Estrogen-induced genes in the uterus of ovariectomized rats and their regulation by droloxifene and tamoxifen

Evaluation of serum cysteine-rich protein 61 levels in patients with coronary artery disease

AIM

The aim is to evaluate serum cysteine-rich protein 61 (Cyr61) levels in patients with coronary artery disease (CAD).

PATIENTS & METHODS

Serum Cyr61 levels were measured in 180 patients with CAD and 74 participants without CAD.

RESULTS

Serum Cyr61 levels were significantly higher in CAD patients. Patients with acute coronary syndrome showed significantly higher Cyr61 than those with stable angina pectoris. Serum Cyr61 levels in complex lesion group were significantly higher. Serum Cyr61 was positively correlated with Gensini score and C-reactive protein. Multivariable logistic regression analyses demonstrated that serum Cyr61 levels were independently correlated with the existence of CAD (p = 0.01).

CONCLUSION

Our study suggested Cyr61 as a potential biomarker in characterizing CAD and therapeutic target for CAD.

Nutritional and Acquired Deficiencies in Inositol Bioavailability. Correlations with Metabolic Disorders

Communities eating a western-like diet, rich in fat, sugar and significantly deprived of fibers, share a relevant increased risk of both metabolic and cancerous diseases. Even more remarkable is that a low-fiber diet lacks some key components-as phytates and inositols-for which a mechanistic link has been clearly established in the pathogenesis of both cancer and metabolic illness. Reduced bioavailability of inositol in living organisms could arise from reduced food supply or from metabolism deregulation. Inositol deregulation has been found in a number of conditions mechanistically and epidemiologically associated to high-glucose diets or altered glucose metabolism. Indeed, high glucose levels hinder inositol availability by increasing its degradation and by inhibiting both myo-Ins biosynthesis and absorption. These underappreciated mechanisms may likely account for acquired, metabolic deficiency in inositol bioavailability.

Variations in hepatic biomarkers in American alligators (Alligator mississippiensis) from three sites in Florida, USA

Sub-individual biomarkers are sub-lethal biological responses commonly used in the assessment of wildlife exposure to environmental contaminants. In this study, we examined the activity of glutathione-s-transferase (GST) and lactate dehydrogenase (LDH), and metallothionein (MT) concentrations among captive-raised alligator hatchlings, wild-caught juveniles, and wild-caught adults. Juveniles and adults were collected from three locations in Florida (USA) with varying degrees of contamination (i.e. Lake Apopka (organochlorine polluted site), Merritt Island National Wildlife Refuge (NWR) (metal polluted site), and Lake Woodruff NWR (reference site)). We examined whether changes in the response of these three biomarkers were age and sex dependent or reflected site-specific variations of environmental contaminants. Juvenile alligators from Merritt Island NWR had higher MT concentrations and lower GST activity compared to those from the other two sites. This outcome was consistent with higher metal pollution at this location. Sexually dimorphic patterns of MT and GST (F > M) were observed in juvenile alligators from all sites, although this pattern was not observed in adults. GST activity was lower in captive-raised alligators from Lake Apopka and Merritt Island NWR as compared to animals from Lake Woodruff NWR, suggesting a possible developmental modulator at these sites. No clear patterns were observed in LDH activity. We concluded that GST and MT demonstrate age and sex specific patterns in the alligators inhabiting these study sites and that the observed variation among sites could be due to differences in contaminant exposure.

Estrogen-induced CCN1 is critical for establishment of endometriosis-like lesions in mice

Endometriosis is a prevalent gynecological disorder in which endometrial tissue proliferates in extrauterine sites, such as the peritoneal cavity, eventually giving rise to painful, invasive lesions. Dysregulated estradiol (E) signaling has been implicated in this condition. However, the molecular mechanisms that operate downstream of E in the ectopic endometrial tissue are unknown. To investigate these mechanisms, we used a mouse model of endometriosis. Endometrial tissue from donor mice was surgically transplanted on the peritoneal surface of immunocompetent syngeneic recipient mice, leading to the establishment of cystic endometriosis-like lesions. Our studies revealed that treatment with E led to an approximately 3-fold increase in the lesion size within a week of transplantation. E also caused a concomitant stimulation in the expression of connective tissue growth factor/Cyr61/Nov (CCN1), a secreted cysteine-rich matricellular protein, in the lesions. Interestingly, CCN1 is highly expressed in human ectopic endometriotic lesions. To address its role in endometriosis, endometrial tissue from Ccn1-null donor mice was transplanted in wild-type recipient mice. The resulting ectopic lesions were reduced up to 75% in size compared with wild-type lesions due to diminished cell proliferation and cyst formation. Notably, loss of CCN1 also disrupted the development of vascular networks in the ectopic lesions and reduced the expression of several angiogenic factors, such as vascular endothelial growth factor-A and vascular endothelial growth factor-C. These results suggest that CCN1, acting downstream of E, critically controls cell proliferation and neovascularization, which support the growth and survival of endometriotic tissue at ectopic sites. Blockade of CCN1 signaling during the early stages of lesion establishment may provide a therapeutic avenue to control endometriosis.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Inositol synthesis regulates the activation of GSK-3α in neuronal cells

The synthesis of inositol provides precursors of inositol lipids and inositol phosphates that are pivotal for cell signaling. Mood stabilizers lithium and valproic acid, used for treating bipolar disorder, cause cellular inositol depletion, which has been proposed as a therapeutic mechanism of action of both drugs. Despite the importance of inositol, the requirement for inositol synthesis in neuronal cells is not well understood. Here, we examined inositol effects on proliferation of SK-N-SH neuroblastoma cells. The essential role of inositol synthesis in proliferation is underscored by the findings that exogenous inositol was dispensable for proliferation, and inhibition of inositol synthesis decreased proliferation. Interestingly, the inhibition of inositol synthesis by knocking down INO1, which encodes inositol-3-phosphate synthase, the rate-limiting enzyme of inositol synthesis, led to the inactivation of GSK-3α by increasing the inhibitory phosphorylation of this kinase. Similarly, the mood stabilizer valproic acid effected transient decreases in intracellular inositol, leading to inactivation of GSK-3α. As GSK-3 inhibition has been proposed as a likely therapeutic mechanism of action, the finding that inhibition of inositol synthesis results in the inactivation of GSK-3α suggests a unifying hypothesis for mechanism of mood-stabilizing drugs. Inositol is an essential metabolite that serves as a precursor for inositol lipids and inositol phosphates. We report that inhibition of the rate-limiting enzyme of inositol synthesis leads to the inactivation of glycogen synthase kinase (GSK) 3α by increasing inhibitory phosphorylation of this kinase. These findings have implications for the therapeutic mechanisms of mood stabilizers and suggest that inositol synthesis and GSK 3α activity are intrinsically related.

