Ena-DATASET-GTI-21-01-2020-14:13:35:184-2 - samples
Ontology highlight
ABSTRACT:
PROVIDER: EGAD00001005798 | EGA |
REPOSITORIES: EGA
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Project description:Background: Previous studies found that cell-free DNA (cfDNA) generated from tumors was shorter than that from healthy cells, and selecting short cfDNA could enrich for tumor cfDNA and improve its usage in early cancer diagnosis and treatment monitoring; however, the underlying mechanism of shortened tumor cfDNA was still unknown, which potentially limits its further clinical application.Results: Using targeted sequencing of cfDNA in a large cohort of solid tumor patient, sequencing reads harboring tumor-specific somatic mutations were isolated to examine the exact size distribution of tumor cfDNA. For the majority of studied cases, 166bp remained as the peak size of tumor cfDNA, with tumor cfDNA showing an increased proportion of short fragments (100-150bp). Less than 1% of cfDNA samples were found to be peaked at 134/144bp and independent of tumor cfDNA purity. Using whole-genome sequencing of cfDNA, we discovered a positive correlation between cfDNA shortening and the magnitude of chromatin inaccessibility, as measured by transcription, DNase I hypersensitivity, and histone modifications. Tumor cfDNA shortening occurred simultaneously at both 5’ and 3’ ends of the DNA wrapped around nucleosomes. Conclusions: Tumor cfDNA shortening exhibited two distinctive modes. Tumor cfDNA purity and chromatin inaccessibility were contributing factors but insufficient to trigger a global transition from 166bp dominant to 134/144bp dominant phenotype.
| EGAS00001004135 | EGA
Project description:cfDNA (Cell-free DNA) was extracted from serum exosome of gastric cancer patient. We analyzed cfDNA by aCGH (array comparative genomic hybridization).
2018-03-31 | GSE108602 | GEO
Project description:Blood cell counts often fail to report on immune processes occurring in remote tissues. Here we use 25 immune cell type-specific methylation patterns in circulating cell-free DNA (cfDNA) for studying 26 human immune cell dynamics. We characterized cfDNA released from specific immune cell types in 27 healthy individuals (N=242), cross sectionally and longitudinally. Immune cfDNA levels had no 28 individual steady state as opposed to blood cell counts, suggesting that cfDNA concentration reflects 29 adjustment of cell survival to maintain homeostatic cell numbers. We also observed selective elevation 30 of immune-derived cfDNA upon perturbations of immune homeostasis. Following influenza 31 vaccination (N=92), B-cell-derived cfDNA levels increased prior to elevated B-cell counts and 32 predicted efficacy of antibody production. Patients with Eosinophilic Esophagitis (N=21) and B-cell 33 lymphoma (N=27) showed selective elevation of eosinophil and B-cell cfDNA respectively, which 34 were undetectable by cell counts in blood. Immune-derived cfDNA provides a novel biomarker for 35 monitoring immune responses to physiological and pathological processes that are not accessible using 36 conventional methods.
2021-11-26 | GSE186888 | GEO
Project description:As a non-invasive blood testing, the detection of cell-free DNA (cfDNA) methylation in plasma is raising increasing interest due to its diagnostic and biology applications. Although extensively used in cfDNA methylation analysis, bisulfite sequencing is less cost-effective. Through enriching methylated cfDNA fragments with MeDIP followed by deep sequencing, we aimed to characterize cfDNA methylome in cancer patients. In this study, we investigated the cfDNA methylation patterns in lung cancer patients by MeDIP-seq. MEDIPS package was used for the identification of differentially methylated regions (DMRs) between patients and normal ones. Overall, we identified 330 differentially methylated regions (DMRs) in gene promoter regions, 33 hypermethylation and 297 hypomethylation respectively, by comparing lung cancer patients and healthy individuals as controls. The 33 hypermethylation regions represent 32 genes. Some of the genes had been previously reported to be associated with lung cancers, such as GAS7, AQP10, HLF, CHRNA9 and HOPX. Taken together, our study provided an alternative method of cfDNA methylation analysis in lung cancer patients with potential clinical applications.
2019-03-31 | E-MTAB-7163 | biostudies-arrayexpress
Project description:We use mice containing a gene trap in the first intron of the Rest gene, which effectively eliminates transcription from all coding exons, to prematurely remove REST from neural progenitors. We find catastrophic DNA damage that occurs during S-phase of the cell cycle and concominant with activation of p53 pro-apoptotic sgnalling, with consequences including abnormal chromosome separation, apoptosis, and smaller brains.
2015-08-01 | GSE68459 | GEO
Project description:Current methods for mapping the tissue-of-origin of circulating cell-free DNA (cfDNA) are still insufficient. Here, we have extended a previously developed methylated CpG tandems amplification and sequencing (MCTA-Seq) method for quantitative analysis of tissue-of-origin of plasma cfDNA. By comparing paired plasma cfDNA and white blood cell genomic DNA, we have demonstrated that the liver is the major non-hematopoietic tissue contributing to plasma cfDNA in healthy adults, accounting for approximately 2%. Furthermore, we have detected changes in liver-derived DNA in patients with benign liver diseases and increases in pancreas-derived DNA in acute pancreatitis patients. