Alterations in Placental Inflammation-Related Gene Expression Partially Mediate the Effects of Prenatal Alcohol Consumption on Maternal Iron Homeostasis.

Prenatal alcohol exposure (PAE) is associated with alterations in maternal and infant iron homeostasis that are consistent with changes seen in the setting of inflammation. We hypothesized that PAE leads to alterations in the placental expression of genes related to iron metabolism and inflammation that play functional roles in the teratogenic effects of alcohol on iron homeostasis. A total of 126 heavy-drinking women (≥1 oz (30 mL) absolute alcohol/day (~1.67 standard drinks/day) or women reporting binge drinking (≥2 drinks/occasion)) and 80 control women (<0.5 oz AA per day, no binging) in Cape Town, South Africa were interviewed prenatally regarding demographics, and alcohol, smoking, and drug use around conception and during pregnancy. Prenatal/maternal and infant hemoglobin and ferritin were measured. Whole-transcriptome RNA sequencing analysis was performed on flash-frozen transplacental tissue samples. Gene sets related to iron metabolism (n = 398) and inflammation (n = 467) were constructed by searching the Molecular Signatures Database for related ontology terms. Principal component analysis (PCA) yielded 59 factors for each theme. In multivariable regression models, PAE was related to 2 iron metabolism PCA factors (PCs) and 5 inflammation PCs, among which 2 iron metabolism and 4 inflammation factors were related to at least 1 key maternal or infant iron outcome. In causal inference analyses based on marginal structural models and the product method, the alterations in the expression profile of genes with functions in immune cell regulation, cytokine activity, angiogenesis, hematopoiesis, and ubiquitous cell processes appeared to partially mediate the relation of prenatal drinking frequency (days/week) around conception to a lower maternal hemoglobin-to-log(ferritin) ratio (proportion mediation = 51.35%). These findings suggest that placental inflammation may be partly responsible for the differences in alcohol-related iron homeostasis patterns between pregnant and non-pregnant adults.

A meta-analysis of pre-pregnancy maternal body mass index and placental DNA methylation identifies 27 CpG sites with implications for mother-child health.

Higher maternal pre-pregnancy body mass index (ppBMI) is associated with increased neonatal morbidity, as well as with pregnancy complications and metabolic outcomes in offspring later in life. The placenta is a key organ in fetal development and has been proposed to act as a mediator between the mother and different health outcomes in children. The overall aim of the present work is to investigate the association of ppBMI with epigenome-wide placental DNA methylation (DNAm) in 10 studies from the PACE consortium, amounting to 2631 mother-child pairs. We identify 27 CpG sites at which we observe placental DNAm variations of up to 2.0% per 10 ppBMI-unit. The CpGs that are differentially methylated in placenta do not overlap with CpGs identified in previous studies in cord blood DNAm related to ppBMI. Many of the identified CpGs are located in open sea regions, are often close to obesity-related genes such as GPX1 and LGR4 and altogether, are enriched in cancer and oxidative stress pathways. Our findings suggest that placental DNAm could be one of the mechanisms by which maternal obesity is associated with metabolic health outcomes in newborns and children, although further studies will be needed in order to corroborate these findings.

The associations of healthy lifestyle index with breast cancer incidence and mortality in a population-based study.

PURPOSE: To investigate how a healthy lifestyle index (HLI) is associated with breast cancer risk and survival in a population-based breast cancer study. METHODS: The study included 1319 breast cancer cases and 1310 controls from the population-based Long Island Breast Cancer Study Project and its follow-up study where vital status was ascertained using the National Death Index (521 deaths, 210 from breast cancer; median follow-up 214.5 months). HLI scores were generated from body mass index, physical activity, intake of plant and animal foods, alcohol consumption, breastfeeding, and smoking, with higher values corresponding to healthier behaviors obtained from baseline questionnaire. Multivariable logistic and Cox regression models were used to estimate breast cancer odds ratios (ORs) and mortality hazards ratios (HRs), respectively. RESULTS: Compared to women in the low HLI tertile, a significant reduction in risk of breast cancer was observed for women in the intermediate (OR = 0.78, 95% CI 0.64-0.93) and high (OR = 0.73, 95% CI 0.60-0.88) tertiles; a one-point increase in HLI score was associated with a 14% reduction in breast cancer risk (OR = 0.86, 95% CI 0.80-0.93). For survival, a significant reduction in all-cause mortality was also observed in women in the intermediate (HR = 0.68, 95% CI 0.56-0.84) and high (HR = 0.72, 95% CI 0.58-0.88) HLI tertiles with a 17% reduction in all-cause mortality (HR = 0.83, 95% CI 0.76-0.91) for one-point increase in HLI score. These inverse associations were more prominent among postmenopausal women. CONCLUSION: A healthy lifestyle is beneficial not only in reducing breast cancer risk but also in improving overall survival after breast cancer diagnosis, especially among postmenopausal women.

