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Query: UMLS:C0476089 (endometrial cancer)
 11,379 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pattern of transcriptional activation by 17beta-estradiol (E2) and 4-hydroxytamoxifen (4-OHT) was determined in ZR-75 and MDA-MB-231 breast, ECC1 and HEC1A endometrial and HepG2 liver cancer cell lines cotransfected with E2-responsive constructs and wild-type estrogen receptor alpha (ER alpha) or ER beta (ER beta) or variant forms of ER alpha expressing activation function 1, AF1 (ER alpha-AF1) or activation function 2, AF2 (ER alpha-AF2). The E2-responsive constructs contained promoter inserts from the human complement C3 (pC3), human cathepsin D (pCD) and rat creatine kinase B (pCKB) genes. Minimal ER beta-dependent transactivation (<2.5-fold induction) was observed for E2 only in ECC1 and MDA-MB-231 cells transfected with pCKB or pC3, whereas 4-OHT was inactive as an ER beta agonist for all promoters in the four cell lines. The ER alpha agonist and/or antagonist activities for E2 and 4-OHT were highly variable and the transactivation was dependent on ER subtype, ER alpha variant expressed, gene promoter, and cell context. For example, E2 did not activate pCD in HepG2 cells transfected with wild-type or variant ER alpha, whereas E2 activated reporter gene activity in the four endometrial and breast cancer cell lines transfected with ER alpha and pCD, pCKB or pC3. Hormone activation of these constructs by ER alpha-AF1 or ER alpha-AF2 was highly variable among the different cell lines and even in the same cell line transfected with the three E2-responsive constructs. Similar variability was observed for 4-OHT. For example, 4-OHT activates pC3 in HepG2 cells transfected with ER alpha or ER alpha-AF1, and pCKB in HEC1A cells. However, AF1-dependent activation by 4-OHT is not observed for pCKB in ECC1 cells or for pC3 and pCD in HEC1A or ECC1 endometrial cancer cells. The results of this study suggest that transcriptional activation by E2 and 4-OHT induces recruitment of different transcription factor complexes that are dependent on the cell type and also the gene promoter.
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PMID:17 beta-estradiol- and 4-hydroxytamoxifen-induced transactivation in breast, endometrial and liver cancer cells is dependent on ER-subtype, cell and promoter context. 1264 21

Despite their versatility and power in controlling gene regulation in nature, nuclear hormone receptors (NHRs) have largely eluded utility in heterologous gene regulation applications such as gene therapy and metabolic engineering. The main reason for this void is the pleiotropic interference of the receptor-ligand combination with regulatory networks in the host organism. In recent years, numerous strategies have been developed to engineer ligand-receptor pairs that do not cross-interact with host regulatory pathways. However, these strategies have either met with limited success or cannot be readily extended to other ligand-receptor pairs. Here, we present a simple, effective, and readily generalizable strategy for reengineering NHRs to respond specifically to a selected synthetic ligand. The method involves generation of genetic diversity by stepwise individual site saturation mutagenesis of a fixed set of ligand-contacting residues and random point mutagenesis, followed by phenotypic screening based on a yeast two-hybrid system. As a test case, this method was used to alter the specificity of the NHR human estrogen receptor alpha in favor of the synthetic ligand 4,4'-dihydroxybenzil, relative to the natural ligand 17beta-estradiol, by >10(7)-fold. The resulting ligand-receptor pair is highly sensitive to the synthetic ligand in human endometrial cancer cells and is essentially fully orthogonal to the wild-type receptor-natural ligand pair. This method should provide a powerful, broadly applicable tool for engineering receptors/enzymes with improved or novel ligand/substrate specificity.
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PMID:Directed evolution of specific receptor-ligand pairs for use in the creation of gene switches. 1581 44

