Chlorinated biphenyls effect on estrogen-related receptor expression, steroid secretion, mitochondria ultrastructure but not on mitochondrial membrane potential in Leydig cells

Status of estrogen receptor expression and epigenetic methylation in Leydig cells after exposure to metalloestrogen - selenium

The trace element selenium (Se) is essential for the maintenance of spermatogenesis and fertility. A growing volume of evidence shows that Se is necessary for testosterone synthesis, and Se can stimulate Leydig cell proliferation. However, Se can also act as a metalloestrogen, which can mimic estrogen and activate the estrogen receptors. This study aimed to investigate Se effect on estrogen signaling and the epigenetic status of Leydig cells. Mouse Leydig cells (MA-10) were cultured in a medium supplemented with different Se concentrations (4, 8µM) for 24hours. Next, cells were assessed for morphological and molecular (qRT PCR, western blot, immunofluorescence) analyses. Immunofluorescence revealed strong immunosignal for 5-methylcytosine in both control and treated cells, with a stronger signal in the 8μM treated group. qRT-PCR confirmed an increased expression of methyltransferase 3β (Dnmt3b) in 8μM cells. Analysis of the expression of γH2AX (a marker for double-stranded DNA breaks) revealed an increase in the DNA breaks in cells exposed to 8μM Se. Selenium exposure did not affect the expression of canonical estrogen receptors (ERα and ERβ), however, an increase in membrane estrogen receptor G-protein coupled (GPER) protein expression was observed. To sum up, in a high concentration (8μM) Se affects GPER expression (non-genomic estrogen signaling) in Leydig cells possibly via acting on receptor protein and/or its binding. This causes DNA breaks and induces changes in Leydig cell methylation status, especially in de novo methylation which is mediated by Dnmt3b.

Changes in Polychlorinated Biphenyl Residues in Milk during Lactation: Levels of Contamination, Influencing Factors, and Infant Risk Assessment

Given the importance of breastfeeding infants, the contamination of human milk is a significant public concern. The aim of this study was to assess the contamination of human milk with dioxin-like PCBs (dl-PCBs) and non-dioxin-like PCBs (ndl-PCBs) in relation to the duration of lactation and other influencing factors, especially the frequency of the consumption of selected foods during pregnancy. Based on this, the health risk to infants was assessed and compared to the tolerable daily intake (TDI). PCB determinations were performed using gas chromatography/mass spectrometry. The ∑ndl-PCB content ranged from 0.008 to 0.897 ng/g w.w., at an average of 0.552 ng/g wet weight, which was 55% of the maximum level according to the EU guidelines for foods for infants and young children. The toxic equivalent (TEQ) was in the range of 0.033-5.67 pg-TEQ/g w.w. The content of non-ortho, mono-ortho, and ndl-PCBs in human milk decreased the longer lactation continued. Moreover, when pregnant women smoked tobacco, this correlated significantly with increases in the concentrations of PCB congeners 156, 118, and 189 in human milk. The human milk contents of PCB congeners 77, 81, 186, 118, and 189 were strongly positively correlated with the amount of fish consumed. The content of stable congeners PCB 135 and PCB 153 increased with age.

Effect of prevalent polychlorinated biphenyls (PCBs) food contaminant on the MCF7, LNCap and MDA-MB-231 cell lines viability and PON1 gene expression level: proposed model of binding

BACKGROUND

Polychlorinated biphenyls (PCBs) are a group of synthetic organic chlorine compounds known as an organic pollutant in food sources, which play important roles in malignancies. The present study aimed to investigate the direct effects of prevalent PCBs in food in hormone-responsive and non-responsive cell lines.

METHODS

In the current study, MCF-7, LNCap, and MDA-MB231 cell lines were treated with serial concentrations (0.001-100 μM) of PCBs for 48 h and cell viability assessment was performed using MTT assay. The best concentration then applied and the expression level of PON1 was evaluated using real-time PCR. Besides, molecular docking was performed to determine the binding mechanism and predicted binding energies of PBCs compounds to the AhR receptor.