Matricellular protein CCN1 (CYR61) expression is associated with high-grade ductal carcinoma in situ

Cysteine-rich protein 61, connective tissue growth factor, and nephroblastoma overexpressed gene (CCN) comprise a family of matricellular proteins that have multiple physiologic functions including development, tissue repair, cell adhesion, migration, and proliferation. The expression of CCN1, cyclin D1, β-catenin, and p53 was explored by immunohistochemistry in different grades of ductal carcinoma in situ (DCIS) cases. These cases did not contain any infiltrating carcinoma components. In addition, all cysteine-rich protein 61 gene exons (encoding the CCN1 protein) were sequenced in 30 samples. Allred and H-scores were calculated for expression in both DCIS and the surrounding benign breast tissue. All cases of DCIS showed degrees of cytoplasmic CCN1 staining with median H-scores of 170, 160, and 60 in grades 3, 2, and 1, respectively (P = .043). Twelve of 28 DCIS 3, 1 of 15 DCIS 2, and 0 of 18 DCIS 1 also showed nuclear staining for CCN1. The cytoplasmic staining difference was preserved when the cases were divided into estrogen receptor (ER)+/DCIS grade 1, ER+/DCIS 2 and 3, and ER-/DCIS 2 and 3 by the H-score (P = .037). Cyclin D1 expression was positively correlated with the CCN1 cytoplasmic H-score in all DCIS samples (P = .038). Membranous β-catenin expression correlated with the grade of intraepithelial carcinoma by both H-score (P = .047) and Allred score (P = .026). Our results suggest that CCN1 has a role in the development of intraepithelial carcinoma. CCN1 expression correlates with grade of DCIS independent of ER status. It can induce cell cycle progression through cyclin D1. It is warranted to study high expression of CCN1 in DCIS as an independent risk factor in a larger cohort.

Estrogen receptor modulatory effects of germinated brown rice bioactives in the uterus of rats through the regulation of estrogen-induced genes

Purpose

The expression of genes regulated by estrogen in the uterus was studied in ovariectomized (OVX) rats treated with germinated brown rice (GBR) bioactives, and compared to Remifemin or estrogen at different doses to identify the regulation of these genes in the uterus and their molecular mechanisms.

Methods

Rats were treated orally with GBR bioactives (phenolics), acylated steryl glucosides (ASG), γ-amino butyric acid (GABA), and γ-oryzanol (ORZ) at 100 and 200 mg/kg, Remifemin (REM) at 10 mg/kg and 20 mg/kg, or estrogen (EST) at 0.2 mg/kg. Ribonucleic acid (RNA) was extracted from the uterus, and messenger (m)RNA expression of selected genes encoding estrogen receptor-beta (ER-β), calcium-binding protein (CaBP9k), complement protein (C3), heat shock protein 70 kDa (HSP70), and interleukin (IL)-4 receptor were quantified. Similarly, serum steroid hormone concentration was monitored at 2, 4, and 8 weeks after treatments. ER-β antibody binding to the uterus sections was also studied using immunohistochemistry.

Results

The group treated with EST (0.2 mg/kg) upregulated ER-β, C3, and IL-4 receptor genes compared to other groups (P<0.001). GBR phenolics (200 mg/kg) treatment upregulated the ER-β gene almost to the level of the sham non-treated group. The CaBP9k gene showed upregulation in groups treated with ASG (200 mg/kg), EST (0.2 mg/kg), and ORZ (200 mg/kg) (P<0.05). Estrogen levels increased in groups treated with EST, ASG, and ORZ (200 mg/kg) compared to the OVX untreated group (P<0.05), and there was a slight non-significant decrease (P>0.05) in the progesterone levels in the OVX untreated group compared to the sham and other treated groups. There was a significant increase at 8 weeks in the level of FSH (P<0.05) in the treated groups compared to the OVX untreated group. There was no significant difference (P>0.05) in serum luteinizing hormone (LH) between the OVX untreated group and other groups. The sham and GBR phenolics treated group showed ER-β reactivity at the glandular epithelium, while the group treated with EST showed immunoreactivity at the glandular, luminal, and stromal epithelium.

Conclusion

GBR phenolics moderately regulate the expression of ER-β, HSP70, and IL-4 receptor genes, and gave a positive immunoreaction to ER-β antigen in the uterus. ASG regulates the expression of CaBP9k and IL-4 receptor genes, and ORZ regulates the expression of the CaBP9k gene, while GABA at 100 mg/kg regulates the expression of the HSP70 gene. GBR and its bioactives might have an effect on estrogen-regulated genes in the uterus of rats.

CCN1/CYR61: the very model of a modern matricellular protein

CCN1 (CYR61) is a dynamically expressed, multifunctional matricellular protein that plays essential roles in cardiovascular development during embryogenesis, and regulates inflammation, wound healing and fibrogenesis in the adult. Aberrant CCN1 expression is associated with myriad pathologies, including various cancers and diseases associated with chronic inflammation. CCN1 promotes diverse and sometimes opposing cellular responses, which can be ascribed, as least in part, to disparate activities mediated through its direct binding to distinct integrins in different cell types and contexts. Accordingly, CCN1 promotes cell proliferation, survival and angiogenesis by binding to integrin α(v)β(3), and induces apoptosis and senescence through integrin α(6)β(1) and heparan sulfate proteoglycans. The ability of CCN1 to trigger the accumulation of a robust and sustained level of reactive oxygen species underlies some of its unique activities as a matrix cell-adhesion molecule. Emerging studies suggest that CCN1 might be useful as a biomarker or therapeutic target in certain diseases.

Identification of myo-inositol-3-phosphate synthase isoforms: characterization, expression, and putative role of a 16-kDa gamma(c) isoform

Myo-inositol is an important constituent of membrane phospholipids and is a precursor for the phosphoinositide signaling pathway. It is synthesized from glucose 6-phosphate by myo-inositol-3-phosphate synthase (IP synthase), a homotrimer composed of a 68-kDa polypeptide in most mammalian tissues. It is a putative target for mood-stabilizing drugs such as lithium and valproate. Here, we show that the rat gene (Isyna1) encoding this enzyme generates a number of alternatively spliced transcripts in addition to the fully spliced form that encodes the 68-kDa subunit (the alpha isoform). Specifically, we identify a small 16-kDa subunit (the gamma(c) isoform) derived by an intron retention mechanism and provide evidence for its existence in rat tissues. The gamma(c) isoform is highly conserved in mammals, but it lacks the catalytic domain while retaining the NAD(+) binding domain. Both alpha and gamma(c) isoforms are predominantly expressed in many rat tissues and display apparent stoichiometry in purified enzyme preparations. An IP synthase polyclonal antibody not only detects the alpha and gamma(c) isoforms but also several other isoforms in pancreas, intestine, and testis suggesting that the holoenzyme is composed of unique subunits in various tissues. Interestingly, the alpha isoform is not expressed in the intestine. IP synthase activity assays using purified alpha and gamma(c) isoforms indicate that the latter negatively modulates alpha isoform activity, possibly by competing for NAD(+) molecules. Our findings have important ramifications for understanding the mood stabilization process and suggest that inositol biosynthesis is a highly regulated and dynamic process.

