Unique effect of 4-hydroxyestradiol and its methylation metabolites on lipid and cholesterol profiles in ovariectomized female rats

Strong Protection by 4-Hydroxyestrone against Erastin-Induced Ferroptotic Cell Death in Estrogen Receptor-Negative Human Breast Cancer Cells: Evidence for Protein Disulfide Isomerase as a Mechanistic Target for Protection

Ferroptosis is a recently identified form of regulated cell death, characterized by excessive iron-dependent lipid peroxidation. Recent studies have demonstrated that protein disulfide isomerase (PDI) is an important mediator of chemically induced ferroptosis and also a new target for protection against ferroptosis-associated cell death. In the present study, we identified that 4-hydroxyestrone (4-OH-E1), a metabolic derivative of endogenous estrogen, is a potent small-molecule inhibitor of PDI, and can strongly protect against chemically induced ferroptotic cell death in the estrogen receptor-negative MDA-MB-231 human breast cancer cells. Pull-down and CETSA assays demonstrated that 4-OH-E1 can directly bind to PDI both in vitro and in intact cells. Computational modeling analysis revealed that 4-OH-E1 forms two hydrogen bonds with PDI His256, which is essential for its binding interaction and thus inhibition of PDI's catalytic activity. Additionally, PDI knockdown attenuates the protective effect of 4-OH-E1 as well as cystamine (a known PDI inhibitor) against chemically induced ferroptosis in human breast cancer cells. Importantly, inhibition of PDI by 4-OH-E1 and cystamine or PDI knockdown by siRNAs each markedly reduces iNOS activity and NO accumulation, which has recently been demonstrated to play an important role in erastin-induced ferroptosis. In conclusion, this study demonstrates that 4-OH-E1 is a novel inhibitor of PDI and can strongly inhibit ferroptosis in human breast cancer cells in an estrogen receptor-independent manner. The mechanistic understanding gained from the present study may also aid in understanding the estrogen receptor-independent cytoprotective actions of endogenous estrogen metabolites in many noncancer cell types.

Pharmaceuticals and endocrine disrupting compounds modulate adverse effects of climate change on resource quality in freshwater food webs

Freshwater biodiversity, ecosystem functions and services are changing at an unprecedented rate due to the impacts of vast number of stressors overlapping in time and space. Our study aimed at characterizing individual and combined impacts of pollution with pharmaceuticals (PhACs) and endocrine disrupting compounds (EDCs) and increased water temperature (as a proxy for climate change) on primary producers and first level consumers in freshwaters. We conducted a microcosm experiment with a simplified freshwater food web containing moss (Bryophyta) and shredding caddisfly larvae of Micropterna nycterobia (Trichoptera). The experiment was conducted with four treatments; control (C), increased water temperature + 4 °C (T2), emerging contaminants' mix (EC = 15 PhACs & 5 EDCs), and multiple stressor treatment (MS = EC + T2). Moss exhibited an overall mild response to selected stressors and their combination. Higher water temperature negatively affected development of M. nycterobia through causing earlier emergence of adults and changes in their lipidome profiles. Pollution with PhACs and EDCs had higher impact on metabolism of all life stages of M. nycterobia than warming. Multiple stressor effect was recorded in M. nycterobia adults in metabolic response, lipidome profiles and as a decrease in total lipid content. Sex specific response to stressor effects was observed in adults, with impacts on metabolome generally more pronounced in females, and on lipidome in males. Thus, our study highlights the variability of both single and multiple stressor impacts on different traits, different life stages and sexes of a single insect species. Furthermore, our research suggests that the combined impacts of warming, linked to climate change, and contamination with PhACs and EDCs could have adverse consequences on the population dynamics of aquatic insects. Additionally, these findings point to a potential decrease in the quality of resources available for both aquatic and potentially terrestrial food webs.

