Estrogen receptor beta (ERβ) is expressed in brain astrocytic tumors and declines with dedifferentiation of the neoplasm

Purpose Estrogen receptor (ER) is the second identified receptor mediating the effects of estrogen on target tissues. The role of ER in cancer pathobiology is largely unknown, because specific antibodies have not been available until recently. Initial studies have shown that ER expression declines in breast, ovarian, prostatic, and colon carcinomas. Tamoxifen, a synthetic anti-estrogen compound that is a mixed agonist/antagonist of estrogen receptor (ER) and a pure antagonist of ER, has moderate beneficial effects in human astrocytic neoplasms. However, most published studies agree that glial tumors do not express ER. The purpose of this study was to explore the expression of ER in astrocytic neoplasms.Methods ER expression was monitored immunohistochemically in 56 cases of astrocytomas of all grades (grade I–IV) and in adjacent non-neoplastic brain tissue.Results Moderate or strong nuclear immunopositivity was obtained in non-neoplastic astrocytes and in low-grade astrocytomas, whereas the majority of high-grade tumors were immunonegative or displayed weak immunoreactivity. The progressive decline in ER expression paralleled the increase in tumor grade.Conclusions In as much as ER is possibly the only ER expressed in astrocytes, its decreased expression may play an important role in astrocytic tumor initiation and in the potential response of glial neoplasms to tamoxifen.     

Reduction of dendritic spines and elevation of GABAergic signaling in the brains of mice treated with an estrogen receptor β ligand

An estrogen receptor (ER) β ligand (LY3201) with a preference for ERβ over ERα was administered in s.c. pellets releasing 0.04 mg/d. The brains of these mice were examined 3 d after treatment had begun. Although estradiol-17β is known to increase spine density and glutaminergic signaling, as measured by Golgi staining, a clear reduction in spines was evident on the dendritic branches in LY3201-treated mice but no morphological alteration and no difference in the number of dendritic spines on dendritic stems were observed. In the LY3201-treatment group, there was higher expression of glutamic acid decarboxylase (GAD) in layer V of cortex and in the CA1 of hippocampus, more GAD(+) terminals surrounding the pyramidal neurons and less glutamate receptor (NMDAR) on the neurons in layer V. There were no alterations in expression of Iba1 or in Olig2 or CNPase. However, GFAP(+) astrocytes were increased in the LY3201-treatment group. There were also more projections characteristic of activated astrocytes and increased expression of glutamine synthetase (GS). No expression of ERβ was detectable in the nuclei of astrocytes. Clearly, LY3201 caused a shift in the balance between excitatory and inhibitory neurotransmission in favor of inhibition. This shift was due in part to increased synthesis of GABA and increased removal of glutamate from the synaptic cleft by astrocytes. The data reveal that treatment with a selective ERβ agonist results in changes opposite to those reported in estradiol-17β-treated mice and suggests that ERα and ERβ play opposing roles in the brain.     

A window of opportunity for abatacept in RA: is disease duration an independent predictor of low disease activity/remission in clinical practice?

The objective of the study was to examine whether disease duration independently predicts treatment response among biologic-naïve patients with rheumatoid arthritis (RA) initiating abatacept in clinical practice. Using the Corrona RA registry (February 2006–January 2015), biologic-naïve patients with RA initiating abatacept with 12-month (±3 months) follow-up and assessment of disease activity (Clinical Disease Activity Index [CDAI]) at initiation and at 12 months were identified. The primary outcome was mean change in CDAI (ΔCDAI) from baseline to 12 months. Secondary outcomes at 12 months included achievement of low disease activity (LDA; CDAI ≤10 in patients with moderate/high disease activity at initiation) and remission (CDAI ≤2.8 in patients with low, moderate or high disease activity at initiation). Linear and logistic regression analyses were performed to examine the relationship between disease duration and response to abatacept. There were 281 biologic-naïve patients with RA initiating abatacept (disease duration 0–2 years, n = 107; 3–5 years, n = 45; 6–10 years, n = 50; >10 years, n = 79). Increased disease duration was associated with older age (p = 0.047), and the median number of prior conventional disease-modifying antirheumatic drugs used was lowest in the 0- to 2-year duration group (p < 0.001). Mean ΔCDAI (SE) ranged from ?10.22 (1.19) for 0–2 years to ?4.63 (1.38) for >10 years. In adjusted analyses, shorter disease duration was significantly associated with greater mean ΔCDAI (p = 0.015) and greater likelihood of achieving LDA (p = 0.048). In biologic-naïve patients with RA initiating abatacept, earlier disease (shorter disease duration) was associated with greater ΔCDAI and likelihood of achieving LDA.     

