Expression Of Sex Steroid Receptors Research Articles

1,25-dihydroxyvitamin D3 regulates expression of sex steroid receptors in human uterine fibroid cells.

Uterine fibroids (UFs) are the most common benign tumors in premenopausal women. In this study, we evaluated the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] for the treatment of UFs. To determine the role of 1,25(OH)2D3 on the expression of sex steroid receptors in human UF cells. Human UFs and their adjacent myometrium were analyzed for expression of estrogen receptor (ER)-α, progesterone receptor (PR)-A, and PR-B, as well as members of the steroid receptor coactivator (SRC) family. Immortalized human uterine fibroid (human uterine leiomyoma [HuLM]) cells were treated with 1,25(OH)2D3 and assayed for the expression and localization of the aforementioned receptors and SRCs using Western blot, immunohistochemistry, immunofluorescence, and immunoprecipitation assays. We discovered a correlation between reduced levels of vitamin D receptor (VDR) and increased levels of ER-α, PR-A, and PR-B in these tissues. We evaluated the effects of 1,25(OH)2D3 on the regulation of the aforementioned sex steroid receptors. We observed an inverse correlation between the up-regulated ER-α, PR-A, and PR-B and expression of VDR in UFs. Treatment with 1,25(OH)2D3 significantly decreased levels of ER-α, PR-A, and PR-B, as well as SRCs in HuLM cells (P < .05). In contrast, 1,25(OH)2D3 self-induced its own VDR, which resulted in an induction of VDR-retinoid X receptor-α complex in HuLM cells. Together, these results suggest that 1,25(OH)2D3 functions as an antagonist of sex steroid hormone receptors in HuLM cells. 1,25(OH)2D3 functions as a potent antiestrogenic/antiprogesteronic agent that may have utility as a novel therapeutic option for UF.

The role of Dicer1 in the male reproductive tract

Dicer1 is an RNase III enzyme necessary for microRNA (miRNA) biogenesis, as it cleaves pre-miRNAs into mature miRNAs. miRNAs are important regulators of gene expression. In recent years, several miRNA-independent roles of Dicer1 have been identified. They include the production of endogenous small interfering RNAs, detoxifying retrotransposon-derived transcripts, and binding to new targets; messenger RNAs and long noncoding RNAs. Further, in this review, the functional significance of Dicer1 in the male reproductive tract is discussed. Conditional Dicer1 knock-out mouse models have demonstrated a requisite role for Dicer in male fertility. Deletion of Dicer1 from somatic or germ cells in the testis cause spermatogenic problems rendering male mice infertile. The lack of Dicer1 in the proximal epididymis causes dedifferentiation of the epithelium, with unbalanced sex steroid receptor expression, defects in epithelial lipid homeostasis, and subsequent male infertility. In addition, Dicer1 ablation from the prostate leads to increased apoptosis of the differentiated luminal cells, followed by epithelial hypotrophy of the ventral prostate. However, further studies are needed to clarify which functions of Dicer1 are responsible for the observed phenotypes in the male reproductive tract.

Short-term administration of ulipristal acetate modulates endometrial sex steroid receptor expression and cell proliferation markers

Short-term administration of ulipristal acetate modulates endometrial sex steroid receptor expression and cell proliferation markers

Antiestrogenic effects of the fetal estrogen estetrol in women with estrogen-receptor positive early breast cancer.