RESULTS

Unlike MCF-7 and LNCap cells, the viability of MDA-MB231 cells did not significantly change by different concentrations of PCBs. Meanwhile, quantitative gene expression analysis showed that the PON1 was significantly more expressed in MCF-7 and LNCap lines treated with PCB28 and PCB101. However, the expression level of this gene in other groups and also MDA-MB231cells did not demonstrate any significantly change. Also, the results of molecular docking showed that PBCs had steric interaction with AhR receptor.

CONCLUSIONS

Current results showed that despite of hormone non-responsive cells the PCBs have a significant positive effect on hormone-responsive cell. Therefore, and regarding to the existence of PCBs contamination in food there should be serious concern about their impact on the prevalence of different malignancies which certainly should result in a standard limit for this material. This study aimed to investigate the direct effects of prevalent PCBs in food in hormone-responsive and non-responsive cell lines. Cell lines were treated with serial concentrations of PCBs and cell viability assessment was performed using MTT assay. The expression level of PON1 was evaluated using real-time PCR. Molecular docking was performed to determine the binding mechanism and predicted binding energies of PBCs compounds to the AhR receptor. PCBs contamination in food there should be serious concern about their impact on the prevalence of different malignancies which certainly should result in a standard limit for this material.

Dynamic transcriptome response in Meretrix meretrix to Aroclor 1254 exposure

Polychlorinated biphenyls (PCBs) are well-known persistent organic pollutants; they have toxic effects on the immune system, reproductive system, and endocrine system by changing the metabolism of the body. To elucidate the underlying molecular mechanism, the clam Meretrix meretrix was exposed to 10 and 1000 ng/L Aroclor 1254 and natural seawater (control). Samples from clams exposed to natural seawater and those exposed to Aroclor 1254 for 1 and 3 days were individually collected for transcriptome analysis. After assembly, more than 535,157 transcripts with a mean length of 949 bp and an N50 length of 1279 bp were obtained; a final set of 177,142 unigenes was generated. In the present study, 5101 differentially expressed genes were identified. The differentially expressed genes were related to detoxification metabolism, oxidative stress, immune response, and endocrine system disruption. Of these genes, under the Aroclor 1254 exposure, cytochrome P450 20A1 (2.06-4.46 folds), glutathione S-transferase (2.25-3.80 folds), multidrug resistance-associated protein 1-like (1.49-2.92 folds), peroxidase-like protein (1.33-4.26 folds), lysozyme (1.61-2.05 folds), bcl-2 like 1 protein (1.14-2.29 folds) and vitellogenin (1.09-1.19 folds) showed been significantly induced expressed. At the same time, some genes were down regulated, including cytochrome P450 2J5 (-1.20 ~ -2.86 folds), cytochrome P450 3A24 (-1.40 ~ -4.08 folds), C1q (-1.27 ~ -1.66 folds), Sulfotransferase (-1.51 ~ -1.84 folds), monocarboxylate transporter 10 (-1.30 ~ -4.70 folds), 3-beta hydroxysteroid dehydrogenase (-1.43 ~ -2.81 folds) and beta-galactosidase (-1.23 ~ -2.23 folds). Furthermore, it showed that the expression levels of CYP2J5, glutathione S-transferase, 3-beta hydroxysteroid dehydrogenase and beta-galactosidase had time responses and dose responses. The present study provided insights into the toxic effects of Aroclor 1254 exposure in M. meretrix.

Cell membrane-related toxic responses and disruption of intercellular communication in PCB mechanisms of toxicity: A review

An understanding of polychlorinated biphenyl (PCB) congener-specific effects on cell membrane and intercellular communication is important within the studies of PCB absorption, organ-related PCB accumulation and exertion of toxic responses. Toxic potential of PCBs is linked to various deleterious effects on human health, including neurotoxicity, immunotoxicity, reproductive toxicity and genotoxicity and, recently in 2016 International Agency for Research on Cancer (IARC) has upgraded the classification of PCBs to Group 1 "Carcinogenic to humans." Proposed mechanisms of aforementioned PCBs adverse effects at cellular membrane level are: (i) downregulation of gap junction intercellular communication and/or connexins; (ii) compromised membrane integrity; and (iii) altered tight junction barrier function. This study, based on an extensive literature survey, shows the progress in scientific research of each of these three levels with the aim of pointing out the earliest toxic events of PCBs, which can result in serious cell/tissue/organ damage.

