Antiandrogenic mechanisms of pesticides in human LNCaP prostate and H295R adrenocortical carcinoma cells

Toxicologic effect and transcriptome analysis for sub-chronic exposure to carbendazim, prochloraz, and their combination on the liver of mice

Carbendazim (CBZ) and prochloraz (PCZ) are broad-spectrum fungicides used in agricultural peat control. Both fungicides leave large amounts of residues in fruits and are toxic to non-target organisms. However, the combined toxicity of the fungicides to non-target organisms is still unknown. Therefore, we characterized the toxic effects of dietary supplementation with CBZ, PCZ, and their combination for 90 days in 6-week-old male Institute of Cancer Research (ICR) mice. CBZ-H (100 mg/kg day), PCZ-H (10 mg/kg day), and their combination treatments increased the relative liver weights and caused liver injury. The serum total cholesterol (TC), triglyceride (TG), glucose (Glu), pyruvate (PYR), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were reduced, and synergistic toxicity was observed. Hepatic transcriptome revealed that 326 differentially expressed genes (DEGs) of liver were observed in the CBZ treatment group, 149 DEGs in the PCZ treatment group, and 272 DEGs in the combination treatment group. According to KEGG enrichment analysis, the fungicides and their combination affected lipid metabolism, amino acid metabolism, and ferroptosis. In addition, the relative mRNA levels of key genes involved in lipid metabolism were also examined. Compared with individual exposure, combined exposure to CBZ and PCZ caused a more obvious decrease in the expression of some genes related to glycolipid metabolism. Furthermore, the relative mRNA levels of some key genes in the combination treatment group were lower than those in the CBZ and PCZ treated groups. In summary, CBZ, PCZ, and their combination generally caused hepatotoxicity and glycolipid metabolism disorders, which could provide new insights for investigating the combined toxicity of multiple fungicides to animals.

Extended steroid profiling in H295R cells provides deeper insight into chemical-induced disturbances of steroidogenesis: Exemplified by prochloraz and anabolic steroids

Human adrenocortical H295R cells have been validated by the OECD Test Guideline 456 to detect chemicals disrupting testosterone and 17β-estradiol (estradiol) biosynthesis. This study evaluated a novel approach to detect disturbances of steroidogenesis in H295R cells, exemplified by prochloraz and five anabolic steroids. Steroid profiles were assessed by an untargeted LC-MS-based method, providing a relative quantification of 57 steroids annotated according to their accurate masses and retention times. Such a panel of steroids included several mineralocorticoids, glucocorticoids, progestins and adrenal androgens. The coverage of a high number of metabolites in this extended steroid profiling facilitated grouping of chemicals with similar effects and detecting subtler differences between chemicals. It allowed, for example, distinguishing between the effects of turinabol and oxymetholone, supposed to act similarly in a previous characterization including only nine adrenal steroids. Furthermore, the results revealed that product/substrate ratios can provide superior information on altered enzyme activities compared to individual metabolite levels. For example, the 17α-hydroxypregnenolone/pregnenolone ratio was found to be a more sensitive marker for detecting 17α-hydroxylase inhibition by prochloraz than the corresponding individual steroids. These results illustrate that chemical grouping and calculation of product/substrate ratios can provide valuable information on mode-of-action and help prioritizing further experimental work.

Glyphosate and Aminomethylphosphonic Acid (AMPA) Modulate Glutathione S-Transferase in Non-Tumorigenic Prostate Cells

Glyphosate (GLY) was developed in the early 1970s and has become the most used broad-spectrum herbicide in the world so far. Its main metabolite is aminomethylphosphonic acid (AMPA), and the accumulation of GLY and its derivative compounds raises some concerns regarding possible health outcomes. In this study, we aimed to evaluate the effects of GLY and AMPA on prostate cell lines by evaluating cell viability, proliferation, gene and protein expression, and cellular pathways involved in the response to oxidative stress. Our results indicated that GLY and AMPA reduced the cell viability of tumorigenic and non-tumorigenic prostate cell lines only at higher concentrations (10 mM GLY and 20 mM AMPA). In contrast, both compounds increased the clonogenicity of non-tumorigenic PNT2 cells, mainly at concentrations below the IC50 (5 mM GLY and 10 mM AMPA). Moreover, treatment of non-tumorigenic cells with low concentrations of GLY or AMPA for 48 h increased GSTM3 expression at both mRNA and protein levels. In contrast, the treatments decrease the GST activity and induced an increase in oxidative stress, mainly at lower concentrations. Therefore, both compounds can cause cellular damage even at lower concentrations in non-tumorigenic PNT2 cells, mainly affecting cell proliferation and oxidative stress.