Estetrol (E4) is a fetal estrogen with estrogenic effects on reproductive organs and bone in preclinical models and in postmenopausal women. However, E4 exerts antiestrogenic effects on breast cancer (BC) cell growth in vitro and in vivo. We have investigated the effect of 14 days preoperative treatment with 20mg E4 per day on tumor proliferation markers, sex steroid receptor expression and endocrine parameters in a prospective, randomized, placebo-controlled, preoperative window trial in 30 pre- and post-menopausal women with estrogen-receptor positive early BC. E4 had a significant pro-apoptotic effect on tumor tissue, whereas Ki67 expression remained unchanged in both pre- and post-menopausal women. E4 increased sex-hormone-binding globulin significantly thereby reducing the concentrations of bioavailable estradiol. Follicle-stimulating hormone levels decreased in postmenopausal women only and luteinizing hormone levels remained unchanged. Systemic insulin growth factor-1 levels decreased significantly. Intratumoral epithelial ERα expression decreased significantly and a trend was found towards an increased expression of ERβ. This clinical data support the preclinical findings that E4 has antiestrogenic effects on BC cells, whereas earlier studies have shown that E4 has estrogenic effects on reproductive tissues and bone. Further clinical studies seem acceptable and are needed to confirm the safety and efficacy of E4 for the breast in hormone replacement therapy, including hormone replacement therapy in women who have or have had BC, especially in those BC patients treated with aromatase inhibitors and suffering from serious complaints due to estrogen deficiency.

Current Literature Review

Editorial Comment: Lower urinary tract symptoms (LUTS) and benign prostatic hyperplasia (BPH) are associated with obesity, hypogonadism, and metabolic syndrome (MetS). Clinical studies suggest that there is an inverse relationship between testosterone serum levels and LUTS/BPH. The clinical findings are supported by preclinical animal studies. This paper describes the use of a rabbit model of MetS, induced by feeding a high-fat diet for 12 weeks that has been previously characterized. In this model, in addition to the metabolic changes that characterize MetS, inflammatory, hypoxia, and tissue remodeling of the prostate and bladder was reported that were related to low testosterone and high estrogen levels. The present study describes the role of estrogen in this model by administering tamoxifen to rabbits with MetS. Tamoxifen was chosen because of its dual action as an estrogen receptor antagonist and G protein-coupled estrogen receptor (GPER) agonist. Tamoxifen had a differential effect on the MetS-induced changes in bladder and prostatic inflammatory mediators. In the bladder, tamoxifen reduced the MetS-induced changes, whereas it had little effect in the prostate. This paper provides evidence that this differential effect on the bladder and prostate occurs due to the differential expression of sex steroid receptors (particularly ER alpha and progesterone receptors/GPERs). This research may have clinical relevance relating to future management of treatment therapies using compounds that specifically target subsets of estrogen receptors.

Angiotensin II modulates sex steroid receptors and their metabolizing enzymes in rat cardiac fibroblast (701.10)

Sex steroids influence angiotensin II (AngII)‐induced cardiac remodeling; however, the importance of local sex steroid metabolism in this process is not known. We previously demonstrated that AngII increased aromatase levels, the enzyme that converts testosterone (T) to 17β‐estradiol, in cultured coronary vascular smooth muscle cells. In the present study we investigated the impact of AngII on sex steroid receptor and enzyme expression in primary rat cardiac fibroblasts. Fibroblasts were isolated from adult male rats and treated at P1 in 2% charcoal‐stripped FBS with AngII or vehicle (18h), followed by T (6h) in the presence or absence of anastrozole (aromatase inhibitor; 6.5h). Cardiac fibroblasts expressed receptors ERα, ERβ, and AR, as well as the enzymes aromatase and 5α‐reductase. AngII significantly reduced mRNA expression of ERβ. 5α‐reductase, AR, and ERβ levels increased when anastrazole was administered with T. This is the first demonstration that cardiac fibroblasts express the enzymes and receptors necessary for local sex steroid metabolism and action. Enzymes and receptor levels are differentially impacted by AngII. Additionally, aromatase inhibition in the presence of T alters steroid receptor and 5α‐reductase (testosterone metabolizing enzyme) levels. Given the major role of the fibroblast in pathogenic cardiac remodeling, the relative balance of T to estrogen in these cells may play an important role in the development of AngII‐mediated fibrosis.Grant Funding Source: Supported by American Heart Association

Nonobese diabetic/severe combined immunodeficient murine xenograft model for human uterine leiomyoma

