Genetic analyses identify brain imaging-derived phenotypes associated with the risk of amyotrophic lateral sclerosis.

Brain imaging-derived phenotypes have been suggested to be associated with amyotrophic lateral sclerosis in observational studies, but whether these associations are causal remains unclear. We aimed to assess the potential bidirectional causal associations between imaging-derived phenotypes and amyotrophic lateral sclerosis using bidirectional 2-sample Mendelian randomization analyses. Summary statistics for 469 imaging-derived phenotypes (33,224 individuals) and amyotrophic lateral sclerosis (20,806 cases and 59,804 controls) were obtained from 2 large-scale genome-wide association studies of European ancestry. We used the inverse-variance weighted Mendelian randomization method in the main analysis to assess the bidirectional associations between imaging-derived phenotypes and amyotrophic lateral sclerosis, followed by several sensitivity analyses for robustness validation. In the forward Mendelian randomization analyses, we found that genetically determined high orientation dispersion index in the right cerebral peduncle was associated with the increased risk of amyotrophic lateral sclerosis (odds ratio = 1.30, 95% confidence interval = 1.16-1.45, P = 2.26 × 10-6). In addition, the reverse Mendelian randomization analysis indicated that amyotrophic lateral sclerosis had no effect on 469 imaging-derived phenotypes. Mendelian randomization-Egger regression analysis showed no directional pleiotropy for the association between high orientation dispersion index in the right cerebral peduncle and amyotrophic lateral sclerosis, and sensitivity analyses with different Mendelian randomization models further confirmed these findings. The present systematic bidirectional Mendelian randomization analysis showed that high orientation dispersion index in the right cerebral peduncle might be the potential causal mediator of amyotrophic lateral sclerosis, which may provide predictive guidance for the prevention of amyotrophic lateral sclerosis. Further studies are warranted to replicate our findings and clarify the underlying mechanisms.

Associations between brain imaging-derived phenotypes and cognitive functions.

We aimed to evaluate the potential causal relationship between brain imaging-derived phenotypes and cognitive functions via Mendelian randomization analyses. Genetic instruments for 470 brain imaging-derived phenotypes were selected from a genome-wide association study based on the UK Biobank (n = 33,224). Statistics for cognitive functions were obtained from the genome-wide association study based on the UK Biobank. We used the inverse variance weighted Mendelian randomization method to investigate the associations between brain imaging-derived phenotypes and cognitive functions, and reverse Mendelian randomization analyses were performed for significant brain imaging-derived phenotypes to examine the reverse causation for the identified associations. We identified three brain imaging-derived phenotypes to be associated with verbal-numerical reasoning, including cortical surface area of the left fusiform gyrus (beta, 0.18 [95% confidence interval, 0.11 to 0.25], P = 4.74 × 10-7), cortical surface area of the right superior temporal gyrus (beta, 0.25 [95% confidence interval, 0.15 to 0.35], P = 6.30 × 10-7), and orientation dispersion in the left superior longitudinal fasciculus (beta, 0.14 [95% confidence interval, 0.09 to 0.20], P = 8.37 × 10-7). The reverse Mendelian randomization analysis indicated that verbal-numerical reasoning had no effect on these three brain imaging-derived phenotypes. This Mendelian randomization study identified cortical surface area of the left fusiform gyrus, cortical surface area of the right superior temporal gyrus, and orientation dispersion in the left superior longitudinal fasciculus as predictors of verbal-numerical reasoning.

Association of semenogelin (SEMG) gene variants in idiopathic male infertility in Chinese-Han population.

