Quantitative RT-PCR methods for evaluating toxicant-induced effects on steroidogenesis using the H295R cell line

Impacts of iron on ultrastructural features of NCI-H295R cell line related to steroidogenesis

The current study was intended to evaluate impacts of both iron (Fe) enrichment and overload (in the form of ferrous sulphate heptahydrate, FeSO4.7H2O) on ultrastructural characteristics of human adrenocarcinoma NCI-H295R cell line. Here, the NCI-H295R cells were treated with 0, 3.90, and 1000 µM FeSO4.7H2O, and consequently proceeded for purposes of ultrastructural studies. Micrographs taken under transmission electron microscope (TEM) were investigated from the qualitative and quantitative (unbiased stereological approaches) aspects, and obtained findings were compared among the three groups of the cells. The ultrastructural features related to the steroidogenic process were found to be similar between the untreated and both Fe-exposed cell populations, with conspicuous mitochondria with well-defined lamellar cristae (creating clusters of varying sizes in the regions of increased energy demands) and concentric whorls of smooth endoplasmic reticulum (SER) being the most noticeable characteristics. The precise estimates of the component (volume, surface) fractions of the nucleus, mitochondria, and lipid droplets (LDs), as well as of the nucleus/cytoplasm (N/C) ratio have revealed close similarities (P > 0.05) in all cell groups investigated. Nonetheless, the low concentration of FeSO4.7H2O exhibited beneficial action on ultrastructural organization of the NCI-H295R cells. In effect, these cells were distinguished by mitochondria with smoother surfaces and clearer outlines, higher density of thin, parallel lamellar cristae (deeply extending into the mitochondrial matrix), and more widespread distribution of fine SER tubules as compared to the control ones, all of them suggesting higher level of energy requirements and metabolic activity, and more intensive rate of steroidogenesis. Interestingly, no obvious ultrastructural modifications were observed in the NCI-H295R cells treated with high FeSO4.7H2O concentration. This finding can be linked to either an adaptive ultrastructural machinery of these cells to cope with the adverse effect of the element or to insufficient dose of FeSO4.7H2O (1000 µM) to induce ultrastructural signs of cytotoxicity. Purposefully, the results of the current study complement our previous paper dealing with impacts of FeSO4.7H2O on the NCI-H295R cell viability and steroidogenesis at the molecular level. Hence, they fill a knowledge gap considering structure-function coupling in this cellular model system upon the metal exposure. This integrated approach can enhance our understanding of the cellular responses to Fe enrichment and overload which can be helpful for individuals with reproductive health concerns.

Exposure, toxicological mechanism of endocrine disrupting compounds and future direction of identification using nano-architectonics

Endocrine-disrupting compounds (EDC) are a group of exogenous chemicals that structurally mimic hormones and interfere with the hormonal signaling cascade. EDC interacts with hormone receptors, transcriptional activators, and co-activators, altering the signaling pathway at both genomic and non-genomic levels. Consequently, these compounds are responsible for adverse health ailments such as cancer, reproductive issues, obesity, and cardiovascular and neurological disorders. The persistent nature and increasing incidence of environmental contamination from anthropogenic and industrial effluents have become a global concern, resulting in a movement in both developed and developing countries to identify and estimate the degree of exposure to EDC. The U.S. Environment Protection Agency (EPA) has outlined a series of in vitro and in vivo assays to screen potential endocrine disruptors. However, the multidisciplinary nature and concerns over the widespread application demand alternative and practical techniques for identifying and estimating EDC. The review chronicles the state-of-art 20 years (1990-2023) of scientific literature regarding EDC's exposure and molecular mechanism, highlighting the toxicological effects on the biological system. Alteration in signaling mechanisms by representative endocrine disruptors such as bisphenol A (BPA), diethylstilbestrol (DES), and genistein has been emphasized. We further discuss the currently available assays and techniques for in vitro detection and propose the prominence of designing nano-architectonic-sensor substrates for on-site detection of EDC in the contaminated aqueous environment.

Development and validation of an activated immune model with zebrafish eleutheroembryo based on caudal fin acupuncture

Environmental pollutants are ubiquitous in global aquatic ecosystems and may cause immunotoxicity in aquatic organisms. However, disadvantages remain in the existing in vivo immunotoxicological methods, which make it difficult to meet the increasing demands for screening and for discriminating the immunotoxicity of environmental pollutants. In this study, the immune response in zebrafish eleutheroembryo was activated by acupuncture of the caudal fin at 72 hours post fertilization (hpf), and this immune model was further validated with a well-defined immunosuppressor, beclomethasone dipropionate (BDP). It was shown that acupuncture resulted in no increase in mortality in zebrafish eleutheroembryos. The transcription and protein levels of most immune genes were significantly increased after acupuncture, which indicated that acupuncture can effectively activate the immune response in zebrafish eleutheroembryos. Following exposure to BDP (0.01-1 μmol/L), the suppressive effects on the immune system were more significant in zebrafish that received acupuncture than in zebrafish that did not receive acupuncture. Considering these advantages, including its sensitivity, safety, and simple operation, over existing methods, the established immune model of zebrafish is promising for assessing the immunotoxicity of environmental pollutants.

Stereoisomeric selectivity in the endocrine-disrupting potential of cypermethrin using in vitro, in vivo, and in silico assays

Despite the ubiquity of cypermethrin (CYP) stereoisomers in environment biota, the stereoisomeric selectivity of endocrine-disrupting potency of α-CYP, β-CYP, and θ-CYP has not been well studied. In this study, dual-luciferase reporter gene assays were adopted to analyze their potential endocrine-disrupting effects via four receptors (ERα, GRα, MR and RXR). The results showed that α-CYP was antagonistic to ERα, GRα, and MR with RIC₂₀ of 9.1 × 10^-7, 7.6 × 10^-7, and 1.0 × 10^-6 M, respectively. β-CYP exhibited only ERα-mediated agonistic activity with a REC₂₀ of 2.1 × 10^-6 M. None of the CYP stereoisomers interacted with RXR. Molecular docking indicated that α-CYP had the strongest binding capacity to GRα among the compounds. The expression levels of steroid hormone-related genes in human adrenocortical carcinoma (H295R) cells displayed that all three compounds inhibited the transcription of 3-βHSD, indicating the block of turning cholesterol into different hormones. Both α-CYP and β-CYP upregulated genes encoding estrogen- and aldosterone-forming enzymes including 17-βHSD, CYP19, STAR, and CYP11B2. Mortality and malformation toxicity assays in zebrafish embryos revealed that the order of toxicity was α-CYP > β-CYP > θ-CYP. Our results indicated that α-CYP may pose the strongest endocrine-disrupting effects. The data provided here will be helpful to systematically understand stereoisomeric selectivity in the endocrine-disrupting effects of cypermethrin.

Integrated Analysis of miR-430 on Steroidogenesis-Related Gene Expression of Larval Rice Field Eel Monopterus albus

The present study aims to reveal the mechanism by which miR-430s regulate steroidogenesis in larval rice field eel Monopterus albus. To this end, M. albus embryos were respectively microinjected with miRNA-overexpressing mimics (agomir430a, agomir430b, and agomir430c) or miRNA-knockdown inhibitors (antagomir430a, antagomir430b, and antagomir430c). Transcriptome profiling of the larvae indicated that a total of more than 149 differentially expressed genes (DEGs) were identified among the eight treatments. Specifically, DEGs related to steroidogenesis, the GnRH signaling pathway, the erbB signaling pathway, the Wnt signaling pathway, and other pathways were characterized in the transcriptome. We found that steroidogenesis-related genes (hydroxysteroid 17-beta dehydrogenase 3 (17β-hsdb3), hydroxysteroid 17-beta dehydrogenase 7 (17β-hsdb7), hydroxysteroid 17-beta dehydrogenase 12 (17β-hsdb12), and cytochrome P450 family 19 subfamily a (cyp19a1b)) were significantly downregulated in miR-430 knockdown groups. The differential expressions of miR-430 in three gonads indicated different roles of three miR-430 (a, b, and c) isoforms in regulating steroidogenesis and sex differentiation. Mutation of the miR-430 sites reversed the downregulation of cytochrome P450 family 17 (cyp17), cyp19a1b, and forkhead box L2 (foxl2) reporter activities by miR-430, indicating that miR-430 directly interacted with cyp17, cyp19a1b, and foxl2 genes to inhibit their expressions. Combining these findings, we concluded that miR-430 regulated the steroidogenesis and the biosynthesis of steroid hormones by targeting cyp19a1b in larval M. albus. Our results provide a novel insight into steroidogenesis at the early stage of fish at the molecular level.

