Maternal and newborn metabolomic changes associated with urinary polycyclic aromatic hydrocarbon metabolite concentrations at delivery: an untargeted approach.

INTRODUCTION: Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse human health outcomes. To explore the plausible associations between maternal PAH exposure and maternal/newborn metabolomic outcomes, we conducted a cross-sectional study among 75 pregnant people from Cincinnati, Ohio. METHOD: We quantified 8 monohydroxylated PAH metabolites in maternal urine samples collected at delivery. We then used an untargeted high-resolution mass spectrometry approach to examine alterations in the maternal (n = 72) and newborn (n = 63) serum metabolome associated with PAH metabolites. Associations between individual maternal urinary PAH metabolites and maternal/newborn metabolome were assessed using linear regression adjusted for maternal and newborn factors while accounting for multiple testing with the Benjamini-Hochberg method. We then conducted functional analysis to identify potential biological pathways. RESULTS: Our results from the metabolome-wide associations (MWAS) indicated that an average of 1% newborn metabolome features and 2% maternal metabolome features were associated with maternal urinary PAH metabolites. Individual PAH metabolite concentrations in maternal urine were associated with maternal/newborn metabolome related to metabolism of vitamins, amino acids, fatty acids, lipids, carbohydrates, nucleotides, energy, xenobiotics, glycan, and organic compounds. CONCLUSION: In this cross-sectional study, we identified associations between urinary PAH concentrations during late pregnancy and metabolic features associated with several metabolic pathways among pregnant women and newborns. Further studies are needed to explore the mediating role of the metabolome in the relationship between PAHs and adverse pregnancy outcomes.

Stem Cell Theory of Cancer: Clinical Implications of Epigenomic versus Genomic Biomarkers in Cancer Care.

Biomarkers play a crucial role in the diagnosis, prognosis, and therapeutics of cancer. We use biomarkers to identify, image, monitor, and target cancer. In many respects, the discovery of pertinent biomarkers that distinguish fulminant from indolent neoplasms and sensitive from refractory malignancies would be a holy grail of cancer research and therapy. We propose that a stem cell versus genetic theory of cancer may not only enable us to track and trace the biological evolution of cancer but also empower us to attenuate its clinical course and optimize the clinical outcome of patients with cancer. Hence, a biomarker that identifies cancer stem cells (CSCs) and distinguishes them from non-CSCs may serve to elucidate inter-tumoral and intra-tumoral heterogeneity, elevate the values and utility of current prognostic and predictive tests, and enhance drug versus therapy development in cancer care. From this perspective, we focus on CSC biomarkers and discuss stemness or stem-like biomarkers in the context of a unified theory and a consideration of stem cell versus genetic origin. We review their role in primary and mixed tumors, in the elaboration of tumor subtypes, and in the imaging and monitoring of minimal residual diseases. We investigate how scientific theories influence the direction of scientific research and interpretation of experimental results, and how genomics and epigenomics affect the dynamics and trajectories of biomarkers in the conduct of cancer research and in the practice of cancer care.

The androgen receptor inhibits transcription of GPER1 by preventing Sp1 and Sp3 from binding to the promoters in prostate cancer cells.

G-1, a GPER1 agonist, was shown to inhibit the growth of castration-resistant mouse xenografts but not their parental androgen-dependent tumors. It is currently unknown how the androgen receptor (AR) represses GPER1 expression. Here, we found that two GPER1 mRNA variants (GPER1v2 and GPER1v4) were transcriptionally repressed, not via transcript destabilization, by the androgen-activated AR. Although no AR binding was found in all active promoters near GPER1, data from promoter assays suggested that both variants' promoters were inhibited by androgen treatment. Site-directed mutagenesis on Sp1/Sp3 binding sites revealed their role in supporting the basal expression of GPER1. Knockdown of Sp1 and Sp3 together but not separately repressed GPER1 expression whereas overexpression of both Sp1 and Sp3 together was required to alleviate AR repression of GPER1. Based on the chromatin immunoprecipitation data, Sp3 was found to bind to the promoters prior to the binding of Sp1 and RNA polymerase II. However, the binding of all three transcription factors was inhibited by DHT treatment. Concordantly, DHT treatment induced nuclear interactions between AR and Sp1 or Sp3. Taken together, these results indicate that AR represses transcription of GPER1 by binding to Sp1 and Sp3 independently to prevent their transactivation of the GPER1 promoters.