Infertility is known to occur frequently worldwide, and the incidence is continuing to rise in China. It is known that semenogelin (SEMG) protein secreted by human seminal vesicles plays an important role in male reproductive system function. However, an association between alterations in SEMG gene functions and idiopathic male infertility occurrence in Chinese-Han population has not been examined. The aim of this study was thus to investigate the inherent relationship between SEMG gene alterations and idiopathic male infertility using a method of variant genotyping selection and semen quality analysis. A population of 484 males with clinically diagnosed idiopathic male infertility and 246 fertile controls were selected after signing consent forms. Results demonstrated a significantly increased frequency of idiopathic infertility with abnormal semen parameters such as semen volume, sperm concentration, sperm number per ejaculate, and sperm motility in variants carrying the rs2301366 TA genotype. Combined association analysis from target single-nucleotide polymorphisms (SNPs) was selected from the genotype database of unrelated Chinese-Han in Beijing individuals from the Hap Map. SNP array analysis in blood samples in each group was carried out by TaqMan Universal PCR Master Mix and TaqMan SNP Genotyping Assays. In addition, the interaction between SEMG SNPs and binding protein epididymal protease inhibitor (EPPIN) SNPs was determined. Our findings demonstrated that the presence of SEMG SNPs and EPPIN SNPs increased the frequency of idiopathic male infertility in Chinese-Han population. It is proposed that measurement of SEMG SNPs and EPPIN SNPs in carriers may thus be utilized to identify idiopathic male infertility.

Circadian rhythm genes mediate fenvalerate-induced inhibition of testosterone synthesis in mouse Leydig cells.

Fenvalerate (Fen), a widely used pesticide, is known to impair male reproductive functions by mechanisms that remain to be elucidated. Recent studies indicated that circadian clock genes may play an important role in successful male reproduction. The aim of this study was to determine the effects of Fen on circadian clock genes involved in the biosynthesis of testosterone using TM3 cells derived from mouse Leydig cells. Data demonstrated that the circadian rhythm of testosterone synthesis in TM3 cells was disturbed following Fen treatment as evidenced by changes in the circadian rhythmicity of core clock genes (Bmal1, Rev-erbα, Rorα). Further, the observed altered rhythms were accompanied by increased intracellular Ca2+ levels and modified steroidogenic acute regulatory (StAR) mRNA expression. Thus, data suggested that Fen inhibits testosterone synthesis via pathways involving intracellular Ca2+ and clock genes (Bmal1, Rev-Erbα, Rorα) as well as StAR mRNA expression in TM3 cells.

Inhibitory effect of melatonin on testosterone synthesis is mediated via GATA-4/SF-1 transcription factors.

The aim of the present study was to elucidate whether the GATA-4/SF-1 signalling pathway is involved in the inhibitory effects of melatonin on testosterone production in both the TM3 Leydig cell line and in C57BL/6J mice. In-vitro experiments demonstrated that melatonin treatment significantly reduced testosterone levels in cell culture medium (P < 0.05 or P < 0.01); and decreased intracellular cyclic adenosine monophospha accumulation (P < 0.05 or P < 0.01) and mRNA/protein expression of GATA-4, SF-1 (NR5A1), StAR, P450SCC (CYP11A1) and 3ß-HSD (P < 0.05 or P < 0.01). These effects were blocked by N-acetyl-2-benzyltryptamin, a melatonin receptor antagonist. Similar effects of melatonin on testosterone production (P < 0.05 or P < 0.01) and down-regulation of transcription factors GATA-4 and SF-1 (P < 0.01) were also observed in mice treated with intratesticular injections of melatonin. Overall, the data suggest that the inhibitory effects of melatonin on testosterone production are mediated via down-regulation of GATA-4 and SF-1 expression.

Association between Plasma Brain-derived Neurotrophic Factor Level and Alzheimer's Disease: A Mendelian Randomization Study.

BACKGROUND: High brain-derived neurotrophic factor (BDNF) concentrations have been found to be associated with a decreased risk of Alzheimer's disease (AD) in observational studies, but the causality for this association remains unclear. Therefore, we aimed to examine the association between genetically determined plasma BDNF levels and AD using a two-sample Mendelian randomization (MR) method. METHODS: Twenty single-nucleotide polymorphisms associated with plasma BDNF concentrations were identified as genetic instruments based on a genome-wide association study with 3301 European individuals. Summary-level data on AD were obtained from the International Genomics of Alzheimer's Project, involving 21,982 AD cases and 41,944 controls of European ancestry. To evaluate the relationship between plasma BDNF concentrations and AD, we employed the inverse-variance weighted method along with a series of sensitivity analyses. RESULTS: The inverse-variance weighted MR analysis showed that genetically determined BDNF concentrations were associated with a decreased risk of AD (odds ratio per SD increase, 0.91; 95% confidence interval, 0.86-0.96; p =0.001). The association between plasma BDNF concentrations and AD was further confirmed through sensitivity analyses using different MR methods, and MR-Egger regression suggested no directional pleiotropy for this association. CONCLUSION: Genetically determined BDNF levels were associated with a decreased risk of AD, suggesting that BDNF was implicated in the development of AD and might be a promising target for the prevention of AD.