The meaning of non-classical estrogen receptors and peroxisome proliferator-activated receptor for boar Leydig cell of immature testis

Communication in biological systems involves diverse-types of cell-cell interaction including cross-talk between receptors expressed by the target cells. Recently, novel sort of estrogen receptors (G protein - coupled estrogen receptor; GPER and estrogen-related receptor; ERR) that signal directly via estrogen binding and/or via mutual interaction-regulated estrogen signaling were reported in various organs including testis. Peroxisome proliferator - activated receptor (PPAR) is responsible for maintaining of lipid homeostasis that is critical for sex steroid production in the testis. Here, we investigated the role of interaction between GPER, ERRβ and PPARγ in steroidogenic Leydig cells of immature boar testis. Testicular fragments cultured ex vivo were treated with GPER or PPARγ antagonists. Then, cell ultrastructure, expression and localization of GPER, ERRβ, PPARγ together with the molecular receptor mechanism, through cyclic AMP and Raf/Ras/extracellular signal activated kinases (ERK), in the control of cholesterol concentration and estrogen production by Leydig cells were studied. In the ultrastructure of antagonist-treated Leydig cells, mitochondria were not branched and not bifurcated as they were found in control. Additionally, in PPARγ-blocked Leydig cells changes in the number of lipid droplets were revealed. Independent of used antagonist, western blot revealed decreased co-expression of GPER, ERRβ, PPARγ with exception of increased expression of ERRβ after PPARγ blockage. Immunohistochemistry confirmed presence of all receptors partially located in the nucleus or cytoplasm of Leydig cells of both control and treated testes. Changes in receptor expression, decreased cholesterol and increased estradiol tissue concentrations occurred through decreased cAMP level (with exception after GPER blockage) as well as Raf/Ras/ERK pathway expression. These all findings indicate that GPER-ERRβ-PPARγ interaction exists in immature boar testis and regulates Leydig cell function. Further detailed studies and considerations on GPER-ERRβ-PPARγ as possible diagnosis/therapy target in disturbances of testis steroidogenic function are needed.

Effect of estrogen-related receptor silencing on miRNA protein machinery expression, global methylation, and deacetylation in bank vole (Myodes glareolus) and mouse tumor Leydig cells

The function of estrogen-related receptor (ERR) in testicular cells is at the beginning of exploration. Our previous findings showed that expression pattern of estrogen-related receptor (ERR) in mouse Leydig cell depends on physiological status of the cell. Exogenous hormones/hormonally active chemicals affect ERR expression. In Leydig cells in vitro, ERRα and ERRγ show opposing regulatory properties. The aim of this study was to examine the role of ERR in epigenetic processes in cells with altered level of secreted estrogens; mouse tumor Leydig cells and bank vole Leydig cells, respectively. In Leydig cells, ERRα and ERRγ were silenced via siRNA. mRNA and protein expression and protein localization of molecules required for miRNA biogenesis and function (Exportin 5, Dicer, Drosha and Argonaute 2; Ago2) were studied with the use of qRT-PCR, Western blotting, and immunohistochemistry. Global DNA methylation and histone deacetylation status together with estradiol secretion were determined with fluorometric, and immunoenzymatic assays. Regardless of ERR type knockdown in tumor Leydig cells, downregulation (P < 0.05; P < 0.01; P < 0.001) of Exportin5, Dicer, Drosha but not Ago2 was revealed while at protein level only Drosha was downregulated (P < 0.01) by both ERRα and ERRγ. Oppositely, Exportin5, Dicer and Ago2 showed ERR type-dependent regulation (downregulation; P < 0.01 by ERRα and upregulation; P < 0.01; P < 0.001 by ERRγ). In ERR-silenced vole Leydig cells, expression of Exportin5, endonucleases and Ago2 was not changed. Immunolocalization of Dicer and Ago2 was independent of the cell origin in contrast to localization of Exportin5 and Drosha which was dependent on the cell origin and ERR type knockdown. Absence of ERR effected on cell methylation status (ERRα increased it; P < 0.01 while ERRγ decreased it; P < 0.01, P < 0.001) but it not changed histone deacetylates activity. ERRα and ERRγ silencing decreased (P < 0.01, P < 0.001) estradiol secretion in both tumor and vole Leydig cells. In mouse and bank vole Leydig cell, Exportin5, Dicer, Drosha and Ago2 expression as well as methylation status are regulated by ERR in a manner related to receptor type, molecule type, cell origin and level of secreted estrogen.