Urinary glyphosate concentration in pregnant women in relation to length of gestation.

Human exposure to glyphosate-based herbicides (GBH) is increasing rapidly worldwide. Most existing studies on health effects of glyphosate have focused on occupational settings and cancer outcomes and few have examined this common exposure in relation to the health of pregnant women and newborns in the general population. We investigated associations between prenatal glyphosate exposure and length of gestation in The Infant Development and the Environment Study (TIDES), a multi-center US pregnancy cohort. Glyphosate and its primary degradation product [aminomethylphosphonic acid (AMPA)] were measured in urine samples collected during the second trimester from 163 pregnant women: 69 preterm births (<37 weeks) and 94 term births, the latter randomly selected as a subset of TIDES term births. We examined the relationship between exposure and length of gestation using multivariable logistic regression models (dichotomous outcome; term versus preterm) and with weighted time-to-event Cox proportional hazards models (gestational age in days). We conducted these analyses in the overall sample and secondarily, restricted to women with spontaneous deliveries (n = 90). Glyphosate and AMPA were detected in most urine samples (>94 %). A shortened gestational length was associated with maternal glyphosate (hazard ratio (HR): 1.31, 95 % confidence interval (CI) 1.00-1.71) and AMPA (HR: 1.32, 95%CI: 1.00-1.73) only among spontaneous deliveries using adjusted Cox proportional hazards models. In binary analysis, glyphosate and AMPA were not associated with preterm birth risk (<37 weeks). Our results indicate widespread exposure to glyphosate in the general population which may impact reproductive health by shortening length of gestation. Given the increasing exposure to GBHs and the public health burden of preterm delivery, larger confirmatory studies are needed, especially in vulnerable populations such as pregnant women and newborns.

Germline determinants of humoral immune response to HPV-16 protect against oropharyngeal cancer.

Although several oropharyngeal cancer (OPC) susceptibility loci have been identified, most previous studies lacked detailed information on human papillomavirus (HPV) status. We conduct a genome-wide analysis by HPV16 serology status in 4,002 oral cancer cases (OPC and oral cavity cancer (OCC)) and 5,256 controls. We detect four susceptibility loci pointing to a distinct genetic predisposition by HPV status. Our most notable finding in the HLA region, that is now confirmed to be specific of HPV(+)OPC risk, reveal two independent loci with strong protective effects, one refining the previously reported HLA class II haplotype association. Antibody levels against HPV16 viral proteins strongly implicate the protective HLA variants as major determinants of humoral response against L1 capsid protein or E6 oncoprotein suggesting a natural immune response against HPV(+)OPC promoted by HLA variants. This indicates that therapeutic vaccines that target E6 and attenuate viral response after established HPV infections might protect against HPV(+)OPC.

Large-scale cross-cancer fine-mapping of the 5p15.33 region reveals multiple independent signals.