Association Between Human Blood Metabolome and the Risk of Psychiatric Disorders.

BACKGROUND AND HYPOTHESIS: To identify promising drug targets for psychiatric disorders, we applied Mendelian randomization (MR) design to systematically screen blood metabolome for potential mediators of psychiatric disorders and further predict target-mediated side effects. STUDY DESIGN: We selected 92 unique blood metabolites from 3 metabolome genome-wide association studies (GWASs) with totally 147 827 participants. Summary statistics for bipolar disorder (BIP), attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), major depressive disorder (MDD), schizophrenia (SCZ), panic disorder (PD), autistic spectrum disorder (ASD), and anorexia nervosa (AN) originated from the Psychiatric Genomics Consortium, involving 1 143 340 participants. Mendelian randomization (MR) analyses were conducted to estimate associations of blood metabolites with psychiatric disorders. Phenome-wide MR analysis was further performed to predict side effects mediated by metabolite-targeted interventions. RESULTS: Eight metabolites were identified associated with psychiatric disorders, including five established mediators: N-acetylornithine (BIP: OR, 0.72 [95% CI, 0.66-0.79]; SCZ: OR, 0.74 [0.64-0.84]), glycine (BIP: OR, 0.62 [0.50-0.77]), docosahexaenoic acid (MDD: OR, 0.96 [0.94-0.97]), 3-Hydroxybutyrate (MDD: OR, 1.14 [1.08-1.21]), butyrylcarnitine (SCZ: OR, 1.22 [1.12-1.32]); and three novel mediators: 1-arachidonoylglycerophosphocholine (1-arachidonoyl-GPC)(BIP: OR, 0.31 [0.23-0.41]), glycoproteins (BIP: OR, 0.94 [0.92-0.97]), sphingomyelins (AN: OR, 1.12 [1.06-1.19]). Phenome-wide MR analysis showed that all identified metabolites except for N-acetylornithine and 3-Hydroxybutyrate had additional effects on nonpsychiatric diseases, while glycine, 3-Hydroxybutyrate, N-acetylornithine, and butyrylcarnitine had no adverse side effects. CONCLUSIONS: This MR study identified five established and three novel mediators for psychiatric disorders. N-acetylornithine, glycine, 3-Hydroxybutyrate, and butyrylcarnitine might be promising targets against psychiatric disorders with no predicted adverse side effects.

Association of the methylenetetrahydrofolate reductase gene A1298C polymorphism with male infertility: a meta-analysis.

Published data on the association between the methylenetetrahydrofolate reductase (MTHFR) gene A1298C (rs1801131) polymorphism and male infertility risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. In this meta-analysis, a total of seven case-control studies including 1633 cases and 1735 controls were selected to evaluate the possible association. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association in the additive model, dominant model, recessive model, and allele-frequency genetic model. In the overall analysis, the frequency of the C1298 allele (C vs. A) was significantly associated with susceptibility to male infertility (OR = 1.12, 95% CI = 1.00-1.26). A subgroup analysis of the subjects showed that MTHFR 1298C was associated with significant increased risk of azoospermia in homozygote comparison (CC vs. AA) and recessive mode (CC vs. AA/AC) (OR = 1.66 for CC vs. AA genotype; OR = 1.67 for CC vs. AA/AC genotype). However, no statistically significant increased risk of oligoasthenoteratozoospermia was found in any of the genetic models. In conclusion, this meta-analysis supports that the MTHFR A1298C polymorphism is capable of causing male infertility susceptibility, especially azoospermia.

Endocrine disruption effects of 2,2',4,4',6-pentabromodiphenylether (BDE100) in reporter gene assays.

