Estrogenic Activity Regulator Research Articles

The potential role of estrogen receptor β2 in breast cancer

Endocrine therapy is provided to all patients with estrogen receptor (ER)-positive breast cancer, but only a subset of them derives clinical benefit. The discovery of ERβ and its five isoforms added another layer of complexity in the regulation of estrogen activity in breast cancer cells. Two large retrospective studies showed conflicting results with regard to the prognostic value of the different ERβ isoforms in patients treated with tamoxifen in an adjuvant setting. This study tested the hypothesis that ERβ1 and, or ERβ2 are correlated with clinical outcome. We identified patients with breast cancer who had undergone surgery at Bucheon St. Mary's Hospital, the Catholic University of Korea, between January 2004 and March 2006. We evaluated 101 consecutive cases for ERβ1 and ERβ2 expression using immunohistochemical staining and obtained other clinicopathology by reviewing medical records. ERβ1 was expressed in 81.2% (79 of 97) and ERβ2 was expressed in 50.5% (51 of 101) of primary breast cancer tissues. Disease-free survival (DFS) and overall survival (OS) of patients with cancers expressing ERβ2 was significantly worse. Moreover, in subgroup analysis according to the tamoxifen treatment, ERβ2 expression was significantly associated with shorter DFS of tamoxifen-treated patients. This study indicates that breast cancer with ERβ2 expression was associated with worse DFS and OS, especially in tamoxifen treated patients. Our results suggest a role for ERβ2 as an independent prognostic marker and might serve as a new therapeutic target.

Excess Estrogen Sulfoconjugation Causes a Weak Sign of Delivery in Somatic Cell Clone Recipient Cows.

This study was conducted to elucidate a factor causing a weak sign of delivery and a prolonged gestation, which are frequently observed in cows carrying somatic clone fetus, in spite of the maturity of fetal size or the occurrence of large offspring syndrome. Till date, several investigators have suggested morphological and functional abnormalities of the placenta in clone fetus in the various gestational stages. However, the roles for the placenta in the final process of clone pregnancy, namely placental estrogen synthesis and regulation of estrogen activity with sulfoconjugation, have not been fully understood. In IETS (2007 in Kyoto, Japan), we reported that prepartum rise of estrone and estradiol-17b concentrations in clone pregnancy was subtle, but estrone-sulfate concentration in clone pregnancy was higher than that in cows carrying fetus derived from in vivo embryo. In this study, we analyzed mRNA expression levels of estrogen-related genes, estrogen sulfotransferase (SULT1E1), estrogen sulfatase (STS) and aromatase (CYP19), in placental tissues, cotyledon (COT) and caruncle (CAR). Placentomes were obtained immediately after purtrition from cows, which delivered clone and in vivo calves after induction of parturition (gestation length was 284 to 289 days). Correlation analyses between mRNA abundances in placental tissues and maternal estrogen concentrations at parturition were performed using the data obtained from clones. Localization of gene expression in placentome was examined with in situ hybridization (SULT1E1 and STS) and immunohistochemistry (CYP19). Number of binucleate cells (BNC), existing in placentome, was counted from sections stained with hematoxylin-eosin. mRNA abundance of SULT1E1 was tended to be high in COT compared with CAR, clone pregnancy showed significantly higher (p<0.05) expression level than in vivo pregnancy. In situ hybridization signal of SULT1E1 was detected in binucleate cells. SULT1E1 mRNA abundance was negatively and positively correlated with maternal estrone (p<0.05) and estrone-sulfate (p<0.05) at parturition, respectively. mRNA abundances of STS and CYP19 were significantly higher in CAR and COT, respectively. In situ hybridization and immunohistochemistry showed that BNC and carunclar epithelial cells expressed both genes. Expression levels of STS and CYP19 mRNA were similar between clone and in vivo pregnancy, and were positively correlated (p<0.05) with maternal estradiol-17b at parturition of clones. Population of BNC in placentome did not differ between clone (vaginally delivered clone; 18.8}1.4/0.1mm2, cesarean section delivered clone; 18.6}1.7/0.1mm2) and in vivo (18.9}1.8/0.1mm2) pregnancy. Therefore, it can be surmised that increased SULT1E1 mRNA abundance in clone placental tissue was due to an increased transcription of the gene, rather than to an increased proportion of SULT1E1 producing BNC. The results obtained here suggested that excess estrogen sulfoconjugation in placenta was reasonable for the confusion of the ratio of unconjugated (active) and sulfoconjugated (inactive) estrogens. The hormonal abnormality would cause the weak sign of delivery and the prolonged gestation in cows carrying clone.

Estrogen sulfotransferase and sulfatase: Roles in the regulation of estrogen activity in human uterine endometrial carcinomas.

The regulation of estrogen activity through the formation and cleavage of sulfoconjugates of estrogens is known to be related to the progression and metastasis of estrogen-dependent breast carcinomas, but the involvement of sulfoconjugates in the steroid stimulation of endometrial functions and the progression of endometrial adenocarcinomas is not clearly understood yet. Estrogen sulfotransferase (EST) in the uterine endometria during the follicular phase was more active than during the luteal phase, but estrogen sulfate (ES) sulfatase exhibited lower activity during the follicular phase than during the luteal phase. However, ES sulfatase activities in cancerous tissues were lower than those in normal endometria and endometrial adenocarcinoma-derived cells, among which the activity was exceedingly high in Ishikawa cells, suggesting that ES sulfatase in Ishikawa cells contributes to the estrogen-dependent growth of these cells. EST activities higher than that in Ishikawa cells were found in only 3 of 24 cancerous tissues. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of the EST and ES sulfatase genes in carcinoma-derived cells demonstrated the extensive expression of both genes in Ishikawa cells. The isolated EST gene was transfected into Ishikawa cells with a mammalian expression vector to establish cell clones with enhanced EST activity, and the estrogen-dependent cell growth of the resultant cell clones was found to be abolished, due to the enhanced sulfoconjugation of estrogen. Since ES sulfatase activity in cancerous tissues was significantly lower than that in Ishikawa cells, it might be not involved in the enhancement of estrogen activity associated with the pathogenesis of endometrial adenocarcinoma tissues.