To establish a novel xenograft model using a severely immunocompromised host that is more convenient for uterine leiomyoma research compared with a pre-existing model using nonobese diabetic/severe combined immunodeficient (NOD/SCID) IL-2Rγ-null mice. Experimental study. University and an attached animal facility. NOD/SCID, SCID, BALB/c nude, and NOD/SCID IL-2Rγ-null mice. Xenografts consisting of primary cultured leiomyoma and myometrial cells in the subrenal and subcutaneous (SC) spaces in ovariectomized mice, followed by sex steroids (estrogen and P) administration. Viability, volume, histology, and sex steroid receptor expression of xenografts in response to sex steroid administration, to evaluate feasibility of the model; and messenger RNA expression levels of 12 genes representative of leiomyoma in the xenografts, to characterize the model. Leiomyoma xenografts increased in volume at the highest frequency (55.1%) in response to sex steroids in NOD/SCID mice. Xenografts reproduced the histology and maintained expression of sex steroids receptors and representative genes of the original tissues. Subrenal xenografts were significantly larger than the SC xenografts, whereas those consisting of myometrial cells never increased. The modified NOD/SCID murine subrenal leiomyoma xenograft model reproduced most characteristics of the original leiomyoma tissue. Our model provides a more convenient research tool to investigate the pathogenesis of uterine leiomyoma.

Development and evaluation of animal models for sex steroid deficient dry eye

Purpose: The present study was conducted to develop animal models to mimic postmenopausal/androgen deficiency dry eye and to evaluate the expression of sex steroid receptors (NR3A1, NR3A2 and NR3C4) in the ocular tissues of the developed models. Methods: The study was conducted in healthy Wistar rats of either sex weighing 180–250g. Bilateral ovariectomy was performed in female rats and oral finasteride (dose of 1.16mg/kg/day) challenge was given to both male and female rats. Along with time tear film stability was assessed by using cotton thread method and tear breakup time (TBUT). Dew point calculation was done using August–Roche–Magnus approximation during the tear assessments to correlate environmental factors affecting the tear function tests. At the end, animals were sacrificed and ocular tissues (lacrimal gland and cornea) were subjected for the quantification of the expression of NR3A1 (ER-α), NR3A2 (ER-β) and androgen (NR3C4) receptors. Results: The impact of ovariectomy caused a significant tear film deficiency from the 20th day onwards in all female rats. The ten day finasteride administration also showed a significant tear film deficiency in both male and female rats. However, subjecting 60days post ovariectomy rats to finasteride challenge did not show any further decrease in tear flow. Gene expression analysis also revealed a significant downregulation of sex steroid receptors in ocular tissues after ovariectomy and finasteride challenge. Discussion and conclusion: From this study, it has been concluded that ovariectomized and finasteride treated antiandrogenic models produced a significant tear deficiency in the rats which can be explored for pharmacological screening of topical agents and understanding the disease process in postmenopausal and androgen deficiency dry eye disorders.

Acute exposure to ultraviolet‐B radiation modulates sex steroid hormones and receptor expression in the skin and may contribute to the sex bias of melanoma in a fish model

Using the Xiphophorus fish melanoma model, we show a strong male bias for sunlight-induced malignant melanoma, consistent with that seen in the human population. To examine underlying factors, we exposed adult X. couchianus fish to a single, sublethal dose of UVB and measured circulating sex steroid hormones and expression of associated hormone receptor genes over a 24-h period. We found that a single exposure had profound effects on circulating levels of steroid hormones with significant decreases for all free sex steroids at 6 and 24 h and increases in conjugated 2-estradiol and 11-ketotestosterone at 6 and 24 h, respectively. Whereas ARα expression increased in male and female skin, neither ARβ nor either of the ERs showed significant responses to UVB in either sex. The rapid response of male androgens and their receptors in the skin after UVB irradiation implicates hormones in the male bias of skin cancer and suggests that the photoendocrine response immediately after UV exposure may be relevant to melanomagenesis.

A study to correlate histopathology, biochemical marker and immunohistochemical expression of sex-steroid receptors in prostatic growth.