Polybrominated diphenyl ethers (PBDEs) constitute an important group of flame retardants. 2,2',4,4',6-Pentabromodiphenylether (BDE100) is a prominent PBDE congener in some human populations. The potential of BDE100 to modulate responses mediated by the estrogen (ER), thyroid hormone (ThR) or androgen receptors (AR) were investigated by use of transactivation reporter gene assays. The African green monkey kidney CV-1 cell transiently transfected with the constructed reporter gene plasmid ERE-TATA-Luc and pUAS-tk-Luc with luciferase (Luc) under control of the estrogen response (ERE), or thyroid hormone response (ThRE) elements were used to evaluate (anti)estrogen and thyroid effects of BDE100. The (anti)androgenic potency of BDE100 was also evaluated by use of MDA-kb2 cells, which were stably transfected with MMTV-luciferase. The assays displayed appropriate responses to known natural estrogen 17ß-estradiol (E2), ThR ligand triiodothyronine (T3), and the AR agonist 5α-dihydrotestosterone (DHT). 10 or 50 µM BDE100 significantly up-regulated expression of Luc under control of the ER. Antiestrogenic potency was observed for BDE100 (IC50 = 6.21 µM). Co-exposure to 50 µM BDE100 significantly enhanced expression of Luc caused by 5 nM T3. BDE100 was antiandrogenic at 10 and 50 µM with an IC50 of 28.60 µM BDE100. These results suggest that BDE100 can modulate the endocrine system in multiple ways by interfering with several hormonal signaling pathways simultaneously.

Metabolomic Profiles of Shift Workers and Day Workers: A Cross-Sectional Study.

OBJECTIVE: The purpose of this study was to characterize the metabolomic profiles of shift workers and day workers and to discover the effect of shift work on workers' metabolic health. METHODS: A total of 824 participants aged 25 to 55 years were recruited, and 485 (275 shift workers and 210 day workers) completed the study. The mean age of the shift workers was 37.32 (5.53) years old, and that of day workers was 36.50 (7.83) years old. Serum and salivary samples were collected for the detection of key biochemical indicators (melatonin, cholesterol, and low-density lipoprotein cholesterol) and for metabolome profile analyses. RESULTS: Compared with female day workers, female shift workers had a higher BMI, waist circumference, and hip circumference. Correspondingly, we identified 76 significant metabolites (false discovery rate < 0.05) in shift workers, including L-tryptophan, acylcarnitines, and several fatty acids. Three pathways that presented significant differences were biosynthesis of unsaturated fatty acids, linoleic acid metabolism, and ubiquinone and other terpenoid-quinone biosynthesis. CONCLUSIONS: Compared with day workers, shift workers were more prone to weight gain and central obesity and were at a higher risk for impaired lipid metabolism with disrupted circadian rhythms.

Lack of association between DAZ gene methylation patterns and spermatogenic failure.

BACKGROUND: Abnormal DNA methylation of the male germ line is proposed as a possible mechanism causing compromised spermatogenesis in some men diagnosed with idiopathic infertility. Previous studies suggested that aberrant DNA methylation of several genes is associated with disruptions in spermatogenesis. However, little information is available on DNA methylation patterns of testis-specific genes in idiopathic male infertility. METHODS: To investigate the association between DAZ gene methylation patterns and spermatogenic failure, we performed an analysis of methylation patterns in 174 idiopathic infertile patients and 58 fertile controls using bisulfite-modified sequencing. RESULTS: We found that the methylation patterns of CpG island (CGI) in the DAZ gene promoter region were different between somatic cells and spermatic cells in the control group. DAZ gene methylation patterns among groups with different spermatogenic status were the same in somatic cells, completely methylated, and in spermatic cells. The results were concordant, except for the group with azoospermia (AZ) which were completely unmethylated. CONCLUSIONS: Our data indicate that the methylation patterns of the DAZ gene are not associated with spermatogenic failure. This suggests that epigenetic modification of DAZ is unlikely to be involved in the etiology of spermatogenic failure.

Endocrine-disrupting equivalents in industrial effluents discharged into Yangtze River.