Tumorigenic effects of tamoxifen on the female genital tract

Tamoxifen is widely used for endocrine treatment and breast cancer prevention. It acts as both an estrogen antagonist in breast tissue and an estrogen agonist in the female lower genital tract. Tamoxifen causes severe gynecologic side effects, such as endometrial cancer. This review focuses on the effects of prolonged tamoxifen treatment on the human female genital tract and considers its tumorigenicity in the gynecologic organs through clinical data analysis. Tamoxifen is associated with an increased incidence of benign endometrial lesions such as polyps and hyperplasia and a two- to four-fold increased risk of endometrial cancer in postmenopausal patients. Moreover, the incidence of functional ovarian cysts is significantly high in premenopausal tamoxifen users. To prevent tamoxifen from having severe side effects in gynecologic organs, frequent gynecological examination should be performed for both premenopausal and postmenopausal patients with breast cancer who are treated with this drug.

The effects of estrogen and testosterone on gene expression in the rat mesenteric arteries

A dramatic difference exists in the timing of development of cardiovascular disease in men vs. women. The primary candidates underlying the cause of this gender difference are the sex steroids, estrogen and testosterone. The vasculature is considered to be a site of action of these steroids. In spite of these concepts there is little data on the direct effects of estrogen and testosterone on gene expression in the vasculature. In this study, ovariectomized Sprague Dawley rats were treated for 4 days with vehicle (sesame oil), estradiol benzoate (0.15 mg/kg/day), or testosterone (1 mg/kg/day). The mesenteric arteries were obtained, total RNA was extracted, and CodeLink Uniset Rat I DNA microarrays were used to identify differential gene expression. Seven genes were identified as differentially expressed from the DNA microarray data and confirmed by real time RT-PCR. The expression of D site albumin promoter binding protein and fatty acid synthase were increased in response to both estrogen and testosterone. 3 alpha-hydroxysteroid dehydrogenase, interleukin 4 receptor, JunB and c-Fos expression were increased by estrogen but not by testosterone. Aryl hydrocarbon nuclear translocator-like gene was reduced by testosterone. These data identify genes not previously known to be responsive to estrogen and testosterone in the vasculature.

Functional properties and intracellular signaling of CCN1/Cyr61

CCN1/Cyr61 is a member of the protein family that can be promptly induced by growth factors. CCN1/Cyr61 promotes cell proliferation, adhesion, and differentiation. It plays important roles in angiogenesis and extracellular matrix production. In addition, CCN1/Cyr61 has many potential functions in tumorigenesis, development, embryo implantation, as well as formation of endometriotic lesions. Expression of CCN1/Cyr61 is regulated by a variety of agents including cytokines, growth factors, steroid hormones, and some drugs. These inducers regulate the transcription of CCN1/Cyr61 through several signaling transduction pathways. CCN1/Cyr61 is able to interact either with the cell itself or the surrounding cells through an autocrine-paracrine mechanism. It has been reported that CCN1/Cyr61 exerts its functions via interacting with at least five integrins as well as heparan sulfate proteoglycan. By activating Wnt, NF-kappaB, or tyrosine kinase signaling pathways, CCN1/Cyr61 is not only able to control the growth of epithelial cells and fibroblasts, but also induce or suppress apoptosis in a cell type-specific manner.

Endometrial Expression of Cyr61

OBJECTIVE

To compare the expression of Cyr61 in normal cycling endometrium with endometrium from women with polycystic ovarian syndrome (PCOS) and endometrial hyperplasia and adenocarcinoma.

METHODS

This is a retrospective study of 59 samples of normal and abnormal endometrium. Endometrial biopsies were obtained from normal fertile controls throughout the menstrual cycle and compared with endometrium from ovulatory and anovulatory women with PCOS and complex endometrial hyperplasia and endometrioid adenocarcinoma. Cyr61 expression was evaluated by using immunohistochemistry and reverse transcription PCR for Cyr61, estrogen receptor (ER)-alpha, a marker of cell proliferation (Ki67), and another marker of early estrogen action, cFos. Regulation of Cyr61 protein was studied in a steroid-responsive endometrial carcinoma cell line, ECC1.

RESULTS

Cyr61 protein was regulated by estrogen. In normal endometrium, Cyr61 was highest in the proliferative phase and lowest in the normal midsecretory phase. In contrast, elevated levels of Cyr61, ER-alpha, Ki67, and cFos were all found in the midsecretory endometrium of ovulatory PCOS patients, endometrial cancer patients, and hyperplasia patients.

CONCLUSION

Cyr61 is overexpressed in PCOS endometrium, reflecting a heightened responsiveness to estrogen. As a unique marker of estrogen action, Cyr61 may be an early biomarker for the development of hyperplasia or adenocarcinoma in this group of women.

Candidate genes and their response to environmental agents in the etiology of hypospadias

The molecular events that lead to isolated hypospadias remain largely unknown, and the etiology of this common congenital anomaly seems to be multifactorial. We have explored the response of several candidate genes to environmental agents that cause hypospadias in a mouse model. Here, we provide an overview of current findings in relation to candidate genes and their response to environmental agents, including the results of genomic analyses of both mouse and human tissues. In addition to steroid-hormone receptors, one gene of specific interest is activating transcription factor 3 (ATF3). We hypothesize a potential mechanism of action for ATF3 and other identified genes, including TGF-B.