Prostate gland is a fibromusculoglandular structure situated at the neck of urinary bladder. So, enlargement or growth of prostate due to nodular hyperplasia (NHP) or prostatic intraepithelial neoplasia (PIN) or adenocarcinoma may give rise to bladder outlet obstruction. Malignant growth i.e., PIN or adenocarcinoma cases are associated with increased blood level of prostate-specific antigen (PSA) and increased expression of different sex-steroid receptors because the growth is dependent on the interactions of androgen, progesterone and estrogen. The aim of our study is to correlate the histopathology, PSA levels and expression of different sex-steroid receptors by immunohistochemistry in different prostatic growth lesions. Among the total 50 cases received, inclusive of transurethral resection of prostate (TURP), transrectal ultrasound-guided biopsy and radical prostatectomy, 34 cases were diagnosed as NHP, 4 cases as PIN and 12 cases as adenocarcinoma histopathologically. Serum PSA values above 10 ng/ml were seen in 2 cases of PIN and 11 cases of adenocarcinoma and none of NHP. Estrogen receptor (ER) () expressions were negative in all cases. Progesterone receptor (PR) expressions were strongly positive in 35% cases of both NHP and adenocarcinoma, whereas androgen receptor (AR) expressions were strong among all cases of adenocarcinoma and only in four cases of NHP. By observing these findings it can be suggested that antiandrogen and antiprogesterone therapy simultaneously will do better than antiandrogen alone in treating prostatic growth lesions.

An immunohistochemical analysis of sex-steroid receptors, tumor suppressor gene p53 and Ki-67 in the normal and neoplastic uterine cervix squamous epithelium.

Malignant transformation of sex-steroid dependent tissues is associated with the loss of expression of sex steroid receptors as well as of the tumor suppression gene p53. The aim of this study is to evaluate the expression of sex-steroid receptors, p53 and Ki-67 in specimens from pre-malignant and malignant cervical epithelial lesions throughout the menstrual cycle. Immunohistochemical staining was performed on formalin fixed, paraffin embedded tissue sections of normal squamous cervical epithelium, cervical intraepithelial neoplasia and invasive squamous cervical carcinoma, specimens utilizing antibodies against estrogen receptors, progesterone receptors, p53 protein and Ki-67 antigen. In the samples taken from the normal cervical tissue, basal cells were usually estrogen receptor-positive, progesterone receptor-negative, p53-negative and Ki-67-negative throughout the menstrual cycle. In contrast, para-basal cells were estrogen receptor-positive and progesterone receptor-negative in the follicular phase, but estrogen receptor-negative and progesterone receptor-positive and Ki-67 positive in the luteal phase. In cervical precancerous and cancer tissue samples (cervical intraepithelial neoplasia and squamous cervical carcinoma), the expression of estrogen receptors decreased. 31.15% of cervical intraepithelial neoplasia and 11.5% of squamous cervical carcinoma were positive for estrogen receptors. However, the expression of progesterone receptors increased. 29.5% of cervical intraepithelial neoplasia and 49.2% of squamous cervical carcinoma were positive for progesterone receptors. Positive staining for p53 was observed in 15 (24.59%) cases of cervical intraepithelial neoplasia and in 39 (64%) of squamous cervical carcinoma. The expression Ki-67 index in squamous cervical carcinoma cases (47.60%) was significantly higher than of cervical intraepithelial neoplasia cases (30.2%) (p = 0.041). The findings of this study suggest that tumor cervical cells evade normal growth control by sex steroid hormones while synchronously abnormal regulatory mechanisms acquire control of the cell cycle.