Anxiolytic effects and neuroanatomical targets of estrogen receptor-β (ERβ) activation by a selective ERβ agonist in female mice

The dichotomous anxiogenic and anxiolytic properties of estrogens have been reported to be mediated by two distinct neural estrogen receptors (ER), ERα and ERβ, respectively. Using a combination of pharmacological and genetic approaches, we confirmed that the anxiolytic actions of estradiol are mediated by ERβ and extended and these observations to demonstrate the neuroanatomical targets involved in ERβ activation in these behavioral responses. We examined the effects of the biologically active S-enantiomer of diarylpropionitrile (S-DPN) on anxiety-related behavioral measures, the corresponding stress hormonal response to hypothalamo-pituitary-adrenal axis reactivity, and potential sites of neuronal activation in mutant female mice carrying a null mutation for ERβ gene (βERKO). S-DPN administration significantly reduced anxiety-like behaviors in the open field, light-dark exploration, and the elevated plus maze (EPM) in ovariectomized wild-type (WT) mice, but not in their βERKO littermates. Stress-induced corticosterone (CORT) and ACTH were also attenuated by S-DPN in the WT mice but not in the βERKO mice. Using c-fos induction after elevated plus maze, as a marker of stress-induced neuronal activation, we identified the anterodorsal medial amygdala and bed nucleus of the stria terminalis as the neuronal targets of S-DPN action. Both areas showed elevated c-fos mRNA expression with S-DPN treatment in the WT but not βERKO females. These studies provide compelling evidence for anxiolytic effects mediated by ERβ, and its neuroanatomical targets, that send or receive projections to/from the paraventricular nucleus, providing potential indirect mode of action for the control of hypothalamo-pituitary-adrenal axis function and behaviors.     

The significance of the nuclear farnesoid X receptor (FXR) in β cell function

Bile acids (BAs) are important signaling molecules that are involved in the regulation of their own metabolism, lipid metabolism, energy expenditure and glucose homeostasis. The nuclear farnesoid X receptor (FXR) and the G-protein-coupled TGR-5 are the most prominent BA receptors. FXR is highly expressed in liver and activation of liver FXR profoundly affects glucose homeostasis. Strikingly, the effect of FXR activation on glucose metabolism seems to depend on the nutritional status of the organism, i.e., slimness or obesity. Recently, it became evident that FXR is present in pancreatic β cells and that activation of β cell FXR contributes to the regulation of glucose homeostasis. Interestingly, FXR activation increases glucose-induced insulin secretion by non-genomic effects on stimulus-secretion coupling. The first chapter of this review shortly introduces the role of liver FXR in glucose metabolism, the second part focuses on the impact of FXR in lean and obese animals, and the third chapter highlights the significance of FXR in β cells.     

TGFβ is required for the formation of capillary-like structures in three-dimensional cocultures of 10T1/2 and endothelial cells

New vessels form de novo (vasculogenesis) or from pre-existing vessels (angiogenesis) in a process that involves the interaction of endothelial cells (EC) and pericytes/smooth muscle cells (SMC). One basic component of this interaction is the endothelial-induced recruitment, proliferation and subsequent differentiation of pericytes and SMC. We have previously demonstrated that TGFβ induces the differentiation of C3H/10T1/2 (10T1/2) mesenchymal cells toward a SMC/pericyte lineage. The current study tests the hypothesis that TGFβ not only induces SMC differentiation but stabilizes capillary-like structures in a three-dimensional (3D) model of in vitro angiogenesis. 10T1/2 and EC in Matrigel™ were used to establish cocultures that form cord structures that are reminiscent of new capillaries in vivo. Cord formation is initiated within 2–3 h after plating and continues through 18 h after plating. In longer cocultures the cord structures disassemble and form aggregates. 10T1/2 expression of proteins associated with the SMC/pericyte lineage, such as smooth muscle α-actin (SMA) and NG2 proteoglycan, are upregulated in these 3D cocultures. Application of neutralizing reagents specific for TGFβ blocks cord formation and inhibits expression of SMA and NG2 in the 10T1/2 cells. We conclude that TGFβ mediates 10T1/2 differentiation to SMC/pericytes in the 3D cocultures and that association with differentiated mural cells is required for formation of capillary-like structures in Matrigel™. This revised version was published online in June 2006 with corrections to the Cover Date.     