Three-Generation Study of Male Rats Gestationally Exposed to High Butterfat and Bisphenol A: Impaired Spermatogenesis, Penetrance with Reduced Severity.

Gestational high butterfat (HFB) and/or endocrine disruptor exposure was previously found to disrupt spermatogenesis in adulthood. This study addresses the data gap in our knowledge regarding transgenerational transmission of the disruptive interaction between a high-fat diet and endocrine disruptor bisphenol A (BPA). F0 generation Sprague-Dawley rats were fed diets containing butterfat (10 kcal%) and high in butterfat (39 kcal%, HFB) with or without BPA (25 µg/kg body weight/day) during mating and pregnancy. Gestationally exposed F1-generation offspring from different litters were mated to produce F2 offspring, and similarly, F2-generation animals produced F3-generation offspring. One group of F3 male offspring was administered either testosterone plus estradiol-17ß (T + E2) or sham via capsule implants from postnatal days 70 to 210. Another group was naturally aged to 18 months. Combination diets of HFB + BPA in F0 dams, but not single exposure to either, disrupted spermatogenesis in F3-generation adult males in both the T + E2-implanted group and the naturally aged group. CYP19A1 localization to the acrosome and estrogen receptor beta (ERbeta) localization to the nucleus were associated with impaired spermatogenesis. Finally, expression of methyl-CpG-binding domain-3 (MBD3) was consistently decreased in the HFB and HFB + BPA exposed F1 and F3 testes, suggesting an epigenetic component to this inheritance. However, the severe atrophy within testes present in F1 males was absent in F3 males. In conclusion, the HFB + BPA group demonstrated transgenerational inheritance of the impaired spermatogenesis phenotype, but severity was reduced in the F3 generation.

Genetic and epigenetic changes in the eutopic endometrium of women with endometriosis: association with decreased endometrial αvß3 integrin expression.

About 40% of women with infertility and 70% of women with pelvic pain suffer from endometriosis. The pregnancy rate in women undergoing IVF with low endometrial integrin αvß3 (LEI) expression is significantly lower compared to the women with high endometrial integrin αvß3 (HEI). Mid-secretory eutopic endometrial biopsies were obtained from healthy controls (C; n=3), and women with HEI (n=4) and LEI (n=4) and endometriosis. Changes in gene expression were assessed using human gene arrays and DNA methylation data were derived using 385 K Two-Array Promoter Arrays. Transcriptional analysis revealed that LEI and C groups clustered separately with 396 differentially expressed genes (DEGs) (P<0.01: 275 up and 121 down) demonstrating that transcriptional and epigenetic changes are distinct in the LEI eutopic endometrium compared to the C and HEI group. In contrast, HEI vs C and HEI vs LEI comparisons only identified 83 and 45 DEGs, respectively. The methylation promoter array identified 1304 differentially methylated regions in the LEI vs C comparison. The overlap of gene and methylation array data identified 14 epigenetically dysregulated genes and quantitative RT-PCR analysis validated the transcriptomic findings. The analysis also revealed that aryl hydrocarbon receptor (AHR) was hypomethylated and significantly overexpressed in LEI samples compared to C. Further analysis validated that AHR transcript and protein expression are significantly (P<0.05) increased in LEI women compared to C. The increase in AHR, together with the altered methylation status of the 14 additional genes, may provide a diagnostic tool to identify the subset of women who have endometriosis-associated infertility.

Low-Dose Bisphenol A in a Rat Model of Endometrial Cancer: A CLARITY-BPA Study.