Undernutrition and laterality of the corpus luteum affects gene expression in oviduct and uterus of pregnant ewes

The effect of undernutrition on gene expression of progesterone and oestrogen receptors (PGR and ESR1), and insulin-like growth factors 1 and 2 (IGF1 and IGF2) in the uterus and oviducts of ewes on day 5 after oestrus was investigated. The effect of the side of the uterus/oviduct regarding the ovary bearing a corpus luteum (CL) (ipsi vs. contralateral) was also analyzed. Fourteen oestrous synchronized ewes were fed either 1.5 (C, n=7) or 0.5 (L, n=7) times their maintenance requirements from the onset of the hormonal treatment (day -14), till slaughter on day 5 post-oestrus. Oviducts and samples of uterus were collected and their gene expression studied by real time RT-PCR. Undernourished ewes had greater PGR expression in the oviduct than control ewes, but lower expression of IGF1 in uterus and of IGF2 in oviducts. The ipsilateral oviduct presented lower expression of PGR, ESR1 and IGF2 mRNA than the contralateral one, but this did not occur in the uterus. In conclusion, there is an effect of undernutrition on gene expression that is transcript and organ dependent (uterus/oviduct). This work reports for the first time that growth factors and sex steroid receptor expression on day 5 after oestrus vary depending on the side of the CL-bearing ovary and the region of the reproductive tract.

Sex differences and similarities in the neuroendocrine regulation of social behavior in an African cichlid fish

An individual's position in a social hierarchy profoundly affects behavior and physiology through interactions with community members, yet little is known about how the brain contributes to status differences between and within the social states or sexes. We aimed to determine sex-specific attributes of social status by comparing circulating sex steroid hormones and neural gene expression of sex steroid receptors in dominant and subordinate male and female Astatotilapia burtoni, a highly social African cichlid fish. We found that testosterone and 17β-estradiol levels are higher in males regardless of status and dominant individuals regardless of sex. Progesterone was found to be higher in dominant individuals regardless of sex. Based on pharmacological manipulations in males and females, progesterone appears to be a common mechanism for promoting courtship in dominant individuals. We also examined expression of androgen receptors, estrogen receptor α, and the progesterone receptor in five brain regions that are important for social behavior. Most of the differences in brain sex steroid receptor expression were due to sex rather than status. Our results suggest that the parvocellular preoptic area is a core region for mediating sex differences through androgen and estrogen receptor expression, whereas the progesterone receptor may mediate sex and status behaviors in the putative homologs of the nucleus accumbens and ventromedial hypothalamus. Overall our results suggest sex differences and similarities in the regulation of social dominance by gonadal hormones and their receptors in the brain.

Melatonin and ethanol intake exert opposite effects on circulating estradiol and progesterone and differentially regulate sex steroid receptors in the ovaries, oviducts, and uteri of adult rats

Chronic ethanol intake is associated with sex hormone disturbances, and it is well known that melatonin plays a key role in regulating several reproductive processes. We report the effects of ethanol intake and melatonin treatment (at doses of 100μg/100gBW/day) on sex hormones and steroid receptors in the ovaries, oviducts and uteri of ethanol-preferring rats. After 150 days of treatment, animals were euthanized, and tissue samples were harvested to evaluate androgen, estrogen, progesterone and melatonin receptor subunits (AR, ER-α and ER-β, PRA, PRB and MT1R, respectively). Melatonin decreased estradiol (E2) and increased progesterone (P4) and 6-sulfatoxymelatonin (6-STM), while an ethanol–melatonin combination reduced both P4 and E2. Ovarian AR was not influenced by either treatment, and oviduct AR was reduced after ethanol–melatonin combination. Oviduct ER-α, ER-β and uterine ER-β were down-regulated by either ethanol or melatonin. Conversely, ovarian PRA and PRB were positively regulated by ethanol and ethanol–melatonin combination, whereas PRA was down-regulated in the uterus and oviduct after ethanol consumption. MT1R was increased in ovaries and uteri of melatonin-treated rats. Ethanol and melatonin exert opposite effects on E2 and P4, and they differentially regulate the expression of sex steroid receptors in female reproductive tissues.

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.

