At Risk of Autistic Offspring? Sperm DNA Methylation May Hold the Answer
2015 Study Abstract
Epigenetic mechanisms such as altered DNA methylation have been suggested to play a role in autism, beginning with the classical association of Prader-Willi syndrome, an imprinting disorder, with autistic features.
Here we tested for the relationship of paternal sperm DNA methylation with autism risk in offspring, examining an enriched-risk cohort of fathers of autistic children.
We examined genome-wide DNA methylation (DNAm) in paternal semen biosamples obtained from an autism spectrum disorder (ASD) enriched-risk pregnancy cohort, the Early Autism Risk Longitudinal Investigation (EARLI) cohort, to estimate associations between sperm DNAm and prospective ASD development, using a 12-month ASD symptoms assessment, the Autism Observation Scale for Infants (AOSI). We analysed methylation data from 44 sperm samples run on the CHARM 3.0 array, which contains over 4 million probes (over 7 million CpG sites), including 30 samples also run on the Illumina Infinium HumanMethylation450 (450K) BeadChip platform (∼485 000 CpG sites). We also examined associated regions in an independent sample of post-mortem human brain ASD and control samples for which Illumina 450K DNA methylation data were available.
Using region-based statistical approaches, we identified 193 differentially methylated regions (DMRs) in paternal sperm with a family-wise empirical P-value [family-wise error rate (FWER)]
These data suggest that epigenetic differences in paternal sperm may contribute to autism risk in offspring, and provide evidence that directionally consistent, potentially related epigenetic mechanisms may be operating in the cerebellum of individuals with autism.
Sources and more information
Paternal sperm DNA methylation associated with early signs of autism risk in an autism-enriched cohort, Int. J. Epidemiol, doi: 10.1093/ije/dyv028, April 14, 2015.
At Risk of Autistic Offspring? Sperm DNA Methylation May Hold the Answer, epigenie, APRIL 23, 2015.
Adult women exposed to DES in utero had no evidence of large persistent changes in blood DNA methylation
2015 Study Summary
In utero exposure to Diethylstilbestrol (DES) has been associated with increased risk of adverse health outcomes such as fertility problems and vaginal as well as breast cancer. Animal studies have linked prenatal DES exposure to lasting DNA methylation changes. We investigated genome-wide DNA methylation and in utero DES exposure in a sample of non-Hispanic white women aged 40-59 years from the Sister Study, a large United States cohort study of women with a family history of breast cancer. Using questionnaire information from women and their mothers, we selected 100 women whose mothers reported taking DES while pregnant and 100 control women whose mothers had not taken DES. DNA methylation in blood was measured at 485,577 CpG sites using the Illumina HumanMethylation450 BeadChip. Associations between CpG methylation and DES exposure status were analyzed using robust linear regression with adjustment for blood cell composition and multiple comparisons. Although four CpGs had p<105, after accounting for multiple comparisons using the false discovery rate (FDR), none reached genome-wide significance. In conclusion, adult women exposed to DES in utero had no evidence of large persistent changes in blood DNA methylation.
Sources and Full Study
In utero exposure to diethylstilbestrol and blood DNA methylation in women ages 40-59 years from the sister study, NCBI, PMID: 25751399, March 2015.
Neonatal exposure to DES induced permanent alterations in DNA methylation status of specific genes in mouse uteri
2008 Study Summary
We have provided evidence that early-life exposure of the mice to the xenoestrogen Diethylstilbestrol (DES) or the phytoestrogen GEN induces life reprogramming of the mouse uterine epigenome. Specific genes with no previously documented associations with the uterus were identified by an unbiased methylation profiling methodology. These genes encode proteins involved in a wide-range of cellular functions. Detailed studies were conducted on one of the reprogrammable genes, Nucleosomal Binding Protein 1 (Nsbp1), which is a nucleosome binding and transcriptional activation element. Our data support the paradigm that manifestation of early-life epigenetic reprogrammed gene expression in the mouse uterus is dependent on adult ovarian steroids and changes over the course of natural aging of the animal. The complex interplay among the type of estrogen, timing of exposure, reproductive status, and aging time line all significantly contribute to the phenotypical outcome of the epigenetic reprogramming in this model system.