A novel in vivo model of tamoxifen-stimulated endometrial cancer was developed and the role of HER-2/neu investigated by using trastuzumab. Tamoxifen-stimulated tumors (ECC-1TAM) were growth stimulated by 17beta-estradiol (E2), tamoxifen, or raloxifene. Trastuzumab inhibited growth of E2-stimulated ECC-1E2 tumors by 50% and tamoxifen-stimulated ECC-1TAM tumors by 100%. ECC-1 tumors expressed functional estrogen receptor alpha (ER alpha) as measured by induction of pS2 and c-myc mRNAs. E2 induced pS2 and c-myc mRNAs up to 40-fold in ECC-1E2 and ECC-1TAM. Tamoxifen induced pS2 and c-myc mRNAs up to 5-fold in ECC-1E2 tumors and up to 10-fold in ECC-TAM tumors. Trastuzumab blocked E2-induced pS2 mRNA (P < 0.01) in ECC-1E2 by 50% and tamoxifen-induced c-myc mRNA (P < 0.1) in ECC-1TAM tumors by 70%. Trastuzumab decreased phosphorylated and total HER-2/neu protein in ECC-1E2 and ECC-1TAM tumors. However, only phospho-ERK-1/2 and not phospho-Akt protein was decreased by trastuzumab in tamoxifen-treated ECC-1TAM tumors. The insulin-like growth factor (IGF-I) signaling pathway also activates extracellular signal-related kinase (ERK)-1/2 and could block the efficacy of trastuzumab in ECC-1E2 tumors. The results showed that IGF-I, IGF-IR mRNAs, and phospho-insulin receptor substrate-1 (IRS-1) protein were decreased in ECC-1TAM compared with ECC-1E2 tumors. The results show that trastuzumab is an effective therapy for both E2-stimulated and tamoxifen-stimulated endometrial cancer. The data suggest estrogenic activities of E2 and tamoxifen at ER alpha-regulated pS2 and c-myc genes are in part mediated by HER-2/neu. However, trastuzumab is a better growth inhibitor of ECC-1TAM tumors where there is diminished IGF-I signaling allowing for complete blockade of the downstream phospho-ERK-1/2 signal.
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PMID:Trastuzumab therapy for tamoxifen-stimulated endometrial cancer. 1616 31

The growth of both normal and transformed epithelial cells of the female reproductive system is stimulated by estrogens, mainly through the activation of estrogen receptor alpha (ERalpha), which is a ligand-regulated transcription factor. The selective ER modulator tamoxifen (TAM) has been widely used as an ER antagonist in breast tumor; however, long-term treatment is associated with an increased risk of endometrial cancer. To provide new insights into the potential mechanisms involved in the agonistic activity exerted by TAM in the uterus, we evaluated the potential of 4-hydroxytamoxifen (OHT), the active metabolite of TAM, to transactivate wild-type ERalpha and its splice variant expressed in Ishikawa and HEC1A endometrial tumor cells, respectively. OHT was able to antagonize only the activation of ERalpha by 17beta-estradiol (E2) in Ishikawa cells, whereas it up-regulated c-fos expression in a rapid manner similar to E2 and independently of ERalpha in both cell lines. This stimulation occurred through the G protein-coupled receptor named GPR30 and required Src-related and epidermal growth factor receptor tyrosine kinase activities, along with the activation of both ERK1/2 and phosphatidylinositol 3-kinase/AKT pathways. Most importantly, OHT, like E2, stimulated the proliferation of Ishikawa as well as HEC1A cells. Transfecting a GPR30 antisense expression vector in both endometrial cancer cell lines, OHT was no longer able to induce growth effects, whereas the proliferative response to E2 was completely abrogated only in HEC1A cells. Furthermore, in the presence of the inhibitors of MAPK and phosphatidylinositol 3-kinase pathways, PD 98059 and wortmannin, respectively, E2 and OHT did not elicit growth stimulation. Our data demonstrate a new mode of action of E2 and OHT in endometrial cancer cells, contributing to a better understanding of the molecular mechanisms involved in their uterine agonistic activity.
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PMID:The G protein-coupled receptor GPR30 mediates the proliferative effects induced by 17beta-estradiol and hydroxytamoxifen in endometrial cancer cells. 1623 58