Modulation of estrogen receptor transactivation and estrogen-induced gene expression by ormeloxifene-a triphenylethylene derivative

The study was aimed to investigate the interaction of D,L-ormeloxifene (Orm), a triphenylethylene and its hydroxy derivative with estrogen receptor subtypes alpha and beta, its influence on ERE-driven transcriptional activation and progesterone receptor expression. In competitive binding experiments using human recombinant ERalpha and ERbeta, Orm showed interaction with both ER subtypes, with more selectivity and higher affinity towards ERalpha (8.8%) as compared to ERbeta (3%). In case of 7-hydroxy derivative, the relative binding affinity for both ERs was enhanced several folds. Orm showed lower Ki, i.e. higher affinity for ERalpha (250 nM) than for ERbeta (750 nM). It was observed that Orm promoted the formation of ER-ERE complexes in uterine tissue extract whereas its hydroxy derivative showed inhibitory effects. Transient co-transfection assay in COS-1 cells using ERE-luciferase reporter construct, revealed that Orm showed estrogenic response whereas its hydroxy-derivative was potent antiestrogen at ERalpha at transcription level. In immature rats, Orm (2 mg/kg) was associated with less increase in uterine weight and in luminal epithelial cell height than E2 or Tam. Orm also induced the expression of PR mRNA but the expression level was significantly less than estradiol treated group. These results suggest that ER-ERE complexes formed under the influence of 7-hydroxy Orm appear to be transcriptionally less effective hence antagonizing the E2-regulated gene expression in this target tissue.

Induced Endometriosis in the Baboon (Papio anubis) Increases the Expression of the Proangiogenic Factor CYR61 (CCN1) in Eutopic and Ectopic Endometria1

The expression of human CYR61 (cysteine-rich, angiogenic inducer, 61; CCN1) mRNA has been previously shown to be deregulated in the endometrium of women with endometriosis. We have chosen the baboon model (Papio anubis) of induced endometriosis to clarify whether CYR61 mRNA upregulation is predisposed to an inappropriately differentiated endometrium or is deregulated as a response to the presence of ectopic lesions. In the baboon, endometrial CYR61 mRNA expression underwent moderate cyclical variation, with a significant 7.3-fold increase detected at Day 2 postmenses when compared to endometrium from the proliferative and secretory phases. The CYR61 transcript was extensively upregulated in the eutopic endometrium from all baboons with induced endometriosis, as early as 1 mo postinoculation of menstrual tissue into the peritoneal cavity. CYR61 mRNA expression then decreased throughout progression of the disease, but remained higher compared to control tissues. Ectopic endometriotic lesions showed a further increase in CYR61 mRNA, with highest expression found in red lesions. Moreover, the expression levels of CYR61 transcripts correlated significantly with those of VEGF. Immunohistochemistry revealed the presence of CYR61 protein in glandular and luminal epithelial cells as well as in blood vessels of eutopic and ectopic endometrium. As in humans, increased levels of CYR61 mRNA correlated with the development of endometriosis in baboons. The increase of CYR61 mRNA in eutopic endometrium of baboons following peritoneal inoculation with menstrual endometrium provides evidence for a feedback mechanism from resulting lesions to induce a shift in gene expression patterns in the eutopic endometrium.

Vascular development in endometriosis

Endometriosis, defined as the presence of endometrial tissue outside the uterus, is an estrogen-dependent disease which causes pelvic pain and subfertility in women of reproductive age. The condition has a dramatic impact on the professional, social and marital life of sufferers. Direct and indirect evidence suggests that angiogenesis is required for the development and persistence of endometriosis. In this review the state-of-the-art with regard to our understanding of the role of angiogenesis in the ectopic implantation and survival of menstrual endometrial tissue will be discussed.

Gene expression changes related to growth and differentiation in the fetal and juvenile reproductive system of the female rat: evaluation of microarray results

Microarrays make it possible to evaluate the responses of a major fraction of the genome in response to physiological perturbation or exogenous insult. This represents a huge advance in our ability to detect changes in gene expression that may be responsible for physiological or toxicological responses. Our laboratory is interested in the effects of estrogens on female reproductive system development and function. We have evaluated the changes in gene expression in response to estrogens in the female reproductive tract of rats during embryo/fetal development and in the juvenile rat (which is capable of mounting a uterotrophic response). The results of these experiments indicate that a number of genes (dozens to hundreds) are changed in a reproducible, dose-related manner in response to estrogens. These results have been published elsewhere; the purpose of this review is to evaluate, based on information from the literature, the potential role of selected genes on processes of cell proliferation and differentiation, and to suggest plausible relationships among these genes in eliciting responses at the tissue or organ level. We also discuss the utility of gene-expression experiments in elucidating the shape of the dose-response curve at low doses. In particular, we show that the dose-response for gene expression in the juvenile rat uterus is monotonic down to levels a few orders of magnitude below the NOEL for a uterotrophic response, suggesting that gene expression (and by inference higher order responses) do not follow patterns that are unpredictable based on response at higher dosages.

Gene expression changes induced in the testis by transplacental exposure to high and low doses of 17{alpha}-ethynyl estradiol, genistein, or bisphenol A

The purpose of this study was to determine (1) the transcriptional program elicited by exposure to three estrogen receptor (ER) agonists: 17 alpha-ethynyl estradiol (EE), genistein (Ges), and bisphenol A (BPA) during fetal development of the rat testis and epididymis; and (2) whether very low dosages of estrogens (evaluated over five orders of magnitude of dosage) produce unexpected changes in gene expression (i.e., a non-monotonic dose-response curve). In three independently conducted experiments, Sprague-Dawley rats were dosed (sc) with 0.001-10 microg EE/kg/day, 0.001-100 mg Ges/kg/day, or 0.002-400 mg BPA/kg/day. While morphological changes in the developing reproductive system were not observed, the gene expression profile of target tissues were modified in a dose-responsive manner. Independent dose-response analyses of the three studies identified 59 genes that are significantly modified by EE, 23 genes by Ges, and 15 genes by BPA (out of 8740), by at least 1.5 fold (up- or down-regulated). Even more genes were observed to be significantly changed when only the high dose is compared with all lower doses: 141, 46, and 67 genes, respectively. Global analyses aimed at detecting genes consistently modified by all of the chemicals identified 50 genes whose expression changed in the same direction across the three chemicals. The dose-response curve for gene expression changes was monotonic for each chemical, with both the number of genes significantly changed and the magnitude of change, for each gene, decreasing with decreasing dose. Using the available annotation of the gene expression changes induced by ER-agonist, our data suggest that a variety of cellular pathways are affected by estrogen exposure. These results indicate that gene expression data are diagnostic of mode of action and, if they are evaluated in the context of traditional toxicological end-points, can be used to elucidate dose-response characteristics.

