have not been detailed in human endometrium.

METHODS AND RESULTS

Real-time PCR showed that mRNA for the p65 and p105 NFkappaB subunits is maximally expressed in endometrium from the putative implantation window. Both subunits are localized in the endometrial epithelium throughout the menstrual cycle. Reporter assays for estrogen response element (ERE) activity were used to examine functional interactions between ER and NFkappaB in telomerase immortalized endometrial epithelial cells (TERT-EEC). E2 and IL-1beta treatment of TERT-EECs enhances ERE activity by a NFkappaB and ER dependent mechanism; this effect could be mediated by ERalpha or ERbeta. E2 and IL-1beta also positively interact to increase endogenous gene expression of prostaglandin E synthase and c-myc. This is a gene-dependent action as there is no additive effect on cyclin D1 or progesterone receptor expression.

CONCLUSION

In summary, we have established that NFkappaB signalling proteins are expressed in normal endometrium and report that IL-1beta can enhance the actions of E2 in a cell line derived from healthy endometrium. This mechanism may allow IL-1beta, possibly from the developing embryo, to modulate the function of the endometrial epithelium to promote successful implantation, for example by regulating prostaglandin production. Aberrations in the interaction between the ER and NFkappaB signalling pathways may have a negative impact on implantation contributing to pathologies such as early pregnancy loss and infertility.

Positive cross-talk between estrogen receptor and NF-kappaB in breast cancer

Estrogen receptors (ER) and nuclear factor-kappaB (NF-kappaB) are known to play important roles in breast cancer, but these factors are generally thought to repress each other's activity. However, we have recently found that ER and NF-kappaB can also act together in a positive manner to synergistically increase gene transcription. To examine the extent of cross-talk between ER and NF-kappaB, a microarray study was conducted in which MCF-7 breast cancer cells were treated with 17beta-estradiol (E(2)), tumor necrosis factor alpha (TNFalpha), or both. Follow-up studies with an ER antagonist and NF-kappaB inhibitors show that cross-talk between E(2) and TNFalpha is mediated by these two factors. We find that although transrepression between ER and NF-kappaB does occur, positive cross-talk is more prominent with three gene-specific patterns of regulation: (a) TNFalpha enhances E(2) action on approximately 30% of E(2)-upregulated genes; (b) E(2) enhances TNFalpha activity on approximately 15% of TNFalpha-upregulated genes; and (c) E(2) + TNFalpha causes a more than additive upregulation of approximately 60 genes. Consistent with their prosurvival roles, ER and NF-kappaB and their target gene, BIRC3, are involved in protecting breast cancer cells against apoptosis. Furthermore, genes positively regulated by E(2) + TNFalpha are clinically relevant because they are enriched in luminal B breast tumors and their expression profiles can distinguish a cohort of patients with poor outcome following endocrine treatment. Taken together, our findings suggest that positive cross-talk between ER and NF-kappaB is more extensive than anticipated and that these factors may act together to promote survival of breast cancer cells and progression to a more aggressive phenotype.

Synergistic up-regulation of prostaglandin E synthase expression in breast cancer cells by 17beta-estradiol and proinflammatory cytokines

Inflammatory mediators, such as cytokines and prostaglandins, play a fundamental role in estrogen-dependent breast cancer through their ability to up-regulate aromatase expression and subsequent local production of estrogens in the breast. To study the link between estrogens and inflammation further, we examined the regulation of prostaglandin E synthase (PTGES), a key enzyme in the production of prostaglandin E2. We found that 17beta-estradiol (E2) rapidly and robustly up-regulates PTGES mRNA and protein levels in estrogen receptor (ER)-positive breast cancer cells through ER recruitment to an essential estrogen response element located in the 5' flanking region of the PTGES gene. PTGES is also up-regulated by the proinflammatory cytokines TNFalpha or IL-1beta. Surprisingly, the combination of E2 and cytokines leads to a synergistic up-regulation of PTGES in an ER and nuclear factor-kappaB (NFkappaB)-dependent manner. This is in contrast to the mutual transrepression between ER and NFkappaB that has been well characterized in other cell types. Furthermore, we found enhanced recruitment of ERalpha as well as the NFkappaB family member, p65, to the PTGES estrogen response element by the combination of E2 and TNFalpha compared with either E2 or TNFalpha alone. The synergistic up-regulation of PTGES may result in enhanced prostaglandin E2 production, which in turn may further enhance aromatase expression and production of local estrogens. Our findings suggest that a finely tuned positive feedback mechanism between estrogens and inflammatory factors may exist in the breast and contribute to hormone-dependent breast cancer growth and progression.

