Weak Estrogen Research Articles

Combined estrogenic and anti-estrogenic properties of estetrol on breast cancer may provide a safe therapeutic window for the treatment of menopausal symptoms.

Increased risk of breast cancer is a critical side effect associated with the use of a menopausal hormone therapy (MHT). Estetrol (E4) is a natural estrogen produced by the human fetal liver and is a promising compound for clinical use in MHT. However, its impact on breast cancer is controversial and poorly defined. In this preclinical study, we show that E4 acts as a weak estrogen by stimulating the growth of hormone-dependent breast cancer only at concentrations exceeding menopausal therapeutic needs. E4 presents also an antitumor activity by decreasing the strong proliferative effect of estradiol (E2). While estrogen receptor alpha (ERα) is the predominant receptor mediating its effects, the dual weak-estrogenic/anti-estrogenic feature of E4 results from differential signaling pathways activation. Both nuclear and rapid extra-nuclear signaling pathway are necessary for a complete estrogenic effect of E4. However, the antitumor action of E4 is not due to a capacity to antagonize E2-induced nuclear activity. Altogether, our results highlight that E4 has a limited impact on breast cancer and may offer a safe therapeutic window for the treatment of menopausal symptoms.

Bisphenol A accumulation in eggs disrupts the endocrine regulation of growth in rainbow trout larvae

Bisphenol A (BPA), a monomer used in the production of plastics and epoxy resins, is ubiquitously present in the aquatic environment. BPA is considered a weak estrogen in fish, but the effects of this chemical on early developmental events are far from clear. We tested the hypothesis that BPA accumulation in eggs, mimicking maternal transfer, disrupts growth hormone/insulin-like growth factor (GH/IGF) axis function, leading to defects in larval growth in rainbow trout. Trout oocytes were exposed to 0 (control), 0.3, 3, and 30μgml−1 BPA for 3h, which led to an accumulation of around 0, 1, 4 and 40ng BPA per egg, respectively. All treatment groups were fertilized with clean milt and reared in clean water for the rest of the experiment. The embryo BPA content declined over time in all groups and was completely eliminated by 42 days post-fertilization (dpf). Hatchlings from BPA accumulated eggs had higher water content and reduced total energy levels prior to first feed. There was an overall reduction in the specific growth rate and food conversion ratio in larvae reared from BPA-laden eggs. BPA accumulation disrupted the mRNA abundance of genes involved in GH/IGF axis function, including GH isoforms and their receptors, IGF-1 and -2 and IGF receptors, in a life stage-dependent manner. Also, there was a temporal disruption in the mRNA levels of thyroid hormone receptors in the larvae raised from BPA-laden eggs. Altogether, BPA accumulation in eggs, mimicking maternal transfer, affects larval growth and the mode of action involves disruption of genes involved in the GH/IGF and thyroid axes function in trout.

Combined Estrogenic and Antiestrogenic Properties of Estetrol on Breast Cancer may provide a Safe Therapeutic Window for the Treatment of Menopausal Symptoms

Abstract Increased risk of breast cancer is a critical side-effect associated with the use of a menopausal hormone therapy (MHT). Estetrol (E4) is a natural estrogen produced by the human fetal liver and is a promising compound for clinical use in MHT. However, its impact on breast cancer is controversial and poorly defined. In this preclinical study, we show that E4 acts as a weak estrogen by stimulating the growth of hormone-dependent breast cancer only at concentrations exceeding menopausal therapeutic needs. Estetrol (E4) presents also an antitumor activity by decreasing the strong proliferative effect of estradiol (E2). While estrogen receptor alpha (ERá) is the predominant receptor mediating its effects, the dual weak-estrogenic/antiestrogenic feature of E4 results from differential signaling pathways activation. Both nuclear and rapid extranuclear signaling pathway are necessary for a complete estrogenic effect of E4. However, the antitumor action of E4 is not due to a capacity to antagonize E2-induced nuclear activity. Altogether, our results highlight that E4 has a limited impact on breast cancer and may offer a safe therapeutic window for the treatment of menopausal symptoms.