Genome-wide association studies (GWASs) have identified thousands of cancer risk loci revealing many risk regions shared across multiple cancers. Characterizing the cross-cancer shared genetic basis can increase our understanding of global mechanisms of cancer development. In this study, we collected GWAS summary statistics based on up to 375,468 cancer cases and 530,521 controls for fourteen types of cancer, including breast (overall, estrogen receptor [ER]-positive, and ER-negative), colorectal, endometrial, esophageal, glioma, head/neck, lung, melanoma, ovarian, pancreatic, prostate, and renal cancer, to characterize the shared genetic basis of cancer risk. We identified thirteen pairs of cancers with statistically significant local genetic correlations across eight distinct genomic regions. Specifically, the 5p15.33 region, harboring the TERT and CLPTM1L genes, showed statistically significant local genetic correlations for multiple cancer pairs. We conducted a cross-cancer fine-mapping of the 5p15.33 region based on eight cancers that showed genome-wide significant associations in this region (ER-negative breast, colorectal, glioma, lung, melanoma, ovarian, pancreatic, and prostate cancer). We used an iterative analysis pipeline implementing a subset-based meta-analysis approach based on cancer-specific conditional analyses and identified ten independent cross-cancer associations within this region. For each signal, we conducted cross-cancer fine-mapping to prioritize the most plausible causal variants. Our findings provide a more in-depth understanding of the shared inherited basis across human cancers and expand our knowledge of the 5p15.33 region in carcinogenesis.

Placental DNA methylation signatures of maternal smoking during pregnancy and potential impacts on fetal growth.

Maternal smoking during pregnancy (MSDP) contributes to poor birth outcomes, in part through disrupted placental functions, which may be reflected in the placental epigenome. Here we present a meta-analysis of the associations between MSDP and placental DNA methylation (DNAm) and between DNAm and birth outcomes within the Pregnancy And Childhood Epigenetics (PACE) consortium (N = 1700, 344 with MSDP). We identify 443 CpGs that are associated with MSDP, of which 142 associated with birth outcomes, 40 associated with gene expression, and 13 CpGs are associated with all three. Only two CpGs have consistent associations from a prior meta-analysis of cord blood DNAm, demonstrating substantial tissue-specific responses to MSDP. The placental MSDP-associated CpGs are enriched for environmental response genes, growth-factor signaling, and inflammation, which play important roles in placental function. We demonstrate links between placental DNAm, MSDP and poor birth outcomes, which may better inform the mechanisms through which MSDP impacts placental function and fetal growth.

Genome-wide association meta-analysis identifies pleiotropic risk loci for aerodigestive squamous cell cancers.

Squamous cell carcinomas (SqCC) of the aerodigestive tract have similar etiological risk factors. Although genetic risk variants for individual cancers have been identified, an agnostic, genome-wide search for shared genetic susceptibility has not been performed. To identify novel and pleotropic SqCC risk variants, we performed a meta-analysis of GWAS data on lung SqCC (LuSqCC), oro/pharyngeal SqCC (OSqCC), laryngeal SqCC (LaSqCC) and esophageal SqCC (ESqCC) cancers, totaling 13,887 cases and 61,961 controls of European ancestry. We identified one novel genome-wide significant (Pmeta<5x10-8) aerodigestive SqCC susceptibility loci in the 2q33.1 region (rs56321285, TMEM273). Additionally, three previously unknown loci reached suggestive significance (Pmeta<5x10-7): 1q32.1 (rs12133735, near MDM4), 5q31.2 (rs13181561, TMEM173) and 19p13.11 (rs61494113, ABHD8). Multiple previously identified loci for aerodigestive SqCC also showed evidence of pleiotropy in at least another SqCC site, these include: 4q23 (ADH1B), 6p21.33 (STK19), 6p21.32 (HLA-DQB1), 9p21.33 (CDKN2B-AS1) and 13q13.1(BRCA2). Gene-based association and gene set enrichment identified a set of 48 SqCC-related genes rel to DNA damage and epigenetic regulation pathways. Our study highlights the importance of cross-cancer analyses to identify pleiotropic risk loci of histology-related cancers arising at distinct anatomical sites.

Evaluating shared genetic influences on nonsyndromic cleft lip/palate and oropharyngeal neoplasms.