Role of sex steroid receptors in pathobiology of hepatocellular carcinoma

The striking gender disparity observed in the incidence of hepatocellular carcinoma (HCC) suggests an important role of sex hormones in HCC pathogenesis. Though the studies began as early as in 1980s, the precise role of sex hormones and the significance of their receptors in HCC still remain poorly understood and perhaps contribute to current controversies about the potential use of hormonal therapy in HCC. A comprehensive review of the existing literature revealed several shortcomings associated with the studies on estrogen receptor (ER) and androgen receptor (AR) in normal liver and HCC. These shortcomings include the use of less sensitive receptor ligand binding assays and immunohistochemistry studies for ERα alone until 1996 when ERβ isoform was identified. The animal models of HCC utilized for studies were primarily based on chemical-induced hepatocarcinogenesis with less similarity to virus-induced HCC pathogenesis. However, recent in vitro studies in hepatoma cells provide newer insights for hormonal regulation of key cellular processes including interaction of ER and AR with viral proteins. In light of the above facts, there is an urgent need for a detailed investigation of sex hormones and their receptors in normal liver and HCC. In this review, we systematically present the information currently available on androgens, estrogens and their receptors in normal liver and HCC obtained from in vitro, in vivo experimental models and clinical studies. This information will direct future basic and clinical research to bridge the gap in knowledge to explore the therapeutic potential of hormonal therapy in HCC.

Associations of endogenous sex hormones with the vasculature in menopausal women: the Study of Women's Health Across the Nation (SWAN)

OBJECTIVE

As associations between endogenous sex hormones and the vasculature are not well characterized, the objective was to examine the cross-sectional associations of menopausal status and endogenous sex hormones with vascular characteristics.

DESIGN

Common carotid artery adventitial diameter and intima-media thickness were determined using B-mode ultrasonography among 483 middle-aged women enrolled in the Pittsburgh and Chicago sites of the Study of Women's Health Across the Nation.

RESULTS

Sixty-two percent of women were pre- or early perimenopausal (<3 mo amenorrhea), 12% were late perimenopausal (3-12 mo amenorrhea), and 27% were postmenopausal (>or=12 mo amenorrhea). After adjustment for age, compared with pre-/early perimenopause, late perimenopause was associated with a 0.28-mm larger adventitial diameter (P=0.001), whereas postmenopause was associated with a 0.15-mm larger adventitial diameter (P=0.040). Adjustment for traditional cardiovascular risk factors slightly attenuated these associations, but the association with late perimenopause remained statistically significant (P=0.001). Each SD lower log estradiol value was associated with a 0.07-mm larger adventitial diameter after adjustment for traditional cardiovascular risk factors (P=0.023), whereas other endogenous hormones showed no associations. Intima-media thickness values were not significantly associated with menopausal status or endogenous sex hormones after adjustment for age.

CONCLUSIONS

The menopausal transition and declining estrogen levels are associated with alterations of the peripheral vasculature, which may help to explain the increased risk of cardiovascular disease with postmenopause.

Estrogen-mediated protection in myocardial ischemia-reperfusion injury

Before menopause, a woman has a relatively low risk for developing cardiovascular disease. After menopause, however, the risk increases nearly twofold and cardiovascular disease remains the number one cause of death among women. Observational trials and studies in animal models of cardiovascular disease suggested that females have reduced injury after myocardial ischemia and reperfusion injury. However, two large clinical trials, the women's health initiative (WHI) and the heart estrogen and progestin replacement study (HERS), found an increase in cardiovascular incidences in women taking hormone replacement therapy. The discrepancy between these data highlights the need for further research on the mechanism of estrogen in the cardiovascular system. Animal studies have demonstrated protective effects by endogenous estrogen (gender differences) and also by the administration of exogenous estrogen. In vivo studies suggest a possible anti-inflammatory mechanism of estrogen. Exogenous estrogen has been shown to have anti-oxidant activities. Pre-treatment with estrogen prior to myocardial ischemia and reperfusion causes a decrease in neutrophil infiltration into the irreversibly injured myocardium, decrease in C-reactive protein expression, and deposition of the membrane attack complex. This review will summarize the protection afforded by estrogen as well as discuss several possible mechanisms of protection for exogenous estrogen administration.

The role of estrogen in the formation of experimental abdominal aortic aneurysm

OBJECTIVE

The current study sought to investigate the role of estrogen in the formation of experimental abdominal aortic aneurysm (AAA).