In vitro assessment of the impact of nickel on the viability and steroidogenesis in the human adrenocortical carcinoma (NCI-H295R) cell line

Nickel is a ubiquitous environmental pollutant, which has various effects on reproductive endocrinology. In this study, human adrenocortical carcinoma (NCI-H295R) cell line was used as an in vitro biological model to study the effect of nickel chloride (NiCl2) on the viability and steroidogenesis. The cells were exposed to different concentrations (3.90; 7.80; 15.60; 31.20; 62.50; 125; 250 and 500 microM) of NiCl2 and compared with control group (culture medium without NiCl2). The cell viability was measured by the metabolic activity assay. Production of sexual steroid hormones was quantified by enzyme linked immunosorbent assay. Following 48 h culture of the cells in the presence of NiCl2 a dose-dependent depletion of progesterone release was observed even at the lower concentrations. In fact, lower levels of progesterone were detected in groups with higher doses (>/=125 microM) of NiCl2 (P<0.01), which also elicited cytotoxic action. A more prominent decrease in testosterone production (P<0.01) was also noted in comparison to that of progesterone. On the other hand, the release of 17beta-estradiol was substantially increased at low concentrations (3.90 to 62.50 microM) of NiCl2. The cell viability remained relatively unaltered up to 125 microM (P>0.05) and slightly decreased from 250 microM of NiCl2 (P<0.05). Our results indicate endocrine disruptive effect of NiCl2 on the release of progesterone and testosterone in the NCI-H295R cell line. Although no detrimental effect of NiCl2 (</=62.50 microM) could be found on 17beta-estradiol production, its toxicity may reflect at other points of the steroidogenic pathway.

Copper affects steroidogenesis and viability of human adrenocortical carcinoma (NCI-H295R) cell line in vitro

Copper is an environmental risk factor, which has various effects on reproductive endocrinology. In this study human adrenocortical carcinoma (NCI-H295R) cell line was used as an in vitro biological model to study the effect of copper sulfate (CuSO₄.5H₂O) on steroidogenesis and cytotoxicity. The cell cultures were exposed to different concentrations (3.90, 62.50, 250, 500, 1000 µM) of CuSO₄.5H₂O and compared to control group (medium without CuSO₄.5H₂O). Cell viability was measured by the metabolic activity assay. Quantification of sexual steroid production directly from the medium was performed by ELISA assay. Following 48 h culture of NCI-H295R cell line in the presence of CuSO₄.5H₂O a dose-dependent depletion of progesterone release was observed even at the lower concentrations of CuSO₄.5H₂O. The lowest levels of progesterone were detected in groups with the higher doses (≥ 250 µM) of CuSO₄.5H₂O, which elicited significant cytotoxic action. Testosterone production decreased significantly, and this decline was more prominent in comparison to that of progesterone. The lowest release of testosterone was recorded at 1000 µM of CuSO₄.5H₂O. The cytotoxic effect of CuSO₄.5H₂O was evident at all concentrations used in the study. The presented data suggest that copper has detrimental effects on sexual steroid hormones and consecutively on reproductive physiology.

The potential endocrine disruption of pesticide transformation products (TPs): The blind spot of pesticide risk assessment

The ecological and health risk assessment of environmental pesticide residues have attracted ever-growing attention; however, their transformation products (TPs) have seldom been considered. Herein, we examined the endocrine-disrupting effects of 4 widely used pesticides as pyriproxyfen (Pyr), malathion (ML), benalaxyl (BX), and fenoxaprop-ethyl (FE), together with their 21 TPs through in vitro and in silico approaches, and found approximately 50% of the TPs exhibited stronger endocrine-disrupting effects than their corresponding parent compounds. Specifically, Pyr and 9 TPs (five TPs of Pyr, one of ML, one of BX, and two of FE) exhibited estrogen-disrupting effects, which were also confirmed by results of E-screen and pS2 expression assays, and molecular docking showed that certain hydroxylated TPs could well mimic the binding mode of estrogen with ERα. Meanwhile, two TPs of Pyr, ML and its TP demonstrated weak glucocorticoid antagonistic activities partially contributed by hydrogen bonds. We also discovered that in H295R cells, all the endocrine disruptors increased hormone secretion and the related gene expression levels. Conclusively, since an increasing number of pesticide TPs have been being detected in various environmental media, a more comprehensive understanding of the ecological risk of pesticide TPs is imperative for risk assessments more extensively and regulatory policy-making on pesticide restriction in the future.

Determination of Endocrine Disruption Potential of Bisphenol A Alternatives in Food Contact Materials Using In Vitro Assays: State of the Art and Future Challenges

Alternatives to bisphenol A (BPA) are developed for food contact materials as a result of increasing evidence of exposure-correlated harmful effects of BPA. In vitro assays provide the fast, affordable, and mechanism insightful ways to screen endocrine disruption (ED), which is a major concern of new BPA alternatives. In this review, we summarize the safety and regulation information on the alternatives to BPA, review the state of the art of in vitro assays for ED evaluation, highlight their advantages and limitations, and discuss the challenges and future research needs. Our review shows that ligand binding, reporter gene, cell proliferation, and steroidogenesis are four commonly used in vitro assays to determine the ED at the response of receptor, gene transcription, and whole cell level. Major challenges are found from in vitro-in vivo translation and identification of ED chemicals in polymers. More studies on these areas are needed in the future.

Enantioselectivity in endocrine disrupting effects of four cypermethrin enantiomers based on in vitro models

Cypermethrin (CP) is a kind of chiral pesticides that has been defined as endocrine disrupting chemical. The diversity in bioactivity, toxicity, metabolism, bioaccumulation, and degradation behaviors of CP enantiomers as well as the research deficiency had made the risk assessment of CP enantiomers very complicated. Herein, four CP enantiomers were separated as target chemicals to investigate their enantioselective endocrine disrupting effects. Firstly, dual-luciferase reporter gene assays were adopted to investigate their potential endocrine disrupting effects via various receptors. The expression levels of steroid hormones related genes and hormone secretion levels in H295R cell were measured to verify the results. Results from the reporter gene assay showed that 1R-cis-αS-CP (CP11) exhibited glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and thyroid receptor (TR) antagonistic activity with the RIC₂₀ values of 9.22 × 10^-7, 3.33 × 10^-7, and 4.47 × 10^-7 M, respectively; 1R-trans-αS-CP (CP21) also showed androgen receptor (AR) agonist activity and estrogen receptor (ER) antagonistic activity with the REC₂₀ and RIC₂₀ values were 1.07 × 10^-4 M and 4.78 × 10^-6 M, respectively. Results of qRT-PCR and hormone measurement also showed that CP11 and CP21 could disturb the expression of steroid hormones related genes and hormone secretion accordingly. Results provided here can help to understand the enantioselective ecological and health risks of CP enantiomers comprehensively and provide constructive guidance for the safe use of chiral pesticides and the invention of green pesticides.

Effects of defined mixtures of POPs and endocrine disruptors on the steroid metabolome of the human H295R adrenocortical cell line

The presence of environmental pollutants in our ecosystem may impose harmful health effects to wildlife and humans. Several of these toxic chemicals have a potential to interfere with the endocrine system. The adrenal cortex has been identified as the main target organ affected by endocrine disrupting chemicals. The aim of this work was to assess exposure effects of defined and environmentally relevant mixtures of chlorinated, brominated and perfluorinated chemicals on steroidogenesis, using the H295R adrenocortical cell line model in combination with a newly developed liquid chromatography tandem mass spectrometry (LC-MS/MS) method. By using this approach, we could simultaneously analyze 19 of the steroids in the steroid biosynthesis pathway, revealing a deeper insight into possible disruption of steroidogenesis. Our results showed a noticeable down-regulation in steroid production when cells were exposed to the highest concentration of a mixture of brominated and fluorinated compounds (10,000-times human blood values). In contrast, up-regulation was observed with estrone under the same experimental condition, as well as with some other steroids when cells were exposed to a perfluorinated mixture (1000-times human blood values), and the mixture of chlorinated and fluorinated compounds. Interestingly, the low concentration of the perfluorinated mixture alone produced a significant, albeit small, down-regulation of pregnenolone, and the total mixture a similar effect on 17-hydroxypregnenolone. Other mixtures resulted in only slight deviations from the control. Indication of synergistic effects were noted when we used a statistical model to improve data interpretation. A potential for adverse outcomes of human exposures is indicated, pointing to the need for further investigation into these mixtures.