The endocrine-disrupting equivalents in effluents from three chemical industry wastewater treatment systems in the vicinity of Yangtze River were determined by several transactivation reporter gene assays. Transient transfections of African green monkey kidney cell line (CV-1) were used to determine the estrogenic, anti-androgenic and anti-thyroid equivalents in the effluents. Organic extracts of the effluents contained compounds that were potent anti-androgens and the activities measured as an equivalent concentration of flutamide were 45.53, 34.65 and 91.61 nM, respectively. The extracts also contained detectable concentrations of thyroid antagonists. Estrogenic activities, measured with the reporter gene assay, were near or below the method detection limit (0.58 pM as E2). Concentrations of some of the major constituents such as di(2-ethylhexyl)phthalate, dibutyl phthalate, 2,6-dinitrotoluene and nitrobenzene were quantified. The data suggest that the reporter gene assay is useful to predication of endocrine disrupting effects in polluted aquatic body.

Carbaryl, 1-naphthol and 2-naphthol inhibit the beta-1 thyroid hormone receptor-mediated transcription in vitro.

Effects of pesticides on the function of thyroid have attracted lots of attention because thyroid hormones (THs) play a major role in mammalian brain development. In order to screen for compounds that acted on the thyroid hormone receptor (TR) signaling pathway, we transiently transfected the vector pGal4-L-TRbeta1 (Gal4 DBD fused to hTRbeta1 LBD) and Gal4-responsive luciferase reporter pUAS-tk-Luc into HepG2 cell, developing a reporter gene assay which showed good response to triiodothyronine (T3) and thyroxine (T4) with the median effective concentration (EC(50)) of 0.46 and 25.53 nM, respectively. Bisphenol A exhibited weak anti-thyroid hormone activity with median inhibitory concentration (IC(50)) value of 6.45 x 10(-5)M. The assay showed acceptable repeatability to T3 with intra coefficient of variability (CV) of 5.9% and inter CV of 11.7%. Carbaryl, 1-naphthol (1-NAP) and 2-naphthol (2-NAP) were tested for their agonist and antagonist activities. As a result, we found that all the three related chemicals possessed TR antagonist activity and none of them showed the agonist activity. These results further indicated that TR might be the targets of industrial chemicals. And this assay provided a useful tool for investigating the effects of environment chemicals on thyoid function.

Variants of the CLOCK gene affect the risk of idiopathic male infertility in the Han-Chinese population.

Recent experimental animal studies suggested that the circadian locomotor output cycles kaput protein gene (CLOCK) has been reported to play a critical role in sperm function and male fertility. The aim of this study was to determine whether variants of the CLOCK gene are involved in idiopathic male infertility. The study included 478 idiopathic infertile men and 194 fertile controls who completed physical examinations. Each subject donated 5 ml of peripheral blood and a sample of semen in the ejaculate. An aliquot of each blood sample was used to separate the serum for the measurement of testosterone as well as follicular stimulating hormone (FSH) using the standard radioimmunoassay. The rest of the blood samples was used to extract the DNA for the assay of three tagging single-nucleotide polymorphisms of CLOCK gene, viz., rs1801260, rs3817444 and rs3749474, using the real-time fluorescence quantitative PCR. The ejaculate of each subject was used for semen analysis by computer-assisted semen analysis system. The results indicated: (a) the variant rs1801260 associated with normal semen parameters was linked to a significant increase in the risk of idiopathic infertility, (b) the variant rs3817444 associated with both normal and abnormal semen parameters also indicated an increased risk of idiopathic infertility, and (c) the variants rs3749474 associated with both normal and abnormal semen parameters, on the other hand, conferred no significant risk for male infertility. Furthermore, elevated serum testosterone and FSH levels were correlated with the three variants of CLOCK gene in idiopathic infertility. The findings demonstrate that the human subjects with variants of the CLOCK gene are associated with idiopathic male infertility and therefore may be applied as a risk factor of male infertility.

Circadian alterations of reproductive functional markers in male rats exposed to 1800 MHz radiofrequency field.