E2F1 regulation of the human myo-inositol 1-phosphate synthase (ISYNA1) gene promoter

Human myo-inositol 1-phosphate synthase (IP synthase; E.C. 5.5.1.4), encoded by ISYNA1, catalyzes the de novo synthesis of inositol 1-phosphate from glucose 6-phosphate. It is a potential target for mood-stabilizing drugs such as lithium and valproate. But, very little is known about the regulation of human IP synthase. Here, we have characterized the minimal promoter of ISYNA1 and show that it is upregulated by E2F1. Upregulation occurs in a dose-dependent fashion and can be suppressed by ectopic expression of Rb. EMSA and antibody supershift analysis identified a functional E2F binding motif at -117. Complex formation at this site was competed by an excess of unlabeled Sp1 oligo consistent with the -117 E2F site overlapping an Sp1 motif. Because the -117 E2F motif is not a high-affinity binding site, we propose that the upregulation of ISYNA1 occurs through the cooperative interaction of several low-affinity E2F binding motifs present in the minimal promoter.

Identification of temporal patterns of gene expression in the uteri of immature, ovariectomized mice following exposure to ethynylestradiol

Estrogen induction of uterine wet weight provides an excellent model to investigate relationships between changes in global gene expression and well-characterized physiological responses. In this study, time course microarray GeneChip data were analyzed using a novel approach to identify temporal changes in uterine gene expression following treatment of immature ovariectomized C57BL/6 mice with 0.1 mg/kg 17alpha-ethynylestradiol. Functional gene annotation information from public databases facilitated the association of changes in gene expression with physiological outcomes, which allowed detailed mechanistic inferences to be drawn regarding cell cycle control and proliferation, transcription and translation, structural tissue remodeling, and immunologic responses. These systematic approaches confirm previously established responses, identify novel estrogen-regulated transcriptional effects, and disclose the coordinated activation of multiple modes of action that support the uterotrophic response elicited by estrogen. In particular, it was possible to elucidate the physiological significance of the dramatic induction of arginase, a classic estrogenic response, by elucidating its mechanistic relevance and delineating the role of arginine and ornithine utilization in the estrogen-stimulated induction of uterine wet weight.

Regulation of uterine hsp90alpha, hsp72 and HSF-1 transcription in B6C3F1 mice by beta-estradiol and bisphenol A: involvement of the estrogen receptor and protein kinase C

We have previously demonstrated that bisphenol A (BPA)- and beta-estradiol (E2)-induced increases in uterine weight and heat shock protein (hsp) 90alpha and hsp72 levels are mediated through the estrogen receptor (ER). It is not, however, clear if BPA and E2 regulation of hsps is at the transcriptional or post-transcriptional level. Therefore, in this study we examined the ability of BPA and E2 to increase uterine weight and regulate transcription of these hsps and of heat shock factor (HSF)-1 in ovariectomized B6C3F1 mice at 6 or 24 h after a single subcutaneous injection of E2 (1 microg/kg) or BPA (100 mg/kg). The role of the ER and protein kinase C (PKC) in these E2 and BPA effects was evaluated by co-administration of the antiestrogen ICI 182,780 (5 mg/kg) or the PKC inhibitor GF 109203X (0.5 mg/kg), respectively. The results demonstrated ER involvement in uterine weight increases. Uterine hsp mRNA levels are increased by E2 and BPA through a direct effect on their transcription and/or, in the case of E2, through an increase in HSF-1 mRNA. PKC is involved in the BPA-induced increases in hsp90alpha mRNA levels. We conclude that E2 and BPA regulate hsp90alpha and hsp72alpha transcription via similar and distinct pathways.

cDNA cloning and gene expression analysis of human myo-inositol 1-phosphate synthase

myo-Inositol 1-phosphate synthase (EC 5.5.1.4) (IPS) is a key enzyme in myo-inositol biosynthesis pathway. This study describes the molecular cloning of the full length human myo-inositol 1-phosphate synthase (hIPS) cDNA, tissue distribution of its mRNA and characterizes its gene expression in cultured HepG2 cells. Human testis, ovary, heart, placenta, and pancreas express relatively high level of hIPS mRNA, while blood leukocyte, thymus, skeletal muscle, and colon express low or marginal amount of the mRNA. In the presence of glucose, hIPS mRNA level increases 2- to 4-fold in HepG2 cells. hIPS mRNA is also up-regulated 2- to 3-fold by 2.5 microM lovastain. This up-regulation is prevented by mevalonic acid, farnesol, and geranylgeraniol, suggesting a G-protein mediated signal transduction mechanism in the regulation of hIPS gene expression. hIPS mRNA expression is 50% suppressed by 10mM lithium ion in these cells. Neither 5mM myo-inositol nor the three hormones: estrogen, thyroid hormone, and insulin altered hIPS mRNA expression in these cells.

Current status of estrogen receptors

Increasing knowledge on structure and function of estrogen receptors is providing information on the mechanism of action of estrogen agonists, as well as antagonists, and in understanding their tissue-selective action. However, there are still many factors associated with estrogen response which are poorly understood. Therefore, the task of designing a tissue-selective estrogen for use as a pharmaceutical in estrogen-dependent disorders remains an uncertain game. This review provides information on the current status of estrogen receptors for a better understanding.

Overview of in vitro tools to assess the estrogenic and antiestrogenic activity of phytoestrogens

There is an intense discussion in the scientific and even more so in the public community as well as regulatory agencies about the potential benefits or detrimental effects of plant-derived compounds that may affect the endocrine system, especially estrogen signaling pathways. These so-called phytoestrogens are found in the normal western diet and predominantly in an eastern or soy-based diet and the potency of the isolated compounds to interact with the known receptors for estrogen varies tremendously. The estrogen receptors, ER alpha and ER beta, mediate the effects of endogenous estrogens, i.e. regulation of reproductive function, tissue development, cell proliferation and differentiation. In this review, in vitro test systems available to date for the screening of estrogenic and antiestrogenic activity including mechanism-based assays are described. The potency of phytoestrogens determined using these in vitro assays are compared with the potency of endogenous estrogens and results obtained in vitro are compared with effects in vivo. Finally, the impact of in vitro assays to determine estrogenicity on human hazard assessment is discussed as well as other non ER-mediated mechanisms that may contribute to potential beneficial or adverse effects of phytoestrogens in man.

