Biotransformation and bioconcentration of steroid estrogens by Chlorella vulgaris

The biotransformation and bioconcentration of natural and synthetic steroid estrogens by Chlorella vulgaris were investigated using batch shaking experiments with incubation for 48 hours in the light or dark. Estradiol and estrone were inter-convertible in both light and dark conditions, however this biotransformation showed a preference to estrone. In the light, 50% of estradiol was further metabolized to an unknown product. Apart from biotransformation, estrone as well as hydroxyestrone, estriol and ethinylestradiol were relatively stable in the algal culture, while estradiol valerate was hydrolyzed to estradiol and then estrone within 3 hours of incubation. All the tested estrogens exhibited a degree of partitioning to C. vulgaris, however, the concentrations of estriol, hydroxyestrone, ethinylestradiol and estradiol valerate were always below the quantification limits. For estradiol and estrone, the partitioning of these estrogens in the algal extracts to the filtrates was below 6% of the total present. The average concentration factor for estrone was around 27, however the concentration factor for estradiol is not reported since no equilibrium was reached between aqueous solution and that within the cells due to continuing biotransformation

17,β-estradiol inhibits hepatitis C virus mainly by interference with the release phase of its life cycle

Rationale & Aim: Estrogen and estrogen-mediated signalling protect from hepatitis C virus through incompletely understood mechanisms. We aimed to ascertain which phase(s) of HCV life cycle is/are affected by estrogens. Methods: Huh7 cells infected with the JFH1 virus (genotype 2a) were exposed to dehydroepiandrosterone, testosterone, progesterone and 17β-estradiol (tested with/without its receptor antagonist fulvestrant). Dose-response curves were established to calculate IC50 values. To dissect how 17β-estradiol interferes with phases of HCV life cycle, its effects were measured on the HCV pseudo-particle system (viral entry), the sub-genomic replicon N17/JFH1 and the replicon cell line Huh7-J17 (viral replication). Finally, in a dual-step infection model, infectious supernatants, collected from infected cells exposed to hormones, were used to infect naïve cells. Results: Progesterone and testosterone showed no inhibitory effect on HCV; dehydroepiandrosterone was only mildly inhibitory. In contrast, 17β-estradiol inhibited infection by 64-67% (IC50 values 140 to 160 nM). Fulvestrant reverted the inhibition by 17β-estradiol in a dose-dependent manner. 17β-estradiol exerted only a slight inhibition (<20%) on HCV pseudo-particles, and had no effect on cells either transiently or stably (Huh7-J17 cells) expressing the N17/JFH1 replicon. In the dual-step infection model, a significant IC50 decline occurred between primary (134 nM) and secondary (100 nM) infections (p=0.02), with extracellular HCV RNA and infectivity being reduced to a higher degree in comparison to its intracellular counterpart. Conclusions: 17β-estradiol inhibits HCV acting through its intracellular receptors, mainly interfering with late phases (assembly/release) of the HCV life cycle

Non-genomic actions of estradiol and 4-OH-tamoxifen on murine breast cancer cells

Estrogens and tamoxifen do not only exert their effects at the genomic level, but also play a role at the cell membrane activating downstream signaling pathways. We recently characterized an estrogen receptor-positive epithelial murine breast cancer cell line, LM05-E. Utilizing this cell line and MCF-7 cells, we compared the non-genomic effects of estradiol and 4-OH-tamoxifen. We showed that, similar to estradiol, tamoxifen activated the MAPK/ERK 1/2 pathway; however, we did not find activation of PI3K/AKT by either estradiol or tamoxifen. Short-term treatments with estradiol stimulated, whereas tamoxifen inhibited cell proliferation. Using pharmacological inhibitors we showed that the effect of estradiol was mediated by the MAPK/ERK 1/2 pathway, but that inhibition of this pathway did not affect tamoxifen. Surprisingly, however, blocking of PI3K/AKT signaling interfered with the inhibitory effect of tamoxifen. Analysis of the involvement of the EGFR support previous findings that designate this receptor as a mediator of the non-genomic effects of estradiol; blocking EGFR also reverses the inhibitory effect of tamoxifen. Finally, matrix metalloproteinases (MMPs) were confirmed to be involved in the proliferative effect of estradiol. These results demonstrated the novel non-genomic effects of tamoxifen and revealed that pathways downstream of EGFR and PI3K/AKT are involved in the inhibition of cell proliferation. Caution should be exercised when analyzing strategies that aim at combining endocrine therapy with specific signaling inhibitors.Fil: Raffo, Diego Alejandro. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pontiggia, Osvaldo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología ; ArgentinaFil: Bal, Elisa Dora. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología ; ArgentinaFil: Simian, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología ; Argentin

3D model of amphioxus steroid receptor complexed with estradiol

The origins of signaling by vertebrate steroids are not fully understood. An important advance was the report that an estrogen-binding steroid receptor [SR] is present in amphioxus, a basal chordate with a similar body plan as vertebrates. To investigate the evolution of estrogen binding to steroid receptors, we constructed a 3D model of amphioxus SR complexed with estradiol. This 3D model indicates that although the SR is activated by estradiol, some interactions between estradiol and human ER[alpha] are not conserved in the SR, which can explain the low affinity of estradiol for the SR. These differences between the SR and ER[alpha] in the steroid-binding domain are sufficient to suggest that another steroid is the physiological regulator of the SR. The 3D model predicts that mutation of Glu-346 to Gln will increase the affinity of testosterone for amphioxus SR and elucidate the evolution of steroid binding to nuclear receptors

Reference Profile Correlation Reveals Estrogen-like Trancriptional Activity of Curcumin

Background: Several secondary metabolites from herbal nutrient products act as weak estrogens (phytoestrogens), competing with endogenous estrogen for binding to the estrogen receptors and inhibiting steroid converting enzymes. However, it is still unclear whether these compounds elicit estrogen dependent transcription of genes at physiological concentrations. Methods: We compare the effects of physiological concentrations (100 nM) of the two phytoestrogens Enterolactone and Quercetin and the suspected phytoestrogen Curcumin on gene expression in the breast cancer cell line MCF7 with the effects elicited by 17-beta-estradiol (E2). Results: All three phytocompounds have weak effects on gene transcription; most of the E2 genes respond to the phytoestrogens in the same direction though to a much lesser extent and in the order Curcumin > Quercetin > Enterolactone. Gene regulation induced by these compounds was low for genes strongly induced by E2 and similar to the latter for genes only weakly regulated by the classic estrogen. Of interest with regard to the treatment of menopausal symptoms, the survival factor Birc5/survivin and the oncogene MYBL1 are strongly induced by E2 but only marginally by phytoestrogens. Conclusion: This approach demonstrates estrogenic effects of putative phytoestrogens at physiological concentrations and shows, for the first time, estrogenic effects of Curcumin. Copyright (C) 2010 S. Karger AG, Base

Influence of 17 beta-estradiol, progesterone, and dexamethasone on diapedesis and viability of bovine blood polymorphonuclear leukocytes

The aim of the current study was to investigate whether polymorphonuclear leukocyte (PMN) diapedesis and viability are influenced by steroid hormones. Using an in vitro model with different types of cell layers ( bovine mammary epithelial cells and fibroblasts), we investigate whether steroid hormone treatments (17beta-estradiol, progesterone, and dexamethasone) have an influence on the diapedesis capacity and viability of PMN. In addition, we studied apoptosis of PMN in the in vitro model and evaluated the influence of different types of cell layers and steroid hormone treatments on this process. A significant decrease in the number of viable PMN in the lower compartment of the in vitro model (i.e., number of migrated PMN x viability after migration) was found after 17beta-estradiol treatment, whereas no influence was detected after progesterone or dexamethasone treatment. The effect of 17beta-estradiol was not due to a lower viability before migration as none of the treatments caused a significant effect on the viability before diapedesis. This treatment effect was not influenced by endogenous 17beta-estradiol or progesterone levels before isolation because there was no correlation between these plasma levels and PMN diapedesis capacity or viability. Furthermore, migration through epithelial cells caused a significant decrease in viability of PMN due to increased apoptosis but not necrosis

Estrogen stimulates dimethylarginine dimethylaminohydrolase activity and the metabolism of asymmetric dimethylarginine.