Metabolic alteration of circulating steroid hormones in women with gestational diabetes mellitus and the related risk factors

Background

Abnormally changed steroid hormones during pregnancy are closely related to the pathological process of gestational diabetes mellitus (GDM). Our aim was to systematically profile the metabolic alteration of circulating steroid hormones in GDM women and screen for risk factors.

Methods

This study was a case-control study with data measured from 40 GDM women and 70 healthy pregnant women during their 24-28 gestational weeks. 36 kinds of steroid hormones, including 3 kinds of corticosteroids, 2 kinds of progestins, 5 kinds of androgens and 26 kinds of downstream estrogens in serum were systematically measured using a combined sensitive UPLC-MS/MS method. The flux of different metabolic pathways of steroid hormones was analyzed. Logistic regression and ROC curve model analyses were performed to identify potential steroid markers closely associated with GDM development.

Results

Serum corticosteroids, progestins and almost all the estrogen metabolites via 16-pathway from parent estrogens were higher in GDM women compared with healthy controls. Most of the estrogen metabolites via 4-pathway and more than half of the metabolites via 2-pathway were not significantly different. 16α-hydroxyestrone (16OHE1), estrone-glucuronide/sulfate (E1-G/S) and the ratio of total 2-pathway estrogens to total estrogens were screened as three indicators closely related to the risk of GDM development. The adjusted odds ratios of GDM for the highest quartile compared with the lowest were 72.22 (95% CI 11.27-462.71, P _trend <0.001) for 16OHE1 and 6.28 (95% CI 1.74-22.71, P _trend <0.05) for E1-G/S. The ratio of 2-pathway estrogens to total estrogens was negatively associated with the risk of GDM.

Conclusion

The whole metabolic flux from cholesterol to downstream steroid hormones increased in GDM condition. The most significant changes were observed in the 16-pathway metabolism of estrogens, rather than the 2- or 4-pathway or other types of steroid hormones. 16OHE1 may be a strong marker associated with the risk for GDM.

Association of Leu432Val (rs1056836) polymorphism of the CYP1B1 gene with lipid profile in hypertensive Slovak women

Leu432Val (rs1056836) polymorphism of the CYP1B1 gene was examined in relationship with lipid profile in hypertensive Slovak women according to their menopausal status. The entire study sample comprised 255 women suffering from hypertension aged from 39 to 65 years who were recruited from different localities in the western, southern, and middle parts of Slovakia. The participants provided a saliva or blood sample for DNA genotyping and a blood sample for biochemical analysis. The Leu432Val genotypes demonstrated statistically significant associations with all monitored atherogenic indices – total cholesterol-to-HDL-Cholesterol (AI1), Non-HDL-Cholesterol (AI2), LDL-Cholesterol-to-HDL-Cholesterol (AI3), and the logarithm of the ratio of plasma concentration of triglycerides to HDL-cholesterol (AIP log) in hypertensive pre/perimenopausal women. The mean values were significantly lower in women carrying the Val/Val genotype. In early postmenopausal hypertensive women the Leu432Val genotypes were statistically significant and associated with LDL-cholesterol (LDL-C) and AI2. The mean values of LDL-C and AI2 were significantly lower in women carrying the Leu/Leu genotype. In conclusion, the Leu432Val polymorphism may be associated with the atherogenic indices and LDL-C in hypertensive women.

17β-Estradiol-Induced Conformational Changes of Human Microsomal Triglyceride Transfer Protein: A Computational Molecular Modelling Study