Estrogen-stimulated growth of the malignant human endometrium can be balanced by the differentiating properties of progesterone. To study the molecular basis behind this, gene expression profiling was performed using complementary DNA microarray analysis. In this study, the human endometrial cancer cell lines ECC-1 and PRAB-36 were used as models. The ECC-1 cell line, which expresses high levels of estrogen receptor alpha and is stimulated in growth by estrogens, was used to study estrogen regulation of gene expression. The Ishikawa sub-cell line PRAB-36, expressing both PRA and PRB, progesterone receptor isoforms, and inhibited in growth by progestagens, was used to study progesterone regulation of gene expression. Using these two well-differentiated human endometrial cancer cell lines, 148 estrogen- and 148 progesterone-regulated genes were identified. After functional classification, the estrogen- and progesterone-regulated genes could be categorized in different biologically relevant groups. Within the group of "cell growth and/or maintenance," 81 genes were clustered, from which a number of genes could be involved in arranging the cross talk that exists between estrogen and progesterone signaling. On the basis of analysis of the current findings, it is hypothesized that cross talk between estrogen and progestagen signaling does not occur by counterregulation of single genes, but rather at the level of differential regulation of different genes within the same functional families.
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PMID:Growth regulation and transcriptional activities of estrogen and progesterone in human endometrial cancer cells. 1644 20

The estrogen receptor alpha (ERalpha) has proven to be the single most important target in breast cancer over the last 30 years. The use of the selective ER modulator (SERM) tamoxifen for the treatment and prevention of breast cancer has changed therapeutics. The SERM raloxifene, approved for the treatment of osteoporosis, lacks tamoxifen's increased risk for endometrial cancer and is being evaluated for the prevention of breast cancer. Other SERMs approved or under development for use against breast cancer or osteoporosis include toremifene, GW5638, GW7604 (the active metabolite of GW5638), idoxifene, lasofoxifene, arzoxifene, bazedoxifene, EM-800 and acolbifene (the active metabolite of EM-800). Aromatase inhibitors (AIs) have recently proven to be more efficacious than tamoxifen as first-line therapy, efficacious for second-line therapy (e.g. against tamoxifen-resistant disease), and useful for extended adjuvant therapy after tamoxifen. The AIs include the non-steroidal agents letrozole and anastrole, and the steroidal agent exemestane. The pure antiestrogen fulvestrant has proven to be just as effective as AIs. Other pure antiestrogens, ZK-703, ZK-253, RU 58668 and TAS-108 show great promise. The development of resistance to endocrine therapy remains a clinically important problem, and laboratory models based on human breast cancer cells grown as tumors in immune-compromised mice have led to important insights into this problem. Progesterone receptor-negative status of ER-positive breast cancers may reflect altered growth factor receptor signaling, and helps to explain why this subclass of tumors exhibits lower response rates to tamoxifen compared to cancers typed progesterone receptor-positive. Crosstalk among plasma membrane-localized ER, growth factor receptor signaling, and nuclear-localized ER provide further insights into antihormonal-resistant breast cancer.
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PMID:Estrogen receptors as therapeutic targets in breast cancer. 1651 78

PTEN is a tumor suppressor gene frequently mutated in human cancers. In vitro and in vivo studies have shown that PTEN can exert its tumor suppressive function through a variety of mechanisms, including regulation of cell death and cell proliferation. However, it is still unclear which of the many downstream pathways are critical in each different tissue, in vivo. Loss of PTEN is the earliest detectable genetic lesion in the estrogen-related type I (endometrioid) endometrial cancer. Pten(+/-) mice develop endometrial neoplastic lesions with full penetrance, thus providing a model system to dissect the genetic and biochemical events leading to the transition from normal to hyperplastic and neoplastic endometrial epithelium. Here, we show that loss of Pten in the mouse endometrium activates Akt and results in increased phosphorylation of estrogen receptor alpha (ERalpha) on Ser(167). ERalpha phosphorylation results, in turn, in the activation of this nuclear receptor both in vivo and in vitro, even in the absence of ligand, and in its increased ability to activate the transcription of several of its target genes. Strikingly, reduction of endometrial ERalpha levels and activity dramatically reduces the neoplastic effect of Pten loss in the endometrium, in contrast to complete estrogen depletion. Thus, we provide for the first time in vivo evidence supporting the hypothesis that loss of Pten and subsequent Akt activation result in the activation of ERalpha-dependent pathways that play a pivotal role in the neoplastic process.
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PMID:Akt-mediated phosphorylation and activation of estrogen receptor alpha is required for endometrial neoplastic transformation in Pten+/- mice. 1658 56

