Impact of Cellular miRNAs on Circulating miRNA Biomarker Signatures

Effective diagnosis and surveillance of complex multi-factorial disorders such as cancer can be improved by screening of easily accessible biomarkers. Highly stable cell free Circulating Nucleic Acids (CNA) present as both RNA and DNA species have been discovered in the blood and plasma of humans. Correlations between tumor-associated genomic/epigenetic/transcriptional changes and alterations in CNA levels are strong predictors of the utility of this biomarker class as promising clinical indicators. Towards this goal microRNAs (miRNAs) representing a class of naturally occurring small non-coding RNAs of 19–25 nt in length have emerged as an important set of markers that can associate their specific expression profiles with cancer development. In this study we investigate some of the pre-analytic considerations for isolating plasma fractions for the study of miRNA biomarkers. We find that measurement of circulating miRNA levels are frequently confounded by varying levels of cellular miRNAs of different hematopoietic origins. In order to assess the relative proportions of this cell-derived class, we have fractionated whole blood into plasma and its ensuing sub-fractions. Cellular miRNA signatures in cohorts of normal individuals are catalogued and the abundance and gender specific expression of bona fide circulating markers explored after calibrating the signal for this interfering class. A map of differentially expressed profiles is presented and the intrinsic variability of circulating miRNA species investigated in subsets of healthy males and females

MicroRNA profiling of diverse endothelial cell types

<p>Abstract</p> <p>Background</p> <p>MicroRNAs are ~22-nt long regulatory RNAs that serve as critical modulators of post-transcriptional gene regulation. The diversity of miRNAs in endothelial cells (ECs) and the relationship of this diversity to epithelial and hematologic cells is unknown. We investigated the baseline miRNA signature of human ECs cultured from the aorta (HAEC), coronary artery (HCEC), umbilical vein (HUVEC), pulmonary artery (HPAEC), pulmonary microvasculature (HPMVEC), dermal microvasculature (HDMVEC), and brain microvasculature (HBMVEC) to understand the diversity of miRNA expression in ECs.</p> <p>Results</p> <p>We identified 166 expressed miRNAs, of which 3 miRNAs (miR-99b, miR-20b and let-7b) differed significantly between EC types and predicted EC clustering. We confirmed the significance of these miRNAs by RT-PCR analysis and in a second data set by Sylamer analysis. We found wide diversity of miRNAs between endothelial, epithelial and hematologic cells with 99 miRNAs shared across cell types and 31 miRNAs unique to ECs. We show polycistronic miRNA chromosomal clusters have common expression levels within a given cell type.</p> <p>Conclusions</p> <p>EC miRNA expression levels are generally consistent across EC types. Three microRNAs were variable within the dataset indicating potential regulatory changes that could impact on EC phenotypic differences. MiRNA expression in endothelial, epithelial and hematologic cells differentiate these cell types. This data establishes a valuable resource characterizing the diverse miRNA signature of ECs.</p

MicroRNA signatures in B-cell lymphomas

Accurate lymphoma diagnosis, prognosis and therapy still require additional markers. We explore the potential relevance of microRNA (miRNA) expression in a large series that included all major B-cell non-Hodgkin lymphoma (NHL) types. The data generated were also used to identify miRNAs differentially expressed in Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) samples. A series of 147 NHL samples and 15 controls were hybridized on a human miRNA one-color platform containing probes for 470 human miRNAs. Each lymphoma type was compared against the entire set of NHLs. BL was also directly compared with DLBCL, and 43 preselected miRNAs were analyzed in a new series of routinely processed samples of 28 BLs and 43 DLBCLs using quantitative reverse transcription-polymerase chain reaction. A signature of 128 miRNAs enabled the characterization of lymphoma neoplasms, reflecting the lymphoma type, cell of origin and/or discrete oncogene alterations. Comparative analysis of BL and DLBCL yielded 19 differentially expressed miRNAs, which were confirmed in a second confirmation series of 71 paraffin-embedded samples. The set of differentially expressed miRNAs found here expands the range of potential diagnostic markers for lymphoma diagnosis, especially when differential diagnosis of BL and DLBCL is required

A Densely Interconnected Genome-Wide Network of MicroRNAs and Oncogenic Pathways Revealed Using Gene Expression Signatures