It has been hypothesised that nonsyndromic cleft lip/palate (nsCL/P) and cancer may share aetiological risk factors. Population studies have found inconsistent evidence for increased incidence of cancer in nsCL/P cases, but several genes (e.g., CDH1, AXIN2) have been implicated in the aetiologies of both phenotypes. We aimed to evaluate shared genetic aetiology between nsCL/P and oral cavity/oropharyngeal cancers (OC/OPC), which affect similar anatomical regions. Using a primary sample of 5,048 OC/OPC cases and 5,450 controls of European ancestry and a replication sample of 750 cases and 336,319 controls from UK Biobank, we estimate genetic overlap using nsCL/P polygenic risk scores (PRS) with Mendelian randomization analyses performed to evaluate potential causal mechanisms. In the primary sample, we found strong evidence for an association between a nsCL/P PRS and increased odds of OC/OPC (per standard deviation increase in score, odds ratio [OR]: 1.09; 95% confidence interval [CI]: 1.04, 1.13; p = .000053). Although confidence intervals overlapped with the primary estimate, we did not find confirmatory evidence of an association between the PRS and OC/OPC in UK Biobank (OR 1.02; 95% CI: 0.95, 1.10; p = .55). Mendelian randomization analyses provided evidence that major nsCL/P risk variants are unlikely to influence OC/OPC. Our findings suggest possible shared genetic influences on nsCL/P and OC/OPC.

Publisher Correction: Shared heritability and functional enrichment across six solid cancers.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The Ramazzini Institute 13-week pilot study glyphosate-based herbicides administered at human-equivalent dose to Sprague Dawley rats: effects on development and endocrine system.

BACKGROUND: Glyphosate-based herbicides (GBHs) are broad-spectrum herbicides that act on the shikimate pathway in bacteria, fungi, and plants. The possible effects of GBHs on human health are the subject of an intense public debate for both its potential carcinogenic and non-carcinogenic effects, including potential effects on the endocrine system The present pilot study examine whether exposure to GBHs at the dose of glyphosate considered to be "safe" (the US Acceptable Daily Intake - ADI - of 1.75 mg/kg bw/day), starting from in utero life, affect the development and endocrine system across different life stages in Sprague Dawley (SD) rats. METHODS: Glyphosate alone and Roundup Bioflow, a commercial brand of GBHs, were administered in drinking water at 1.75 mg/kg bw/day to F0 dams starting from the gestational day (GD) 6 (in utero) up to postnatal day (PND) 120. After weaning, offspring were randomly distributed in two cohorts: 8 M + 8F/group animals belonging to the 6-week cohort were sacrificed after puberty at PND 73 ± 2; 10 M + 10F/group animals belonging to the 13-week cohort were sacrificed at adulthood at PND 125 ± 2. Effects of glyphosate or Roundup exposure were assessed on developmental landmarks and sexual characteristics of pups. RESULTS: In pups, anogenital distance (AGD) at PND 4 was statistically significantly increased both in Roundup-treated males and females and in glyphosate-treated males. Age at first estrous (FE) was significantly delayed in the Roundup-exposed group and serum testosterone concentration significantly increased in Roundup-treated female offspring from the 13-week cohort compared to control animals. A statistically significant increase in plasma TSH concentration was observed in glyphosate-treated males compared with control animals as well as a statistically significant decrease in DHT and increase in BDNF in Roundup-treated males. Hormonal status imbalances were more pronounced in Roundup-treated rats after prolonged exposure. CONCLUSIONS: The present pilot study demonstrate that GBHs exposure, from prenatal period to adulthood, induced endocrine effects and altered reproductive developmental parameters in male and female SD rats. In particular, it was associated with androgen-like effects, including a statistically significant increase of AGDs in both males and females, delay of FE and increased testosterone in female.

Shared heritability and functional enrichment across six solid cancers.