Phytoestrogens and Mitochondrial Biogenesis in Breast Cancer. Influence of Estrogen Receptors Ratio

Phytoestrogens were originally identified as compounds having a close similarity in structure to estrogens and harboring weak estrogen activity. The interest in phytoestrogens as potential therapeutic agents has recently risen in the field of oncology, since population based studies have linked phytoestrogens consumption with a decreased risk of mortality due to several types of cancer. This review departs from the main focus of these articles by describing recent advances in our understanding of phytoestrogen potential action on mitochondria, specifically on mitochondrial biogenesis, dynamics and functionality, as well as mitoptosis in breast cancer. Further studies are necessary to explain the effects of individual phytoestrogens on mitochondrial biogenesis and dynamics and for designing of new therapy targets for cancer treatment, nevertheless area promising therapeutic approach.

Effects of bisphenol A and fadrozole exposures on cyp19a1 expression in the Murray rainbowfish, Melanotaenia fluviatilis.

Several endocrine-disrupting chemicals (EDCs) have been attributed to the alteration of reproduction in fish through disrupting endogenous sex steroidogenic pathways including aromatisation of androgens to oestrogen by CYP19 aromatase. Here we investigate this hypothesis in adult male and female Melanotaenia fluviatilis by examining the mRNA expression of cyp19a1 isoforms after exposure for ≤96 h to two EDCs with contrasting modes of action: one a weak oestrogen mimic, bisphenol A [BPA (100 or 500 μg/L)], and the other a nonsteroidal aromatase inhibitor, fadrozole [FAD (10 or 50 µg/L)]. The results suggest that BPA did not affect cyp19a1a expression significantly at both concentrations, whereas 50 µg/L of FAD significantly upregulated its expression in ovary. In contrast, BPA exposures increased expression of cyp19a1b in brain of both males and females, whilst FAD had contrasting effects in brain: It increased in males but decreased in females. Similar contrasting responses of cyp19a1b were induced by BPA in gonads: upregulation in ovary and downregulation in testis. FAD did not have a significant effect on gonadal expression of cyp19a1b. Collectively, the results suggest that BPA and FAD can disrupt cyp19a1b activity more readily than can cyp19a1a, albeit with contrasting effects in either a tissue- or sex-specific context that is conceivably consistent with their (BPA and FAD) opposing modes of action. Enhanced spatial and temporal sensitivity of cyp19a1b compared with cyp19a1a suggests that brain sex of fish is more susceptible to disruption by environmental pollutants such as BPA and FAD. Therefore, we propose that the response of cyp19a1b in brain tissue of M. fluviatilis is a more suitable indicator of oestrogenic pollution in the aquatic environment.

The Relationship between Umbilical Cord Estrogens and Perinatal Characteristics

Prenatal estrogen exposure is thought to contribute to later life diseases such as breast cancer. However, few studies have directly measured prenatal estrogens and most have relied on proposed "markers" of estrogen exposure. We used a large population-based birth cohort to directly measure the relationship between prenatal estrogens and perinatal characteristics, including putative markers of estrogen exposure. Total estrone (E1), estradiol (E2), estriol (E3), and estetrol (E4) were assayed by liquid chromatography/tandem mass spectrometry from archived mixed arterial and venous serum from 860 umbilical cord blood samples. Values for all estrogens were strongly intercorrelated. Cord estrogen concentrations did not differ between males and females. Levels of all estrogens were reduced in twins and concentrations increased with gestational age. Neither E1 nor E2 was correlated with birth weight, but E3 and E4 levels correlated weakly, whereas onset of labor was associated with higher estrogen concentrations. E1 and E2 concentrations were not associated with preeclampsia in the current pregnancy, but E3 and E4 concentrations were lower in pregnancies complicated by preeclampsia and antepartum hemorrhage. Umbilical cord estrogen concentrations vary with gestational age, mode of delivery, pregnancy complications, and twinning, but not with infant sex. Putative markers of prenatal estrogen exposure, preeclampsia, and birth weight did not correlate with direct fetal measures of the most potent estrogen (E2) but were associated with weaker estrogens (E3 and E4). Twins had lower concentrations of all estrogens. This is the largest and best characterized dataset of prenatal estrogen concentrations, measured using highly accurate mass spectrometry/spectroscopy. These observations represent the new "gold standard" for umbilical cord estrogens, and will inform the interpretation of other datasets and the early life origins of health and disease. Cancer Epidemiol Biomarkers Prev; 23(6); 946-52. ©2014 AACR.