Expression of Steroids Sex Hormone Receptors in the External Genitalia of She‐Camels (Camelus dromedarius)

To explore the role of hormonal fluctuations on external genitalia function in female camels, the localization and distribution of steroid sex hormone receptors were examined by immunohistochemistry in vestibule, vulva, and clitoris acquired during breeding and non‐breeding seasons. Animals (n=6 per season) were adults (5 – 10 years) with no history of reproductive tract or systemic disease. Estrogen receptor‐a (ERa) was expressed throughout all mucosal and submucosal tissues in all three regions. Progesterone receptor (PR) was expressed throughout the vestibule and along the mucosal surface of the vulva, but it could not be seen in vulvar skin and the clitoris. Androgen receptor (AR) was expressed throughout the vestibule, clitoris and vulvar mucosa. Epithelial expression of ERa and PR was higher during the breeding season, but AR was higher during the non‐breeding season. These data suggest that significant seasonal changes (p&lt;0.05) in sex steroid receptor expression may play a role regulating external genitalia function in female camels.This paper was supported by grant from the government of Egypt (MAE and EME).

Three cases of intraocular mesectodermal leiomyoma expressing progesterone and androgen receptors

A prospective study identified three patients between 2004 and 2010 with mesectodermal leiomyoma. The study was conducted to analyse the presence or absence of sex steroid hormone receptors in mesectodermal leiomyomas. The clinical features were collated. All three patients had operative procedures to either remove or sample the mesectodermal leiomyomas. The tissue was fixed in formalin and exposed to conventional histological processing. Immunohistochemistry using antibodies to androgen (AR), oestrogen (ER), and progesterone (PR) receptors was performed, followed by stain scoring to assess for expression status. All three cases were confirmed by histology to be examples of mesectodermal leiomyomas. All three expressed sex steroid hormone receptors. One case expressed both PR and AR, one case PR only and another case AR only. None of the cases expressed ER receptors. All three cases displayed some sex steroid hormone receptor expression. This is supportive evidence that sex steroid hormones may have a role in the pathogenesis of this tumour and suggest that it may be amenable to hormonal manipulation therapy, in a manner similar to conventional uterine leiomyomas.

Signal transduction pathway analysis in desmoid‐type fibromatosis: Transforming growth factor–β, COX2 and sex steroid receptors

Despite reports of sex steroid receptor and COX2 expression in desmoid-type fibromatosis, responses to single agent therapy with anti-estrogens and non-steroidal anti-inflammatory drugs are unpredictable. Perhaps combination pharmacotherapy might be more effective in desmoid tumors that co-express these targets. Clearly, further understanding of the signaling pathways deregulated in desmoid tumors is essential for the development of targeted molecular therapy. Transforming growth factor-β (TGFβ) and bone morphogenetic proteins (BMP) are important regulators of fibroblast proliferation and matrix deposition, but little is known about the TGFβ superfamily in fibromatosis. A tissue microarray representing 27 desmoid tumors was constructed; 14 samples of healing scar and six samples of normal fibrous tissue were included for comparison. Expression of selected receptors and activated downstream transcription factors of TGFβ family signaling pathways, β-catenin, sex steroid hormone receptors and COX2 were assessed using immunohistochemistry; patterns of co-expression were explored via correlational statistical analyses. In addition to β-catenin, immunoreactivity for phosphorylated SMAD2/3 (indicative of active TGFβ signaling) and COX2 was significantly increased in desmoid tumors compared with healing scar and quiescent fibrous tissue. Low levels of phosphorylated SMAD1/5/8 were detected in only a minority of cases. Transforming growth factor-β receptor type 1 and androgen receptor were expressed in both desmoid tumors and scar, but not in fibrous tissue. Estrogen receptor-β was present in all cases studied. Transforming growth factor-β signaling appears to be activated in desmoid-type fibromatosis and phosphorylated SMAD2/3 and COX2 immunoreactivity might be of diagnostic utility in these tumors. Given the frequency of androgen receptor, estrogen receptor-β and COX2 co-expression in desmoid tumors, further assessment of the efficacy of combination pharmacotherapy using hormonal agonists/antagonists together with COX2 inhibitors should be considered.