Effects of 17α‑ethinylestradiol on caudal fin regeneration in zebrafish larvae

The ability to restore tissue function and morphology after injury is a key advantage of many fish for a greater chance of survival. The tissue regeneration process is regulated by multiple pathways, and it can therefore be hypothesized that environmental contaminants targeting components of these signaling pathways, may disrupt the fish's capability to repair or regenerate. This could lead to higher mortality and eventually even to a decline in populations. In this study, the effects of 17α‑ethinylestradiol (EE2), a synthetic estrogen, were assessed on the regenerative capacity of larval zebrafish. Zebrafish aged 2 hour post fertilization (hpf) were exposed to 1, 10, or 100 ng/L EE2, and the caudal fins were amputated at 72 hpf. It was found that EE2 exposure significantly inhibited fin regeneration and changed locomotor behavior. The transcription levels for most of the genes involved in the signaling networks regulating the fin regeneration, such as axin2, fgfr1, bmp2b and igf2b, were down-regulated in the amputated fish in response to EE2 exposure, which was in contrast to their increased patterns in the vehicle-exposed control fish. Additionally, the mRNA levels of several immune-related genes, such as il-1β, il-6, il-10 and nf-κb2, were significantly decreased after EE2 exposure, accompanied by a lower density of neutrophils migrated into the wound site. In conclusion, the present study indicated for the first time that estrogenic endocrine disrupting chemicals (EEDCs) could inhibit the regenerative capacity of zebrafish, and this effect was speculated to be mediated through the alteration in regeneration-related signaling pathways and immune competence. This work expands our knowledge of the potential effects of EEDCs on injured aquatic organisms, and highlights the ecotoxicological significance of relationships between regenerative process and endocrine system. This study also implies the potential application of fin regeneration assay for assessing immunotoxicity in ecotoxicological risk assessment.

Estrogenic potency of MC-LR is induced via stimulating steroidogenesis: In vitro and in vivo evidence

Waterborne microcystin-LR (MC-LR) has been reported to disrupt sex hormones, while its estrogenic potency remains controversial. We hypothesized that MC-LR could induce estrogenic effects via disrupting sex hormone synthesis, and verified this hypothesis by in vitro and in vivo assays. Effects of MC-LR (1, 10, 100, 500, 1000 and 5000 μg/L) on steroidogenesis were assessed in the H295R cells after 48 h. The contents of 17β-estradiol (E2) and testosterone (T) increased in a non-dose-dependent manner, which showed positive correlations with the expression of steroidogenic genes. In the in vivo assay, adult male zebrafish were exposed to 0.3, 1, 3, 10 and 30 μg/L MC-LR for 30 d. Similarly, E2 and T contents in the testis were increased, accompanied by extensive up-regulation of steroidogenic genes, especially cyp19a. Meanwhile, the percentage of spermatid in the testis declined. In the liver, the vtg1 gene was significantly up-regulated while both the transcriptional and protein levels of the estrogenic receptor (ER) declined. These results indicate that MC-LR induced non-dose-dependent estrogenic effects at environmental concentrations, which may result from steroidogenesis stimulation via a non-ER-mediated pathway. Our findings support a paradigm shift in the risk assessment of MC-LR from traditional toxicity to estrogenic risk, particularly at low concentrations, and emphasize the potential threat to the male reproductive capacity of wildlife in bloom areas.

Real-time PCR array to study the effects of chemicals on the growth hormone/insulin-like growth factors (GH/IGFs) axis of zebrafish embryos/larvae

Growth hormone/insulin-like growth factors (GH/IGFs) axis PCR array of zebrafish (Danio rerio) larvae was developed based on the quantification of mRNA expressions of 19 genes that were confirmed to play vital roles in the regulation of fish growth. Zebrafish embryos were exposed to each of four concentrations of the six representative chemicals, bisphenol A (BPA), perfluorooctane sulfonates (PFOS), tris (1,3-dichloroisopropyl) phosphate (TDCIPP), cadmium chloride (CdCl₂), mercury (II) chloride (HgCl₂) and lead (II) acetate (PbAc) from 2 h post fertilization (hpf) to 96 hpf. Developmental endpoints and transcriptional profiles of the genes involved in GH/IGFs axis of zebrafish larvae were examined at 96 hpf. Body length of zebrfish larvae was found to be a more susceptible endpoint in zebrafish embryo toxicity test than other endpoints, including survival rate, hatching rate, malformation incidence and heart rate after exposure to each of those representative chemicals selected. Perturbation of mRNA expressions of GH/IGF axis genes accompanied by decreased body length indicated that indicated that the growth inhibition observed might be attributed to the dysregulation of GH/IGFs axis. Therefore, GH/IGF axis PCR array of zebrafish larvae could be used to evaluate the effects of chemicals on GH/IGF endocrine system.

LC-MS/MS based profiling and dynamic modelling of the steroidogenesis pathway in adrenocarcinoma H295R cells

Endocrine disrupting chemicals have been reported to exert effects directly on enzymes involved in steroid biosynthesis. Here, we present a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for profiling the steroid metabolome of H295R human adrenocarcinoma cells. Our method can simultaneously analyse 19 precursors, intermediates and end-products, representing the adrenal steroid biosynthesis pathway. In order to obtain better insights into the processes of steroidogenesis, we investigated the dose-response relationship of forskolin, an activator of adenylate cyclase, on steroid production in H295R cells. We observed that 1.5 μM forskolin stimulated steroid production at approximately 50% of the maximum rate for most steroids. Hence, we studied the time course for steroid synthesis over 72 h in H295R cells that were stimulated with forskolin. At 24 h, we observed a peak in steroid levels for the intermediate metabolites, such as progesterone and pregnenolone, while end-products such as testosterone and cortisol continued to increase until 72 h. Finally, we show how global data provide a unique basis to develop a comprehensive, dynamic model for steroidogenesis using first order kinetics. The timeline data made it possible to estimate all reaction rate constants of the network. We propose this method as a unique and sensitive screening tool to identify effects on adrenal steroidogenesis by endocrine disrupting compounds.

In vitro assessment of sex steroids and related compounds in water and sediments - a critical review

Detection of endocrine disrupting compounds in water and sediment samples has gained much importance since the evidence of their effects was reported in aquatic ecosystems in the 1990s. The aim of this review is to highlight the advances made in the field of in vitro analysis for the detection of hormonally active compounds with estrogenic, androgenic and progestogenic effects in water and sediment samples. In vitro assays have been developed from yeast, mammalian and in a few cases from fish cells. These assays are based either on the hormone-mediated proliferation of sensitive cell lines or on the hormone-mediated expression of reporter genes. In vitro assays in combination with various sample enrichment methods have been used with limits of detection as low as 0.0027 ng L^-1 in water, and 0.0026 ng g^-1 in sediments for estrogenicity, 0.1 ng L^-1 in water, and 0.5 ng g^-1 in sediments for androgenicity, and 5 ng L^-1 in water for progestogenicity expressed as equivalent concentrations of standard reference compounds of 17β-estradiol, dihydrotestosterone and progesterone, respectively. The experimental results and limits of quantification, however, are influenced by the methods of sample collection, preparation, and individual laboratory practices.

A hierarchical testing strategy for micropollutants in drinking water regarding their potential endocrine-disrupting effects-towards health-related indicator values

In Germany, micropollutants that (may) occur in drinking water are assessed by means of the health-related indicator value (HRIV concept), developed by the German Federal Environment Agency. This concept offers five threshold values (≤ 0.01 to ≤ 3 μg l^-1) depending on availability and completeness of data regarding genotoxicity, neurotoxicity, and germ cell-damaging potential. However, the HRIV concept is yet lacking integration of endocrine disruptors as one of the most prominent toxicological concerns in water bodies, including drinking water. Thresholds and proposed bioassays hence urgently need to be defined. Since endocrine disruption of ubiquitary chemicals as pharmaceuticals, industrial by-products, or pesticides is a big issue in current ecotoxicology, the aim of this study was to explore endocrine effects, i.e., estrogenic and androgenic effects, as an important, additional toxicological mode of action for the HRIV concept using a hierarchical set of well-known but improved bioassays. Results indicate that all of the 13 tested substances, industrial chemicals and combustion products (5), pharmaceuticals and medical agents (4), and pesticides and metabolites (4), have no affinity to the estrogen and androgen receptor in human U2OS cells without metabolic activation, even when dosed at their water solubility limit, while in contrast some of these substances showed estrogenic effects in the RYES assay, as predicted in pre-test QSAR analysis. Using a specifically developed S9-mix with the U2OS cells, those micropollutants, i.e., Benzo[a]pyrene, 2,4-Dichlorophenol, 3,3-Dichlorbenzidin, 3,4-Dichloranilin, and diclofenac, they show estrogenic effects at the same concentration range as for the yeast cells. Three of the drinking water-relevant chemicals, i.e., atrazine, tributyltin oxide, and diclofenac, caused effects on hormone production in the H295R assay, which can be correlated with changes in the expression of steroidogenic genes. One chemical, 17α-Ethinylestradiol, caused an estrogenic or anti-androgenic effect in the reproduction test with Potamopyrgus antipodarum. Considering these results, a proposal for a test strategy for micropollutants in drinking water regarding potential endocrine effects (hormonal effects on reproduction and sexual development) will be presented to enhance the existing HRIV concept.