Telocytes in the mouse testicular interstitium: implications of G-protein-coupled estrogen receptor (GPER) and estrogen-related receptor (ERR) in the regulation of mouse testicular interstitial cells

Telocytes (TCs), a novel type of interstitial cells, are involved in tissue homeostasis maintenance. This study aimed to investigate TC presence in the interstitium of mouse testis. Additionally, inactivation of the G-coupled membrane estrogen receptor (GPER) in the testis was performed to obtain insight into TC function, regulation, and interaction with other interstitial cells. Mice were injected with a GPER antagonist (G-15; 50 μg/kg bw), and the GPER-signaling effect on TC distribution, ultrastructure, and function, as well as the interstitial tissue interaction of GPER with estrogen-related receptors (ERRs), was examined. Microscopic observations of TC morphology were performed with the use of scanning and transmission electron microscopes. Telocyte functional markers (CD34; c-kit; platelet-derived growth factor receptors α and β, PDGFRα and β; vascular endothelial growth factor, VEGF; and vimentin) were analyzed by immunohistochemistry/immunofluorescence and Western blot. mRNA expression of CD34 as well as ERR α, β, and γ was measured by qRT-PCR. Relaxin and Ca2+ concentrations were analyzed by immunoenzymatic and colorimetric assays, respectively. For the first time, we reveal the presence of TCs in the interstitium together with the peritubular area of mouse testis. Telocytes were characterized by specific features such as a small cell body and extremely long prolongations, constituting a three-dimensional network mainly around the interstitial cells. Expression of all TC protein markers was confirmed. Based on scanning electron microscopic observation in GPER-blocked testis, groups of TCs were frequently seen. No changes were found in TC ultrastructure in GPER-blocked testis when compared to the control. However, tendency to TC number change (increase) after the blockage was observed. Concomitantly, no changes in mRNA CD34 expression and increase in ERR expression were detected in GPER-blocked testes. In addition, Ca2+ was unchanged; however, an increase in relaxin concentration was observed. Telocytes are an important component of the mouse testicular interstitium, possibly taking part in maintaining its microenvironment as well as contractile and secretory functions (via themselves or via controlling of other interstitial cells). These cells should be considered a unique and useful target cell type for the prevention and treatment of testicular interstitial tissue disorders based on estrogen-signaling disturbances.

Modulation of the transcriptomic profile of the R2C tumor Leydig cell line by the adipose tissue derived hormone leptin

Leptin is an important adipose derived hormone being secreted by adipocytes and involved in appetite regulation. Disruption of normal plasma levels of leptin has been associated with the pathogenesis of obesity. It is now well established that obesity is associated to an increased risk of cancer development, including testicular cancers. Recently, we have shown that high levels of leptin have inhibitory effects on cAMP-dependent steroidogenic genes expression in MA-10 Leydig cells. Hence, we examined if leptin could alter the transcriptome of the constitutively steroidogenic rat tumor Leydig cell line R2C. These cells were treated with high levels of leptin (1000 ng/ml) for 4 h, followed by mRNA extraction and RNA-Seq analysis. Interestingly, leptin had no effect on steroidogenic gene expression or pathways promoting tumorigenesis of this cell line. Genes being upregulated or downregulated by leptin were enriched in biological processes that were non-relevant to Leydig cell function. Surprisingly, lepr isoforms were weakly expressed in R2C cells and may explain in part the low levels of leptin's response for tumor Leydig cells. Hence, the current findings suggest that acute treatments of tumor Leydig cells with high levels of leptin have negligible effects on transcriptomics and rather supports that leptin would have a central effect on the hypothalamus to influence testicular function.