Effects of Estetrol on Migration and Invasion in T47-D Breast Cancer Cells through the Actin Cytoskeleton.

Estetrol (E4) is a natural human estrogen present at high concentrations during pregnancy. Due to its high oral bioavailability and long plasma half-life, E4 is particularly suitable for therapeutic applications. E4 acts as a selective estrogen receptor (ER) modulator, exerting estrogenic actions on the endometrium or the central nervous system, while antagonizing the actions of estradiol in the breast. We tested the effects of E4 on its own or in the presence of 17β-estradiol (E2) on T47-D ER+ breast cancer cell migration and invasion of three-dimensional matrices. E4 administration to T47-D cells weakly stimulated migration and invasion. However, E4 decreased the extent of movement and invasion induced by E2. Breast cancer cell movement requires a remodeling of the actin cytoskeleton. During exposure to E4, a weak, concentration-dependent, re-distribution of actin fibers toward the cell membrane was observed. However, when E4 was added to E2, an inhibition of actin remodeling induced by E2 was seen. Estrogens stimulate ER+ breast cancer cell movement through the ezrin–radixin–moesin family of actin regulatory proteins, inducing actin and cell membrane remodeling. E4 was a weak inducer of moesin phosphorylation on Thr558, which accounts for its functional activation. In co-treatment with E2, E4 blocked the activation of this actin controller in a concentration-related fashion. These effects were obtained through recruitment of estrogen receptor-α. In conclusion, E4 acted as a weak estrogen on breast cancer cell cytoskeleton remodeling and movement. However, when E2 was present, E4 counteracted the stimulatory actions of E2. This contributes to the emerging hypothesis that E4 may be a naturally occurring ER modulator in the breast.

0218: The uterine and vascular actions of estetrol delineate an original distinctive profile of estrogen receptor α modulation, uncoupling nuclear and membrane activation

Estetrol (E4) is a natural estrogen produced by the human fetal liver only during pregnancy. Its distinctive biological profile offers potential benefits in women's health, such as contraception and hormone replacement therapy. The crystal structures of the estrogen receptor α (ERα) ligand binding domain with 17beta-estradiol (E2) and E4 were very similar, whereas these two estrogens showed distinct positioning within phospholipid bilayers. Using in vivo approaches, we demonstrated that high doses of E4 stimulate genomic, ERα-dependent effects in the uterus leading to epithelial proliferation and prevent atheroma in hypercholesterolemic mice to a similar extent as E2. In contrast to E2, however, E4 failed to promote membrane-initiated ERα signaling such as acceleration of endothelial healing. Moreover, E4 antagonized this endothelial effect of E2. We conclude that E4 is a weak estrogen able to modulate the nuclear/transcriptional activity of ERα, and is not only devoid of membrane-initiated steroid signal, but also able to antagonize the membrane effects of E2, thereby delineating a distinctive profile of ERα activation.

Soy protein isolate and estradiol differ in their effects on the mammary gland of weanling male and female rats (818.1)

Isoflavones are phytochemical components of soy diets that bind weakly to estrogen receptors (ERs). To study potential estrogen‐like actions of soy in the mammary gland, we fed weanling male and female Sprague‐Dawley rats a casein diet from PND21 to PND33, the same diet substituting soy protein isolate (SPI) for casein, or the casein diet supplemented with estradiol (E2) at 10 μg/kg/day. In contrast to E2, the SPI diet induced no significant change in mammary morphology. In males, there were 34 genes for which expression changed 蠅2‐fold in the SPI group versus 509 changed significantly by E2, and 8 versus 174 genes in females. Nearly half of SPI‐responsive genes in males were also E2‐responsive, including adipogenic genes. Serum insulin was found to be decreased by SPI in males. SPI and E2 both down‐regulated the expression of ERα (Esr1) in males and females, and ERβ (Esr2) only in males. Chromatin immunoprecipitation (ChIP) revealed an increased binding of ERα to the promoter of the progesterone receptor (Pgr) and Esr1 in both SPI and E2 treated males compared to the casein group but differential recruitment of ERβ. ER promoter binding did not correlate with differences in Pgr mRNA expression. This suggests that SPI fails to recruit appropriate co‐activators at E2‐inducible genes. Our results indicate that SPI behaves like a selective estrogen receptor modulator rather than a weak estrogen in the developing mammary gland.Grant Funding Source: Supported by USDA‐ARS CRIS 6251‐51999‐007‐04S

