Sex steroid receptor expression and localization in benign prostatic hyperplasia varies with tissue compartment

Androgens and estrogens, acting via their respective receptors, are important in benign prostatic hyperplasia (BPH). The goals of this study were to quantitatively characterize the tissue distribution and staining intensity of androgen receptor (AR) and estrogen receptor-alpha (ERα), and assess cells expressing both AR and ERα, in human BPH compared to normal prostate. A tissue microarray composed of normal prostate and BPH tissue was used and multiplexed immunohistochemistry was performed to detect AR and ERα. We used a multispectral imaging platform for automated scanning, tissue and cell segmentation and marker quantification. BPH specimens had an increased number of epithelial and stromal cells and increased percentage of epithelium. In both stroma and epithelium, the mean nuclear area was decreased in BPH relative to normal prostate. AR expression and staining intensity in epithelial and stromal cells was significantly increased in BPH compared to normal prostate. ERα expression was increased in BPH epithelium. However, stromal ERα expression and staining intensity was decreased in BPH compared to normal prostate. Double positive (AR and ERα) epithelial cells were more prevalent in BPH, and fewer double negative (AR and ERα) stromal and epithelial negative cells were observed in BPH. These data underscore the importance of tissue layer localization and expression of steroid hormone receptors in the prostate. Understanding the tissue-specific hormone action of androgens and estrogens will lead to a better understanding of mechanisms of pathogenesis in the prostate and may lead to better treatment for BPH.     

Social dominance regulates androgen and estrogen receptor gene expression

In Astatotilapia burtoni, dominant males have higher levels of sex steroid hormones than subordinate males. Because of the complex regulatory interactions between steroid hormones and receptors, we asked whether dominance is also associated with variation in sex steroid receptor gene expression. Using quantitative PCR, we compared the expression of specific subtypes of androgen (AR) and estrogen (ER) receptor genes between dominant and subordinated males in 3 divisions of the brain, the pituitary, and the testes. We measured mRNA levels of AR-alpha, AR-beta, ER-alpha, ER-betaa, and ER-betab, gonadotropin-releasing hormone 1 (GnRH1), and GnRH receptor 1 (GnRH-R1) relative to 18S rRNA. In the anterior part of the brain, we found that dominant males had higher mRNA expression of AR-alpha, AR-beta, ER-betaa, and ER-betab, but not ER-alpha, compared to subordinate males. This effect of dominance was reflected in a positive correlation between testes size and AR-alpha, AR-beta, ER-betaa, and ER-betab in the anterior brain. In addition, mRNA levels of all ARs and ERs in the anterior brain were positively correlated with mRNA level of GnRH1. In the middle and posterior portions of the brain, as well as the testes, steroid receptor mRNA levels were similar among dominants and subordinates. In the pituitary, ER-alpha mRNA level was positively correlated with testes size and AR-alpha mRNA was positively correlated with GnRH-R1 mRNA level. These data suggest that dominant male brains could be more sensitive to sex steroids, which may contribute to the increased complexity of the behavioral repertoires of dominant males.     

Sexually dimorphic androgen and estrogen receptor mRNA expression in the brain of túngara frogs

Sex steroid hormones are potent regulators of behavior and they exert their effects through influences on sensory, motor, and motivational systems. To elucidate where androgens and estrogens can act to regulate sex-typical behaviors in the túngara frog (Physalaemus pustulosus), we quantified expression of the androgen receptor (AR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ) genes in the brains of male and females. To do so, we cloned túngara-specific sequences for AR, ERα, and ERβ, determined their distribution in the brain, and then quantified their expression in areas that are important in sexual communication. We found that AR, ERα, and ERβ were expressed in the pallium, limbic forebrain (preoptic area, hypothalamus, nucleus accumbens, amygdala, septum, striatum), parts of the thalamus, and the auditory midbrain (torus semicircularis). Males and females had a similar distribution of AR and ER expression, but expression levels differed in some brain regions. In the auditory midbrain, females had higher ERα and ERβ expression than males, whereas males had higher AR expression than females. In the forebrain, females had higher AR expression than males in the ventral hypothalamus and medial pallium (homolog to hippocampus), whereas males had higher ERα expression in the medial pallium. In the preoptic area, striatum, and septum, males and females had similar levels of AR and ER expression. Our results suggest that sex steroid hormones have sexually dimorphic effects on auditory processing, sexual motivation, and possibly memory and, therefore, have important implications for sexual communication in this system.     