Quantifying the genetic correlation between cancers can provide important insights into the mechanisms driving cancer etiology. Using genome-wide association study summary statistics across six cancer types based on a total of 296,215 cases and 301,319 controls of European ancestry, here we estimate the pair-wise genetic correlations between breast, colorectal, head/neck, lung, ovary and prostate cancer, and between cancers and 38 other diseases. We observed statistically significant genetic correlations between lung and head/neck cancer (rg = 0.57, p = 4.6 × 10-8), breast and ovarian cancer (rg = 0.24, p = 7 × 10-5), breast and lung cancer (rg = 0.18, p =1.5 × 10-6) and breast and colorectal cancer (rg = 0.15, p = 1.1 × 10-4). We also found that multiple cancers are genetically correlated with non-cancer traits including smoking, psychiatric diseases and metabolic characteristics. Functional enrichment analysis revealed a significant excess contribution of conserved and regulatory regions to cancer heritability. Our comprehensive analysis of cross-cancer heritability suggests that solid tumors arising across tissues share in part a common germline genetic basis.

Fine mapping of MHC region in lung cancer highlights independent susceptibility loci by ethnicity.

Lung cancer has several genetic associations identified within the major histocompatibility complex (MHC); although the basis for these associations remains elusive. Here, we analyze MHC genetic variation among 26,044 lung cancer patients and 20,836 controls densely genotyped across the MHC, using the Illumina Illumina OncoArray or Illumina 660W SNP microarray. We impute sequence variation in classical HLA genes, fine-map MHC associations for lung cancer risk with major histologies and compare results between ethnicities. Independent and novel associations within HLA genes are identified in Europeans including amino acids in the HLA-B*0801 peptide binding groove and an independent HLA-DQB1*06 loci group. In Asians, associations are driven by two independent HLA allele sets that both increase risk in HLA-DQB1*0401 and HLA-DRB1*0701; the latter better represented by the amino acid Ala-104. These results implicate several HLA-tumor peptide interactions as the major MHC factor modulating lung cancer susceptibility.

The Ramazzini Institute 13-week pilot study on glyphosate and Roundup administered at human-equivalent dose to Sprague Dawley rats: effects on the microbiome.

BACKGROUND: Glyphosate-based herbicides (GBHs) are broad-spectrum herbicides that act on the shikimate pathway in bacteria, fungi, and plants. The possible effects of GBHs on human health are the subject of an intense public debate for both its potential carcinogenic and non-carcinogenic effects, including its effects on microbiome. The present pilot study examines whether exposure to GBHs at doses of glyphosate considered to be "safe" (the US Acceptable Daily Intake - ADI - of 1.75 mg/kg bw/day), starting from in utero, may modify the composition of gut microbiome in Sprague Dawley (SD) rats. METHODS: Glyphosate alone and Roundup, a commercial brand of GBHs, were administered in drinking water at doses comparable to the US glyphosate ADI (1.75 mg/kg bw/day) to F0 dams starting from the gestational day (GD) 6 up to postnatal day (PND) 125. Animal feces were collected at multiple time points from both F0 dams and F1 pups. The gut microbiota of 433 fecal samples were profiled at V3-V4 region of 16S ribosomal RNA gene and further taxonomically assigned and assessed for diversity analysis. We tested the effect of exposure on overall microbiome diversity using PERMANOVA and on individual taxa by LEfSe analysis. RESULTS: Microbiome profiling revealed that low-dose exposure to Roundup and glyphosate resulted in significant and distinctive changes in overall bacterial composition in F1 pups only. Specifically, at PND31, corresponding to pre-pubertal age in humans, relative abundance for Bacteriodetes (Prevotella) was increased while the Firmicutes (Lactobacillus) was reduced in both Roundup and glyphosate exposed F1 pups compared to controls. CONCLUSIONS: This study provides initial evidence that exposures to commonly used GBHs, at doses considered safe, are capable of modifying the gut microbiota in early development, particularly before the onset of puberty. These findings warrant future studies on potential health effects of GBHs in early development such as childhood.

Pulmonary microRNA profiling: implications in upper lobe predominant lung disease.