In this study, we explored the circadian effects of daily radiofrequency field (RF) exposure on reproductive functional markers in adult male Sprague-Dawley rats. Animals in circadian rhythm (as indicated by melatonin measurements), were divided into several groups and exposed to 1800 MHz RF at 205 µw/cm(2) power density (specific absorption rate 0.0405 W/kg) for 2 h/day for 32 days at different zeitgeber time (ZT) points, namely, ZT0, ZT4, ZT8, ZT12, ZT16 and ZT20. Sham-exposed animals were used as controls in the study. From each rat, testicular and epididymis tissues were collected and assessed for testosterone levels, daily sperm production and sperm motility, testis marker enzymes γ-GT and ACP, cytochrome P450 side-chain cleavage (p450cc) mRNA expression, and steroidogenic acute regulatory protein (StAR) mRNA expression. Via these measurements, we confirmed the existence of circadian rhythms in sham-exposed animals. However, rats exposed to RF exhibited a disruption of circadian rhythms, decreased testosterone levels, lower daily sperm production and sperm motility, down-regulated activity of γ-GT and ACP, as well as altered mRNA expression of cytochrome P450 and StAR. All of these observations were more pronounced when rats were exposed to RF at ZT0. Thus, our findings indicate potential adverse effects of RF exposure on male reproductive functional markers, in terms of both the daily overall levels as well as the circadian rhythmicity.

Endocrine effects of methoxylated brominated diphenyl ethers in three in vitro models.

Methoxylated brominated diphenyl ethers (MeO-BDEs) in aquatic environments have been found to be primarily of natural origin in the marine environment and not from biotransformation of synthetic PBDEs. Two of the eight MeO-PBDEs (2'-MeO-BDE-68 and 6-MeO-BDE-47) that were detected in anchovy from the Yangtze River Delta, were natural products from marine organisms. So 2'-MeO-BDE-68 and 6-MeO-BDE-47 were chosen to study the potential to modulate androgen, estrogen, or thyroid hormone receptor- (AR, ER, ThR) mediated responses by use of reporter gene assays. 2'-MeO-BDE-68 was antiandrogenic at 50 µM, estrogenic at 10 µM and antiestrogenic at 10 and 50 µM (IC50=4.88 µM). 2'-MeO-BDE-68 enhanced luciferase expression by 5 nM T3 at 50 µM. 6-MeO-BDE-47 exhibited potent antiandrogenicity at 1 µM and greater (IC50=41.8 µM) and possessed estrogenic activity at 10 µM and antiestrogenic activity at 10 and 50 µM (IC50=6.02 µM).

In vitro profiling of endocrine disrupting potency of 2,2',4,4'-tetrabromodiphenyl ether (BDE47) and related hydroxylated analogs (HO-PBDEs).

The potential of 2,2',4,4'-tetrabromodiphenyl ether (BDE47) and its related hydroxylated analogs (2'-HO-BDE28, 6-HO-BDE47, 4'-HO-BDE17, and 4'-HO-BDE49) to modulate estrogen/thyroid/androgen receptor-(ER, TR, AR), mediated responses were investigated by use of reporter gene assays. Exposure to 1 or 10 µM, 4'-HO-BDE17 significantly up-regulated expression of Luc, whereas other four chemicals did not induce Luc expression under control of the ER. Anti-estrogenic potency was observed for 4'-HO-BDE17 (IC50=1.14 µM)>6-HO-BDE47 (IC50=2.65 µM)>2'-HO-BDE28 (IC50=9.49 µM)>BDE47 (IC50=21.11 µM). No anti-estrogenic effect of 4'-HO-BDE49 was observed. Both 4'-HO-BDE17, 4'-HO-BDE49 resulted in greater responses of Luc expression induced by T3. BDE47, 2'-HO-BDE28, 6-HO-BDE47 did not show any effect on the expression of Luc induced by 5 nM T3. 6-HO-BDE47 (IC50=0.34 µM)>4'-HO-BDE17 (IC50=1.41 µM)>BDE47 (IC50=3.83 µM)>2'-HO-BDE28 (IC50=29.22 µM) exhibited anti-androgenic potency, while 4'-HO-BDE49 did not show androgenic transcriptional activity.

Thyroid disruption by Di-n-butyl phthalate (DBP) and mono-n-butyl phthalate (MBP) in Xenopus laevis.