Endocrine disrupting potential of PAHs and their alkylated analogues associated with oil spills

Polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs are known to be major toxic contaminants in spills of petroleum hydrocarbons (oil). Spilled oil undergoes weathering and over time, PAHs go through a series of compositional changes. PAHs can disrupt endocrine functions, and the type of functions affected and associated potencies vary with the type and alkylation status of PAH. In this study, the potential of five major PAHs of crude oil, i.e., naphthalene, fluorene, dibenzothiophene, phenanthrene, and chrysene, and their alkylated analogues (n = 25), to disrupt endocrine functions was evaluated by use of MVLN-luc and H295R cell lines. In the MVLN-luc bioassay, seven estrogen receptor (ER) agonists were detected among 30 tested PAHs. The greatest ER-mediated potency was observed for 1-methylchrysene (101.4%), followed by phenanthrene and its alkylated analogues (range of %-E2max from 1.6% to 47.3%). In the H295R bioassay, significantly greater syntheses of steroid hormones were observed for 20 PAHs. For major PAHs and their alkylated analogues, disruption of steroidogenesis appeared to be more significant than ER-mediated effects. The number and locations of alkyl-moieties alone could not explain differences in the types or the potencies of toxicities. This observation shows that disruption of endocrine functions by some constituents of oil spills could be underestimated if only parent compounds are considered in assessments of hazard and risk.

Effects and mechanisms of waterborne copper exposure influencing ovary development and related hormones secretion in yellow catfish Pelteobagrus fulvidraco

The present study was conducted to determine the effects and mechanism of waterborne copper (Cu) exposure influencing ovary development and related hormones secretion in yellow catfish Pelteobagrus fulvidraco. To this end, two experiments were conducted. In Exp. 1, the partial cDNA sequences of three steroidogenesis-related genes (androgen receptor (ar), steroidogenic factor 1 (sf-1) and steroidogenic acute regulatory protein (star)) were firstly characterized from P. fulvidraco. The predicted amino acid sequences for the P. fulvidraco ar, sf-1 and star contained the main structural features characteristic in other species. In Exp. 2, P. fulvidraco were exposed to three waterborne Cu concentrations (control, 30μg/l and 60μg/l, respectively) for 56days. Sampling occurred on day 28 and day 56, respectively. On day 28, the levels of serum sex-steroid hormones (FSH and LH) and the mRNA levels of steroidogenesis-related genes (3β-hsd, cyp11a1, cyp17, cyp19a, sf-1 and star) were significantly increased in ovary of P. fulvidraco exposed to 30μg Cu/l. The immunohistochemical analysis showed the positive reaction of ER, VTG and aromatase in low dose exposure group. These indicated that in low dose and relative short-term exposure, Cu was beneficial. In contrast, 60μg Cu/l exposure significantly reduced the levels of serum FSH, LH, E2 and P, and the mRNA levels of ovarian 20β-hsd, cyp19a and erα in P. fulvidraco. On day 56, waterborne Cu concentration exposure reduced the levels of serum gonadotropins and sex hormones, and down-regulated the mRNA levels of steroidogenesis-related genes, indicating long-term Cu exposure had toxic effect on the secretion of sex-steroid hormone in P. fulvidraco. For the first time, our study cloned cDNA sequences of ar, sf-1 and star in P. fulvidraco, and demonstrated the effects and mechanism of waterborne Cu exposure influencing hormones secretion and synthesis in dose- and time-dependent manner in P. fulvidraco, which will help to understand the Cu-induced reproductive toxicity at both protein and transcriptional levels in fish.

Responses of the zebrafish hypothalamic-pituitary-gonadal-liver axis PCR array to prochloraz are dependent on timing of sampling

A PCR array, based on expression of genes along the hypothalamic-pituitary-gonadal-liver (HPGL) axis of fish, has been suggested as a useful method for screening of endocrine-disrupting chemicals (EDCs). However, effects of circadian rhythm on responses of the HPGL axis to exposure to chemicals were unknown. In this study, profiles of expression of genes along the HPGL axis and concentrations of 17β-estradiol (E2) in blood plasma of female zebrafish were compared at two sampling times of day (8:00 AM and 7:00 PM). Prochloraz (PCZ) was selected as a model chemical to evaluate differences in responses of the HPGL axis at these two times of day. Profiles of responses of concentrations of E2 in plasma and expressions of genes along the HPGL axis genes were different between the two times of sampling. Concentrations of E2 were less, and abundances of mRNA for several genes along the HPGL axis were significantly greater or lesser when samples were collected at 7:00 PM than they were when samples were collected at 8:00 AM. Exposure to three concentrations of PCZ (3, 30 or 300μg/L) for 48h resulted in significantly lesser concentrations of plasma E2 and caused compensatory up-regulation of genes included in hypothalamus, pituitary and ovary. Expressions of genes along the HPGL were more responsive to PCZ at 8:00 AM than they were when samples were collected at 7:00 PM. Correlations among parameters in samples collected at the two times indicated the effects might be due to different concentrations of E2 in plasma due to exposure to PCZ.

Sensitive electrochemiluminescence detection of cancer cells based on a CdSe/ZnS quantum dot nanocluster by multibranched hybridization chain reaction on gold nanoparticles

We prepared a novel amplified electrochemiluminescence signal probe based on CdSe/ZnS quantum dots by multibranched DNA hybridization chain reaction on gold nanoparticles, and developed a sensitive ECL biosensor for detection of cancer cells.

Disruption of endocrine function in H295R cell in vitro and in zebrafish in vivo by naphthenic acids

Oil sands process-affected water (OSPW) have been reported to exhibit endocrine disrupting effects on aquatic organisms. Although the responsible compounds are unknown, naphthenic acids (NAs) have been considered to be implicated. The current study was designed to investigate the endocrine disruption of OSPW extracted NAs (OS-NAs) and commercial NAs (C-NAs) using a combination of in vitro and in vivo assays. The effects of OS-NAs and C-NAs on steroidogenesis were assessed both at hormone levels and expression levels of hormone-related genes in the H295R cells. The transcriptions of biomarker genes involved in endocrine systems in zebrafish larvae were investigated to detect the effects of OS-NAs and C-NAs on endocrine function in vivo. Exposure to OS-NAs and C-NAs significantly increased production of 17β-estradiol (E2) and progesterone (P4), and decreased production of testosterone (T). Both OS-NAs and C-NAs significantly induced the expression of several genes involved in steroidogenesis. The abundances of transcripts of biomarker gene CYP19b, ERα, and VTG were significantly up-regulated in zebrafish larvae exposed to OS-NAs and C-NAs, which indicated that NAs had negative effects on estrogen-responsive gene transcription in vivo. These results indicated that NAs should be partly responsible for the endocrine disrupting effects of OSPW.

Silver nanoparticles disrupt regulation of steroidogenesis in fish ovarian cells

Despite the influx of silver nanoparticles (nAg) into the marine environment, their effects on fish reproduction remain completely unexplored. Using ovarian primary cells from marine medaka (Oryzias melastigma), in vitro studies were carried out to evaluate the effects of two differently coated nAg particles (Oleic Acid, (OA) nAg and Polyvinylpyrrolidone, (PVP) nAg) on fish ovarian tissues, using AgNO3 as a positive control. Cytotoxicity was evaluated by MTT assay and expression of key genes regulating steroidogenesis (StAR, CYP 19a, CYP 11a, 3βHSD and 20βHSD) were determined by Q-RT-PCR. EC50 values for PVP nAg, OA nAg and AgNO3 were 7.25μgL(-1), 924.4μgL(-1), and 42.0μgL(-1) respectively, showing that toxicity of silver was greatly enhanced in the PVP coated nano-form. Down regulation of CYP 19a was observed in both nAg and AgNO3 treatments, while down regulation of 3βHSD was only found in the OA nAg and AgNO3 treatments. For the first time, our results demonstrated that nAg can affect specific genes regulating steroidogenesis, implicating nAg as a potential endocrine disruptor.