BACKGROUND: Bisphenol A (BPA) is known to be biologically active in experimental models even at low levels of exposure. However, its impact on endometrial cancer remains unclear. OBJECTIVES: This study aimed to investigate whether lifelong exposure to different doses of BPA induced uterine abnormalities and molecular changes in a rat model. METHODS: Sprague-Dawley rats were exposed to 5 doses of BPA [0, 25, 250, 2,500, or 25,000µg/kg body weight (BW)/d] or 2 doses of 17α-ethynylestradiol (EE2) (0.05 and 0.5µg/kg BW/d) starting from gestational day 6 up to 1 y old according to the CLARITY-BPA consortium protocol. The BW, uterus weight, and histopathology end points of the uteri were analyzed at postnatal (PND) day 21, 90, and 365. Estrous cycling status was evaluated in PND90 and PND365 rats. Transcriptomic analyses of estrus stage uteri were conducted on PND365 rats. RESULTS: Based on the analysis of the combined effects of all testing outcomes (including immunohistological, morphological, and estrous cycle data) in a semiblinded fashion, using statistical models, 25µg/kg BW/d BPA [BPA(25)], or 250µg/kg BW/d BPA [BPA(250)] exerted effects similar to that of EE2 at 0.5µg/kg BW/d in 1-y-old rats. Transcriptome analyses of estrus stage uteri revealed a set of 710 genes shared only between the BPA(25) and BPA(250) groups, with 115 of them predicted to be regulated by estradiol and 57 associated with female cancers. An interesting finding is that the expression of 476 human orthologous genes in this rat BPA signature robustly predicted the overall survival (p=1.68×10-5, hazard ratio=2.62) of endometrial cancer patients. DISCUSSION: Lifelong exposure of rats to low-dose BPA at 25 and 250µg/kg BW/d altered the estrous cycle and uterine pathology with similarity to EE2. The exposure also disrupted a unique low-dose BPA-gene signature with predictive value for survival outcomes in patients with endometrial cancer. https://doi.org/10.1289/EHP6875.

Data integration, analysis, and interpretation of eight academic CLARITY-BPA studies.

"Consortium Linking Academic and Regulatory Insights on BPA Toxicity" (CLARITY-BPA) was a comprehensive "industry-standard" Good Laboratory Practice (GLP)-compliant 2-year chronic exposure study of bisphenol A (BPA) toxicity that was supplemented by hypothesis-driven independent investigator-initiated studies. The investigator-initiated studies were focused on integrating disease-associated, molecular, and physiological endpoints previously found by academic scientists into an industry standard guideline-compliant toxicity study. Thus, the goal of this collaboration was to provide a more comprehensive dataset upon which to base safety standards and to determine whether industry-standard tests are as sensitive and predictive as molecular and disease-associated endpoints. The goal of this report is to integrate the findings from the investigator-initiated studies into a comprehensive overview of the observed impacts of BPA across the multiple organs and systems analyzed. For each organ system, we provide the rationale for the study, an overview of methodology, and summarize major findings. We then compare the results of the CLARITY-BPA studies across organ systems with the results of previous peer-reviewed studies from independent labs. Finally, we discuss potential influences that contributed to differences between studies. Developmental exposure to BPA can lead to adverse effects in multiple organs systems, including the brain, prostate gland, urinary tract, ovary, mammary gland, and heart. As published previously, many effects were at the lowest dose tested, 2.5µg/kg /day, and many of the responses were non-monotonic. Because the low dose of BPA affected endpoints in the same animals across organs evaluated in different labs, we conclude that these are biologically - and toxicologically - relevant.

A novel Cas9-targeted long-read assay for simultaneous detection of IDH1/2 mutations and clinically relevant MGMT methylation in fresh biopsies of diffuse glioma.