Evaluating structure-based activity in a high-throughput assay for steroid biosynthesis

Data from a high-throughput human adrenocortical carcinoma assay (HT-H295R) for steroid hormone biosynthesis are available for >2000 chemicals in single concentration and 654 chemicals in multi-concentration (mc). Previously, a metric describing the effect size of a chemical on the biosynthesis of 11 hormones was derived using mc data referred to as the maximum mean Mahalanobis distance (maxmMd). However, mc HT-H295R assay data remain unavailable for many chemicals. This work leverages existing HT-H295R assay data by constructing structure-activity relationships to make predictions for data-poor chemicals, including: (1) identification of individual structural descriptors, known as ToxPrint chemotypes, associated with increased odds of affecting estrogen or androgen synthesis; (2) a random forest (RF) classifier using physicochemical property descriptors to predict HT-H295R maxmMd binary (positive or negative) outcomes; and, (3) a local approach to predict maxmMd binary outcomes using nearest neighbors (NNs) based on two types of chemical fingerprints (chemotype or Morgan). Individual chemotypes demonstrated high specificity (85-98%) for modulators of estrogen and androgen synthesis but with low sensitivity. The best RF model for maxmMd classification included 13 predicted physicochemical descriptors, yielding a balanced accuracy (BA) of 71% with only modest improvement when hundreds of structural features were added. The best two NN models for binary maxmMd prediction demonstrated BAs of 85 and 81% using chemotype and Morgan fingerprints, respectively. Using an external test set of 6302 chemicals (lacking HT-H295R data), 1241 were identified as putative estrogen and androgen modulators. Combined results across the three classification models (global RF model and two local NN models) predict that 1033 of the 6302 chemicals would be more likely to affect HT-H295R bioactivity. Together, these in silico approaches can efficiently prioritize thousands of untested chemicals for screening to further evaluate their effects on steroid biosynthesis.

Transcriptomic and targeted metabolomic analysis revealed the toxic effects of prochloraz on larval zebrafish

Prochloraz (PCZ), an imidazole fungicide, has been extensively used in horticulture and agriculture to protect against pests and diseases. To investigate the potential toxicity of PCZ on aquatic organisms, larval zebrafish, as a model, were exposed to a series of concentrations (0, 20, 100, and 500 μg/L) of PCZ for 7 days. With transcriptomic analysis, we found that exposure to high dose PCZ could produce 76 downregulated and 345 upregulated differential expression genes (DEGs). Bioinformatics analysis revealed that most of the DEGs were characterized in the pathways of glycolipid metabolism, amino acid metabolism and oxidative stress in larval zebrafish. Targeted metabolomic analysis was conducted to verify the effects of PCZ on the levels of acyl-carnitines and some amino acids in larval zebrafish. In addition, biochemical indicators related to glycolipid metabolism were affected obviously, manifested as elevated triglyceride (TG) levels and decreased glucose (Glu) levels in whole larvae. The expression levels of genes associated with glycolipid metabolism were affected in larvae after exposure to PCZ (PK, GK, PEPckc, SREBP, ACO). Interestingly, we further confirmed that PCZ could induce oxidative stress by the changing enzyme activities (T-GSH, GSSG) and upregulating several related genes levels in larval zebrafish. Generally, our results revealed that the endpoints related to glycolipid metabolism, amino acid metabolism and oxidative stress were influenced by PCZ in larval zebrafish.

Intracellular distribution of vinclozolin and its metabolites differently affects 5α-dihydrotestosterone (DHT)-induced PSA secretion in LNCaP cells

Endocrine disruption mechanisms in prostate are an overlooked issue. The anti-androgenic properties of the fungicide vinclozolin (VIN) and its active metabolites - 2-[[(3,5- dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1) and 3'5'-dichloro-2-hydroxy-2- methylbut-3-enanilide (M2) - were assessed on human prostate-derived cells (LNCaP); the effects were investigated also upon co-treatment with 5α-dihydrotestosterone (DHT), the physiological androgen receptor (AR)-agonist, and compared to the anti-androgenic drugs, 2-hydroxy-flutamide (2OH-FTA) and bicalutamide (BIC). Assessed endpoints were the cellular uptake and subcellular localization of VIN, M1 and M2, DHT-induced PSA gene expression and secretion. VIN, its metabolites, and the reference drugs, significantly reduced DHT-induced PSA secretion and gene expression, M2 showing the strongest downregulation. In absence of DHT, 2OH-FTA and BIC showed a very high (>98%) LNCaP uptake with a predominant intranuclear localization (BIC=80%, 2OH-FTA=70%). VIN cellular uptake was 42%: 24.7% made up by M2, mostly localized at nuclear level, differently from VIN and M1. Upon DHT co-treatment, VIN intracellular uptake increased by 28%, especially in the microsomal fraction (MF); M2 also increased mainly in MF but also, to a lower extent, in the intranuclear fraction. Finally, in a 72-hr time-course, the LNCaP uptake of VIN and its metabolites was much faster compared to purified M1 and M2. Overall, M2 resulted the leading compound for VIN endocrine-disrupting effects in LNCaP.

Endocrine Disruptors and Prostate Cancer

The role of endocrine disruptors (EDs) in the human prostate gland is an overlooked issue even though the prostate is essential for male fertility. From experimental models, it is known that EDs can influence several molecular mechanisms involved in prostate homeostasis and diseases, including prostate cancer (PCa), one of the most common cancers in the male, whose onset and progression is characterized by the deregulation of several cellular pathways including androgen receptor (AR) signaling. The prostate gland essentiality relies on its function to produce and secrete the prostatic fluid, a component of the seminal fluid, needed to keep alive and functional sperms upon ejaculation. In physiological condition, in the prostate epithelium the more-active androgen, the 5α-dihydrotestosterone (DHT), formed from testosterone (T) by the 5α-reductase enzyme (SRD5A), binds to AR and, upon homodimerization and nuclear translocation, recognizes the promoter of target genes modulating them. In pathological conditions, AR mutations and/or less specific AR binding by ligands modulate differently targeted genes leading to an altered regulation of cell proliferation and triggering PCa onset and development. EDs acting on the AR-dependent signaling within the prostate gland can contribute to the PCa onset and to exacerbating its development.

Chronic Atrazine Exposure Beginning Prenatally Impacts Liver Function and Sperm Concentration With Multi-Generational Consequences in Mice

Atrazine is a commonly used herbicide frequently detected in waterways and drinking water around the world. Worryingly, atrazine is an endocrine and metabolic disruptor but there is a lack of research regarding the effects of long-term exposure beginning in utero. In this study we investigated how chronic exposure to atrazine (5 mg/kg bw/day) in drinking water from E9.5 until 12 or 26 weeks of age affected metabolic and reproductive characteristics in male mice. We then examined whether mating these males to unexposed females altered in vitro embryo characteristics. Atrazine exposure caused a decrease in liver weight and changes in both liver and testis gene expression, specifically in genes involved in lipid uptake and fatty acid metabolism in the liver, as well as androgen conversion in the testis. Notably, atrazine exposure decreased epididymal sperm concentration and subsequent embryo cell numbers generated from the 12-week cohort males. Collectively, these data suggest that atrazine exposure, beginning prenatally, affects both metabolic and reproductive characteristics, and highlights the importance of assessing atrazine effects at different life stages and over multiple generations. The continued widespread use of atrazine warrants further studies, as it is essential to understand the health risks for all species, including humans.

Agrochemicals and obesity

Obesity has become a very large concern worldwide, reaching pandemic proportions over the past several decades. Lifestyle factors, such as excess caloric intake and decreased physical activity, together with genetic predispositions, are well-known factors related to obesity. There is accumulating evidence suggesting that exposure to some environmental chemicals during critical windows of development may contribute to the rapid increase in the incidence of obesity. Agrochemicals are a class of chemicals extensively used in agriculture, which have been widely detected in human. There is now considerable evidence linking human exposure to agrochemicals with obesity. This review summarizes human epidemiological evidence and experimental animal studies supporting the association between agrochemical exposure and obesity and outlines possible mechanistic underpinnings for this link.