Estrogen receptor alpha inhibits IL-1beta induction of gene expression in the mouse liver

Estrogens have been suggested to modulate several inflammatory processes. Here, we show that IL-1beta treatment induced the expression of approximately 75 genes in the liver of ovariectomized mice. 17alpha-Ethinyl estradiol (EE) pretreatment reduced the IL-1beta induction of approximately one third of these genes. Estrogen receptor alpha (ERalpha) was required for this inhibitory activity, because EE inhibition of IL-1beta-stimulated gene expression occurred in ERbeta knockout mice, but not in ERalpha knockout mice. EE treatment induced expression of 40 genes, including the transcriptional repressor short heterodimer partner and prostaglandin D synthase, known modulators of nuclear factor-kappaB signaling. However, the ER agonists genistein and raloxifene both inhibited IL-1beta gene induction without stimulating the expression of prostaglandin D synthase, short heterodimer partner, or other ER-inducible genes, indicating that induction of gene expression was not required for ER inhibition of IL-1beta signaling. Finally, the ability of EE to repress IL-1beta gene induction varied among tissues. For example, EE inhibited IL-1beta induction of lipopolysaccharide-induced c-x-c chemokine (LIX) in the liver, but not in the spleen or lung. The degree of EE repression did not correlate with ER expression. cAMP response element binding protein-binding protein (CBP)/p300 levels also varied between tissues. Together, these results are consistent with a model of in vivo ER interference with IL-1beta signaling through a coactivator-based mechanism.

Expression and regulation of Cyr61 in human breast cancer cell lines

We have shown that Cyr61, an angiogenic regulator, is overexpressed in invasive and metastatic human breast cancer cells and tumor biopsies. We have further demonstrated that Cyr61 promotes acquisition of estrogen-independence and anti-estrogen resistance in vivo in breast cancer cells. Moreover, we have demonstrated that Cyr61 induces tumor formation and tumor vascularization in vivo, events mediated through the activation of the MAPK and the Akt signaling pathways. Here we investigate how Cyr61 expression is regulated in both estrogen receptor (ER)-positive and ER-negative breast cancer cells. We demonstrate that Cyr61 mRNA and protein expression is inducible by estrogen and anti-estrogens in ER-positive breast cancer cells. We show that a labile protein as well as a negative regulator might be involved in Cyr61 expression in estrogen-dependent breast cancer cells. Other important regulators of Cyr61 expression in breast cancer cells that we found are the phorbol ester TPA, vitamin D, and retinoic acid. TPA causes positive regulation of Cyr61 expression in ER-positive MCF-7 cells. Vitamin D induces a transient stimulatory effect on Cyr61 gene expression. Lastly, retinoic acid has a negative effect on Cyr61 expression and downregulates its expression in MCF-7 cells. Interestingly, most of these effects are not seen in aggressive breast cancer cells that do not express ER and express high levels of Cyr61, such as the MDA-MB-231 cells. Our results are in agreement with our knowledge that Cyr61 promotes tumor growth, and that tumor-promoting agents have a positive impact on cells that express low levels of Cyr61, such as the ER-positive breast cancer cells; however, these agents have no significant effect on cells that express high levels of Cyr61. Our findings suggest an association between increased Cyr61 expression and an aggressive phenotype of breast cancer cells.

Organization and expression of the Cyr61 gene in normal human fibroblasts

We have examined the human Cyr61 gene and its expression in normal fibroblasts. The core promoter, second intron, and 3' untranslated region (UTR) are highly conserved between the human and mouse genes. Cyr61 expression was induced slightly slower but more transiently in human fibroblasts compared to Rat-2 fibroblasts. These differences may relate to the absence of a serum response element in the human Cyr61 promoter, and the presence of additional AU-rich elements within the 3' UTR. Cycloheximide causes accumulation of human Cyr61 RNA in the absence of growth factors, and EGF prevents decay of transcripts in actinomycin-D-treated cells, which suggests that induction by growth factors may partially involve mRNA stabilization. We detect an alternative RNA in serum-stimulated fibroblasts containing an in-frame deletion within exon 4 which disrupts the thrombospondin type 1 repeat. Constitutive expression of the full hCyr61 genomic DNA in rodent fibroblasts causes production of multiple protein species, whereas expression of hCyrDelta4 produces a single stable protein of the expected size. We also observed multiple hCyr61 protein species in normal fibroblasts following serum stimulation, indicating that Cyr61 may normally be produced as alternative isoforms.

Synthesis and reactivity of potential toxic metabolites of tamoxifen analogues: droloxifene and toremifene o-quinones

Tamoxifen remains the endocrine therapy of choice in the treatment of all stages of hormone-dependent breast cancer. However, tamoxifen has been shown to increase the risk of endometrial cancer which has stimulated research for new effective antiestrogens, such as droloxifene and toremifene. In this study, the potential for these compounds to cause cytotoxic effects was investigated. One potential cytotoxic mechanism could involve metabolism of droloxifene and toremifene to catechols, followed by oxidation to reactive o-quinones. Another cytotoxic pathway could involve the oxidation of 4-hydroxytoremifene to an electrophilic quinone methide. Comparison of the amounts of GSH conjugates formed from 4-hydroxytamoxifen, droloxifene, and 4-hydroxytoremifene suggested that 4-hydroxytoremifene is more effective at formation of a quinone methide. However, all three substrates formed similar amounts of o-quinones. Both the tamoxifen-o-quinone and toremifene-o-quinone reacted with deoxynucleosides to give corresponding adducts. However, the toremifene-o-quinone was shown to be considerably more reactive than the tamoxifen-o-quinone in terms of both kinetic data as well as the yield and type of deoxynucleoside adducts formed. Since thymidine formed the most abundant adducts with the toremifene-o-quinone, sufficient material was obtained for characterization by (1)H NMR, COSY-NMR, DEPT-NMR, and tandem mass spectrometry. Cytotoxicity studies with tamoxifen, droloxifene, 4-hydroxytamoxifen, 4-hydroxytoremifene, and their catechol metabolites were carried out in the human breast cancer cell lines S30 and MDA-MB-231. All of the metabolites tested showed cytotoxic effects that were similar to the parent antiestrogens which suggests that o-quinone formation from tamoxifen, droloxifene, and 4-hydroxytoremifene is unlikely to contribute to their cytotoxicity. However, the fact that the o-quinones formed adducts with deoxynucleosides in vitro implies that the o-quinone pathway might contribute to the genotoxicity of the antiestrogens in vivo.