In vitro metabolism of cis- and trans-permethrin by rat liver microsomes, and its effect on estrogenic and anti-androgenic activities

Permethrin is a widely applied broad-spectrum pyrethroid insecticide that consists of a mixture of cis- and trans-isomers. We examined the changes of estrogenic and anti-androgenic activities resulting from metabolism of the isomers. Both cis- and trans-permethrin were hydrolyzed to 3-phenoxybenzyl alcohol (PBAlc) by rat liver microsomes, but the extent of hydrolysis of trans-permethrin was much greater than that of the cis-isomer. In the presence of NADPH, PBAlc was further transformed to 4′-hydroxylated PBAlc (4′-OH PBAlc), 3-phenoxybenzaldehyde (PBAld) and 3-phenoxybenzoic acid (PBAcid). cis-Permethrin, but not trans-permethrin, also afforded its 4′-hydroxylated derivative (4′-OH cis-permethrin). trans-Permethrin was an anti-androgen, but also showed weak estrogenic activity, while cis-permethrin was a weak estrogen and a weak anti-androgen. After incubation with rat liver microsomes in the presence of NADPH, cis-permethrin but not trans-permethrin was metabolically activated for estrogenic activity. On the other hand, estrogenic activity of trans-permethrin was not changed, but its anti-androgenic activity was enhanced after incubation. 4′-OH PBAlc and PBAlc showed estrogenic activity, while PBAld and PBAlc showed anti-androgenic activity. PBAcid showed neither activity. 4′-OH cis-permethrin showed both estrogenic and anti-androgenic activities. Overall, our results indicate that permethrin is metabolically activated for estrogenic and anti-androgen activities, and the microsomal transformation of permethrin to 4′-OH cis-permethrin, 4′-OH PBAlc and PBAlc contributes to the both metabolic activations.

Monitoring of xenobiotic ligands for human estrogen receptor and aryl hydrocarbon receptor in industrial wastewater effluents

Industrial wastewater contains a variety of toxic substances, which may severely contaminate the aquatic environment if discharged without adequate treatment. In this study, effluents from a thin film transistor liquid crystal display wastewater treatment plant and the receiving water were analyzed by bioassays and liquid chromatography–tandem mass spectrometry to investigate the presence of estrogenic compounds, aryl hydrocarbon receptor (AhR) agonists, and genotoxicants. Xenobiotic AhR agonists were frequently detected and, in particular, strong AhR agonist activity and genotoxicity were found in the suspended solids of the aeration tank outflow. The high AhR agonist activity in the final effluent (FE) and the downstream river water suggested that the treatment plant failed to remove the wastewater-related AhR agonists. In contrast, although significant estrogenic potency could be detected in raw wastewater or effluents from different treatment processes, the FE and the receiving river water exhibited no or weak estrogenicity. Instrumental analysis showed that bisphenol A was often detected in water samples. However, the investigated estrogenic compounds could only account for a small portion of the estrogenicity in the collected samples. Therefore, further investigation is necessary to identify the major estrogenic compounds and AhR agonist contaminants in the wastewater effluents.

Urinary Phytoestrogen Levels and Frailty in Older American Women of the National Health and Nutrition Examination Survey (NHANES) 1999-2002: A Cross-Sectional Study

Background/Aims: A deficit of various hormones during the process of aging and/or a heightened inflammatory state may be causally linked to the development of frailty. Phytoestrogens as weak estrogens, antioxidants, and anti-inflammatory agents may counteract this process. Methods: In a cross-sectional study including two cycles of the National Health and Nutrition Examination Survey (NHANES, i.e. 1999-2002), logistic regression was used to analyze the association between urinary concentrations of isoflavones and lignans and frailty in 600 females aged 50 years or older (median age 66.5 years). Participants were classified as ‘frail' (meeting 3 or more of the 5 frailty criteria), ‘prefrail' (meeting 1 or 2 of the criteria), or ‘robust' (meeting none of the criteria). Four percent were frail. Results: For all of the phytoestrogens considered, the unadjusted OR were lower than 1 but generally not statistically significant aside from the association with O-desmethylangolensin (O-DMA) (OR = 0.76; 95% CI 0.61-0.92). Multivariate analysis did not attenuate this finding (OR = 0.74; 95% CI 0.61-0.90). Conclusions: This first analysis of the relationship between phytoestrogens and frailty revealed an inverse association between urinary O-DMA levels and frailty in women. However, the number of frail women was low. Although this finding may be confounded or biased, it seems worthwhile to intensify research on the potential preventive effects of O-DMA.