Regulation of estrogen activity in human endometrium: effect of IL-1beta on steroid sulfatase activity in human endometrial stromal cells.

We investigated the effect of interleukin 1beta (IL-1beta) on steroid sulfatase (STS) activity and the expression of STS mRNA in human endometrial stromal cells. Endometrial tissue samples were obtained from patients undergoing hysterectomy to remove uterine fibroids. Stromal cells were isolated from the tissue preparation and cultured. IL-lbeta (1 approximately 100 ng/ml) was added into the culture medium and incubated for 24 h. The expression of STS mRNA was measured by competitive RT-PCR. The addition of IL-lbeta at 10 and 100 ng/ml suppressed STS mRNA expression to 55.2 +/- 12.8% and 25.1 +/- 10.9%, respectively, of the control sample to which no IL-lbeta had been added. STS activity was measured by radiolabelled steroid metabolite using thin layer chromatography, and this activity was also significantly suppressed in response to the administration of IL-lbeta in a dose-dependent manner. When IL-1 receptor antagonist (IL-1ra) was added together with IL-1beta to the culture medium, mRNA expression and STS activity were recovered. The present study is the first to demonstrate IL-1beta regulation of STS activity locally in human endometrium. IL-1beta suppressed mRNA and activity of STS in stromal cell culture. This initial demonstration of IL-1beta regulation of STS implies that IL-1beta may control the steroid microenvironment in human uterine endometrium by reducing biologic action of estrogen.

Regulation of Estrogen Activity in Human Endometrium: Effect of Cytokines on the Expression of Steroid Sulfatase and Sulfokinase mRNA in Human Endometrial Stromal Cells

Regulation of Estrogen Activity in Human Endometrium: Effect of Cytokines on the Expression of Steroid Sulfatase and Sulfokinase mRNA in Human Endometrial Stromal Cells

Indole-3-Carbinol Is a Negative Regulator of Estrogen Receptor-α Signaling in Human Tumor Cells

Estrogen, via its binding to the estrogen receptor (ER), plays an important role in breast cancer cell proliferation and tumor development. Indole-3-carbinol (I3C), a compound occurring naturally in cruciferous vegetables, exhibits a potent antitumor activity via its regulation of estrogen activity and metabolism. This study was designed to determine the effect of I3C on the potential to inhibit the ER-alpha. Using a reporter gene driven by the estrogen receptor, I3C (10-125 micromol/L) significantly repressed the 17ss-estradiol (E2)-activated ER-alpha signaling in a dose-dependent manner. I3C and breast cancer susceptibility gene 1 (BRCA1) synergistically inhibited transcriptional activity of ER-alpha. Moreover, I3C down-regulated the expression of the estrogen-responsive genes, pS2 and cathepsin-D, and up-regulated BRCA1. The inhibitory effects of I3C did not contribute to its cytotoxic effects because these activities were observed at less than toxic concentrations. These results further suggest that antitumor activities of I3C are associated not only with its regulation of estrogen activity and metabolism, but also its modulation of ER transcription activity.

Regulation of estrogen activity by sulfation in human Ishikawa endometrial adenocarcinoma cells

Sulfation is an important conjugation reaction in the metabolism of steroids. Steroids sulfates do not interact with the appropriate hormone receptors; additionally, the presence of the charged sulfate moiety increases the aqueous solubility and excretion of most steroids. Estrogen sulfotransferase (EST) is the major form of human cytosolic ST involved in the conjugation of estrogens. EST is important in the inactivation of β-estradiol (E2) during the luteal phase of the menstrual cycle. EST has a significantly higher affinity for the sulfation of E2 and 17α-ethinylestradiol (EE2) than for other potent estrogens such as diethylstilbestrol (DES) and equine estrogens. The ability of EST to sulfate these estrogenic compounds at physiologic concentrations is important in regulating their activation of the ER in estrogen responsive cells. Human Ishikawa endometrial adenocarcinoma (ISH) cells possess an estrogen receptor (ER)-regulated alkaline phosphatase (AlkPhos) which is used to assay ER activation. To study the effects of EST activity on the ER activation of different estrogenic compounds, ISH cells were stably transformed with an EST expression vector. Dose–response curves for the induction of AlkPhos activity by the different estrogenic compounds were generated with EST/ISH and control pcDNA/ISH cells. EST/ISH cells were 200-fold less sensitive to E2 and EE2 than were control cells. No differences were observed in the dose–response curves for DES between EST/ISH and pcDNA/ISH cells. EST/ISH cells were approximately 3–10-fold less sensitive to the equine estrogens equilin and 17-equilin as compared to control cells. The ability of EST to decrease the ER activation of an estrogen correlates with the sulfation of these compounds at nanomolar concentrations by EST/ISH and pcDNA/ISH ISH cells. These results indicate that EST is capable of efficiently inactivating E2 and EE2 but is significantly less effective in inhibiting the ER binding of other potent estrogenic compounds.