Effects of Neonicotinoids on Promoter-Specific Expression and Activity of Aromatase (CYP19) in Human Adrenocortical Carcinoma (H295R) and Primary Umbilical Vein Endothelial (HUVEC) Cells

The enzyme aromatase (CYP19; cytochrome P450 19) in humans undergoes highly tissue- and promoter-specific regulation. In hormone-dependent breast cancer, aromatase is over-expressed via several normally inactive promoters (PII, I.3, I.7). Aromatase biosynthesizes estrogens, which stimulate breast cancer cell proliferation. The placenta produces estrogens required for healthy pregnancy and the major placental CYP19 promoter is I.1. Exposure to certain pesticides, such as atrazine, is associated with increased CYP19 expression, but little is known about the effects of neonicotinoid insecticides on CYP19. We developed sensitive and robust RT-qPCR methods to detect the promoter-specific expression of CYP19 in human adrenocortical carcinoma (H295R) and primary umbilical vein endothelial (HUVEC) cells, and determined the potential promoter-specific disruption of CYP19 expression by atrazine and the commonly used neonicotinoids imidacloprid, thiacloprid, and thiamethoxam. In H295R cells, atrazine concentration-dependently increased PII- and I.3-mediated CYP19 expression and aromatase catalytic activity. Thiacloprid and thiamethoxam induced PII- and I.3-mediated CYP19 expression and aromatase activity at relatively low concentrations (0.1-1.0 µM), exhibiting non-monotonic concentration-response curves with a decline in gene induction and catalytic activity at higher concentrations. In HUVEC cells, atrazine slightly induced overall (promoter-indistinct) CYP19 expression (30 µM) and aromatase activity (≥ 3 µM), without increasing I.1 promoter activity. None of the neonicotinoids increased CYP19 expression or aromatase activity in HUVEC cells. Considering the importance of promoter-specific (over)expression of CYP19 in disease (breast cancer) or during sensitive developmental periods (pregnancy), our newly developed RT-qPCR methods will be helpful tools in assessing the risk that neonicotinoids and other chemicals may pose to exposed women.

Perfluorooctyl Iodide Stimulates Steroidogenesis in H295R Cells via a Cyclic Adenosine Monophosphate Signaling Pathway

Perfluorinated iodine alkanes (PFIs) are used widely in the organic fluorine industry. Increased production of PFIs has caused environmental health concerns. To evaluate the potential endocrine-disrupting effect of PFIs, we investigated the effects of perfluorooctyl iodide (PFOI) on steroidogenesis in human adrenocortical carcinoma cells (H295R). Levels of aldosterone, cortisol, 17β-estradiol, and testosterone were measured in H295R culture medium upon treatment with perfluorooctanoic acid (PFOA) and PFIs. Expression of 10 steroidogenic genes (StAR, HMGR, CYP11A1, 3βHSD2, 17βHSD, CYP17, CYP21, CYP11B1, CYP11B2, and CYP19) was measured by real-time polymerase chain reaction. Levels of cyclic adenosine monophosphate (cAMP) and adenylate cyclase (AC) activity were measured to understand the underlying mechanism of steroidogenic perturbations. Levels of production of aldosterone, cortisol, and 17β-estradiol were elevated significantly, and the level of testosterone generation decreased upon treatment with 100 μM PFOI. Similar to the effect induced by forskolin (AC activator), expression of all 10 genes involved in the synthesis of steroid hormones was upregulated significantly upon exposure to 100 μM PFOI. PFOA had no effect on steroid hormone production or steroidogenic gene expression even though it is highly structurally similar with PFOI. Therefore, the terminal -CF2I group in PFOI could be a critical factor for mediation of steroidogenesis. PFOI increased AC activity and cAMP levels in H295R cells, which implied an underlying mechanism for the disturbance of steroidogenesis. These data suggest that PFOI may act as an AC activator, thereby stimulating steroidogenesis by activating a cAMP signaling pathway.

Evidence for microRNA-mediated regulation of steroidogenesis by hypoxia

Environmental hypoxia can occur in both natural and occupational environments. Over the recent years, the ability of hypoxia to cause endocrine disruption via perturbations in steroid synthesis (steroidogenesis) has become increasingly clear. To further understand the molecular mechanism underlying hypoxia-induced endocrine disruption, the steroid-producing human cell line H295R was used to identify microRNAs (miRNAs) affecting steroidogenic gene expression under hypoxia. Hypoxic treatment of H295R cells resulted in the downregulation of seven steroidogenic genes and one of these, CYP19A1 (aromatase), was shown to be regulated by the transcription factor hypoxia-inducible factor-1 (HIF-1). Using bioinformatic and luciferase reporter analyses, miR-98 was identified to be a CYP19A1-targeting miRNA from a subset of HIF-1-inducible miRNAs. Gain- and loss-of-function analysis suggested that under hypoxia, the increased expression of miR-98 led to the downregulation of CYP19A1 mRNA and protein expression and that it may have contributed to a reduction in estradiol (E2) production. Intriguingly, luciferase reporter assays using deletion constructs of a proximal 5′-flanking region of miR-98 did not reveal a hypoxia-responsive element (HRE)-containing promoter. Overall, this study provided evidence for the role of miRNAs in regulating steroidogenesis and novel insights into the molecular mechanisms of hypoxia-induced endocrine disruption.

Endocrine disruptive effects of cadmium on steroidogenesis: human adrenocortical carcinoma cell line NCI-H295R as a cellular model for reproductive toxicity testing

Cadmium (Cd) is a known endocrine disruptor with the ability to affect the production of hormones involved in the regulation of reproductive processes. In this study human adrenocortical carcinoma cell line NCI-H295R was used as an in vitro biological model to study the effect of cadmium (CdCl2) on steroidogenesis. The cell cultures were exposed to different concentrations of CdCl2 (1.90, 3.90, 7.80, 15.60, 31.20 and 62.50 μM) and compared to control (medium without CdCl2). Cell viability was measured by the metabolic activity (MTT) assay for estimation of mitochondria structural integrity. Quantification of sexual steroid production directly from aliquots of the medium was performed by enzyme linked immunosorbent assay (ELISA). Following 48 h culture of the cells in the presence of CdCl2 a concentration-dependent depletion in progesterone production was observed at the lower concentrations of CdCl2. The lowest amount of progesterone was significantly detected in groups with the higher doses (≥ 31.20 μM) of CdCl2, which elicited significant (P < 0.01) cytotoxic action, too. Cadmium decreased testosterone release in the whole applied range even at the lower concentration of CdCl2. The release of 17β-estradiol decreased as well, but the decline was less pronounced compared to decrease of progesterone and testosterone. The cytotoxic effect was significantly (P < 0.01) detected at all concentrations of CdCl2 (1.90-62.50 μM) used in the study. However, the cell viability remained relatively high (>75%) up to 7.80 μM of CdCl2 and significantly (P < 0.01) decreased at 15.60 μM and higher concentrations of CdCl2. These results suggest that cadmium has endocrine disruptive effects on sexual steroid synthesis even at very low concentrations.