Background— Experimental evidence suggests that estrogens stimulate the production of nitric oxide (NO) by vascular endothelial cells. This effect has been attributed to increased expression and enzymatic activity of both the constitutive and inducible isoforms of NO synthase. In this study, we have investigated whether estrogens regulate the metabolism or release of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase. Methods and Results— The concentration of ADMA in the plasma of 15 postmenopausal women was 0.722±0.04 μmol/L (mean±SEM). Two weeks after subcutaneous implantation with estradiol, there was an increase in plasma estradiol concentration from 0.693±0.075 to 0.81±87 nmol/L, which was accompanied by a significant fall in plasma ADMA concentration to 0.588±0.03 μmol/L (P=0.006). Human and murine endothelial cell lines previously cultured in estrogen-free medium and then exposed to 17β-estradiol showed a dose-dependent decrease in the release of ADMA. This reached statistical significance at 10−14 mol/L 17β-estradiol and was accompanied by a corresponding increase in the activity of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that catalyzes the metabolism of ADMA. Conclusions— We have demonstrated that estrogens can alter the catabolism and release of ADMA in vitro and reduce the circulating concentration in vivo. We therefore propose that increased DDAH activity and the subsequent fall in ADMA could contribute to the positive effect of estrogen on NO synthesis

Effects of Incubation and Rearing Temperatures on Caiman latirostris Growth

Different studies found that incubation temperature has an influence on the size of Caiman latirostris hatchlings and determines their gonadal sex. Experimental manipulations revealed that the effects of temperature on growth are independent of sex. Ambient temperature after hatching is also an influential factor: juvenile caiman had lower growth at a cool (29°C) vs. a warm temperature (33°C) independent of incubation temperatures. Two-month-old caiman were raised at 2 different temperatures (29 and 33°C) for 100 d. These animals were subjected to different incubation treatments: 29, 31 (females), 33 (males), and 33°C with 17β-estradiol (females). No differences were found in growth based on incubation temperature or sex. Our data indicate that the evolutionary advantage of a temperature-dependent sex determination, if it exists, is not bound to differential growth between the sexes nor to incubation temperature, at least in the 1st stages of life before hatchlings reach their 1st winter. Temperatures during the development and grow-out phases have direct effects on the size of the broad-snouted caiman.Fil: Parachu Marco, Maria Virginia. Proyecto Yacaré; Argentina. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Piña, Carlos Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina. Proyecto Yacaré; Argentina. Universidad Autónoma de Entre Ríos; ArgentinaFil: Simoncini, Melina Soledad. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina. Proyecto Yacaré; ArgentinaFil: Larriera, Alejandro. Proyecto Yacaré; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; Argentin

Weak if any effect of estrogen on spatial memory in rats

In a number of species, males appear to have spatial abilities that are superior to those of females. The favored explanation for this cognitive difference is hormonal: higher testosterone levels in males than in females. An alternative explanation focuses on the role of varying levels of estrogens in females during the estrus cycle; females perform as well as males on days of low estrogen, but more poorly on days of high estrogen. Other investigators have reported that estrogens improve both types of memory processes, which depend on the striatal (nonspatial navigation) and hippocampal (spatial) memory systems. Additionally, estrogens have been found to protect the working memory. These contradictory results initiated the present study, in which ovariectomized female rats were trained to escape in a Morris water maze. The daily trials were preceded by estradiol application in low doses (Experiment I) or in higher doses (Experiment II). In Experiment I, no differences at all were found between the latencies of the treated and control groups to reach a submerged platform in a Morris water maze. In Experiment II, however, the animals treated with the higher dose of estradiol showed a small deficit in the acquisition of the Morris water maze task. This study indicates that estradiol at around the physiological level has no effect on spatial learning and memory functions