Reciprocal antagonism between estrogen receptor and NF-kappaB activity in vivo

The functional interaction, or "cross-talk," between estrogen receptor (ER) and the proinflammatory transcription factor nuclear factor (NF)-kappaB demonstrated in vitro has been suggested to play a role in estrogen prevention of cardiovascular disease. Here, we demonstrate that this reciprocal cross-talk occurs in vivo. Ovariectomized C57BL/6 mice fed an atherogenic diet had increased hepatic levels of active NF-kappaB and numerous inflammatory genes, including MHC invariant chain (Ii), vascular cell adhesion molecule-1, tumor necrosis factor-alpha, and RANTES. Treatment with 17alpha-ethinylestradiol (EE) strongly blocked induction of these genes but had no effect on their basal expression levels. ER was required for this activity, because the antagonist ICI 182,780 completely blocked the inhibitory activity of EE. Gene activation by EE was not required for inhibition of inflammatory gene expression, because both the phytoestrogen genistein and low doses of EE were effective in blocking inflammatory gene induction without inducing marker genes such as intestinal trefoil factor (ITF) or myo-inositol-1-phosphate synthase (IPS). The in vivo transcriptional interference was reciprocal, with EE induction of ITF and IPS greatly reduced in animals fed the atherogenic diet versus chow-fed controls. This interference was specific to the liver, because diet had no effect on uterine weight increases produced by EE. Transfection experiments confirmed that the extent of inhibition of ER-mediated transcription by inflammatory stimuli correlated with the extent of NF-kappaB activation. These results suggest that the cross-talk between ER and NF-kappaB does occur in vivo and may indeed contribute significantly to the cardioprotective effects of estrogen.

Steroidal regulation of connective tissue growth factor (CCN2; CTGF) synthesis in the mouse uterus

AIMS

To determine mechanisms regulating the production of connective tissue growth factor (CCN2; CTGF) and transforming growth factor beta1 (TGF-beta1) in the mouse uterus.

METHODS

In situ hybridisation and immunohistochemistry were used to localise CCN2 (CTGF) and TGF-beta1 in uteri from sexually mature female mice that had either been (1) mated with sterile males to induce pseudopregnancy or (2) ovariectomised (OVX) and administered estradiol-17beta (E2) or progesterone (P4), either alone or in combination. Uteri collected on days 0.5, 1.5, 2.5, 3.5, 4.5, or 5.5 of pseudopregnancy or at one, three, six, 12, or 24 hours after steroid administration were fixed, sectioned, and incubated with specific riboprobes or antibodies to permit detection and localisation of mRNA or protein for CTGF and TGF-beta1.

RESULTS

On days 0.5-2.5 of pseudopregnancy, CCN2 (CTGF) and TGF-beta1 were principally colocalised to uterine epithelial cells, with much smaller amounts in the stroma. On days 3.5-4.5, there was a reduction of CCN2 (CTGF) and TGF-beta1 in the epithelium but an increase in stromal and endothelial cells, corresponding to a period of extracellular matrix remodelling and neovascularisation within the endometrium. In OVX mice, epithelial cells were weakly positive for both CCN2 (CTGF) and TGF-beta1 in the absence of steroid hormones. Epithelial CTGF mRNA production were strongly but transiently stimulated in OVX mice cells by E2. These effects were antagonised by P4, which itself transiently stimulated epithelial CCN2 (CTGF) production, although less robustly than E2. CTGF and TGF-beta1 protein amounts were high in epithelial cells throughout steroid treatment and were increased in the stroma, where they were relatively long lived. Stromal CCN2 (CTGF) and TGF-beta1 were lower after co-administration of E2 and P4 than in response to each hormone individually. Although ccn2 (ctgf) is a TGF-beta1 inducible gene in other systems, and both growth factors were often co-localised in uterine tissues in these studies, several treatment regimens resulted in high amounts of TGF-beta1 protein in stromal cells without the concomitant production of ccn2 (ctgf) mRNA.

CONCLUSIONS

Maternal factors are principal cues for CCN2 (CTGF) and TGF-beta1 production in the uterus because (1) their expression during pseudopregnancy is comparable to that seen in pregnancy and (2) they are regulated by ovarian steroids. TGF-beta dependent and independent mechanisms of ccn2 (ctgf) gene transcription exist in the uterus that are variably regulated by steroid hormones. Collectively, the data support a role for CCN2 (CTGF) in mediating the effects of steroid hormones and TGF-beta on endometrial function.

Cyr61, a member of the CCN family, is required for MCF-7 cell proliferation: regulation by 17beta-estradiol and overexpression in human breast cancer

Cyr61, a member of the CCN (CTGF/Cyr61/NOV) family of growth regulators, is a secreted cysteine-rich proangiogenic factor that has been implicated in tumorigenesis. Previous studies have also demonstrated that Cyr61 is regulated by 17beta-estradiol (E(2)) in the uterus. Therefore, we hypothesized that hormonal regulation of Cyr61 may be important in estrogen-dependent pathogenic processes such as breast tumorigenesis. Our study demonstrates that both Cyr61 messenger RNA and protein are induced by E(2) in MCF-7 mammary adenocarcinoma cells that primarily overexpress estrogen receptor alpha (ERalpha) in a dose-dependent and immediate early fashion. Cyr61 gene induction by E(2) is transcriptionally regulated by ERalpha as the antiestrogen, ICI 182,780, and actinomycin D blocked induction completely. In addition, Cyr61 is up-regulated in MCF-7 cells by epidermal growth factor (EGF) in an immediate early fashion as well. The functional relevance of steroid induction of Cyr61 in breast cancer cell growth is demonstrated by anti-Cyr61 neutralizing antibodies, which diminished E(2) and EGF-dependent DNA synthesis and dramatically reduced E(2)-driven cell proliferation by more than 70%. Most importantly, Cyr61 is overexpressed in 70% (28 of 40) of breast cancer patients with infiltrating ductal carcinoma and is localized exclusively to hyperplastic ductal epithelial cells. Moreover, the levels of Cyr61 protein are higher in breast tumors that are ER(+)/EGF receptor(+) than those that are ER(-)/EGF receptor(+), suggesting that estrogens may mediate Cyr61 expression in vivo. Collectively, our data suggest that Cyr61 may play a critical role in estrogen- as well as growth factor-dependent breast tumor growth.

Breast cancer. Cyr61 is overexpressed, estrogen-inducible, and associated with more advanced disease

To identify genes involved in breast cancer, polymerase chain reaction-selected cDNA subtraction was utilized to construct a breast cancer-subtracted library. Differential screening of the library isolated the growth factor-inducible immediate-early gene Cyr61, a secreted, cysteine-rich, heparin binding protein that promotes endothelial cell adhesion, migration, and neovascularization. Northern analysis revealed that Cyr61 was expressed highly in the invasive breast cancer cell lines MDA-MB-231, T47D, and MDA-MB-157; very low levels were found in the less tumorigenic MCF-7 and BT-20 breast cancer cells and barely detectable amounts were expressed in the normal breast cells, MCF-12A. Univariate analysis showed a significant or borderline significant association between Cyr61 expression and stage, tumor size, lymph node positivity, age, and estrogen receptor levels. Interestingly, expression of Cyr61 mRNA increased 8- to 12-fold in MCF-12A and 3- to 5-fold in MCF-7 cells after 24- and 48-h exposure to estrogen, respectively. Induction of Cyr61 mRNA was blocked by tamoxifen and ICI182,780, inhibitors of the estrogen receptor. Stable expression of Cyr61 cDNA under the regulation of a constitutive promoter in MCF-7 cells enhanced anchorage-independent cell growth in soft agar and significantly increased tumorigenicity and vascularization of these tumors in nude mice. Moreover, overexpression of Cyr61 in MCF-12A normal breast cells induced their tumor formation and vascularization in nude mice. In summary, these results suggest that Cyr61 may play a role in the progression of breast cancer and may be involved in estrogen-mediated tumor development.