Effect of environmental and pharmaceutical exposures on fetal testis development and function: a systematic review of human experimental data

BACKGROUND

Overall, the incidence of male reproductive disorders has increased in recent decades. Testicular development during fetal life is crucial for subsequent male reproductive function. Non-genomic factors such as environmental chemicals, pharmaceuticals and lifestyle have been proposed to impact on human fetal testicular development resulting in subsequent effects on male reproductive health. Whilst experimental studies using animal models have provided support for this hypothesis, more recently a number of experimental studies using human tissues and cells have begun to translate these findings to determine direct human relevance.

OBJECTIVE AND RATIONALE

The objective of this systematic review was to provide a comprehensive description of the evidence for effects of prenatal exposure(s) on human fetal testis development and function. We present the effects of environmental, pharmaceutical and lifestyle factors in experimental systems involving exposure of human fetal testis tissues and cells. Comparison is made with existing epidemiological data primarily derived from a recent meta-analysis.

SEARCH METHODS

For identification of experimental studies, PubMed and EMBASE were searched for articles published in English between 01/01/1966 and 13/07/2018 using search terms including ‘endocrine disruptor’, ‘human’, ‘fetal’, ‘testis’, ‘germ cells’, ‘testosterone’ and related search terms. Abstracts were screened for selection of full-text articles for further interrogation. Epidemiological studies involving exposure to the same agents were extracted from a recent systematic review and meta-analysis. Additional studies were identified through screening of bibliographies of full-texts of articles identified through the initial searches.

OUTCOMES

A total of 25 experimental studies and 44 epidemiological studies were included. Consistent effects of analgesic and phthalate exposure on human fetal germ cell development are demonstrated in experimental models, correlating with evidence from epidemiological studies and animal models. Furthermore, analgesic-induced reduction in fetal testosterone production, which predisposes to the development of male reproductive disorders, has been reported in studies involving human tissues, which also supports data from animal and epidemiological studies. However, whilst reduced testosterone production has been demonstrated in animal studies following exposure(s) to a variety of environmental chemicals including phthalates and bisphenol A, these effects are not reproduced in experimental approaches using human fetal testis tissues.

WIDER IMPLICATIONS

Direct experimental evidence for effects of prenatal exposure(s) on human fetal testis development and function exists. However, for many exposures the data is limited. The increasing use of human-relevant models systems in which to determine the effects of environmental exposure(s) (including mixed exposures) on development and function of human tissues should form an important part of the process for assessment of such exposures by regulatory bodies to take account of animal–human differences in susceptibility.

KnowTox: pipeline and case study for confident prediction of potential toxic effects of compounds in early phases of development

Risk assessment of newly synthesised chemicals is a prerequisite for regulatory approval. In this context, in silico methods have great potential to reduce time, cost, and ultimately animal testing as they make use of the ever-growing amount of available toxicity data. Here, KnowTox is presented, a novel pipeline that combines three different in silico toxicology approaches to allow for confident prediction of potentially toxic effects of query compounds, i.e. machine learning models for 88 endpoints, alerts for 919 toxic substructures, and computational support for read-across. It is mainly based on the ToxCast dataset, containing after preprocessing a sparse matrix of 7912 compounds tested against 985 endpoints. When applying machine learning models, applicability and reliability of predictions for new chemicals are of utmost importance. Therefore, first, the conformal prediction technique was deployed, comprising an additional calibration step and per definition creating internally valid predictors at a given significance level. Second, to further improve validity and information efficiency, two adaptations are suggested, exemplified at the androgen receptor antagonism endpoint. An absolute increase in validity of 23% on the in-house dataset of 534 compounds could be achieved by introducing KNNRegressor normalisation. This increase in validity comes at the cost of efficiency, which could again be improved by 20% for the initial ToxCast model by balancing the dataset during model training. Finally, the value of the developed pipeline for risk assessment is discussed using two in-house triazole molecules. Compared to a single toxicity prediction method, complementing the outputs of different approaches can have a higher impact on guiding toxicity testing and de-selecting most likely harmful development-candidate compounds early in the development process.

