Expression Of Estrogen-metabolizing Enzymes Research Articles

Estrogen Formation and Inactivation Following TBI: What we Know and Where we Could go.

Traumatic brain injury (TBI) is responsible for various neuronal and cognitive deficits as well as psychosocial dysfunction. Characterized by damage inducing neuroinflammation, this response can cause an acute secondary injury that leads to widespread neurodegeneration and loss of neurological function. Estrogens decrease injury induced neuroinflammation and increase cell survival and neuroprotection and thus are a potential target for use following TBI. While much is known about the role of estrogens as a neuroprotective agent following TBI, less is known regarding their formation and inactivation following damage to the brain. Specifically, very little is known surrounding the majority of enzymes responsible for the production of estrogens. These estrogen metabolizing enzymes (EME) include aromatase, steroid sulfatase (STS), estrogen sulfotransferase (EST/SULT1E1), and some forms of 17β-hydroxysteroid dehydrogenase (HSD17B) and are involved in both the initial conversion and interconversion of estrogens from precursors. This article will review and offer new prospective and ideas on the expression of EMEs following TBI.

Abstract 4298: In-utero, but not pubertal, soy exposure suppresses estrogen-regulated gene expression in non-human primate breast

Abstract Background: Cynomolgus macaques (nonhuman primates, NHP) are highly similar to humans in their genetics, reproductive physiology, and anatomy. More importantly, they undergo a similar mammary gland development process and develop spontaneous breast cancers. Epidemiological studies of humans show that high soy intake is associated with lower breast cancer risk. Since nutrition and/or environmental exposure during youth are critical factors to disease risk in adulthood, timing of intervention may determine soy protective effect to breast cancer. Studies in NHP allow interrogation of developmental effects on the primate breast to a degree not possible in human subjects. We report here novel in-utero developmental effects of soy isoflavones (IF) on the NHP breast. Method: Soy IF were detected in amniotic fluid (255.5 + 93.3 nM) and milk (266.3 nM), which confirmed that soy exposure occurred in-utero and via nursing. We assessed the effects of in-utero and pre-pubertal soy exposure on the breast of NHP during puberty with a focus on changes related to estrogen exposure. We utilized mammary tissues from animals that were exposed to soy beginning in-utero (n=5 for soy and casein/control groups) or before puberty (n=12-17 for soy and casein groups). Animals were fed a diet modeled on a typical North American diet (35% calories from fat) with soy dose approximated at 120-180 mg IF/person/day. We assessed nipple length, mammary gland morphology, markers of mammary gland differentiation, proliferation, and estrogen receptor activity, and concentrations of serum estradiol and progesterone. Results: Regardless of dietary treatment, gene expression of estrogen-responsive markers in the breast was highest during pre-puberty and decreased across the pubertal transition (P<0.0001 for time effect on ESR1, PGR, GREB1, and TFF1). This pattern coincided with a decrease of terminal end bud structures and an increase of lobular differentiation and glandular area. Although an effect of dietary soy was not observed in pre-pubertally exposed animals, in-utero exposed animals showed lower expression of TFF1 (0.03-fold; P<0.05), a classic marker of estrogen receptor alpha (ER) activity. Serum estradiol level was not different with dietary treatment, nor did IF alter mRNA expression of estrogen-metabolizing enzymes in the breast. Conclusions and Future Directions: Our data suggest that timing of exposure may influence the effects of dietary soy on the breast; in-utero soy exposure resulted in modestly lower expression of a gene marker of ER activity, while pre-pubertal exposure had negligible effects on mammary gland outcomes. A follow-up study is currently underway to further examine potential effects of in-utero soy exposure on estrogen responsiveness and pubertal development, and whether epigenetic modulation is the underlying mechanism behind the differential expression of estrogen-related genes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4298. doi:1538-7445.AM2012-4298

The effect of tamoxifen and raloxifene on estrogen metabolism and endometrial cancer risk