METHODS

Elastase perfusion of infrarenal AAA animal model was performed in 20 female and 20 male Wistar rats that were randomly divided into an ovariectomized/sham-operated group and an estradiol (E2) experimental/saline control group, respectively. At day 14, E2 was detected, while the mRNA and protein expressions of matrix metalloproteinases 2 and 9 (MMP-2 and -9) in AAA tissue were detected by immunohistochemistry and polymerase chain reaction (PCR).

RESULTS

The ovariectomized group showed lower estrogen levels and a higher aneurysm dilatation rate and significantly higher MMP-2 and -9 expression compared with the sham-operated group (P < .01), which was in accordance with MMP-2 and -9 mRNA expression. The E2 group showed higher estrogen levels and a lower aneurysm dilatation rate and significantly lower MMP-2 and -9 expression than did the saline control group (P < .01), which was in accordance with MMP-2 and -9 mRNA expression.

CONCLUSIONS

In the pathogenesis of AAA, estrogen may play an inhibitory role by decreasing expression of MMP-2 and MMP-9 synthesis.

Inflammatory status influences aromatase and steroid receptor expression in endometriosis

Aberrant up-regulation of aromatase in eutopic endometrium and implants from women with endometriosis has been reported. Aromatase induction may be mediated by increased cyclooxygenase-2 (COX-2). Recently, we demonstrated that progesterone receptor (PR)-A and PR-B serve an antiinflammatory role in the uterus by antagonizing nuclear factor kappaB activation and COX-2 expression. PR-C, which antagonizes PR-B, is up-regulated by inflammation. Although estrogen receptor alpha (ERalpha) is implicated in endometriosis, an antiinflammatory role of ERbeta has been suggested. We examined stage-specific expression of aromatase, COX-2, ER, and PR isoform expression in eutopic endometrium, implants, peritoneum, and endometrioma samples from endometriosis patients. Endometrial and peritoneal biopsies were obtained from unaffected women and those with fibroids. Aromatase expression in eutopic endometrium from endometriosis patients was significantly increased compared with controls. Aromatase expression in endometriosis implants was markedly increased compared with eutopic endometrium. Aromatase mRNA levels were increased significantly in red implants relative to black implants and endometrioma cyst capsule. Moreover, COX-2 expression was increased in implants and in eutopic endometrium of women with endometriosis as compared with control endometrium. As observed for aromatase mRNA, the highest levels of COX-2 mRNA were found in red implants. The ratio of ERbeta/ERalpha mRNA was significantly elevated in endometriomas compared with endometriosis implants and eutopic endometrium. Expression of PR-C mRNA relative to PR-A and PR-B mRNA was significantly increased in endometriomas compared with eutopic and control endometrium. PR-A protein was barely detectable in endometriomas. Thus, whereas PR-C may enhance disease progression, up-regulation of ERbeta may play an antiinflammatory and opposing role.

Vascular endothelial growth factor receptor-2 expression is down-regulated by 17beta-estradiol in MCF-7 breast cancer cells by estrogen receptor alpha/Sp proteins

17beta-Estradiol (E2) induces and represses gene expression in breast cancer cells; however, the mechanisms of gene repression are not well understood. In this study, we show that E2 decreases vascular endothelial growth factor receptor 2 (VEGFR2) mRNA levels in MCF-7 cells, and this gene was used as a model for investigating pathways associated with E2-dependent gene repression. Deletion analysis of the VEGFR2 promoter indicates that the proximal GC-rich motifs at -58 and -44 are critical for the E2-dependent decreased response in MCF-7 cells. Mutation or deletion of these GC-rich elements results in loss of hormone responsiveness and shows that the -60 to -37 region of the VEGFR2 promoter is critical for both basal and hormone-dependent decreased VEGFR2 expression in MCF-7 cells. Western blot, immunofluorescent staining, RNA interference, and EMSAs support a role for Sp proteins in hormone-dependent down-regulation of VEGFR2 in MCF-7 cells, primarily through estrogen receptor (ER)alpha/Sp1 and ERalpha/Sp3 interactions with the VEGFR2 promoter. Using chromatin immuno-precipitation and transient transfection/RNA interference assays we show that the ERalpha/Sp protein-promoter interactions are accompanied by recruitment of the co-repressors SMRT (silencing mediator of retinoid and thyroid hormone receptor) and NCoR (nuclear receptor corepressor) to the promoter and that SMRT and NCoR knockdown reverse E2-mediated down-regulation of VEGFR2 expression in MCF-7 cells. This study illustrates that both SMRT and NCoR are involved in E2-dependent repression of VEGFR2 in MCF-7 cells.