Novel mechanism of endocrine disruption by fungicides through binding to the membrane androgen receptor, ZIP9 (SLC39A9), and antagonizing rapid testosterone induction of the intrinsic apoptotic pathway

A variety of pesticides including vinclozolin, its metabolite M2 (3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide), and prochloraz have been shown to exert antiandrogenic effects in animal models by competing with androgen binding to nuclear androgen receptors (nAR) and decreasing transcription of androgen-responsive genes. However, it is not known whether these pesticide antiandrogens also interfere with rapid (often described as nongenomic, nonclassical) androgen actions mediated by membrane androgen receptors (mARs). We recently discovered that ZIP9, a member of the zinc transporter ZIP (SLC39A) family, is a specific, high-affinity mAR that mediates rapid testosterone-dependent signaling, zinc influx, and apoptosis in breast and prostate cancer cell lines. Possible disruption by prochloraz, vinclozolin, and M2 of androgen actions through this mAR was investigated in vitro in PC-3 prostate cancer cells (nAR-) over expressing human ZIP9 (PC3-ZIP9 cells). Single-point competitive binding assays showed 1 μM and 10 μM concentrations of all three pesticides displaced specific [³H]-testosterone binding to PC3-ZIP9 cell membranes with binding affinities <10% that of testosterone. The pesticides also exerted antiandrogen actions through ZIP9. Co-treatments with 100 nM prochloraz, vinclozolin and M2 blocked or attenuated the 20 nM testosterone-induced increases in apoptosis, intracellular free zinc levels, and expression of the proapoptotic gene, Bax. Prochloraz also attenuated testosterone activation of MAPkinase. The finding that prochloraz, vinclozolin and M2 are effective competitors of [³H]-testosterone binding to ZIP9 and block testosterone actions mediated through ZIP9 in vitro at nanomolar concentrations suggests that androgen functions mediated by ZIP9 are also susceptible to disruption by pesticide antiandrogens with potential adverse effects on human health.

Environmental inhibitors of the expression of cytochrome P450 17A1 in mammals

Cytochrome P450 17A1 (CYP17A1; EC: 1.14.14.19) is a critically important bifunctional enzyme with nicotinamide adenine dinucleotide phosphate (NADPH) as its cofactor that catalyzes the formation of all endogenous androgens. Its hydroxylase activity catalyzes the 17α-hydroxylation of pregnenolone (PREG)/progesterone (P4) to 17α-OH-pregnenolone/17α-OH-progesterone, and its 17,20-lyase activity converts 17α-OH-pregnenolone/17α-OH-progesterone to dehydroepiandrosterone/androstenedione. Androgens are required for male reproductive development, so androgen deficiency resulting from CYP17A1 inhibition may lead to reproductive disorders. There has been some advances on the study of environmental chemicals inhibiting mammalian CYP17A1 expression but no related review was available so we think it now necessary to review their characteristics and inhibiting properties.

High-Throughput H295R Steroidogenesis Assay: Utility as an Alternative and a Statistical Approach to Characterize Effects on Steroidogenesis

The U.S. Environmental Protection Agency Endocrine Disruptor Screening Program and the Organization for Economic Co-operation and Development (OECD) have used the human adrenocarcinoma (H295R) cell-based assay to predict chemical perturbation of androgen and estrogen production. Recently, a high-throughput H295R (HT-H295R) assay was developed as part of the ToxCast program that includes measurement of 11 hormones, including progestagens, corticosteroids, androgens, and estrogens. To date, 2012 chemicals have been screened at 1 concentration; of these, 656 chemicals have been screened in concentration-response. The objectives of this work were to: (1) develop an integrated analysis of chemical-mediated effects on steroidogenesis in the HT-H295R assay and (2) evaluate whether the HT-H295R assay predicts estrogen and androgen production specifically via comparison with the OECD-validated H295R assay. To support application of HT-H295R assay data to weight-of-evidence and prioritization tasks, a single numeric value based on Mahalanobis distances was computed for 654 chemicals to indicate the magnitude of effects on the synthesis of 11 hormones. The maximum mean Mahalanobis distance (maxmMd) values were high for strong modulators (prochloraz, mifepristone) and lower for moderate modulators (atrazine, molinate). Twenty-five of 28 reference chemicals used for OECD validation were screened in the HT-H295R assay, and produced qualitatively similar results, with accuracies of 0.90/0.75 and 0.81/0.91 for increased/decreased testosterone and estradiol production, respectively. The HT-H295R assay provides robust information regarding estrogen and androgen production, as well as additional hormones. The maxmMd from this integrated analysis may provide a data-driven approach to prioritizing lists of chemicals for putative effects on steroidogenesis.