Feeding soy protein isolate and treatment with estradiol have different effects on mammary gland morphology and gene expression in weanling male and female rats

Isoflavones are phytochemical components of soy diets that bind weakly to estrogen receptors (ERs). To study potential estrogen-like actions of soy in the mammary gland during early development, we fed weanling male and female Sprague-Dawley rats a semipurified diet with casein as the sole protein source from postnatal day 21 to 33, the same diet substituting soy protein isolate (SPI) for casein, or the casein diet supplemented with estradiol (E2) at 10 μg/kg/day. In contrast to E2, the SPI diet induced no significant change in mammary morphology. In males, there were 34 genes for which expression was changed ≥2-fold in the SPI group vs. 509 changed significantly by E2, and 8 vs. 174 genes in females. Nearly half of SPI-responsive genes in males were also E2 responsive, including adipogenic genes. Serum insulin was found to be decreased by the SPI diet in males. SPI and E2 both downregulated the expression of ERα (Esr1) in males and females, and ERβ (Esr2) only in males. Chromatin immunoprecipitation revealed an increased binding of ERα to the promoter of the progesterone receptor (Pgr) and Esr1 in both SPI- and E2-treated males compared with the casein group but differential recruitment of ERβ. ER promoter binding did not correlate with differences in Pgr mRNA expression. This suggests that SPI fails to recruit appropriate co-activators at E2-inducible genes. Our results indicate that SPI behaves like a selective estrogen receptor modulator rather than a weak estrogen in the developing mammary gland.

Soy and Its Isoflavones: The Truth Behind the Science in Breast Cancer

Epidemiological and migratory evidence suggests that dietary soy consumption can lower the risk for breast cancer. The role of soy isoflavones in cancer prevention and promotion is somewhat unclear. There are two views in terms of soy isoflavones and breast cancer. One line of evidence suggests that soy and its isoflavones have exhibited cancer-preventive properties including lengthening the menstrual cycle, altering estrogen metabolism away from cancerous compounds, and demonstrating anti-proliferative properties in vivo. On the contrary, isoflavones found in soy products are suggested to behave as weak estrogens and as such, much speculation surrounds the influence of soy and/or its isoflavones on hormone-receptor-positive cancers. The objective of this review is to present the latest knowledge regarding the role of soy and its isoflavones with the development and advancement of breast cancer, the safety of soy isoflavones for breast cancer survivors, and a comparison of the carcinogenic effects in animal models following soy isoflavone and estrogen administration. This review compares and contrasts literature in terms of the anti-cancer and cancer-promoting effects of soy isoflavones and estrogen in humans and animal models. In conclusion, current human and animal data provide evidence for several anticancer properties of soy and/or its isoflavones. Although the specific quantities and constituents responsible for the observed anti-cancer effects have not been elucidated, it appears that soy isoflavones do not function as an estrogen, but rather exhibit anti-estrogenic properties. However, their metabolism differs between humans and animals and therefore the outcomes of animal studies may not be applicable to humans. The majority of breast cancer cases are hormone-receptor-positive; therefore, soy isoflavones should be considered a potential anti-cancer therapeutic agent and warrant further investigation.

Expression of 17β-hydroxysteroid dehydrogenase type 1 in gastric cancer

There are several findings suggesting the protective role of estrogens in gastric carcinogenesis. Extragonadal 17β-estradiol (E2) may be formed during estrone (E1) reduction to E2 by 17-β-hydroxysteroid dehydrogenase type 1 (HSD17B1). Therefore, we studied the HSD17B1 transcript and protein levels in primary nontumoral and tumoral gastric tissue from the same 21 patients with gastric cancer (GC). We also assessed the effect of 5-Aza-2′-deoxycytidine (5-dAzaC), on the methylation status of HSD17B1 and its expression and conversion of E1 to E2 in HGC-27 and EPG 85-257 GC cells. We identified the presence of HSD17B1 transcript and protein in HGC-27 and EPG 85-257 GC cells as well as in primary nontumoral and tumoral tissues from patients with GC. Moreover, we found that 5-dAzaC significantly up-regulated the HSD17B1 transcript and protein levels, which is associated with increased conversion of E1 to E2 in HGC-27 and EPG 85-257 GC cells. The changes in HSD17B1 expression in both HGC-27 and EPG 85-257 cells were accompanied by 5-dAzaC induced DNA demethylation in the 5′ flanking region. Our results demonstrated that HSD17B1 expression and its ability to convert the weak estrogen E1 to the more potent E2 can be associated with DNA methylation in the 5′ flanking region in GC cells.