Determining the transrepression activity of xenoestrogen on nuclear factor-kappa B in Cos-1 cells by estrogen receptor-alpha

Functional assays have been used to define the estrogenicity of xenoestrogens in cotransfection studies employing estrogen receptors in various cell lines. It is known that estrogen is able to affect transcription from other nuclear transcription factors, especially the nuclear factor-kappa B (NF-kappa B). The ability of selected xenoestrogens (methoxychlor [MXC], dieldrin, and o',p'-DDT) to transrepress the NF-kappa B-mediated transcription in Cos-1 cells was evaluated by cotransfection of human estrogen receptor-alpha (hERalpha). These xenoestrogens have been described as comparably potent xenoestrogens, whereas their relative binding activity (RBA) has been relegated to a lower order as compare to estrogen. The two NF-kappa B response element-containing SV40 promoter and -242/+54 cytomegalovirus (CMV)-expressing firefly luciferase (2 x NRE-PV-Luc and 2 x NRE-CMV-Luc, respectively) were transfected into Cos-1 cells with pRL-tk, expressing the renilla luciferase as internal control. The estrogen receptor was expressed from cytomegalovirus major immediate early promoter (CMV-MIEP) (CMV5-hERalpha). Treatment with 1 nM estrogen (E(2)) (26.2%), 5 nM E(2) (41.4%; p < .05), and xenoestrogens (methoxychlor [1 nM: 29.6%, p < .05; 10 nM: 22.6%), dieldrin [1 nM: 10.3%; 10 nM: 36.06%, p < .05], and o',p'-DDT [1 nM: 17.0%; 10 nM: 7.15%]) repressed transcription from 2 x NREX-PV-Luc. The antiestrogen, ICI 182,780, failed to antagonize the effects of xenoestrogens. The effects of xenoestrogens in transrepression of NF-kappa B by ERalpha were similar when 2 x NRE-CMV-Luc was employed as reporter. Statistically significant (p < .01) repression by 1 nM E(2) (69.2%), 5 nM E(2) (69.1%), 1 nM o',p'-DDT (51.4%), 1 nM dieldrin (47.3%), and 1 nM MXC (73.3%) were observed. The effect of these xenoestrogens without ERalpha cotransfection on 2 x NRE-PV-Luc- and 2 x NRE-CMV-Luc-mediated NF-kappa B transcription was not affected by the treatment alone. It is concluded that xenoestrogens, like estrogens, are capable of producing transrepression of NF-kappa B by hERalpha.

CBP Is a dosage-dependent regulator of nuclear factor-kappaB suppression by the estrogen receptor

The estrogen receptor (ER) protects against debilitating effects of the inflammatory response by inhibiting the proinflammatory transcription factor nuclear factor-kappaB (NFkappaB). Heretofore cAMP response element-binding protein (CREB)-binding protein (CBP) has been suggested to mediate inhibitory cross talk by functioning either as a scaffold that links ER and NFkappaB or as a required cofactor that competitively binds to one or the other transcriptional factor. However, here we demonstrate that ER is recruited to the NFkappaB response element of the MCP-1 (monocyte chemoattractant protein-1) and IL-8 promoters and displaces CBP, but not p65, in the MCF-7 breast cancer cell line. In contrast, ER displaced p65 and associated coregulators from the IL-6 promoter, demonstrating a gene-specific role for CBP in integrating inflammatory and steroid signaling. Further, RNA interference and overexpression studies demonstrated that CBP dosage regulates estrogen-mediated suppression of MCP-1 and IL-8, but not IL-6, gene expression. This work further demonstrates that CBP dosage is a critical regulator of gene-specific signal integration between the ER- and NFkappaB-signaling pathways.

Relationship between estrogen receptor-alpha polymorphism and serum levels of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, C-reactive protein and homocysteine in postmenopausal women

BACKGROUND AND AIM

Genetic variation in the estrogen receptor-gene (ERalpha) may influence the risk of cardiovascular diseases in postmenopausal women. This effect, at least in part, may be dependent on the decrease in expression of injury and inflammatory markers in the vascular wall. The aim of the present study was to evaluate the relationship between ERalpha PvuII and XbaI polymorphisms and serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), C-reactive protein (CRP) and homocysteine in postmenopausal women.