Loss of PTEN is the earliest detectable genetic lesion in the endometrioid subtype of endometrial cancer (EEC), a tumor thought to be associated with an increase in unopposed estrogen activity. Pten(+/-) mice develop endometrial neoplastic lesions with full penetrance, despite having normal estrogen levels. We have utilized oligonucleotide arrays to identify the alterations in gene expression patterns associated with loss of Pten and consequent neoplastic transformation of the endometrium. We show that 487 and 330 genes are substantially up- and downregulated, respectively, in Pten(+/-) mice. Several genes whose expression levels are impacted by loss of Pten are associated with pathways and functions that are relevant to the transformation and progression processes. Strikingly, we found that the expression levels of over 100 genes known to be regulated by estrogen receptor alpha (ERalpha) are also altered in the neoplastic uterus from Pten(+/-) mice, thus mimicking a hyperestrogenic environment. These results provide in vivo evidence supporting the hypothesis that loss of Pten and subsequent Akt activation result in the activation of several ERalpha-dependent pathways that, mimicking increased estrogen signaling, may play a pivotal role in the neoplastic process.
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PMID:Gene expression analysis reveals a signature of estrogen receptor activation upon loss of Pten in a mouse model of endometrial cancer. 1668 64

Polycystic ovarian syndrome (PCOS) is a common endocrinopathy characterized by oligo/anovulatiaon and elevated circulating androgens or evidence of hyperandrogenism after all known potential causes have been excluded. In addition, insulin resistance and accompanying hyperinsulinemia commonly occur in women with PCOS. There is increasing evidence that the endocrinologic and metabolic abnormalities in PCOS may have complex effects on the endometrium, contributing to the infertility and endometrial disorders observed in women with this syndrome. Androgen receptors and steroid receptor co-activators are over-expressed in the endometrium of women with PCOS. Also, biomarkers of endometrial receptivity to embryonic implantation-such as alpha(v)beta3-integrin and glycodelin-are decreased, and epithelial expression of estrogen receptor alpha (ERalpha) abnormally persists in the window of implantation in endometrium in women with PCOS. In addition to being responsive to the steroid hormones estradiol, progesterone, and androgens, the endometrium is also a target for insulin, the receptor for which is cyclically regulated in normo-ovulatory women. In vitro, insulin inhibits the normal process of endometrial stromal differentiation (decidualization). In addition, insulin-like growth factors (IGFs) and their binding proteins are regulated in and act on endometrial cellular constituents, and hyperinsulinemia down-regulates hepatic IGFBP-1, resulting in elevated free IGF-I in the circulation. Thus, elevated estrogen (without the opposing effects of progesterone in the absence of ovulation), hyperinsulinemia, elevated free IGF-I and androgens, and obesity all likely contribute to endometrial dysfunction, infertility, increased miscarriage rate, endometrial hyperplasia, and endometrial cancer common in women with PCOS. The potential mechanisms underlying these disorders, specifically in women with PCOS, are complex and await additional transdisciplinary research for their complete elucidation.
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PMID:Endometrium in PCOS: Implantation and predisposition to endocrine CA. 1677 54

Fractionation of the neutral extract of Onobrychis ebenoides (Leguminosae) yielded a new isoflavone, named ebenosin (1), in addition to the known ones, afrormosin (2), formononetin (3) and daidzein (4). Although the relative binding affinities of 1 - 4 for estrogen receptor alpha (ERalpha) were nearly comparable and matched those of 1-3 for ERbeta, that of 4 for the latter receptor was significantly higher than any of the other. Compounds 1 - 4 induced cell proliferation and gene expression in breast and endometrial cancer cells in an ER-dependent manner. Nonetheless, the rank order of induction potencies ( 4 > 3 >or= 2 >or= 1) matched better that of affinities for ERbeta ( 4 > 3 >or= 2 >or= 1) rather than ERalpha ( 4 >or= 3 >or= 2 >or= 1). While the antiestrogen ICI 182,780 could inhibit the induction of proliferation of ER-positive breast cancer cells by 1-4, it could not prevent 1 from exhibiting significant ER-independent cytotoxicity at 10 microM. By contrast, 1 was much less cytotoxic and only weakly estrogenic for ER-positive endometrial adenocarcinoma cells. In conclusion, our data suggest that the C-8 isoprenyl substituent of 1 renders it cytotoxic and/or estrogenic in a cell-dependent manner.
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PMID:Estrogenic activity of isoflavonoids from Onobrychis ebenoides. 1677 31


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