Abstract 2520: Determination of free bisphenol A (BPA) concentrations in breast milk of U.S. women using a sensitive LC/MS/MS method.

Abstract Bisphenol A (BPA) is a synthetic compound with structural similarities to the hormone 17β-estradiol. BPA is a major component of polycarbonate plastics and epoxy resins, which are used in the production of plastic containers, metal can linings, dental sealants, thermal receipt paper and household paper products. Incomplete polymerization of BPA as well as exposure to high temperatures and acidic or basic conditions can cause BPA monomers to leach from these products. Therefore, most people are exposed to BPA and levels have been quantified in human urine, blood, saliva, amniotic fluid, placental tissue, colostrum and breast milk. BPA is a weak estrogen and is considered a potential endocrine disrupting compound in humans. Initially it was thought that BPA was rapidly conjugated and excreted from the body. However, free BPA has been detected in human samples indicating that humans are internally exposed to estrogenically active BPA. The length of time that free BPA remains in circulation in the body and the extent to which it accumulates in tissues, such as the breast, is unknown. Given the known sources of BPA exposure, it is likely that lifestyle habits lead to varying levels of BPA exposure. Repeated use of products that contain or are packaged in materials with a high BPA content can lead to higher exposure rates. The same lifestyle choices resulting in high BPA exposure may also lead to high body mass index (BMI); for example, frequent consumption of carbonated soft drinks is associated with a high BMI in women and these beverages are often packaged in plastic bottles or metal cans that may contain BPA. Two recent studies have demonstrated a relationship between BPA levels in urine and obesity in adults and children. Because of the difficulty in measuring BPA in a complex fatty matrix such as milk, few studies have reported on BPA levels in breast milk, and none have examined the relationship between BMI and BPA. In the present study we optimized a sensitive method for assessing free BPA in breast milk and determined whether the levels of BPA were related to characteristics including age, race, BMI, child's age, and number of children nursed. BPA was separated from breast milk samples from 21 nursing women in the U.S. by solid-phase extraction and subsequently analyzed by HPLC-MS/MS. Free BPA was detected in 71% (15/21) of the breast milk samples. The method detection limit in water was determined to be 0.11 ng/mL. Free BPA concentrations were detected ranging from below the method detection limit to 10.81 ng/mL (median 0.49, mean 3.06, SD 3.85 ng/mL). No statistical difference in BPA concentrations was observed between women with a low BMI (< 21.00, n = 10) and a high BMI (> 27.00, n = 11). However, there was a significant association between BPA concentration and race. Caucasian women (n = 14) had significantly higher levels of free BPA in their breast milk than non-Caucasian women (n = 7) (Two-tailed test: t = 2.54, p < 0.05). Citation Format: Stephanie M. Zimmers, Eva P. Browne, Patrick O'Keefe, Douglas L. Anderton, David A. Reckhow, Kathleen F. Arcaro. Determination of free bisphenol A (BPA) concentrations in breast milk of U.S. women using a sensitive LC/MS/MS method. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2520. doi:10.1158/1538-7445.AM2013-2520

Estrogenic Potency of Benzophenone UV Filters in Breast Cancer Cells: Proliferative and Transcriptional Activity Substantiated by Docking Analysis