SUBJECTS AND METHODS

Subjects of the study were 64 postmenopausal women. PvuII and XbaI ERalpha gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Mean sVCAM-1 level was significantly higher in pp homozygotes in comparison with PP homozygotes and Pp heterozygotes, as well as higher in xx homozygotes in comparison with XX homozygotes and Xx heterozygotes. Levels of sVCAM-1 were also significantly higher in women with px haplotype compared with PX and Px haplotypes. There were no relationships between investigated genotypes or haplotypes and levels of sICAM-1, CRP and homocysteine.

CONCLUSION

The results of our study suggest that genetic variation in ER gene may influence blood levels of VCAM-1 in women after the menopause.

Estrogen receptor alpha (ERalpha) and insulin-like growth factor I receptor (IGF-IR) cross-talk in the gonadotropic alphaT3-1 cell line

In reproductive tissues such as the breast and the uterus, cell proliferation and differentiation is strongly regulated by complex interactions between estrogen receptor alpha (ERalpha) and growth factor receptors. In the present study, we investigated the potential occurrence of such cross-talk in the murine, gonadotropic alphaT3-1 cell line, which expresses ERalpha and the IGF-I receptor (IGF-IR). Under estrogen-free conditions, basal cell proliferation and ER-mediated gene transcription was strongly inhibited by the selective estrogen receptor modulator (SERM) 4-hydroxy-tamoxifen (4-OH-Tam) and by the pure anti-estrogen ICI 182,780 (ICI). These effects can be reversed by either 17-beta-estradiol (E(2)) or insulin-like growth factor I (IGF-I), both exerting modest mitogenic effects in the alphaT3-1 cell line. Furthermore, IGF-I enhanced both basal and E(2)-induced ER-driven gene transcription. This may be explained, at least in part, by enhanced phosphorylation of ERalpha at serine 118, a prerequisite for the transactivation capacity of the receptor. Finally, the IGF-I-induced response on cell growth and ER-mediated transactivation can be inhibited with either ICI or 4-OH-Tam. In conclusion, our data indicate IGF-IR and ER interactions in the alphaT3-1 cell line, an in vitro model for the pituitary gonadotrophs, hereby suggesting a role of IGF-I in the regulation of gonadotropin synthesis and secretion.

The complex role of estrogens in inflammation

There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

A20/TNFAIP3, a new estrogen-regulated gene that confers tamoxifen resistance in breast cancer cells

The zinc-finger protein A20/TNFAIP3, an inhibitor of nuclear factor-kappaB (NF-kappaB) activation, has been shown to protect MCF-7 breast carcinoma cells from TNFalpha-induced apoptosis. As estrogen receptor (ER) status is an important parameter in the development and progression of breast cancer, we analysed the effect of 17beta-estradiol (E2) treatment on the expression of A20. We found that A20 is a new E2-regulated gene, whose expression correlates with ER expression in both cell lines and tumor samples. With the aim of investigating the impact of A20 expression on MCF-7 cells in response to ER ligands, we established stably transfected-MCF-7 cells overexpressing A20 (MCF-7-A20). These cells exhibited a phenotype of resistance to the 4-hydroxy-tamoxifen cytostatic and pro-apoptotic actions and of hyper-response to E2. Dysregulations in bax, bcl2, bak, phospho-bad, cyclin D1, cyclin E2, cyclin D2 and cyclin A2 proteins expression were shown to be related to the resistant phenotype developed by the MCF-7-A20 cells. Interestingly, we found that A20 was also overexpressed in MVLN and VP tamoxifen-resistant cell lines. Furthermore, high A20 expression levels were observed in more aggressive breast tumors (ER-negative, progesterone receptor-negative and high histological grade). These overall findings strongly suggest that A20 is a key protein involved in tamoxifen resistance, and thus represents both a new breast cancer marker and a promising target for developing new strategies to prevent the emergence of acquired mechanisms of drug resistance in breast cancer.