Molecular biomarkers provide both diagnostic and prognostic results for patients with diffuse glioma, the most common primary brain tumor in adults. Here, we used a long-read nanopore-based sequencing technique to simultaneously assess IDH mutation status and MGMT methylation level in 4 human cell lines and 8 fresh human brain tumor biopsies. Currently, these biomarkers are assayed separately, and results can take days to weeks. We demonstrated the use of nanopore Cas9-targeted sequencing (nCATS) to identify IDH1 and IDH2 mutations within 36 h and compared this approach against currently used clinical methods. nCATS was also able to simultaneously provide high-resolution evaluation of MGMT methylation levels not only at the promoter region, as with currently used methods, but also at CpGs across the proximal promoter region, the entirety of exon 1, and a portion of intron 1. We compared the methylation levels of all CpGs to MGMT expression in all cell lines and tumors and observed a positive correlation between intron 1 methylation and MGMT expression. Finally, we identified single nucleotide variants in 3 target loci. This pilot study demonstrates the feasibility of using nCATS as a clinical tool for cancer precision medicine.

Estrogen activates pyruvate kinase M2 and increases the growth of TSC2-deficient cells.

Lymphangioleiomyomatosis (LAM) is a devastating lung disease caused by inactivating gene mutations in either TSC1 or TSC2 that result in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1). As LAM occurs predominantly in women during their reproductive age and is exacerbated by pregnancy, the female hormonal environment, and in particular estrogen, is implicated in LAM pathogenesis and progression. However, detailed underlying molecular mechanisms are not well understood. In this study, utilizing human pulmonary LAM specimens and cell culture models of TSC2-deficient LAM patient-derived and rat uterine leiomyoma-derived cells, we tested the hypothesis that estrogen promotes the growth of mTORC1-hyperactive cells through pyruvate kinase M2 (PKM2). Estrogen increased the phosphorylation of PKM2 at Ser37 and induced the nuclear translocation of phospho-PKM2. The estrogen receptor antagonist Faslodex reversed these effects. Restoration of TSC2 inhibited the phosphorylation of PKM2 in an mTORC1 inhibitor-insensitive manner. Finally, accumulation of phosphorylated PKM2 was evident in pulmonary nodule from LAM patients. Together, our data suggest that female predominance of LAM might be at least in part attributed to estrogen stimulation of PKM2-mediated cellular metabolic alterations. Targeting metabolic regulators of PKM2 might have therapeutic benefits for women with LAM and other female-specific neoplasms.

Challenges in IBD Research: Environmental Triggers.

Environmental triggers is part of five focus areas of the Challenges in IBD research document, which also includes preclinical human IBD mechanisms, novel technologies, precision medicine and pragmatic clinical research. The Challenges in IBD research document provides a comprehensive overview of current gaps in inflammatory bowel diseases (IBD) research and delivers actionable approaches to address them. It is the result of a multidisciplinary input from scientists, clinicians, patients, and funders, and represents a valuable resource for patient centric research prioritization. In particular, the environmental triggers section is focused on the main research gaps in elucidating causality of environmental factors in IBD. Research gaps were identified in: 1) epidemiology of exposures; 2) identification of signatures of biological response to exposures; and 3) mechanisms of how environmental exposures drive IBD. To address these gaps, the implementation of longitudinal prospective studies to determine disease evolution and identify sub-clinical changes in response to exposures is proposed. This can help define critical windows of vulnerability and risk prediction. In addition, systems biology analysis and in silico modeling were proposed as approaches to integrate the IBD exposome for the identification of biological signatures of response to exposures, and to develop prediction models of the effects of environmental factors in driving disease activity and response to therapy. This research could lead to identification of biomarkers of exposures and new modalities for therapeutic intervention. Finally, hypothesis-driven mechanistic studies to understand gene-environment interactions and to validate causality of priority factors should be performed to determine how environment influences clinical outcomes.

NR2E3 is a key component in p53 activation by regulating a long noncoding RNA DINO in acute liver injuries.