BACKGROUND: Numerous pulmonary diseases manifest with upper lobe predominance including cystic fibrosis, smoking-related chronic obstructive pulmonary disease, and tuberculosis. Zonal hypoxia, characteristic of these pulmonary maladies, and oxygen stress in general is known to exert profound effects on various important aspects of cell biology. Lung macrophages are major participants in the pulmonary innate immune response and regional differences in macrophage responsiveness to hypoxia may contribute in the development of lung disease. MicroRNAs are ubiquitous regulators of human biology and emerging evidence indicates altered microRNA expression modulates respiratory disease processes. The objective of this study is to gain insight into the epigenetic and cellular mechanisms influencing regional differences in lung disease by investigating effect of hypoxia on regional microRNA expression in the lung. All studies were performed using primary alveolar macrophages (n = 10) or bronchoalveolar lavage fluid (n = 16) isolated from human subjects. MicroRNA was assayed via the NanoString nCounter microRNA assay. RESULTS: Divergent molecular patterns of microRNA expression were observed in alternate lung lobes, specifically noted was disparate expression of miR-93 and miR-4454 in alveolar macrophages along with altered expression of miR-451a and miR-663a in bronchoalveolar lavage fluid. Gene ontology was used to identify potential downstream targets of divergent microRNAs. Targets include cytokines and matrix metalloproteinases, molecules that could have a significant impact on pulmonary inflammation and fibrosis. CONCLUSIONS: Our findings show variant regional microRNA expression associated with hypoxia in alveolar macrophages and BAL fluid in the lung-upper vs lower lobe. Future studies should address whether these specific microRNAs may act intracellularly, in a paracrine/endocrine manner to direct the innate immune response or may ultimately be involved in pulmonary host-to-pathogen trans-kingdom cross-talk.

Genome-wide association analyses identify new susceptibility loci for oral cavity and pharyngeal cancer.

We conducted a genome-wide association study of oral cavity and pharyngeal cancer in 6,034 cases and 6,585 controls from Europe, North America and South America. We detected eight significantly associated loci (P < 5 × 10-8), seven of which are new for these cancer sites. Oral and pharyngeal cancers combined were associated with loci at 6p21.32 (rs3828805, HLA-DQB1), 10q26.13 (rs201982221, LHPP) and 11p15.4 (rs1453414, OR52N2-TRIM5). Oral cancer was associated with two new regions, 2p23.3 (rs6547741, GPN1) and 9q34.12 (rs928674, LAMC3), and with known cancer-related loci-9p21.3 (rs8181047, CDKN2B-AS1) and 5p15.33 (rs10462706, CLPTM1L). Oropharyngeal cancer associations were limited to the human leukocyte antigen (HLA) region, and classical HLA allele imputation showed a protective association with the class II haplotype HLA-DRB1*1301-HLA-DQA1*0103-HLA-DQB1*0603 (odds ratio (OR) = 0.59, P = 2.7 × 10-9). Stratified analyses on a subgroup of oropharyngeal cases with information available on human papillomavirus (HPV) status indicated that this association was considerably stronger in HPV-positive (OR = 0.23, P = 1.6 × 10-6) than in HPV-negative (OR = 0.75, P = 0.16) cancers.

Regions of variable DNA methylation in human placenta associated with newborn neurobehavior.

The placenta regulates the in utero environment and functionally impacts fetal development. Candidate gene studies identified variation in placental DNA methylation is associated with newborn neurologic and behavioral outcomes including movement quality, lethargic behavior, attention, and arousal. We sought to identify novel regions of variable DNA methylation associated with newborn attention, lethargy, quality of movement, and arousal by performing an epigenome-wide association study in 335 infants from a US birth cohort. Methylation status was quantified using the Illumina HumanMethylation450 BeadChip array and associations to newborn outcomes assessed by the NICU Network Neurobehavioral Scales (NNNS) were identified while incorporating established bioinformatics algorithms to control for confounding by cell type composition. Methylation of CpGs within FHIT (cg15970800) and ANKRD11 (cg16710656) demonstrated genome-wide significance (P < 1.8 × 10(-7)) in specific associations with infant attention. CpGs whose differential methylation was associated with all 4 neurobehavioral outcomes were common to 50 genes involved in biological processes relating to cellular adhesion and nervous system development. Comprehensive methylation profiling identified relationships between methylation of FHIT and ANKRD11, which have been previously linked to neurodevelopment and behavioral outcomes in genetic association studies. Subtle changes in DNA methylation of these genes within the placenta may impact normal variation of a newborn's ability to alter and track visual and auditory stimuli. Gene ontology analysis suggested that those genes with variable methylation related to these outcomes are over-represented in biological pathways involved in brain development and placental physiology, supportive of our hypothesis for a key role of the placenta in neurobehavioral outcomes.