The pathway-selective estrogen receptor ligand WAY-169916 displays differential activity in ischemia-reperfusion injury models

We previously reported on the development of a pathway-selective estrogen receptor (ER) ligand, WAY-169916, that has ER-dependent antiinflammatory activity and is devoid of classic ER transcriptional activity. In the current study, WAY-169916 and 17beta-estradiol (17beta-E2) were evaluated for protective activity in models of cardiac ischemia-reperfusion injury. In rats subjected to cardiac ischemia-reperfusion injury by occlusion of the left coronary artery, infarct size relative to the area at risk in the left ventricle was significantly attenuated by a single dose of 17beta-E2 (20 microg/kg, SC), and WAY-169916 administered SC (10 mg/kg) or IV (1 mg/kg) during the ischemia phase. In isolated hearts perfused on a Langendorff apparatus and subjected to global ischemia and reperfusion, 17beta-E2 and WAY-169916 both had direct cardioprotective activity when perfused at 1 microM but their effects varied between different end points. Perfusion with 17beta-E2 only improved recovery of left ventricle-developed pressure. Perfusion with WAY-169916 attenuated the elevation in perfusion pressure, diastolic pressure, and release of creatine kinase after ischemia. In contrast to 17alpha-ethinylestradiol, WAY-169916 had no classic estrogen effects on uterine weight or total serum cholesterol in rats treated for 4 days. The data demonstrate that the pathway-selective ER ligand WAY-169916 displays differential activity in vivo on different cardiovascular end points.

17beta-Estradiol inhibits subarachnoid hemorrhage-induced inducible nitric oxide synthase gene expression by interfering with the nuclear factor kappa B transactivation

BACKGROUND AND PURPOSE

Previously, we showed that 17beta-estradiol (E(2)) treatment prevented the subarachnoid hemorrhage (SAH)-induced cerebral vasospasm in male rats. The aim of this study was designed to further delineate the molecular mechanisms underlying E(2)-induced inhibition of inducible nitric oxide synthase (iNOS) upregulation and relief of vasospasm caused by SAH.

METHODS

The 2-hemorrhage SAH model was induced by 2 autologous injections of blood into the cisterna magna of adult male rats. The rats were then subcutaneously implanted of a Silastic tube containing corn oil with or without 17beta-estradiol benzoate and received daily intraperitoneal injections of various doses of ICI 182,780, a nonselective estrogen receptor (ER) antagonist, for 7 days after the first hemorrhage. Basilar arteries were then removed for protein extraction, RNA isolation, and gel mobility assay. The protein levels of iNOS, p65, and ER were examined by Western blot analysis, and that iNOS mRNA expression was evaluated by reverse-transcription polymerase chain reaction.

RESULTS

E(2) prevented the SAH-induced vasospasm and increases of the levels of iNOS protein and mRNA in basilar artery through an ER-dependent mechanism. Treatment of the SAH rat with E(2) did not affect the nuclear translocation of p65 subunit of nuclear factor kappaB, but caused an increase of the association of p65/ER, and reversed the SAH-induced increase of the p65 binding on iNOS promoter.

CONCLUSIONS

E(2) inhibits the SAH-induced increase of iNOS by increasing the association of p65/ER, which in turn inhibits the binding of p65 to iNOS DNA. Our data suggest the potential applications of E(2) in the treatment of SAH patient.

Resveratrol modulates phorbol ester-induced pro-inflammatory signal transduction pathways in mouse skin in vivo: NF-kappaB and AP-1 as prime targets

Functional abnormalities of intracellular signaling network cause the disruption in homeostasis maintained by critical cellular components, thereby accelerating premalignant and malignant transformation. Multiple lines of evidence suggest that an elevated expression of cyclooxygenase-2 (COX-2) is causally linked to tumorigenesis. The exposure to oxidative/pro-inflammatory stimuli turns on signaling arrays mediated by diverse classes of kinases and transcription factors, which may lead to aberrant expression of COX-2. We have attempted to unravel the signal transduction pathways involved in elevated COX-2 expression in mouse skin stimulated with a prototype tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and its modulation by resveratrol, a phytoalexin known to exert potential chemopreventive effects. Our study revealed that topical application of TPA induced COX-2 expression in mouse skin via activation of nuclear factor-kappaB (NF-kappaB), which is regulated by upstream IkappaB kinase (IKK) or differentially by mitogen-activated protein (MAP) kinases. Besides NF-kappaB, the p38 MAP kinase-mediated activation of activator protein-1 (AP-1) has also been attributed to TPA-induced COX-2 expression in mouse skin. Among the MAP kinases, extracellular signal-regulated protein kinase (ERK) and p38 MAP kinase have been shown to regulate TPA-induced NF-kappaB activation, while p38 MAP kinase and c-Jun-N-terminal kinase are preferentially involved in TPA-induced activation of AP-1 in mouse skin in vivo. This commentary focuses on resveratrol modulation of intracellular signaling pathways involved in aberrant COX-2 expression in TPA-stimulated mouse skin to delineate molecular mechanisms underlying antitumor promoting effects of resveratrol.