BACKGROUND: Di-n-butyl phthalate (DBP), a chemical widely used in many consumer products, is estrogenic and capable of producing seriously reproductive and developmental effects in laboratory animals. However, recent in vitro studies have shown that DBP and mono-n-butyl phthalate (MBP), the major metabolite of DBP, possessed thyroid hormone receptor (TR) antagonist activity. It is therefore important to consider DBP and MBP that may interfere with thyroid hormone system. METHODOLOGY/PRINCIPAL FINDINGS: Nieuwkoop and Faber stage 51 Xenopus laevis were exposed to DBP and MBP (2, 10 or 15 mg/L) separately for 21 days. The two test chemicals decelerated spontaneous metamorphosis in X. laevis at concentrations of 10 and 15 mg/L. Moreover, MBP seemed to possess stronger activity. The effects of DBP and MBP on inducing changes of expression of selected thyroid hormone response genes: thyroid hormone receptor-beta (TRß), retinoid X receptor gamma (RXRγ), alpha and beta subunits of thyroid-stimulating hormone (TSHα and TSHß) were detected by qPCR at all concentrations of the compounds. Using mammalian two-hybrid assay in vitro, we found that DBP and MBP enhanced the interactions between co-repressor SMRT (silencing mediator for retinoid and thyroid hormone receptors) and TR in a dose-dependent manner, and MBP displayed more markedly. In addition, MBP at low concentrations (2 and 10 mg/L) caused aberrant methylation of TRß in head tissue. CONCLUSIONS: The current findings highlight potential disruption of thyroid signalling by DBP and MBP and provide data for human risk assessment.

Identification of aberrant promoter hypomethylation of HOXA10 in ovarian cancer.

PURPOSE: The purpose of this study was to determine the relationship between hypomethylation of HOXA10 gene's promoter and high expression in malignant ovarian tissues, and to confirm the level of hypomethylation in ovarian cell lines. EXPERIMENTAL DESIGN: We performed the methylation status of 29 samples from ovarian carcinomas and 16 from normal tissues by methylation-specific polymerase chain reaction (MSP). Then, we evaluated the expression of mRNA and protein of HOXA10 in all samples to work out the relationship between the methylation status of HOXA10 and its expression in transcriptional and translational levels. We then confirmed our present study using SKOV3 and HEY ovarian cancer cell lines treated with the demethylating agent 5-aza-2'-deoxycytidine (5-aza-dC) to detect whether the expression of HoxA10 in the two cell lines was altered. RESULTS: Increased expression of HOXA10 was detected in almost all ovarian carcinomas (p < 0.05). Promoter hypomethylation was found in (17 of 29) 58.62% ovarian cancers and (4 of 16) 25% normal ovaries (p < 0.05). The HOXA10 expression is higher when the status of HOXA10 gene promoter is hypomethylated than in methylated tissues (p < 0.05). After 5-aza-dC treatment, the expression level of HOXA10 mRNA transcript was increased in the two cell lines. CONCLUSION: Our results indicate that promoter hypomethylation is an important mechanism for high expression of HOXA10 in human ovarian cancer and may be a potential prognostic factor in ovarian cancer.

Assessing hormone receptor activities of pyrethroid insecticides and their metabolites in reporter gene assays.

Pyrethroid insecticides, the most commonly used insecticides worldwide, are suspected endocrine-disrupting chemicals. But their interactions with hormone receptors are still unclear. The present study intended to evaluate and compare the hormone receptor (estrogen receptor [ER], androgen receptor [AR], and thyroid hormone receptor [TR]) activities of nine pyrethroids (cycloprothrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, etofenprox, fenvalerate, permethrin, and tetramethrin) and their metabolites (3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropne carboxylic acid [DCCA] and 3-phenoxybenzoic acid [3-PBA]) using receptor-mediated luciferase reporter gene assays. Of the 11 compounds tested, four showed very weak ER agonistic activities and six displayed antiestrogenic effects, among which cyhalothrin and DCCA possessed the most potent estrogenic and antiestrogenic activity respectively. Antagonistic effects to AR were found in 7 compounds, with cyfluthrin and deltamethrin exhibiting stronger AR antagonistic capacity. In the TR assay, all of tested chemicals except DCCA showed antagonistic effects. In this study, we provided evidence that a variety of pyrethroids and their metabolites might disrupt the function of multiple nuclear hormone receptors and thus have the potentials to affect the endocrine and the reproductive systems in humans.