Damage-induced long noncoding RNA (DINO) is a long noncoding RNA that directly interacts with p53 and thereby enhances p53 stability and activity in response to various cellular stresses. Here, we demonstrate that nuclear receptor subfamily 2 group E member 3 (NR2E3) plays a crucial role in maintaining active DINO epigenetic status for its proper induction and subsequent p53 activation. In acetaminophen (APAP)- or carbon tetrachloride-induced acute liver injuries, NR2E3 knockout (KO) mice exhibited far more severe liver injuries due to impaired DINO induction and p53 activation. Mechanistically, NR2E3 loss both in vivo and in vitro induced epigenetic DINO repression accompanied by reduced DINO chromatin accessibility. Furthermore, compared with the efficient reversal by a typical antidote N-acetylcysteine (NAC) treatment of APAP-induced liver injury in wild-type mice, the liver injury of NR2E3 KO mice was not effectively reversed, indicating that an intact NR2E3-DINO-p53-signaling axis is essential for NAC-mediated recovery against APAP-induced hepatotoxicity. These findings establish that NR2E3 is a critical component in p53 activation and a novel susceptibility factor to drug- or toxicant-induced acute liver injuries.-Khanal, T., Leung, Y.-K., Jiang, W., Timchenko, N., Ho, S.-M., Kim, K. NR2E3 is a key component in p53 activation by regulating a long noncoding RNA DINO in acute liver injuries.

Correction: Hsa-miRNA-765 as a Key Mediator for Inhibiting Growth, Migration and Invasion in Fulvestrant-Treated Prostate Cancer.

[This corrects the article DOI: 10.1371/journal.pone.0098037.].

Sex-specific regulation of collagen I and III expression by 17ß-Estradiol in cardiac fibroblasts: role of estrogen receptors.

Aims: Sex differences in cardiac fibrosis point to the regulatory role of 17ß-Estradiol (E2) in cardiac fibroblasts (CF). We, therefore, asked whether male and female CF in rodent and human models are differentially susceptible to E2, and whether this is related to sex-specific activation of estrogen receptor alpha (ERα) and beta (ERß). Methods and results: In female rat CF (rCF), 24 h E2-treatment (10-8 M) led to a significant down-regulation of collagen I and III expression, whereas both collagens were up-regulated in male rCF. E2-induced sex-specific collagen regulation was also detected in human CF, indicating that this regulation is conserved across species. Using specific ERα- and ERß-agonists (10-7 M) for 24 h, we identified ERα as repressive and ERß as inducing factor in female and male rCF, respectively. In addition, E2-induced ERα phosphorylation at Ser118 only in female rCF, whereas Ser105 phosphorylation of ERß was exclusively found in male rCF. Further, in female rCF we found both ER bound to the collagen I and III promoters using chromatin immunoprecipitation assays. In contrast, in male rCF only ERß bound to both promoters. In engineered connective tissues (ECT) from rCF, collagen I and III mRNA were down-regulated in female ECT and up-regulated in male ECT by E2. This was accompanied by an impaired condensation of female ECT, whereas male ECT showed an increased condensation and stiffness upon E2-treatment, analysed by rheological measurements. Finally, we confirmed the E2-effect on both collagens in an in vivo mouse model with ovariectomy for E2 depletion, E2 substitution, and pressure overload by transverse aortic constriction. Conclusion: The mechanism underlying the sex-specific regulation of collagen I and III in the heart appears to involve E2-mediated differential ERα and ERß signaling in CFs.

Metal concentrations in pregnant women and neonates from informal electronic waste recycling.