Conditional transgenic expression of TIR-domain-containing adaptor-inducing interferon-β (TRIF) in the adult mouse heart is protective in acute viral myocarditis

TIR-domain-containing adaptor-inducing interferon-β (TRIF) plays a major role in Toll-like receptor 3 (TLR3) mediated signaling. Mice deficient in TLR3 and TRIF have been shown to be highly susceptible to enterovirus-induced myocardial injury. These mice have decreased production of antiviral cytokines and increased viral replication in the heart. Therefore, we hypothesized that conditional overexpression of TRIF would change cardiac myocyte susceptibility to virus infection by augmenting the antiviral response. We generated double-transgenic MHC-tTA/MHC^tetO-TRIF mice (DT), with conditional cardiac-specific overexpression of TRIF. Naive DT mice had increased cardiac expression of antiviral cytokines and increased cellular infiltration but no alterations in cardiac function. DT mice were less susceptible to encephalomyocarditis virus (EMCV) infection and had a significantly lower viral load in the heart when compared to littermate (LM) and MHC^tetO-TRIF (ST) mice. Histopathological examination showed that the severity of myocarditis was also attenuated in DT mice. Furthermore, the decreased virus titers in the DT mouse hearts led to less cardiac damage and better cardiac function when compared to LM and ST mice. Administration of doxycycline to DT mice suppressed the protective effects of TRIF overexpression in the heart. The findings of the present study establish the importance of cardiac-specific TRIF-mediated signaling in the heart in acute viral myocarditis and identify potentially important targets for diagnostic and therapeutic strategies.     

Modulation of ERα transcriptional activity by the orphan nuclear receptor ERRβ and evidence for differential effects of long- and short-form splice variants

Oestrogen receptor related proteins (ERRs) affect target gene expression without binding oestradiol. We investigated the functional activity of two splice variant isoforms of ERRβ (ERRβS [short], ERRβL [long]) expressed in human endometrium, where they are coexpressed with the oestrogen receptor alpha (ERα). Over-expression of ERRβL enhanced ERα-dependent ligand-induced activation of an ERE-luciferase reporter construct, altered the induction of c-myc mRNA and increased proliferation of Ishikawa cells whereas ERRβS was found to reduce these endpoints.     

Expression of receptor activator of NF-κB ligand (RANKL) mRNA in human multiple myeloma cells

Purpose Increased bone resorption is a hallmark of multiple myeloma and a result of excessive osteoclast activation. Recently, the receptor activator of NF-B ligand (RANKL) was found to be the critical factor for osteoclastogenesis. Studies showed that myeloma cells induce RANKL expression in bone marrow stromal cells, but it remained a controversy whether myeloma cells directly express RANKL.Methods Therefore, we analyzed the expression of RANKL mRNA in freshly isolated CD138 positive plasma cells from patients with multiple myeloma and osteolytic bone lesions, using three different primer pairs against human RANKL.Results RANKL mRNA could be detected in bone marrow plasma cells from myeloma patients with osteolytic myeloma bone disease.Conclusions These findings show that myeloma cells directly express RANKL and indicate that specific blockade of RANKL may be an effective treatment for myeloma bone disease.     