The role of G-protein-coupled membrane estrogen receptor in mouse Leydig cell function-in vivo and in vitro evaluation

In this study, G-coupled estrogen receptor (GPER) was inactivated, by treatment with antagonist (G-15), in testes of C57BL/6 mice: immature (3 weeks old), mature (3 months old) and aged (1.5 years old) (50 μg/kg bw), as well as MA-10 mouse Leydig cells (10 nM/24 h) alone or in combination with 17β-estradiol or antiestrogen (ICI 182,780). In G-15-treated mice, overgrowth of interstitial tissue was found in both mature and aged testes. Depending on age, differences in structure and distribution of various Leydig cell organelles were observed. Concomitantly, modulation of activity of the mitochondria and tubulin microfibers was revealed. Diverse and complex GPER regulation at the mRNA level and protein of estrogen signaling molecules (estrogen receptor α and β; ERα, ERβ and cytochrome P450 aromatase; P450arom) in G-15 Leydig cells was found in relation to age and the experimental system utilized (in vivo and in vitro). Changes in expression patterns of ERs and P450arom, as well as steroid secretion, reflected Leydig cell heterogeneity to estrogen regulation throughout male life including cell physiological status.We show, for the first time, GPER with ERs and P450arom work in tandem to maintain Leydig cell architecture and supervise its steroidogenic function by estrogen during male life. Full set of estrogen signaling molecules, with involvement of GPER, is crucial for proper Leydig cell function where each molecule acts in a specific and/or complementary manner. Further understanding of the mechanisms by which GPER controls Leydig cells with special regard to male age, cell of origin and experimental system used is critical for predicting and preventing testis steroidogenic disorders based on perturbations in estrogen signaling.

The Argentinian mother-and-child contaminant study: a cross-sectional study among delivering women in the cities of Ushuaia and Salta

Several ongoing international multidisciplinary projects have examined linkages between environmental chemicals and health. In contrast to Arctic regions, information for the Southern Hemisphere is scarce. Because of the inherent practice of pesticide utilisation and mismanagement, food security is potentially threatened. The most vulnerable period in human life occurs during pregnancy and early childhood, thus a focus on the body burdens of PTS in pregnant or delivering women is warranted. The current study was designed to investigate health risks related to exposure to PTS and food security in two regions of Argentina (Ushuaia and Salta). Our aims were to quantify concentrations of organic and inorganic toxins in serum or whole blood of delivering women and to collect pertinent dietary and medical information. The overall study design, the basic demographic features and essential clinical chemistry findings are described in the current paper. The socioeconomic differences between the two study areas were evident. On average, the women in Ushuaia were 4 years older than those in Salta (28.8 vs. 24.7 years). Respectively, the proportion of current smokers was 4.5 vs. 9.6%; and Salta had a higher birth rate, with 15.6% being para four or more. Saltanean women reported longer breastfeeding periods. Caesarean sections were more frequent in Ushuaia, with 43% of Caesarean deliveries compared with only 6% in Salta. Employment was high in both communities. Recognised environmental pollution sources in the vicinity of participant dwellings were widespread in Salta (56.1%) compared to Ushuaia (9%). The use of pesticides for insect control in homes was most common in Salta (80%). There is an urgent need for a comprehensive assessment of exposures in areas of the Southern Hemisphere. Our data set and the planned publications of observed concentrations of inorganic and organic environmental contaminants in both mothers and their newborns will contribute to this objective.