The results from recent studies show that some benzophenones (BPs) and their hydroxylated metabolites can function as weak estrogens (E2) in the environment. However, little is known about the structure-activity relationship of these molecules. We have examined the effects of exposure to ten different BPs on the proliferation of estrogen receptor (ER)-positive breast cancer cells and on the transcriptional activity of E2-target genes. We analyzed two genes that are tightly linked with estrogen-mediated proliferation, the CXCL12 and amphiregulin genes and two classical estrogen-responsive genes, the pS2 and progesterone receptor. Significant differences in the BPs efficiency to induce cell proliferation and endogenous E2-target gene expressions were observed. Using ERE-, Sp1-, AP1- and C3-reporter genes that contain different ER-binding sites in their promoter, we also showed significant differences in the BPs efficiency in activation of the ER transactivation. Together, our analyzes showed that the most active molecule is 4-hydroxy-BP. Docking analysis of the interaction of BPs in the ligand-binding pocket of ERα suggests that the minimum structural requirement for the estrogenic activity of BPs is a hydroxyl (OH) group in the phenyl A-ring that allows interaction with Glu-353, Arg-394 or Phe-404, which enhances the stability between BPs and ERα. Our modeling also indicates a loss of interaction between the OH groups of the phenyl B-ring and His-524. In addition, the presence of some OH groups in the phenyl B-ring can create repulsion forces, which may constrain helix 12 in an unfavorable position, explaining the differential estrogenic effects of BPs. These results, together with our analysis of BPs for their potency in activation of cell proliferation and ER-mediated transcription, report an improved understanding of the mechanism and structure–activity relationship of BPs.

The role of lipoxin A4 in endometrial biology and endometriosis.

Lipoxin A4 (LXA4), an endogenous anti-inflammatory and immunomodulatory mediator studied in many disease states, is recently appreciated as a potentially significant player in the endometrium. This eicosanoid, synthesized from arachidonic acid via the action of lipoxygenase enzymes, is likely regulated in endometrial tissue during the menstrual cycle. Recent studies revealed that LXA4 acts as an estrogen receptor agonist in endometrial epithelial cells, antagonizing some estrogen-mediated activities in a manner similar to the weak estrogen estriol, with which it shares structural similarity. LXA4 may also be an anti-inflammatory molecule in the endometrium, though its precise function in various physiological and pathological scenarios remains to be determined. The expression patterns for LXA4 and its receptor in the female reproductive tract suggest a role in pregnancy. The present review provides an oversight of its known and putative roles in the context of immuno-endocrine crosstalk. Endometriosis, a common inflammatory condition and a major cause of infertility and pain, is currently treated by surgery or anti-hormone therapies that are contraceptive and associated with undesirable side effects. LXA4 may represent a potential therapeutic and further research to elucidate its function in endometrial tissue and the peritoneal cavity will undoubtedly provide valuable insights.

The occurrence, causes, and consequences of estrogens in the aquatic environment

The occurrence, causes, and consequences of estrogens in the aquatic environment

In Vitro CYTOTOXIC STUDY FOR PARTIAL PURE LIGNAN EXTRACT FROM FLAX SEED (Linum usitatissirnurn) ON RHABDOMYOSARRCOMA (RD) AND MURINE MAMMARY ADENOCARCINOMA (MMA) CELL LINES

The lignan (Secoisolaricinesinal diglucoside, SDG), was obtained from flaxseed ( Linum usitatissirnurn) appear to act as both anti-estrogens and weak estrogens. The anti-estrogenic potential of lignans has been postulated to protect against hormone sensitive cancers such as breast, prostate and colon cancer. The aim of this study was to examine the cytotoxic effect of partial pure lignan on some cell lines including, the Murine Mammary Adenocarcinoma, Rhabdomyosarcoma RD, L20B and normal cell line (Rat Embryo Fibroblast REF). Four concentrations of partial pure SDG which obtained by using alcohol hydrolysis dioxin / ethanol flaxseed extraction and liquid/liquid partition, have been prepared 5, 10, 15, 20 μM with different of exposure periods 24, 48, 72 h. These parameters have been applied on all cancer and normal cell line. The highest percentage of inhibition appears in 5, 10,15 μM at 24 h (60.11, 49.99, 50.28 %) respectively on RD cell line when treated with partial pure. and the with same concentrations this percentage decreases without any significant difference. In case of L20B cell line in 72 h, the inhibitory effect of partial pure at 5,10 μM, 57.67 and 52.11 % respectively. While the cytotoxicity of partial pure SDG on ANM3 cell line appeared in 24h at 15um which was 64.88%. The lignans are growth inhibitors of colon tumor cells and suggest act through mechanisms other than anti-estrogenic activity.