Species-specific considerations in using the fish embryo test as an alternative to identify endocrine disruption

A number of regulations have been implemented that aim to control the release of potentially adverse endocrine disrupters into the aquatic environment based on evidence from laboratory studies. Currently, such studies rely on testing approaches with adult fish because reliable alternatives have not been validated so far. Fish embryo tests have been proposed as such an alternative, and here we compared two species (medaka and zebrafish) to determine their suitability for the assessment of substances with estrogenic and anti-androgenic activity. Changes in gene expression (in here the phrase gene expression is used synonymously to gene transcription, although it is acknowledged that gene expression is additionally regulated, e.g., by translation and protein stability) patterns between the two species were compared in short term embryo exposure tests (medaka: 7-day post fertilization [dpf]; zebrafish: 48 and 96h post fertilization [hpf]) by using relative quantitative real-time RT-PCR. The tested genes were related to the hypothalamic-gonadal-axis and early steroidogenesis. Test chemicals included 17α-ethinylestradiol and flutamide as estrogenic and anti-androgenic reference compounds, respectively, as well as five additional substances with endocrine activities, namely bisphenol A, genistein, prochloraz, linuron and propanil. Estrogenic responses were comparable in 7-dpf medaka and 48/96-hpf zebrafish embryos and included transcriptional upregulation of aromatase b, vitellogenin 1 as well as steroidogenic genes, suggesting that both species reliably detected exposure to estrogenic compounds. However, anti-androgenic responses differed between the two species, with each species providing specific information concerning the mechanism of anti-androgenic disruption in fish embryos. Although small but significant changes in the expression of selected genes was observed in 48-hpf zebrafish embryos, exposure prolonged to 96hpf was necessary to obtain a response indicative of anti-androgenic activity. In contrast, for medaka clear anti-androgenic response, e.g. transcriptional downregulation of 11β-hydroxylase, 3β-hydroxysteroid-dehydrogenase, gonadotropin-releasing hormone receptor 2, was already observed at the pre-hatch stage. Together, this data suggests that medaka and zebrafish embryos would provide a beneficial alternative testing platform for endocrine disruption that involves additive information on interspecies and exposure time variability when using both species.

Aptamer-conjugated bio-bar-code Au-Fe3O4 nanoparticles as amplification station for electrochemiluminescence detection of tumor cells

An electrochemiluminescence (ECL) assay has been developed for highly sensitive and selective detection of tumor cells based on cell-SELEX aptamer-target cell interactions through a cascaded amplification process by using bio-bar-code Au-Fe3O4 as amplification station. Firstly, bio-bar-code toehold-aptamer/DNA primer/Au-Fe3O4 (TA/DP/Au-Fe3O4) nanoconjugates are fabricated with a ratio of 1:10 to efficiently avoid cross-linking reaction and recognize target cells, which are immobilized on the substrate by hybridizing aptamer to capture probe with 18-mer. Through strand displacement reaction (SDR), the TA/DP/Au-Fe3O4 composites further act as the amplification station to initiate rolling circle amplification (RCA). As a result, on the surface of TA/DP/Au-Fe3O4, a large number of Ru(bpy)2(dcbpy)NHS-labeled probes hybridize to RCA products, which are easily trapped by magnetic electrode to perform the magnetic particle-based ECL platform. Under isothermal conditions, this powerful amplification strategy permits detection of Ramos cells as low as 16 cells with an excellent selectivity. Moreover, analysis of Ramos cells in complex samples and whole blood samples further show the great potential of this ultrasensitive approach in clinical application involving cancer cells-related biological processes.

A rapid screening test for endocrine disrupting chemicals using primary cell culture of the marine medaka

While endocrine disrupting chemicals (EDCs) pose a significant threat to wildlife worldwide, their diverse chemical structures present a major challenge to their detection, particularly since they are present at very low concentrations in the environment. We here report the development of an in vitro system for rapid screening of EDCs, using primary cell cultures (pituitary, ovarian follicular and testicular cells) of the marine medaka (Oryzias melastigma). Pituitary, testis and ovary cell cultures were developed and challenged by environmentally relevant concentrations of three well known EDCs (viz. estradiol, 2,2',4,4'-tetrabromodiphenyl ether, and 4-n-nonylphenol) as well as hypoxia (which has been shown to be a potent endocrine disruptor). In general, the mRNA expression levels of gonadotropins, their receptors and steroidogenic enzymes exhibited dose response relationships to the four endocrine disruptors in different tissues. The sensitivity and responses were also comparable to in vivo responses of whole fish and in vitro responses of the H295R human adrenocortical cell line. Our results suggest that the use of marine medaka primary cultured cells can serve as a cost effective tool for rapid screening of EDCs in the marine environment, and at the same time, sheds light on the underlying mechanisms of EDCs by deciphering their specific target sites along the hypothalamus-pituitary-gonad axis of vertebrates.

Zebrafish embryos/larvae for rapid determination of effects on hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-interrenal (HPI) axis: mRNA expression

To identify and prioritize chemicals that may affect thyroid and adrenal/interregnal endocrine system and to reduce cost and animal use by conventional toxicity assay, an in vivo screening assay was developed using zebrafish embryos/larvae based on measurement of expression of genes that were suggested to play important roles in hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-interrenal (HPI) axis. Model chemicals that could modulate HPT and HPI axis in adult fish were selected in assay validation, including anti-thyroid agent 6-Propyl-2-thiouracil (PTU) and cytochrome P450 11B (Cyp11b) enzyme inhibitor metyrapone (MET). Zebrafish embryos were exposed to different concentrations of model chemical from 4h post-fertilization (hpf) to 5d post-fertilization (dpf). Exposure to PTU increased mRNA expression of sodium iodide symporter (nis) and thyroglobulin (tg) involved in HPT axis, and MET treatment up-regulated all the mRNA expression tested involved in HPI axis by a compensatory mechanism. These results suggested that HPT and HPI axis were active upon chemical exposure at least at 5 dpf zebrafish. Furthermore, we studied the effects of PTU or MET on the cross-talk between HPT and HPI axis. The results demonstrated that PTU and MET could affect cross-talk responses in zebrafish embryos/larvae.

Effects of polar oil related hydrocarbons on steroidogenesis in vitro in H295R cells

Oil pollution from various sources, including exploration, production and transportation, is a growing global concern. Of particular concern is the environmental impact of produced water (PW), the main waste discharge from oil and gas platforms. In this study, we have investigated the potential of polar hydrocarbon pollutants to disrupt or modulate steroidogenesis in vitro, using a human adrenocortical carcinoma cell line, the H295R assay. Effects of two of the major groups of compounds found in the polar fraction of crude oil and PW; alkylphenols (C(2)- and C(3)-AP) and naphthenic acids (NAs), as well as the polar fraction of PW as a whole has been assessed. Endpoints include hormone (cortisol, estradiol, progesterone, testosterone) production at the functional level and key genes for steroidogenesis (17β-HSD1, 17β-HSD4, 3β-HSD2, ACTHR, CYP11A1, CYP11B1, CYP11B2, CYP17, CYP19, CYP21, DAX1, EPHX, HMGR, SF1, STAR) and metabolism (CYP1A) at the molecular level. All compounds induced the production of both estradiol and progesterone in exposed H295R cells, while the C(3)-AP and NAs decreased the production of testosterone. Exposure to C(2)-AP caused an up-regulation of DAX1 and EPHX, while exposure to NAs caused an up-regulation of ACTHR. All compounds caused an up-regulation of CYP1A1. The results indicated that these hydrocarbon pollutants, including PW, have the potential to disrupt the vitally important process of steroidogenesis.

An in vitro investigation of endocrine disrupting effects of the mycotoxin alternariol

Alternariol (AOH) is a mycotoxin commonly produced by Alternaria alternata on a wide range of foods. Few studies to date have been performed to evaluate the effects of AOH on endocrine activity. The present study makes use of in vitro mammalian cellular based assays and gene expression to investigate the ability of AOH to act as an endocrine disruptor by various modes of action. Reporter gene assays (RGAs), incorporating natural steroid hormone receptors for oestrogens, androgens, progestagens and glucocorticoids were used to identify endocrine disruption at the level of nuclear receptor transcriptional activity, and the H295R steroidogenesis assay was used to assess endocrine disruption at the level of gene expression and steroid hormone production. AOH exhibited a weak oestrogenic response when tested in the oestrogen responsive RGA and binding of progesterone to the progestagen receptor was shown to be synergistically increased in the presence of AOH. H295R cells when exposed to 0.1-1000ng/ml AOH, did not cause a significant change in testosterone and cortisol hormones but exposure to 1000ng/ml (3.87μM) AOH resulted in a significant increase in estradiol and progesterone production. In the gene expression study following exposure to 1000ng/ml (3.87μM) AOH, only one gene NR0B1 was down-regulated, whereas expression of mRNA for CYP1A1, MC2R, HSD3B2, CYP17, CYP21, CYP11B2 and CYP19 was up-regulated. Expression of the other genes investigated did not change significantly. In conclusion AOH is a weak oestrogenic mycotoxin that also has the ability to interfere with the steroidogenesis pathway.