Changes in androgen receptor, estrogen receptor alpha, and sexual behavior with aging and testosterone in male rats

Reproductive aging in males is characterized by a diminution in sexual behavior beginning in middle age. We investigated the relationships among testosterone, androgen receptor (AR) and estrogen receptor alpha (ERα) cell numbers in the hypothalamus, and their relationship to sexual performance in male rats. Young (3 months) and middle-aged (12 months) rats were given sexual behavior tests, then castrated and implanted with vehicle or testosterone capsules. Rats were tested again for sexual behavior. Numbers of AR and ERα immunoreactive cells were counted in the anteroventral periventricular nucleus and the medial preoptic nucleus, and serum hormones were measured. Middle-aged intact rats had significant impairments of all sexual behavior measures compared to young males. After castration and testosterone implantation, sexual behaviors in middle-aged males were largely comparable to those in the young males. In the hypothalamus, AR cell density was significantly (5-fold) higher, and ERα cell density significantly (6-fold) lower, in testosterone- than vehicle-treated males, with no age differences. Thus, restoration of serum testosterone to comparable levels in young and middle-aged rats resulted in similar preoptic AR and ERα cell density concomitant with a reinstatement of most behaviors. These data suggest that age-related differences in sexual behavior cannot be due to absolute levels of testosterone, and further, the middle-aged brain retains the capacity to respond to exogenous testosterone with changes in hypothalamic AR and ERα expression. Our finding that testosterone replacement in aging males has profound effects on hypothalamic receptors and behavior has potential medical implications for the treatment of age-related hypogonadism in men.     

Estradiol restores diabetes-induced reductions in sex steroid receptor expression and distribution in the vagina of db/db mouse model

Sex steroid hormones and receptors play an important role in maintaining vaginal physiology. Disruptions in steroid receptor signaling adversely impact vaginal function. Limited studies are available investigating the effects of diabetic complications on steroid receptor expression and distribution in the vagina. The goals of this study were to investigate type 2 diabetes-induced changes in expression, localization and distribution of estrogen (ER), progesterone (PR) and androgen receptors (AR) in the vagina and to determine if estradiol treatment ameliorates these changes. Eight-week-old female diabetic (db/db) mice (strain BKS.Cg-m+/+ Lepr^db/J) were divided into two subgroups: untreated diabetic and diabetic animals treated with pellets containing estradiol. Control normoglycemic littermates were subcutaneously implanted with pellets devoid of estradiol. At 16 weeks of age, animals were sacrificed, vaginal tissues excised and analyzed by Western blot and immunohistochemical methods. Diabetes produced marked reductions in protein expression of ER, PR, and AR. Diabetes also resulted in marked differences in the distribution, staining intensity and proportion of immunoreactive cells containing these steroid receptors in the epithelium, lamina propria and muscularis. Treatment of diabetic animals with estradiol restored receptor protein expression and distribution similar to those levels observed in control animals. This study demonstrates that type 2 diabetes markedly reduces steroid receptor protein expression and distribution in the vagina. Estradiol treatment of diabetic animals ameliorates these diabetes-induced changes.     

Epigenetic setting for long-term expression of estrogen receptor α and androgen receptor in cells

Epigenetic regulation of the nuclear estrogen and androgen receptors, ER and AR, constitutes the molecular basis for the long-lasting effects of sex steroids on gene expression in cells. The effects prevail at hundreds of gene loci in the proximity of estrogen- and androgen-responsive elements and many more such loci through intra- and even inter-chromosomal level regulation. Such a memory system should be active in a flexible manner during the early development of vertebrates, and later replaced to establish more stable marks on genomic DNA. In mammals, DNA methylation is utilized as a very stable mark for silencing of the ERα and AR isoform expression during cancer cell and normal brain development. The factors affecting the DNA methylation of the ERα and AR genes in cells include estrogen and androgen. Since testosterone induces brain masculinization through its aromatization to estradiol in a narrow time window of the perinatal stage in rodents, the autoregulation of estrogen receptors, especially the predominant form of ERα, at the level of DNA methylation to set up the “cell memory” affecting the sexually differentiated status of brain function has been attracting increasing attention. The alternative usage of the androgen-AR system for brain masculinization and estrogenic regulation of AR expression in some species imply that the DNA methylation pattern of the AR gene can be established by closely related but different systems for sex steroid-induced phenomena, including brain masculinization.     

Overexpression and Gender-specific Differences of SRC-3 (SRC-3/AIB1) Immunoreactivity in Human Non–Small Cell Lung Cancer: An In Vivo Study

Steroid receptor coactivator-3 (SRC-3) has been reported to be overexpressed in the development and progression of many tumor types. SRC-3 has been detected in several lung cancer cell lines, but its expression and clinical significance in non–small cell lung cancer (NSCLC) remain unclear. In this study, 48 NSCLC tissues were collected and tissue microarrays were performed. The expression of SRC-3 was examined using nickel-intensified IHC. The results showed that of these 48 cases, 18 (37.5%) exhibited high levels of SRC-3 immunoreactivity, 23 (47.9%) exhibited moderate levels of SRC-3 immunoreactivity, and 7 (14.6%) were negative; thus, the total frequency of SRC-3 overexpression was 85.4% (41/48). This SRC-3 overexpression frequency was similar to the overexpression frequency observed for squamous cell carcinoma and adenocarcinoma (82.1% vs 90%) and for metastasis and non-metastasis patients (84.6% vs 85.7%). Data analysis demonstrated a significantly higher overexpression frequency in male patients compared with that in female patients (88.6% vs 76.9%). However, female patients tended to have higher expression levels of SRC-3, as measured by immunoreactivity, than male patients. These results demonstrate a high frequency of SRC-3 overexpression in NSCLC with a gender difference, suggesting that there is a specific role for SRC-3 in the pathogenesis of NSCLC. (J Histochem Cytochem 58:1121–1127, 2010)     