Human microsomal triglyceride transfer protein (hMTP) plays an essential role in the assembly of apoB-containing lipoproteins, and has become an important drug target for the treatment of several disease states, such as abetalipoproteinemia, fat malabsorption and familial hypercholesterolemia. hMTP is a heterodimer composed of a larger hMTPα subunit and a smaller hMTPβ subunit (namely, protein disulfide isomerase, hPDI). hPDI can interact with 17β-estradiol (E₂), an endogenous female sex hormone. It has been reported that E₂ can significantly reduce the blood levels of low-density lipoprotein, cholesterol and triglyceride, and modulate liver lipid metabolism in vivo. However, some of the estrogen’s actions on lipid metabolism are not associated with estrogen receptors (ER), and the exact mechanism underlying estrogen’s ER-independent lipid-modulating action is still not clear at present. In this study, the potential influence of E₂ on the stability of the hMTP complex is investigated by jointly using multiple molecular dynamics analyses based on available experimental structures. The molecular dynamics analyses indicate that the hMTP complex in the presence of E₂ has reduced interface contacts and surface areas. A steered molecular dynamics analysis shows that the forces required to separate the two subunits (namely, hPDI and hMTPα subunit) of the hMTP complex in the absence of E₂ are significantly higher than the forces required to separate the complex in which its hPDI is already bound with E₂. E₂ makes the interface between hMTPα and hPDI subunits more flexible and less stable. The results of this study suggest that E₂-induced conformational changes of the hMTP complex might be a novel mechanism partly accounting for the ER-independent lipid-modulating effect of E₂.

Occurrence, seasonal variation and risk evaluation of selected endocrine disrupting compounds and their transformation products in Jiulong river and estuary, China

In the present study, 13 endocrine disrupting compounds (EDCs) and their transformation products (TPs) were monitored in Jiulong River and its estuary, China in different seasons. The analytes included antimicrobials [triclosan (TCS) and triclocarbon (TCC)]; estrogens [estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2)]; alkylphenol ethoxylates [4-n-nonylphenol (NP) and 4-n-octylphenol (OP)] and the TPs [methyl triclosan (MeTCS), carbanilide (NCC), dichlorocarbanilide, 4-hydroxy estrone (4-OH E1) and 4-hydroxy estradiol (4-OH E2)]. A significant seasonal variation was observed for most EDCs. Approximately, 79% of the total E2 residues were detected in the normal season in comparison with the wet season to indicate recalcitrant behavior of E2 during the normal season. Risk assessment revealed that E2 was most potent among the EDCs to cause highest risk to both vertebrate and invertebrate aquatic species, whereas, E1, EE2, MeTCS and TCS also showed relatively high risk for some surface water aquatic species.

The hypolipidemic effects of peptides prepared from Cicer arietinum in ovariectomized rats and HepG2 cells

BACKGROUND

The lack of estrogen in postmenopausal women is a key risk factor for disorders of lipid metabolism and for obesity. Except in cases where estrogen replacement therapy (ERT) is being used, chickpea peptides (ChPs) may be a potential candidate for treating hyperlipidemia.

RESULTS

In ovariectomized rats model, ChPs were found to decrease body weight, adipose tissue size, total cholesterol (TC), total triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and the atherogenic index (AI) in serum and liver TC and TG. Serum high-density lipoprotein cholesterol (HDL-C), bile acids in liver and feces, fecal TC and TG were observed to increase significantly (P < 0.05). ChPs play a role in inhibiting the activities of fatty acid synthetase (FAS) and HMG-CoA reductase (HMGR). The expression of peroxisome proliferator-activated receptors (PPAR)γ and sterol regulatory element-binding protein (SREBP)-1c were downregulated and the expression of liver X receptor (LXR) α, estrogen receptor(ER)α and ERβ were upregulated by ChPs. In HepG2 cell experiments, the cellular TC levels decreased and the uptake of NBD-cholesterol increased significantly after treatment with Mw < 1 kDa and Mw < 5 kDa ChPs fractions. Val-Phe-Val-Arg-Asn (VFVRN) could inhibit TC biosynthesis by decreasing the expression of HMGR.

CONCLUSION

We demonstrated that ChPs could effectively regulate lipid metabolism disorders and restrain obesity caused by estrogen deficiency. Val-Phe-Val-Arg-Asn identified from ChPs could reduce the expression of HMGR to inhibit cholesterol biosynthesis. © 2018 Society of Chemical Industry.