Corticosteroid Production in H295R Cells During Exposure to 3 Endocrine Disrupters Analyzed With LC-MS/MS

The adrenocortical human cell line H295R is a valuable tool for screening endocrine disrupting compounds. In general, previous research focus has been on the production of the 2 sex steroids, 17β-estradiol and testosterone, and less attention has been paid to other important steroid end points in the steroidogenesis with a wide range of physiological functions, such as the glucocorticoids (corticosterone and cortisol). A newly developed and validated solid phase extraction (SPE) liquid chromatography–mass spectroscopy (LC-MS/MS) method was used to measure the production of cortisol and corticosterone in the H295R cell line. The method was applied by studying the effects of 2 model endocrine disrupters, ketoconazole and prochloraz, the pharmaceutical budesonide, and the inducer forskolin on the steroid production in this cell line. Dose–response curves were obtained for the correlation between hormone concentrations and the concentration of the individual disruptors. Exposing cells to ketoconazole resulted in a decrease in cortisol and corticosterone concentrations in a dose-dependent manner with EC50 values of 0.24 and 0.40 μmol/L, respectively. The same applied for cells exposed to prochloraz with EC50 values of 0.06 and 0.09 μmol/L for cortisol and corticosterone, respectively. Budesonide also inhibited glucocorticoid secretion. The EC50 value for cortisol was 19.50 μmol/L, whereas the EC50 value for corticosterone was 71.42 μmol/L. Forskolin induced the secretion of both cortisol (EC50 = 4.09 μmol/L) and corticosterone (EC50 = 0.28 μmol/L). The results obtained demonstrated the validity of the method. Based on these findings, quality criteria for the production of these steroids in this cell line were suggested.

In vitro assessment of thyroid hormone disrupting activities in drinking water sources along the Yangtze River

The thyroid hormone disrupting activities of drinking water sources from the lower reaches of Yangtze River were examined using a reporter gene assay based on African green monkey kidney fibroblast (CV-1) cells. None of the eleven tested samples showed thyroid receptor (TR) agonist activity. Nine water samples exhibited TR antagonist activities with the equivalents referring to Di-n-butyl phthalate (DNBP) (TR antagonist activity equivalents, ATR-EQ(50)s) ranging from 6.92 × 10(1) to 2.85 × 10(2) μg DNBP/L. The ATR-EQ(50)s and TR antagonist equivalent ranges (ATR-EQ(30-80) ranges) for TR antagonist activities indicated that the water sample from site WX-8 posed the greatest health risks. The ATR-EQ(80)s of the water samples ranging from 1.56 × 10(3) to 6.14 × 10(3) μg DNBP/L were higher than the NOEC of DNBP. The results from instrumental analysis showed that DNBP might be responsible for the TR antagonist activities in these water samples. Water sources along Yangtze River had thyroid hormone disrupting potential.

Perfluorooctane sulfonate (PFOS) affects hormone receptor activity, steroidogenesis, and expression of endocrine-related genes in vitro and in vivo

Perfluorooctane sulfonate (PFOS) is a widespread and persistent chemical in the environment. We investigated the endocrine-disrupting effects of PFOS using a combination of in vitro and in vivo assays. Reporter gene assays were used to detect receptor-mediated (anti-)estrogenic, (anti-)androgenic, and (anti-)thyroid hormone activities. The effect of PFOS on steroidogenesis was assessed both at hormone levels in the supernatant and at expression levels of hormone-induced genes in the H295R cell. A zebrafish-based short-term screening method was developed to detect the effect of PFOS on endocrine function in vivo. The results indicate that PFOS can act as an estrogen receptor agonist and thyroid hormone receptor antagonist. Exposure to PFOS decreased supernatant testosterone (T), increased estradiol (E2) concentrations in H295R cell medium and altered the expression of several genes involved in steroidogenesis. In addition, PFOS increased early thyroid development gene (hhex and pax8) expression in a concentration-dependent manner, decreased steroidogenic enzyme gene (CYP17, CYP19a, CYP19b) expression, and changed the expression pattern of estrogen receptor production genes (esr1, esr2b) after 500 µg/L PFOS treatment in zebrafish embryos. These results indicate that PFOS has the ability to act as an endocrine disruptor both in vitro and in vivo by disrupting the function of nuclear hormone receptors, interfering with steroidogenesis, and altering the expression of endocrine-related genes in zebrafish embryo.

Effects of mercury on the steroidogenesis of human adrenocarcinoma (NCI-H295R) cell line

In this study the NCI-H295R human adrenocortical carcinoma cell line was used as an in vitro biological model to study the effect of mercury (HgCl(2)) on the steroidogenesis. The cells were cultured for 48 h with addition of 1.0; 5.0; 25; 50 or 100 μM of HgCl(2) and compared to control. Cell viability was measured by the MTT (metabolic activity) assay estimation for the mitochondria structural integrity. Quantification of testosterone and progesterone directly from aliquots of the medium was performed by enzyme linked immunosorbent assay (ELISA). Concentration-dependent depression in testosterone production was detected particularly for higher concentration of Hg(2+). Progesterone production was also decreased, but at the lower concentrations (1.0 and 5.0 μM) of Hg(2+) this decline was lower compared to depression of testosterone. The cell viability significantly decreased at 25 μM and higher concentration of Hg(2+). However, at 25 μM Hg(2+) exposure the cell viability remained relatively high (> 80%). Results of the study indicate dose-dependent decreases in both testosterone and progesterone production of H295R cell culture following a 48 h in vitro HgCl(2) exposure. The results suggest that Hg has detrimental effects on steroid hormone synthesis also at very low concentrations and consecutively on reproductive physiology.

Effects of polycyclic musks HHCB and AHTN on steroidogenesis in H295R cells

1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(γ)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) are widely used in personal care products. Previous studies showed that HHCB and AHTN can be found in various environmental matrices and have potential endocrine disrupting effects. However, the effects on adrenocortical function of HHCB and AHTN are not fully understood. This study evaluated the influences of HHCB and AHTN on seven steroid hormones (progesterone, aldosterone, cortisol, 17α-OH-progesterone, androstenedione, 17β-estradiol, and testosterone) and 10 genes involved in steroidogenic pathways (HMGR, StAR, CYP11A1, 3βHSD2, CYP17, CYP21, CYP11B1, CYP11B2, 17βHSD, and CYP19) using the H295R cell line in the absence and presence of 8-Br-cAMP. MC2R transcription on the cell membrane was also examined to further investigate the effects of HHCB and AHTN on adrenal steroidogenesis. The results demonstrated that HHCB and AHTN could inhibit progesterone and cortisol production mainly by the suppression of 3βHSD2 and CYP21. Meanwhile, high concentrations of AHTN can affect the sensitivity of H295R cells to ACTH by disrupting MC2R transcription. Overall, the results indicate that high concentrations of HHCB and AHTN can affect steroidogenesis in vitro using the H295R cell line.

Biological impact of phthalates

Esters of phthalic acid are chemical agents used to improve the plasticity of industrial polymers. Their ubiquitous use in multiple commercial products results in extensive exposure to humans and the environment. This study investigated cytotoxicity, endocrine disruption, effects mediated via AhR, lipid peroxidation and effects on expression of enzymes of xenobiotic metabolism caused by di-(2-ethy hexyl) phthalate (DEHP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and benzyl butyl phthalate (BBP) in developing fish embryos. Oxidative stress was identified as the critical mechanism of toxicity (CMTA) in the case of DEHP and DEP, while the efficient removal of DBP and BBP by phase 1 enzymes resulted in lesser toxicity. DEHP and DEP did not mimic estradiol (E(2)) in transactivation studies, but at concentrations of 10mg/L synthesis of sex steroid hormones was affected. Exposure to 10mg BBP/L resulted in weak transactivation of the estrogen receptor (ER). All phthalates exhibited weak potency as agonists of the aryl hydrocarbon receptor (AhR). The order of potency of the 4 phthalates studied was; DEHP>DEP>BBP>>DBP. The study highlights the need for simultaneous assessment of: (1) multiple cellular targets affected by phthalates and (2) phthalate mixtures to account for additive effects when multiple phthalates modulate the same pathway. Such cumulative assessment of multiple biological parameters is more realistic, and offers the possibility of more accurately identifying the CMTA.