Frontiers in endocrine disruption: Impacts of organotin on the hypothalamus-pituitary-thyroid axis

Endocrine disruptors (EDs), chemical substances widely used in industry and ubiquitously distributed in the environment, are able to interfere with the synthesis, release, transport, metabolism, receptor binding, action, or elimination of endogenous hormones. EDs affect homeostasis mainly by acting on nuclear and nonnuclear steroid receptors but also on serotonin, dopamine, norepinephrine and orphan receptors in addition to thyroid hormone receptors. Tributyltin (TBT), an ED widely used as a pesticide and biocide in antifouling paints, has well-documented actions that include inhibiting aromatase and affecting the nuclear receptors PPARγ and RXR. TBT exposure in humans and experimental models has been shown to mainly affect reproductive function and adipocyte differentiation. Since thyroid hormones play a fundamental role in regulating the basal metabolic rate and energy homeostasis, it is crucial to clarify the effects of TBT on the hypothalamus-pituitary-thyroid axis. Therefore, we review herein the main effects of TBT on important metabolic pathways, with emphasis on disruption of the thyroid axis that could contribute to the development of endocrine and metabolic disorders, such as insulin resistance and obesity.

Effects of triazole fungicides on androgenic disruption and CYP3A4 enzyme activity

Triazole fungicides are widely used as broad-spectrum fungicides, non-steroidal antiestrogens and for various industrial applications. Their residues have been frequently detected in multiple environmental and human matrices. The increasingly reported toxicity incidents have led triazole fungicides as emerging contaminants of environmental and public health concern. However, whether triazole fungicides behave as endocrine disruptors by directly mimicking environmental androgens/antiandrogens or exerting potential androgenic disruption indirectly through the inhibition of cytochrome P450 (CYP450) enzyme activity is yet an unresolved question. We herein evaluated five commonly used triazole fungicides including bitertanol, hexaconazole, penconazole, tebuconazole and uniconazole for the androgenic and anti-androgenic activity using two-hybrid recombinant human androgen receptor (AR) yeast bioassay and comparatively evaluated their effects on enzymatic activity of CYP3A4 by P450-Glo™ CYP3A4 bioassay. All five fungicides showed moderate anti-androgenic activity toward human AR with the IC₅₀ ranging from 9.34 μM to 79.85 μM. The anti-androgenic activity remained no significant change after the metabolism mediated by human liver microsomes. These fungicides significantly inhibited the activity of CYP3A4 at the environmental relevant concentrations and the potency ranks as tebuconazole > uniconazole > hexaconazole > penconazole > bitertanol with the corresponding IC₅₀ of 0.81 μM, 0.93 μM, 1.27 μM, 2.22 μM, and 2.74 μM, respectively. We found that their anti-androgenic activity and the inhibition potency toward CYP3A4 inhibition was significantly correlated (R² between 0.83 and 0.97, p < 0.001). Our results indicated that the risk assessment of triazole pesticides and structurally similar chemicals should fully consider potential androgenic disrupting effects and the influences on the activity of CYP450s.

Food components and contaminants as (anti)androgenic molecules

Androgens, the main male sex steroids, are the critical factors responsible for the development of the male phenotype during embryogenesis and for the achievement of sexual maturation and puberty. In adulthood, androgens remain essential for the maintenance of male reproductive function and behavior. Androgens, acting through the androgen receptor (AR), regulate male sexual differentiation during development, sperm production beginning from puberty, and maintenance of prostate homeostasis. Several substances present in the environment, now classified as endocrine disruptors (EDCs), strongly interfere with androgen actions in reproductive and non-reproductive tissues. EDCs are a heterogeneous group of xenobiotics which include synthetic chemicals used as industrial solvents/lubricants, plasticizers, additives, agrochemicals, pharmaceutical agents, and polyphenols of plant origin. These compounds are even present in the food as components (polyphenols) or food/water contaminants (pesticides, plasticizers used as food packaging) rendering the diet as the main route of exposure to EDCs for humans. Although huge amount of literature reports the (anti)estrogenic effects of different EDCs, relatively scarce information is available on the (anti)androgenic effects of EDCs. Here, the effects and mechanism of action of phytochemicals and pesticides and plasticizers as possible modulators of AR activities will be reviewed taking into account that insight derived from principles of endocrinology are required to estimate EDC consequences on endocrine deregulation and disease.

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.