NOV (nephroblastoma overexpressed) and the CCN family of genes: structural and functional issues

The CCN family of genes presently consists of six distinct members encoding proteins that participate in fundamental biological processes such as cell proliferation, attachment, migration, differentiation, wound healing, angiogenesis, and several pathologies including fibrosis and tumorigenesis. Whereas CYR61 and CTGF were reported to act as positive regulators of cell growth, NOV (nephroblastoma overexpressed) provided the first example of a CCN protein with negative regulatory properties and the first example of aberrant expression being associated with tumour development. The subsequent discovery of the ELM1, rCOP1, and WISP proteins has broadened the variety of functions attributed to the CCN proteins and has extended previous observations to other biological systems. This review discusses fundamental questions regarding the regulation of CCN gene expression in normal and pathological conditions, and the structural basis for their specific biological activity. After discussing the role of nov and other CCN proteins in the development of a variety of different tissues such as kidney, nervous system, muscle, cartilage, and bone, the altered expression of the CCN proteins in various pathologies is discussed, with an emphasis on the altered expression of nov in many different tumour types such as Wilms's tumour, renal cell carcinomas, prostate carcinomas, osteosarcomas, chondrosarcomas, adrenocortical carcinomas, and neuroblastomas. The possible use of nov as a tool for molecular medicine is also discussed. The variety of biological functions attributed to the CCN proteins has led to the proposal of a model in which physical interactions between the amino and carboxy portions of the CCN proteins modulate their biological activity and ensure a proper balance of positive and negative signals through interactions with other partners. In this model, disruption of the secondary structure of the CCN proteins induced by deletions of either terminus is expected to confer on the truncated polypeptide constitutive positive or negative activities.

Aberrant expression of Cyr61, a member of the CCN (CTGF/Cyr61/Cef10/NOVH) family, and dysregulation by 17 beta-estradiol and basic fibroblast growth factor in human uterine leiomyomas

Uterine leiomyomas are the most common tumors of the reproductive tract, afflicting women between the ages of 30--55 yr. Although considered to be the leading cause of hysterectomies in the United States, little is known of the etiology and mechanisms of pathogenesis in leiomyomas. Accordingly, rapid analysis of differential expression (RADE) was employed to identify genes that are abnormally expressed in leiomyomas. Of the several genes identified, Cyr61, a member of the CCN family of growth and angiogenic regulators, was shown to be markedly down-regulated at the messenger ribonucleic acid (mRNA) and protein levels in leiomyoma tumors compared with the matched uterine myometrial controls (n = 38). In addition, in situ hybridization experiments corroborated the lack of Cyr61 expression in leiomyoma cells, whereas abundant transcript levels were identified in adjacent myometrial smooth muscle cells. To elucidate the mechanisms of Cyr61 gene regulation in leiomyomas, we determined the effects of ovarian steroids, basic fibroblast growth factor (bFGF), and serum, on Cyr61 expression using an ex vivo culture system. Treatment of human myometrial explants with 17 beta-estradiol and bFGF up-regulated Cyr61 transcripts, whereas the progesterone receptor agonist, R5020 (alone or in combination with 17 beta-estradiol), had no effect. Paradoxically, neither 17 beta-estradiol nor bFGF was capable of up-regulating Cyr61 mRNA in leiomyoma explants despite elevated levels of ER alpha mRNA, suggesting a possible defect in steroid and growth factor regulation. Thus, dysregulation of Cyr61 by estrogen and bFGF may contribute to down-regulation of Cyr61 in leiomyomas, which, in turn, may predispose uterine smooth muscle cells toward sustained growth.

Regulation of metallothionein II messenger ribonucleic acid measures exogenous estrogen receptor-beta activity in SAOS-2 and LNCaPLN3 cells

Estrogen receptor-beta (ERbeta) is a recently discovered member of the steroid hormone superfamily. Because its distribution is distinct from that of the classical estrogen receptor, and it is expressed in several nonclassical estrogen target tissues (e.g. prostate and bladder), its role in mediating the action of estrogen is unclear. One approach to elucidating the function of this receptor is to identify genes that it regulates. Using differential display, we profiled the messenger RNAs regulated by 17beta-estradiol in SAOS-2 and LNCaPLN3 cells overexpressing ERbeta. Follow-up studies used cells expressing either ERalpha or ERbeta. One gene, metallothionein II, was regulated by both receptor subtypes in LNCaPLN3 cells, but only by ERbeta in SAOS-2 cells. Because cycloheximide blocks this response, induction is probably mediated through regulation of at least one other protein. Identification of endogenous genes that are regulated differentially by ERalpha and ERbeta will be valuable tools in elucidating the function of ERbeta and the mechanisms by which these two receptors regulate transcription.

Identification of osteoblast/osteocyte factor 45 (OF45), a bone-specific cDNA encoding an RGD-containing protein that is highly expressed in osteoblasts and osteocytes

We describe the cloning and characterization of a novel bone-specific cDNA predicted to encode an extracellular matrix protein. This cDNA was identified by subtractive hybridization based upon its high expression in bone marrow-derived osteoblasts. By Northern blot analysis, we detected a single 2-kilobase mRNA transcript in bone, whereas no expression was detected in other tissues. Immunohistochemistry revealed that the protein was expressed highly in osteocytes within trabecular and cortical bone. RNA and protein expression analysis using in vivo marrow ablation as a model of bone remodeling demonstrated that this gene was expressed only in cells that were embedded within bone matrix in contrast to the earlier expression of known osteoblast markers. The cDNA was predicted to encode a serine/glycine-rich secreted peptide containing numerous potential phosphorylation sites and one RGD sequence motif. The interaction of RGD domain-containing peptides with integrins has been shown previously to regulate bone remodeling by promoting recruitment, attachment, and differentiation of osteoblasts and osteoclasts. Secretion of this RGD-containing protein from osteocytes has the potential to regulate cellular activities within the bone environment and thereby may impact bone homeostasis. We propose the name OF45 (osteoblast/osteocyte factor of 45 kDa) for this novel cDNA.