Placental epigenetic patterning of glucocorticoid response genes is associated with infant neurodevelopment.

AIM: To determine associations between methylation of NR3C1, HSD11B2, FKBP5 and ADCYAP1R1 and newborn neurobehavioral outcomes. METHODS: In 537 newborns, placental methylation was quantified using bisulfite pyrosequencing. Profiles of neurobehavior were derived via the Neonatal Intensive Care Unit Network Neurobehavioral Scales. Using exploratory factor analysis, the relationships between methylation factor scores and neurobehavioral profiles were examined. RESULTS: Increased scores of the factor characterized by NR3C1 methylation were associated with membership in a reactive, poorly regulated profile (odds ratio: 1.47; 95% CI: 1.00-2.18), while increased scores of the factor characterized by HSD11B2 methylation reduced this risk. CONCLUSION: These results suggest that coordinated regulation of these genes influences neurobehavior and demonstrates the importance of examining these alterations in a harmonized fashion.

Global and gene-specific DNA methylation across multiple tissues in early infancy: implications for children's health research.

An increasing number of population studies are assessing epigenetic variation in relation to early-life outcomes in tissues accessible to epidemiologic researchers. Epigenetic mechanisms are highly tissue specific, however, and it is unclear whether the variation observed in one of the tissue types is representative of other sources or whether the variation in DNA methylation is distinct, reflecting potential functional differences across tissues. To assess relations between DNA methylation in various samples from newborns and children in early infancy, we measured promoter or gene-body DNA methylation in matched term placenta, cord blood, and 3-6 mo saliva samples from 27 unrelated infants enrolled in the Rhode Island Child Health Study. We investigated 7 gene loci (KLF15, NR3C1, LEP, DEPTOR, DDIT4, HSD11B2, and CEBPB) and global methylation, using repetitive region LINE-1 and ALUYb8 sequences. We observed a great degree of interlocus, intertissue, and interindividual epigenetic variation in most of the analyzed loci. In correlation analyses, only cord blood NR3C1 promoter methylation correlated negatively with methylation in saliva. We conclude that placenta, cord blood, and saliva cannot be used as a substitute for one another to evaluate DNA methylation at these loci during infancy. Each tissue has a unique epigenetic signature that likely reflects their differential functions. Future studies should consider the uniqueness of these features, to improve epigenetic biomarker discovery and translation.

Distinct patterns of DNA methylation in conventional adenomas involving the right and left colon.

Recent studies have shown two distinct non-CIMP methylation clusters in colorectal cancer, raising the possibility that DNA methylation, involving non-CIMP genes, may play a role in the conventional adenoma-carcinoma pathway. A total of 135 adenomas (65 left colon and 70 right colon) were profiled for epigenome-wide DNA methylation using the Illumina HumanMethylation450 BeadChip. A principal components analysis was performed to examine the association between variability in DNA methylation and adenoma location. Linear regression and linear mixed effects models were used to identify locus-specific differential DNA methylation in adenomas of right and left colon. A significant association was present between the first principal component and adenoma location (P=0.007), even after adjustment for subject age and gender (P=0.009). A total of 168 CpG sites were differentially methylated between right- and left-colon adenomas and these loci demonstrated enrichment of homeobox genes (P=3.0 × 10(-12)). None of the 168 probes were associated with CIMP genes. Among CpG loci with the largest difference in methylation between right- and left-colon adenomas, probes associated with PRAC (prostate cancer susceptibility candidate) gene showed hypermethylation in right-colon adenomas whereas those associated with CDX2 (caudal type homeobox transcription factor 2) showed hypermethylation in left-colon adenomas. A subgroup of left-colon adenomas enriched for current smokers (OR=6.1, P=0.004) exhibited a methylation profile similar to right-colon adenomas. In summary, our results indicate distinct patterns of DNA methylation, independent of CIMP genes, in adenomas of the right and left colon.