The cellular and molecular mechanisms by which insulin influences breast cancer risk and progression

Epidemiological studies have related hyperinsulinemia and type 2 diabetes to an increased breast cancer risk, an aggressive and metastatic phenotype, and a poor prognosis. Furthermore, diabetic retinopathy arises from pathological angiogenesis, which is also essential for breast cancer growth and metastasis. Insulin stimulates the proliferation of some human breast cancer cell lines in vitro by mechanisms that use both the phosphatidylinositol-3 kinase and the mitogen-activated protein kinase/Akt signaling pathways; it is also a cell survival (anti-apoptotic) agent and enhances tumor cell migration and invasive capacity. Hyperinsulinemia affects breast cancer cells via the endocrine system, but experimental studies suggest the importance of paracrine mechanisms operating by the effects of insulin on the secretion of adipokines from tumor-associated adipose tissue. In such a system, one adipokine, leptin, has stimulatory paracrine effects on breast cancer cell proliferation and survival, while a second, adiponectin, is inhibitory. Leptin, vascular endothelial growth factor, another insulin-regulated adipokine, and insulin itself also stimulate angiogenesis. Insulin has complex interactions with estrogens: it induces adipose stromal cell aromatase and tumor cell sex steroid hormone receptor expression and suppresses sex hormone-binding globulin, which may enhance estrogen synthesis and bioactivity with consequent promotion of estrogen-dependent breast cancer. All these actions influence the later steps in breast cancer development but genetic studies are also revealing connections between gene abnormalities related to type 2 diabetes and the initiation stage of breast carcinogenesis. Understanding the various mechanisms by which insulin participates in breast cancer cell biology provides opportunities for novel approaches to treatment.

Expression of Sex Steroid Receptors in Ovine Placental Tissues During Early Pregnancy: Effects of Assisted Reproductive Technologies (ART).

Placental development can be compromised by genetic, epigenetic, environmental, or other factors, leading to poor fetal growth as well as poor pregnancy and postnatal outcomes. Pregnancies established with ART generate especially poor pregnancies (for example, only approximately 40 to 50% of IVF and less than 10% of cloned embryos survive to birth) that are associated with altered vascularization of the placenta. We have shown recently that these placental vascular defects in pregnancies from ART occur within the first few weeks of pregnancy in sheep, at approximately the same time at which substantial embryonic loss begins. Sex steroids and their receptors are important regulators of angiogenesis and growth in reproductive tissues, including the placenta. However, little is known about the expression of sex steroid receptors in placental tissues during early pregnancy or how ART affects their expression. We hypothesized that ART would affect the expression of estrogen receptor alpha and beta, nuclear progesterone receptor, and membrane progesterone receptors alpha, beta, and gamma in utero-placental tissues during early pregnancy in sheep. Pregnancies (n = 7 per group) were achieved through natural breeding (NAT, control), or transfer of embryos generated through natural breeding (NAT-ET), in vitro fertilization (IVF), or in vitro activation (IVA; parthenogenetic clones). On day 22 of pregnancy, samples of caruncle (CAR; maternal utero-placenta) and fetal membranes (FM; fetal placenta [chorioallantois]) were snap-frozen separately for RNA extraction followed by quantitative real-time RT-PCR. In CAR, mRNA expression of estrogen receptor alpha and nuclear progesterone receptor was decreased (P < 0.001) by 64 to 86% in NAT-ET, IVF, and IVA groups compared with NAT. In contrast, in FM mRNA expression of estrogen receptor alpha tended (P = 0.1) to be 2.5- to 6.4-fold greater in the IVA group compared with NAT and NAT-ET, which were similar; expression of estrogen receptor alpha was intermediate in the IVF group. Expression of mRNA for nuclear progesterone receptor in FM, and for estrogen receptor beta and membrane progesterone receptors alpha, beta, and gamma in CAR and FM, did not differ among the pregnancy-type groups. Because sex steroids are critical regulators of utero-placental vascularization, growth, and function, these data suggest that altered expression of placental sex steroid receptors may be an early event leading to poor placental vascularization and growth after ART. These data also provide a basis for understanding the mechanisms by which sex steroids regulate placental growth and vascular development in normal and compromised pregnancies. Supported by USDA 2007-01215 to LPR and ATGB, and NIH HL64141 to LPR and DAR.