The ERβ ligand 5α-androstane, 3β,17β-diol (3β-diol) regulates hypothalamic oxytocin (Oxt) gene expression

The endocrine component of the stress response is regulated by glucocorticoids and sex steroids. Testosterone down-regulates hypothalamic-pituitary-adrenal (HPA) axis activity; however, the mechanisms by which it does so are poorly understood. A candidate testosterone target is the oxytocin gene (Oxt), given that it too inhibits HPA activity. Within the paraventricular nucleus of the hypothalamus, oxytocinergic neurons involved in regulating the stress response do not express androgen receptors but do express estrogen receptor-β (ERβ), which binds the dihydrotestosterone metabolite 3β,17β-diol (3β-diol). Testosterone regulation of the HPA axis thus appears to involve the conversion to the ERβ-selective ligand 5α-androstane, 3β-diol. To study mechanisms by which 3β-diol could regulate Oxt expression, we used a hypothalamic neuronal cell line derived from embryonic mice that expresses Oxt constitutively and compared 3β-diol with estradiol (E2) effects. E2 and 3β-diol elicited a phasic response in Oxt mRNA levels. In the presence of either ligand, Oxt mRNA levels were increased for at least 60 min and returned to baseline by 2 h. ERβ occupancy preceded an increase in Oxt mRNA levels in the presence of 3β-diol but not E2. In tandem with ERβ occupancy, 3β-diol increased occupancy of the Oxt promoter by cAMP response element-binding protein and steroid receptor coactivator-1 at 30 min. At the same time, 3β-diol led to the increased acetylation of histone H4 but not H3. Taken together, the data suggest that in the presence of 3β-diol, ERβ associates with cAMP response element-binding protein and steroid receptor coactivator-1 to form a functional complex that drives Oxt gene expression.     

Downregulation of matrix and β-PDGF receptor gene expression by anti-TGFβ antibody in rat hepatic stellate cells during experimental liver injury

Excess matrix in hepatic fibrosis results from both fibrogenic stimulation of stellate cells by TGFβ1 and cell proliferation due to induction of β-platelet derived growth factor receptor (β-PDGFR). In this paper, treatment of culture-activated rat stellate cells with anti-TGFβ inhibited collagen and fibronectin mRNA expression by 82 and 58%, respectively, versus control cells. In vivo, anti-TGFβ inhibited collagen I gene expression by 86% in stellate cells isolated from rats treated with CC14 compared with control antibody. In contrast to stellate cells, anti-TGFβ had no effect on collagen I gene expression in isolated sinusoidal endothelial cells. Anti-TGFβ administered in vivo to rats with liver injury also reduced expression of stellate cell β-PDGFR mRNA to that of control animals. Anti-TGFβ antibody had no effect on the histologic appearance of the tissue. These data support a role for TGFβ in stellate cell matrix expression and provide evidence for transmodulation of PDGF receptor by TGFβ in vivo. However, inhibition of TGFβ alone may not be adequate to attenuate severe hepatic injury and fibrosis.     

Chemokine (C-C) motif ligand 20 is regulated by PGF2α-F-prostanoid receptor signalling in endometrial adenocarcinoma and promotes cell proliferation

Prostaglandin F_2α (PGF_2α) is an inflammatory mediator which signals through a G-protein coupled receptor, the F-prostanoid (FP) receptor. We have previously shown elevated FP receptor expression in endometrial adenocarcinoma, a common gynaecological malignancy in Western countries. In this study, the expression of the chemokine CC motif Ligand 20 (CCL20) was determined to be regulated by PGF_2α-FP receptor signalling in endometrial adenocarcinoma explants and cell line, and expression of CCL20 and its receptor CCR6 was elevated in endometrial adenocarcinoma compared to non-malignant endometrium. Both CCL20 and CCR6 were localised to neoplastic endometrial epithelial cells. The induction of CCL20 expression by PGF_2α-FP signalling in an endometrial adenocarcinoma cell line stably expressing the FP receptor (FPS cells) was found to be dependent on the intracellular signalling of Gq, EGFR, ERK, calcineurin and nuclear factor of activated T-cells (NFAT) proteins. The treatment of FPS cells with recombinant CCL20 caused a significant increase in proliferation. Therefore these data demonstrate a role for the FP receptor in regulation of the chemokine CCL20, which can mediate proliferation of endometrial adenocarcinoma epithelial cells.