Electronic waste (e-waste) is the fastest growing solid waste stream worldwide and mostly ends up in developing countries where residents use primitive methods for recycling. The most infamous e-waste recycling town, Guiyu in Southeast China, has been recycling since the mid-1990s. E-waste contains several harmful chemicals, including lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn). In 2011-12, the e-waste Recycling Exposures and Community Health (e-REACH) Study enrolled 634 pregnant women living in Guiyu and Haojiang, a control site, both in Shantou, China. The women completed a questionnaire and gave maternal blood, cord blood, and maternal urine, which were analyzed for Pb, Cd, Cr, and Mn. Maternal blood Pb, Cd, and Cr concentrations were significantly higher in Guiyu compared to Haojiang. In Guiyu, the geometric mean of Pb concentration in maternal blood was 6.66 µg/dL (range: 1.87-27.09 µg/dL) and was 1.74-fold greater than in Haojiang (95% CI: 1.60, 1.89). In cord blood, Pb concentration was 1.53-fold higher in Guiyu (95% CI: 1.38, 1.68). In maternal urine, Cd (ratio: 2.15, 95% CI: 1.72, 2.69) and Mn (ratio: 2.60, 95% CI: 2.04, 3.31) concentrations were significantly higher in Guiyu in comparison to Haojiang. In conclusion, pregnant women in Guiyu were at risk for increased exposure to heavy metals.

Differential methylation values in differential methylation analysis.

MOTIVATION: Both ß-value and M-value have been used as metrics to measure methylation levels. The M-value is more statistically valid for the differential analysis of methylation levels. However, the ß-value is much more biologically interpretable and needs to be reported when M-value method is used for conducting differential methylation analysis. There is an urgent need to know how to interpret the degree of differential methylation from the M-value. In M-value linear regression model, differential methylation M-value ΔM can be easily obtained from the coefficient estimate, but it is not straightforward to get the differential methylation ß-value, Δß since it cannot be obtained from the coefficient alone. RESULTS: To fill the gap, we have built a bridge to connect the statistically sound M-value linear regression model and the biologically interpretable Δß. In this article, three methods were proposed to calculate differential methylation values, Δß from M-value linear regression model and compared with the Δß directly obtained from ß-value linear regression model. We showed that under the condition that M-value linear regression model is correct, the method M-model-coef is the best among the four methods. M-model-M-mean method works very well too. If the coefficients α0, α2,…αp are not given (as 'MethLAB' package), the M-model-M-mean method should be used. The Δß directly obtained from ß-value linear regression model can give very biased results, especially when M-values are not in (-2, 2) or ß-values are not in (0.2, 0.8). AVAILABILITY AND IMPLEMENTATION: The dataset for example is available at the National Center for Biotechnology Information Gene Expression Omnibus repository, GSE104778. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Greater susceptibility of girls to airborne Benzo[a]pyrene for obesity-associated childhood asthma.

BACKGROUND: Sexually dimorphic risk of obesity-associated asthma is posited to accelerate around puberty. Yet, the role of air pollution on the lean and obese asthmatic children has never been examined. OBJECTIVE: To compare whether a unit exposure to airborne benzo[a]pyrene (B[a]P) is associated with altered risks of asthma across the overweight/obese (OV/OB) control, lean asthmatic, and OV/OB asthmatic children, respectively, compared to the lean controls, before and after adjusting for oxidant stress markers (i.e. 15­F2t­IsoP, 8­oxo­dG, and Carbonyl). METHODS: Asthmatic and healthy control children, recruited from polluted urban and rural areas, were matched to ambient concentration of B[a]P. A unit increase in B[a]P and multinomial logistic regression on OV/OB control, lean asthmatic, and OV/OB asthma were compared across the sex- and age-groups. RESULTS: The median B[a]P was associated with a linear increase among the female children, according to OV/OB and asthma, respectively, and together, compared to the lean control girls (p = 0.001). While B[a]P was associated with positive relationship with 15­F2t­IsoP level among the OV/OB boys, the same exposure-outcome association was inverse among the OV/OB girls. One natural log-unit increase in ambient B[a]P was associated with 10.5-times greater odds (95% CI, 2.6-39.6; p = 0.001) the adolescent OV/OB boys, compared to the unit odds among the lean controls. In contrast, the adolescent OV/OB girls were associated with highest adjusted odds of the asthma (aOR = 15.4; 95% CI, 2.9-29.1; p < 0.001) compared to the lean control girls. An adjustment for 15­F2t­IsoP, and Carbonyls was associated with greater odds of asthma per unit exposure for the adolescent OV/OB girls (aOR = 16.2; 95% CI, 1.4-181.8; p = 0.024). CONCLUSIONS: B[a]P exposure was associated with a leap in the odds of asthma among the OV/OB adolescents, particularly the girls, after adjusting for 15­F2t­IsoP and Carbonyls.