Estrogen receptor signaling pathways in human non-small cell lung cancer

Lung cancer is the most common cause of cancer mortality in male and female patients in the US. The etiology of non-small cell lung cancer (NSCLC) is not fully defined, but new data suggest that estrogens and growth factors promote tumor progression. In this work, we confirm that estrogen receptors (ER), both ERalpha and ERbeta, occur in significant proportions of archival NSCLC specimens from the clinic, with receptor expression in tumor cell nuclei and in extranuclear sites. Further, ERalpha in tumor nuclei was present in activated forms as assessed by detection of ER phosphorylation at serines-118 and -167, residues commonly modulated by growth factor receptor as well as steroid signaling. In experiments using small interfering RNA (siRNA) constructs, we find that suppressing expression of either ERalpha or ERbeta elicits a significant reduction in NSCLC cell proliferation in vitro. Estrogen signaling in NSCLC cells may also include steroid receptor coactivators (SRC), as SRC-3 and MNAR/PELP1 are both expressed in several lung cell lines, and both EGF and estradiol elicit serine phosphorylation of SRC-3 in vitro. EGFR and ER also cooperate in promoting early activation of p42/p44 MAP kinase in NSCLC cells. To assess new strategies to block NSCLC growth, we used Faslodex alone and with erlotinib, an EGFR kinase inhibitor. The drug tandem elicited enhanced blockade of the growth of NSCLC xenografts in vivo, and antitumor activity exceeded that of either agent given alone. The potential for use of antiestrogens alone and with growth factor receptor antagonists is now being pursued further in clinical trials.     

Clinical implications of steroid receptor coactivator (SRC)-3 in uterine endometrial cancers

Estrogen is recognized as a significant modifier in the development, growth and invasion of uterine endometrial cancer. Steroid receptor coactivator-3 (SRC-3; AIB1, ACTR, RAC3, TRAM-1, and pCIP) is a member of the p160 family of coactivator for nuclear hormone receptors including estrogen receptor (ER). It is reported that SRC-3 is overexpressed in various cancers. However, SRC-3 expression manner in uterine endometrial cancer is not fully understood. In this study, we showed SRC-3 mRNA expression correlates with clinical stage, depth of myometrial invasion and dedifferentiation. The prognosis of the 25 patients with higher expression of SRC-3 mRNA in uterine endometrial cancers was extremely poor (36%), whereas the 24-month survival rate of the 15 patients with lower expression of SRC-3 mRNA was 96%. These data indicate that SRC-3 might be an important indicator of uterine endometrial cancer advancement and survival.     

兴国红鲤ER基因克隆表达及EE2暴露对肝中ER表达的影响

为评估环境内分泌干扰物对鱼类的影响,研究克隆了兴国红鲤雌激素受体（Estrogen receptor,ER）4种亚型ERα、ERβ、ERβ1、ERβ2的全长cDNA序列,氨基酸序列比对发现兴国红鲤ERs分别与3种鲤科鱼类相应亚型具有较高的同源性。实时荧光定量PCR（qRT-PCR）检测结果表明,4种ER亚型mRNA在雌雄成体组织中呈现差异表达,雌性个体中,肝、卵巢和肠中4种ERs的表达量均较高;在雄性个体中,ERα和ERβ主要在肝中表达,ERβ1、ERβ2分别在肠和精巢中的表达量最高。将150日龄的兴国红鲤幼鱼分别暴露在0.01、0.1和1 nmol/L的17α-乙炔基雌二醇（EE2）中4周,检测了雌性幼鱼肝中4种ER基因的表达变化情况。在EE2中暴露1-2周后,兴国红鲤雌性幼鱼肝中ERα基因的表达水平有极显著的提升;各浓度EE2能持续显著促进其肝中ERβ的表达;在1-2周内各浓度EE2对ERβ1表达有所抑制;第1周EE2能够抑制ERβ2基因mRNA的表达,并在0.01 nmol/L时抑制作用达到了显著的水平。上述研究结果表明,EE2暴露能诱导或抑制兴国红鲤雌性幼鱼肝中ER亚型的表达,相对于ERβ、ERβ1和ERβ2、ERα可作为EE2短期（1-2周）敏感性生物学标记。