MicroRNAs (miRNAs) are important components of cellular signaling pathways, acting either as pathway regulators or pathway targets. Currently, only a limited number of miRNAs have been functionally linked to specific signaling pathways. Here, we explored if gene expression signatures could be used to represent miRNA activities and integrated with genomic signatures of oncogenic pathway activity to identify connections between miRNAs and oncogenic pathways on a high-throughput, genome-wide scale. Mapping >300 gene expression signatures to >700 primary tumor profiles, we constructed a genome-wide miRNA–pathway network predicting the associations of 276 human miRNAs to 26 oncogenic pathways. The miRNA–pathway network confirmed a host of previously reported miRNA/pathway associations and uncovered several novel associations that were subsequently experimentally validated. Globally, the miRNA–pathway network demonstrates a small-world, but not scale-free, organization characterized by multiple distinct, tightly knit modules each exhibiting a high density of connections. However, unlike genetic or metabolic networks typified by only a few highly connected nodes (“hubs”), most nodes in the miRNA–pathway network are highly connected. Sequence-based computational analysis confirmed that highly-interconnected miRNAs are likely to be regulated by common pathways to target similar sets of downstream genes, suggesting a pervasive and high level of functional redundancy among coexpressed miRNAs. We conclude that gene expression signatures can be used as surrogates of miRNA activity. Our strategy facilitates the task of discovering novel miRNA–pathway connections, since gene expression data for multiple normal and disease conditions are abundantly available

The Viral and Cellular MicroRNA Targetome in Lymphoblastoid Cell Lines

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus linked to a number of B cell cancers and lymphoproliferative disorders. During latent infection, EBV expresses 25 viral pre-microRNAs (miRNAs) and induces the expression of specific host miRNAs, such as miR-155 and miR-21, which potentially play a role in viral oncogenesis. To date, only a limited number of EBV miRNA targets have been identified; thus, the role of EBV miRNAs in viral pathogenesis and/or lymphomagenesis is not well defined. Here, we used photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) combined with deep sequencing and computational analysis to comprehensively examine the viral and cellular miRNA targetome in EBV strain B95-8-infected lymphoblastoid cell lines (LCLs). We identified 7,827 miRNA-interaction sites in 3,492 cellular 3′UTRs. 531 of these sites contained seed matches to viral miRNAs. 24 PAR-CLIP-identified miRNA:3′UTR interactions were confirmed by reporter assays. Our results reveal that EBV miRNAs predominantly target cellular transcripts during latent infection, thereby manipulating the host environment. Furthermore, targets of EBV miRNAs are involved in multiple cellular processes that are directly relevant to viral infection, including innate immunity, cell survival, and cell proliferation. Finally, we present evidence that myc-regulated host miRNAs from the miR-17/92 cluster can regulate latent viral gene expression. This comprehensive survey of the miRNA targetome in EBV-infected B cells represents a key step towards defining the functions of EBV-encoded miRNAs, and potentially, identifying novel therapeutic targets for EBV-associated malignancies

Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

This is the final version. Available from BMC via the DOI in this record. Individual cohort-level data can be obtained from the respective cohort (see Additional file 1: Table S1 and Additional file 2 for cohort details).BACKGROUND: Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear. METHODS: We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N = 9358) and in children aged 1-11 years (12 cohorts, N = 3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points. RESULTS: We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values < 0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (≥ 50°N), lower (< 50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (≥ 50°N). CONCLUSIONS: In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes.Wellcome TrustBiotechnology and Biological Sciences Research Council (BBSRC)Biotechnology and Biological Sciences Research Council (BBSRC)European Union’s Horizon 2020Economic and Social Research Council (ESRC)Medical Research Council (MRC)Medical Research Council (MRC)European UnionSwedish foundation for strategic research (SSF)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)Environmental Protection Agency (EPA)National Cancer Institute Cancer CenterNational Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)Environmental Protection Agency (EPA)Environmental Protection Agency (EPA)European UnionEuropean UnionEuropean UnionEuropean UnionEuropean Union’s Horizon 2020European Research Council (ERC)German Ministry of Education and ResearchNational Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)Autism SpeaksNational Institutes of Health (NIH)National Institutes of Health (NIH)European UnionEuropean UnionEuropean UnionEuropean UnionEuropean UnionEuropean UnionEuropean UnionEuropean UnionEuropean UnionEuropean Research Council (ERC)Flemisch Scientific Research CouncilFlemisch Scientific Research CouncilFlemisch Scientific Research CouncilEuropean UnionFonds de recherche du Québec - Santé (FRQS)Canadian Institute of Health Research (CIHR)Canadian Institute of Health Research (CIHR)Netherlands Organisation for Scientific Research (NWO)National Institute of Child and Human DevelopmentEuropean Union’s Horizon 2020European Union’s Horizon 2020European Union’s Horizon 2020ZonMwZonMwMedical Research Council Integrative Epidemiology Unit (University of Bristol)Netherlands Heart FoundationNetherlands Heart FoundationNetherlands Organisation for Scientific Research (NWO)European UnionNational Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)Spanish Ministry of ScienceNational Institute for Health and Care Research (NIHR)Wellcome TrustNorwegian Ministry of Health and the Ministry of Education and ResearchNorwegian Ministry of Health and the Ministry of Education and ResearchNorwegian Ministry of Health and the Ministry of Education and ResearchLithuanian Agency for Science Innovation and TechnologySpanish Ministry of HealthSpanish Ministry of HealthSpanish Ministry of HealthSpanish Ministry of HealthSpanish Ministry of HealthInstituto de Salud Carlos IIIInstituto de Salud Carlos IIIEuropean Research Council (ERC)CDMRP/Department of DefenseNIGMSNational Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Asthma Campaign, UKNational Institutes of Health (NIH)Medical Research Council (MRC)National Institutes of Health (NIH)Norwegian Research CouncilNational Institute of Environmental Health SciencesResearch Council of NorwayNational Institute of Environmental Health SciencesNational Institute of Environmental Health SciencesNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institute of Environmental Health SciencesNational Institute of Environmental Health SciencesSwedish Research CouncilSwedish Initiative for research on Microdata in the Social And Medical Sciences (SIMSAM)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)National Institutes of Health (NIH)Medical Research Council Integrative Epidemiology Unit (University of Bristol)Medical Research Council Integrative Epidemiology Unit (University of Bristol)Medical Research Council Integrative Epidemiology Unit (University of Bristol)Swedish Heart-Lung FoundationUniversity of MunichFoundation for Medical Research (FRM)National Agency for ResearchNational Institute for Research in Public HealthFrench Ministry of HealthFrench Ministry of ResearchInserm Bone and Joint Diseases National Research (PRO-A) and Human Nutrition National Research ProgramsParis–Sud UniversityNestléFrench National Institute for Population Health SurveillanceFrench National Institute for Health EducationFrench Agency for Environmental Health SafetyMutuelle Générale de l’Education NationaleFrench National Agency for Food SecurityFrench-speaking association for the study of diabetes and metabolismItalian National Centre for Disease Prevention and ControlItalian Ministry of HealthGreek Ministry of HealthFlemish Government (Department of Economy, Science and Innovations, Agency for Care and Health and Department of Environment)The Research Foundation-FlandersFlemish Institute for Technological ResearchDiabète QuébecErasmus University RotterdamNetherlands Organization for Health Research and Development and the Ministry of Health, Welfare and SportErasmus MCDanish National Research FoundationDanish Regional CommitteesNovo Nordisk FoundationLundbeck FoundationHelmholtz Center for Environmental ResearchGerman Cancer Research CentreAcademy of FinlandEraNetEVOUniversity of Helsinki Research FundsSigne and Ane Gyllenberg foundationEmil Aaltonen FoundationFinnish Medical FoundationJane and Aatos Erkko FoundationJuho Vainio foundationYrjö Jahnsson foundationJalmari and Rauha Ahokas foundationPaivikki and Sakari Sohlberg FoundationSigrid Juselius FoundationSir Jules Thorn Charitable TrustSwedish Asthma and Allergy Association's Research FoundationStiftelsen Frimurare Barnhuset Stockhol

A comprehensive identification of the microrna transcriptome and its application in B cell malignancies

Poster Board 2-380: abstract 2403BACKGROUND: MicroRNAs are 18-22 nucleotide-long RNA molecules that regulate expression of genes. We and others have previously demonstrated a role for microRNAs in the pathogenesis of B cell malignancies. Computational predictions suggest that the human genome encodes several thousand microRNAs. Thus far, about 700 microRNAs have been discovered in humans, including over 200 new microRNAs in the past year alone. The ongoing discovery of microRNAs makes it difficult to comprehensively study their role in a disease group. The advent of high throughput sequencing allows the simultaneous identification of millions of transcripts, thereby providing a sensitivity that is several orders of magnitude higher than conventional methods. We hypothesized that high throughput sequencing would be an effective tool to comprehensively identify microRNAs in normal and malignant B cells …link_to_OA_fulltex