Sources and Full Study
Persistent Hypomethylation in the Promoter of Nucleosomal Binding Protein 1 (Nsbp1) Correlates with Overexpression of Nsbp1 in Mouse Uteri Neonatally Exposed to Diethylstilbestrol or Genistein, NCBI, Endocrinology. 2008;149(12):5922-5931. doi:10.1210/en.2008-0682, PMC2613067, Dec 2008.
In humans, like other vertebrates, there is a susceptibility for epigenomic alteration by the environment during intrauterine development
Environmental toxicants can alter epigenetic regulatory features such as DNA methylation and microRNA expression. As the sensitivity of epigenomic regulatory features may be greatest during the in utero period, when critical windows are narrow, and when epigenomic profiles are being set, this review will highlight research focused on that period. I will focus on work in human populations, where the impact of environmental toxicants in utero, including cigarette smoke and toxic trace metals such as arsenic, mercury and manganese, on genome-wide, gene-specific DNA methylation has been assessed. In particular, arsenic is highlighted, as this metalloid has been the focus of a number of studies and its detoxification mechanisms are well understood. Importantly, the tissues and cells being examined must be considered in context in order to interpret the findings of these studies. For example, by studying the placenta, it is possible to identify potential epigenetic adaptations of key genes and pathways that may alter the developmental course in line with the developmental origins of health and disease paradigm. Alternatively, studies of newborn cord blood can be used to examine how environmental exposure in utero can impact the composition of cells within the peripheral blood, leading to immunological effects of exposure. The results suggest that in humans, like other vertebrates, there is a susceptibility for epigenomic alteration by the environment during intrauterine development, and this may represent a mechanism of plasticity of the organism in response to its environment as well as a mechanism through which long-term health consequences can be shaped.
Sources and more information
Influence of environmental exposure on human epigenetic regulation, jeb.biologists, doi: 10.1242/jeb.106971 January 1, 2015.
Diethylstilboestrol is a synthetic estrogen associated with adverse effects on reproductive organs
2013 Study Abstract
BACKGROUND: Diethylstilboestrol (DES) is a synthetic estrogen associated with adverse effects on reproductive organs. DES-induced toxicity of the mouse seminal vesicle (SV) is mediated by estrogen receptor α (ERα), which alters expression of seminal vesicle secretory protein IV (Svs4) and lactoferrin (Ltf) genes.
We examined a role for nuclear receptor activity in association with DNA methylation and altered gene expression.
We used the neonatal DES exposure mouse model to examine DNA methylation patterns via bisulfite conversion sequencing in SVs of wild-type (WT) and ERα-knockout (αERKO) mice.
The DNA methylation status at four specific CpGs (-160, -237, -306, and -367) in the Svs4 gene promoter changed during mouse development from methylated to unmethylated, and DES prevented this change at 10 weeks of age in WT SV. At two specific CpGs (-449 and -459) of the Ltf gene promoter, DES altered the methylation status from methylated to unmethylated. Alterations in DNA methylation of Svs4 and Ltf were not observed in αERKO SVs, suggesting that changes of methylation status at these CpGs are ERα dependent. The methylation status was associated with the level of gene expression. In addition, gene expression of three epigenetic modifiers-DNMT3A, MBD2, and HDAC2-increased in the SV of DES-exposed WT mice.
DES-induced hormonal toxicity resulted from altered gene expression of Svs4 and Ltf associated with changes in DNA methylation that were mediated by ERα. Alterations in gene expression of DNMT3A, MBD2, and HDAC2 in DES-exposed male mice may be involved in mediating the changes in methylation status in the SV.
Li Y, Hamilton KJ, Lai AY, Burns KA, Li L, Wade PA, Korach KS. 2014. Diethylstilbestrol (DES)-stimulated hormonal toxicity is mediated by ERα alteration of target gene methylation patterns and epigenetic modifiers (DNMT3A, MBD2, and HDAC2) in the mouse seminal vesicle.
Diethylstilbestrol (DES)-stimulated hormonal toxicity is mediated by ERα alteration of target gene methylation patterns and epigenetic modifiers (DNMT3A, MBD2, and HDAC2) in the mouse seminal vesicle, NCBI, PMD: 24316720, 2014 Mar;122(3):262-8. doi: 10.1289/ehp.1307351. Epub 2013 Dec 5.