Selective estrogen receptor modulators (SERMs) demonstrate differential endometrial cancer (EC) risk. While tamoxifen (TAM) use increases the risk of endometrial hyperplasia and malignancy, raloxifene (RAL) has neutral effects on the uterus. How TAM increases the risk of EC and why TAM and RAL differentially modulate the risk for EC, however, remain elusive. Here, we tested the hypothesis that TAM increases the risk for EC, at least in part, by enhancing the local estrogen biosynthesis and directing estrogen metabolism towards the formation of genotoxic and hormonally active estrogen metabolites. In addition, the differential effects of TAM and RAL in EC risk are attributed to their differential effect on estrogen metabolism/metabolites. The endometrial cancer cell line (Ishikawa cells) and the nonmalignant immortalized human endometrial glandular cell line (EM1) were used for the study. The profile of estrogen/estrogen metabolites (EM), depurinating estrogen-DNA adducts, and the expression of estrogen-metabolizing enzymes in cells treated with 17β-estradiol (E2) alone or in combination with TAM or RAL were investigated using high performance liquid chromatography–electrospray ionization-tandem mass spectrometry (HPLC–ESI-MS 2), ultraperformance liquid chromatography/tandem mass spectrometry (UPLC–MS/MS), and Western blot analysis, respectively. TAM significantly increased the total EM and enhanced the formation of hormonally active and carcinogenic estrogen metabolites, 4-hydroxestrone (4-OHE1) and 16α-hydroxyestrone, with concomitant reduction in the formation of antiestrogenic and anticarcinogenic 2-hydroxyestradiol and 2-methoxyestradiol. Furthermore, TAM increased the formation of depurinating estrogen-DNA adducts 4-OHE1 [2]-1-N7Guanine and 4-OHE1 [2]-1-N3 Adenine. TAM-induced alteration in EM and depurinating DNA adduct formation is associated with altered expression of estrogen metabolizing enzymes CYP1A1, CYP1B1, COMT, NQO1, and SF-1 as revealed by Western blot analysis. In contrast to TAM, RAL has minimal effect on EM, estrogen-DNA adduct formation, or estrogen-metabolizing enzymes expression. These data show that TAM perturbs the balance of estrogen-metabolizing enzymes and alters the disposition of estrogen metabolites, which can explain, at least in part, the mechanism for TAM-induced EC. These results also implicate the differential effect of TAM and RAL on estrogen metabolism/metabolites as a potential mechanism for their disparate effects on the endometrium.

Expression of estrogen-metabolizing enzymes and estrogen receptors in cholelithiasis gallbladder

Background Estrogen exposure is a risk factor for gallstone disease (cholelithiasis), which often leads to chronic inflammation (cholecystitis). Studies in various estrogen-sensitive tissues showed that key enzymes involved in the inactivation and activation of estrogens as well as expression of estrogen receptors α and β determine the amount of active estrogen. In estrogen-sensitive tissues, e.g. the female breast, estrone sulfate (E1S), present at high concentrations in the circulation, is converted into the biologically active estrone (E1) by steroid sulfatase (STS) and again reverted into E1S by estrogen sulfotransferase (SULT1E1) providing a local estrogen storage. Aims To assess whether this might also apply for gallbladder epithelia, we determined expression of these two enzymes and of ERα and ERβ in 15 cholelithiasis specimens from tissues with/or without inflammation. Methods Quantitative (Real-time) PCR and immunofluorescence were used as methods. Results We demonstrate mRNA expression of SULT1E1, STS, and ERα in all specimens with mean enrichment of 3.53- vs. 1.72-fold (n.s.), 3.5- vs. 0.91-fold (n.s.), and 3.04- vs. 1.6-fold (n.s.) in the inflammatory and non-inflammatory groups, respectively. Although high expression levels were seen in many specimens (means 4.88-fold vs. 5.77-fold), ERβ mRNA was below the detection limit in two specimens from cholecystitis patients. To further investigate this varying expression pattern of ERβ, immunohistological studies were performed, which indeed showed low expression levels of ERβ in the damaged mucosa, while in specimens with well preserved mucosa, high ERβ levels were seen in the cytosol and in the nucleus. Conclusion The data show expression of an estrogen network of activating STS and inactivating SULT1E1. Together with ERα and ERβ, these enzymes could regulate estrogen concentrations in human gallbladder.

Relative imbalances in the expression of estrogen-metabolizing enzymes in the breast tissue of women with breast carcinoma

Estrogens are a known risk factor for breast cancer. Studies indicate that initiation of breast cancer may occur by metabolism of estrogens to form abnormally high levels of catechol estrogen-3,4-quinones, which can then react with DNA to form depurinating adducts and, subsequently, induce mutations that lead to cancer. Among the key enzymes metabolizing estrogens are two activating enzymes: cytochrome P450 (CYP)19 (aromatase), which converts androgens to estrogens, and CYP1B1, which converts estrogens predominantly to the 4-catechol estrogens that are further oxidized to catechol estrogen-3,4-quinones. Formation of the quinones is prevented by methylation of the 4-catechol estrogens by the enzyme, catechol-O-methyltransferase (COMT). In addition, catechol estrogen quinones can be reduced back to catechol estrogens by NADPH quinone oxidoreductase 1 (NQO1) and/or are coupled with glutathione, preventing reaction with DNA. Thus, COMT and NQO1 are key deactivating enzymes. In this initial study, we examined whether the expression of these four critical estrogen activating/deactivating enzymes is altered in breast cancer. Control breast tissue was obtained from four women who underwent reduction mammoplasty. Breast tissues from five women with breast carcinoma, who underwent mastectomy, were used as cases. The level of expression of CYP19, CYP1B1, COMT and NQO1 mRNAs was quantified from total RNA using a real time RT-PCR method in an ABI PRISM 7700 sequence detection system. The control breast tissues showed lower expression of the activating enzymes, CYP19 and CYP1B1, and higher expression of the deactivating enzymes, COMT and NQO1, compared to the cases. In the cases, the reverse pattern was observed: greater expression of activating enzymes and lower expression of deactivating enzymes. Thus, in women with breast cancer, estrogen metabolism may be related to altered expression of multiple genes. These unbalances appear to be instrumental in causing excessive formation of catechol estrogen quinones that, by reacting with DNA, initiate the series of events leading to breast cancer.