Gene expression and DNA methylation changes in the hypothalamus and hippocampus of adult rats developmentally exposed to bisphenol A or ethinyl estradiol: a CLARITY-BPA consortium study.

Bisphenol A (BPA), an endocrine disrupting chemical (EDC), is a ubiquitous pollutant. As part of the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA), we sought to determine whether exposure of Sprague-Dawley rats to 2,500 µg/kg/day BPA (BPA) or 0.5 µg/kg/day ethinyl estradiol (EE) from gestational day 6 through postnatal day 21 induces behavior-relevant gene expression and DNA methylation changes in hippocampus and hypothalamus at adulthood. RNA and DNA were isolated from both regions. Expression of ten genes (Dnmt1, Dnmt3a, Dnmt3b, Esr1, Esr2, Avp, Ar, Oxt, Otr, and Bdnf) presumably altered by early-life BPA/EE exposure was examined. Three genes (Bdnf, Dnmt3b, and Esr1) were studied for DNA methylation changes in their putative 5' promoter regions. Molecular changes in hippocampus were correlated to prior Barnes maze performance, including sniffing correct holes, distance traveled, and velocity. Exposure to BPA and/or EE disrupted patterns of sexually dimorphic gene expression/promoter DNA methylation observed in hippocampus and hypothalamus of controls. In the hippocampus of female offspring, BPA exposure resulted in hypermethylation of the putative 5' promoter region of Bdnf, while EE exposure induced hypomethylation. Bdnf methylation was weakly associated with Bdnf expression in hippocampi of female rats. Hippocampal Bdnf expression in females showed a weak negative association with sniffing correct hole in Barnes maze. Hippocampal expression of Avp, Esr2, Oxt, and Otr was strongly associated with velocity of control rats in Barnes maze. Findings suggest BPA exposure induced non-EE-like gene expression and epigenetic changes in adult rat hippocampi, a region involved in spatial navigation.

Identification of sex-specific DNA methylation changes driven by specific chemicals in cord blood in a Faroese birth cohort.

Faroe islanders consume marine foods contaminated with methylmercury (MeHg), polychlorinated biphenyls (PCBs), and other toxicants associated with chronic disease risks. Differential DNA methylation at specific CpG sites in cord blood may serve as a surrogate biomarker of health impacts from chemical exposures. We aimed to identify key environmental chemicals in cord blood associated with DNA methylation changes in a population with elevated exposure to chemical mixtures. We studied 72 participants of a Faroese birth cohort recruited between 1986 and 1987 and followed until adulthood. The cord blood DNA methylome was profiled using Infinium HumanMethylation450 BeadChips. We determined the associations of CpG site changes with concentrations of MeHg, major PCBs, other organochlorine compounds [hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and p,p'-dichlorodiphenyltrichloroethane], and perfluoroalkyl substances. In a combined sex analysis, among the 16 chemicals studied, PCB congener 105 (CB-105) exposure was associated with the majority of differentially methylated CpG sites (214 out of a total of 250). In female-only analysis, only 73 CB-105 associated CpG sites were detected, 44 of which were mapped to genes in the ELAV1-associated cancer network. In males-only, methylation changes were seen for perfluorooctane sulfonate, HCB, and p,p'-DDE in 10,598, 1,238, and 1,473 CpG sites, respectively, 15% of which were enriched in cytobands of the X-chromosome associated with neurological disorders. In this multiple-pollutant and genome-wide study, we identified key epigenetic toxicants. The significant enrichment of specific X-chromosome sites in males implies potential sex-specific epigenome responses to prenatal chemical exposures.