Full Text EHP1307351 Environ Health Perspect; DOI:10.1289/ehp.1307351
Role of DNA Methylation and Epigenetic Silencing of HAND2 in Endometrial Cancer Development
Using easily accessible body fluids to accurately identify individuals with early stage womb cancer has the potential to change the cancer landscape, a new study suggests.
By collecting swabs from the entrance to the womb – a similar technique to that used in cervical screening – genetic material can be easily analysed for pre-cancer/cancer without the need for an invasive womb biopsy. This technique could be used as a test, or to screen women for womb cancer, possibly saving lives via early detection.
Endometrial cancer incidence is continuing to rise in the wake of the current ageing and obesity epidemics. Much of the risk for endometrial cancer development is influenced by the environment and lifestyle. Accumulating evidence suggests that the epigenome serves as the interface between the genome and the environment and that hypermethylation of stem cell polycomb group target genes is an epigenetic hallmark of cancer. The objective of this study was to determine the functional role of epigenetic factors in endometrial cancer development.
METHODS AND FINDINGS:
Epigenome-wide methylation analysis of >27,000 CpG sites in endometrial cancer tissue samples (n = 64) and control samples (n = 23) revealed that HAND2 (a gene encoding a transcription factor expressed in the endometrial stroma) is one of the most commonly hypermethylated and silenced genes in endometrial cancer. A novel integrative epigenome-transcriptome-interactome analysis further revealed that HAND2 is the hub of the most highly ranked differential methylation hotspot in endometrial cancer. These findings were validated using candidate gene methylation analysis in multiple clinical sample sets of tissue samples from a total of 272 additional women. Increased HAND2 methylation was a feature of premalignant endometrial lesions and was seen to parallel a decrease in RNA and protein levels. Furthermore, women with high endometrial HAND2 methylation in their premalignant lesions were less likely to respond to progesterone treatment. HAND2 methylation analysis of endometrial secretions collected using high vaginal swabs taken from women with postmenopausal bleeding specifically identified those patients with early stage endometrial cancer with both high sensitivity and high specificity (receiver operating characteristics area under the curve = 0.91 for stage 1A and 0.97 for higher than stage 1A). Finally, mice harbouring a Hand2 knock-out specifically in their endometrium were shown to develop precancerous endometrial lesions with increasing age, and these lesions also demonstrated a lack of PTEN expression.
HAND2 methylation is a common and crucial molecular alteration in endometrial cancer that could potentially be employed as a biomarker for early detection of endometrial cancer and as a predictor of treatment response. The true clinical utility of HAND2 DNA methylation, however, requires further validation in prospective studies. Please see later in the article for the Editors’ Summary.
High-fat or ethinyl-oestradiol intake during pregnancy increases mammary cancer risk in several generations of offspring
” A study by researchers from Georgetown Lombardi Comprehensive Cancer Center and Virginia Tech shows that exposure to diets high in fat or a large amount of estrogen during pregnancy can heighten the risk of breast cancer for numerous subsequent generations of female offspring, including daughters, granddaughters and great-granddaughters. ”
Maternal exposures to environmental factors during pregnancy influence the risk of many chronic adult-onset diseases in the offspring. Here we investigate whether feeding pregnant rats a high-fat (HF)- or ethinyl-oestradiol (EE2)-supplemented diet affects carcinogen-induced mammary cancer risk in daughters, granddaughters and great-granddaughters. We show that mammary tumourigenesis is higher in daughters and granddaughters of HF rat dams and in daughters and great-granddaughters of EE2 rat dams. Outcross experiments suggest that the increase in mammary cancer risk is transmitted to HF granddaughters equally through the female or male germ lines, but it is only transmitted to EE2 granddaughters through the female germ line. The effects of maternal EE2 exposure on offspring’s mammary cancer risk are associated with changes in the DNA methylation machinery and methylation patterns in mammary tissue of all three EE2 generations. We conclude that dietary and oestrogenic exposures in pregnancy increase breast cancer risk in multiple generations of offspring, possibly through epigenetic means.
Read Pregnancy Exposure Increases Breast Cancer Inheritance in Offspring, redorbit, September 2012..
High-fat or ethinyl-oestradiol intake during pregnancy increases mammary cancer risk in several generations of offspring, nature, 11 September 2012.
Pregnancy exposures determine risk of breast cancer in multiple generations of offspring,eurekalert, 11-SEP-2012.