Alternatives to in vivo tests to detect endocrine disrupting chemicals (EDCs) in fish and amphibians--screening for estrogen, androgen and thyroid hormone disruption

Endocrine disruption is considered a highly relevant hazard for environmental risk assessment of chemicals, plant protection products, biocides and pharmaceuticals. Therefore, screening tests with a focus on interference with estrogen, androgen, and thyroid hormone pathways in fish and amphibians have been developed. However, they use a large number of animals and short-term alternatives to animal tests would be advantageous. Therefore, the status of alternative assays for endocrine disruption in fish and frogs was assessed by a detailed literature analysis. The aim was to (i) determine the strengths and limitations of alternative assays and (ii) present conclusions regarding chemical specificity, sensitivity, and correlation with in vivo data. Data from 1995 to present were collected related to the detection/testing of estrogen-, androgen-, and thyroid-active chemicals in the following test systems: cell lines, primary cells, fish/frog embryos, yeast and cell-free systems. The review shows that the majority of alternative assays measure effects directly mediated by receptor binding or resulting from interference with hormone synthesis. Other mechanisms were rarely analysed. A database was established and used for a quantitative and comparative analysis. For example, a high correlation was observed between cell-free ligand binding and cell-based reporter cell assays, between fish and frog estrogenic data and between fish embryo tests and in vivo reproductive effects. It was concluded that there is a need for a more systematic study of the predictive capacity of alternative tests and ways to reduce inter- and intra-assay variability.

Toxicology of water

To protect the quality of water from toxic pollutants for the health of humans and the environment, two approaches are generally applied in the field of toxicology to predict the effects of pollutants and to monitor the toxic pollutants in water. Here we provide our perspective on state-of-the-art methods to develop water quality criteria and the use of molecular techniques for monitoring water quality. Emphasized is the recent development and application of cell-based assays and small fish model in toxicology research of water.

Characterization of a bystander effect induced by the endocrine-disrupting chemical 6-propyl-2-thiouracil in zebrafish embryos

This study was conducted to evaluate possible bystander effects induced by the model chemical 6-propyl-2-thiouracil (PTU) on melanin synthesis. Zebrafish (Danio rerio) embryos were treated with PTU by either microinjection exposure, via waterborne exposure or indirectly through bystander exposure. Melanin content, related mRNA and protein expression were examined at the end of exposure (36 h post-fertilization). Direct exposure to PTU decreased the melanin content, up-regulated mRNA expressions of oculocutaneous albinism type 2 (OCA2), tyrosinase (TYR), dopachrometautomerase (DCT), tyrosinase-related protein 1 (TYRP1) and silver (SILV), and increased the protein expressions of TYR and SILV. Bystander exposure also up-regulated mRNA and protein expressions of TYR and SILV but increased melanin contents. Correlation analysis demonstrated that mRNA expressions of OCA2, TYR, DCT, TYRP1, SILV and protein expressions of TYR and SILV in bystander exposure groups were positively correlated with corresponding expressions in microinjection exposure groups. The results might have environmental implications and highlight the need to consider the bystander effects when assessing potential risks of endocrine-disrupting chemicals.

Disruption of endocrine function in in vitro H295R cell-based and in in vivo assay in zebrafish by 2,4-dichlorophenol

Chlorophenols in the aquatic environment have been of concern due to their potential effects on human and wildlife. In the present study, the endocrine disrupting effects of 2,4-dichlorophenol (2,4-DCP) were investigated in vitro and in vivo. In the in vitro assay, H295R human adrenocortical carcinoma cells were used to determine the potential effects of 2,4-DCP on steroidogenesis. Exposure to 0, 0.1, 0.3 or 1.0 mg 2,4-DCP/L resulted in less production of 17β-estradiol (E2) and alterations in transcript expressions of genes involved in steroidogenesis, including cytochrome P450 (CYP11A, CYP17, CYP19), 3βHSD, 17βHSD and StAR. In the in vivo study, effects of 0, 0.03, 0.1 or 0.3 mg 2,4-DCP/L on concentrations of steroid hormones in plasma of adult zebrafish (Danio rerio) were measured and expression of mRNA of selected genes in hypothalamic-pituitary-gonadal (HPG) axis and liver were determined. Exposure of zebrafish to 2,4-DCP resulted in lesser concentrations of E2 accompanied by down-regulation of CYP19A mRNA in the females. In males, exposure to 2,4-DCP resulted in greater concentrations of testosterone (T) and E2 along with greater mRNA expression of CYP17 and CYP19A. The mRNA expression of prostaglandin synthase (Ptgs2) gene, which regulates ovulation, was down-regulated in females, but up-regulated in males. The hepatic estrogenic receptor (ERα and ERβ) and vitellogenin (VTG1 and VTG3) mRNAs were up-regulated in both females and males. The average number of eggs spawned was significantly less upon exposure to 2,4-DCP. Exposure of adult zebrafish to 2,4-DCP resulted in lesser rates of hatching of eggs. The results demonstrated that 2,4-DCP modulates transcription of steroidogenetic genes in both H295R cells and in the zebrafish HPG-axis and disrupts steroidogenesis, which in turn, can cause adverse effects on reproduction in fish.

Modulation of estrogen synthesis through activation of protein kinase A in H295R cells by extracts of estuary sediments

Sediments from two estuaries within Liaodong Bay, China, were examined for the effects on steroidogenesis using H295R human adrenocortical carcinoma cells. Total extracts (TE) isolated from sediments by Soxhlet extraction were separated into three fractions (F1, F2, and F3) using Florisil columns. After exposing H295R cells to each TE and fractions, the expressions of six steroidogenic genes (cytochrome P450 cholesterol side-chain cleavage [CYP11A], 3β-hydroxysteroid dehydrogenase type 1 [3β-HSD1], 3β-hydroxysteroid dehydrogenase type 2 [3β-HSD2], cytochrome P450 17-hydroxylase/17-20 lyase [CYP17], cytochrome P450 aromatase [CYP19], 17β-hydroxysteroid dehydrogenase [17β-HSD]), and the production of six steroid hormones (progesterone [PGT], 17-hydroxyprogesterone [17-HPT], testosterone [TTR], androstenedione [ADD], estrone [E1], and 17β-estradiol [17β-E2]) were measured. The gene expressions of CYP11A, CYP17, 3β-HSD2, and CYP19, and hormone productions of PGT, 17-HPT, TTR, ADD, E1, and 17β-E2 were significantly increased after exposure to F3 extracts from the Daliao River. In particular, greater concentrations of E1 (up to 48-fold) and 17β-E2 (up to 20-fold), as well as up-regulation of CYP19 gene expression (up to tenfold), were caused by exposure to the F3 fraction from the Daliao River, but not from the Daling River. Insight into the mechanism of action was obtained by use of principal component analysis (PCA), the results of which were consistent with unidentified constituents in F3 from the Daliao River activating the protein kinase A (PKA) pathway. This hypothesis was confirmed by reversal of the effects caused by F3 through a co-exposure of a PKA inhibitor (H89) and F3 extract. The H89 down-regulated CYP19 messenger RNA (mRNA) expression with concomitant lesser production of E1 and 17β-E2 in the co-exposure group, indicating unidentified constituents that could modulate estrogen synthesis, primarily through a mechanism of PKA activation.

Mechanistic profiling of the cAMP-dependent steroidogenic pathway in the H295R endocrine disrupter screening system: new endpoints for toxicity testing

The need for implementation of effects on steroid synthesis and hormone processing in screening batteries of endocrine disruptive compounds is widely acknowledged. In this perspective, hormone profiling in the H295R adrenocortical cell system is extensively examined and recently OECD validated (TG 456) as a replacement of the minced testis assay. To further elucidate the complete mechanisms and endocrine responsiveness of this cell system, microarray-based gene expression profiling of the cAMP response pathway, one of the major pathways in steroidogenesis regulation, was examined in H295R cells. Next to the steroid synthesis pathway, a broader lipid metabolic pathway, including cholesterol uptake/biosynthesis, hormone metabolization and many hormone and nuclear receptors, are sensitive towards cAMP stimulation in this cell system. Moreover, these pathways were clearly dose and time responsive, indicating early regulation (10 h) of cholesterol uptake and mobilization genes and later expression (24-48 h) of cholesterol biosynthesis and steroid synthesis. Transcription network analysis suggested several important transcription factors that could be involved in regulation of the steroid hormone pathway, of which HNF4α, a broader lipid metabolism related transcription factor, might indicate some new transcription regulation patterns in this cell line. Overall we can conclude that the time dependent gene expression patterns of the strongly coordinated cholesterol supply and steroidogenesis pathways in the H295R cell system seem to reflect well the in vivo ACTH/cAMP signalling cascade in adrenal cells. Moreover, the completeness of the steroidogenic related pathways in terms of gene expression sensitivity, indicates the H295R cell line as a promising cell line in omics-based endocrine disruption screening.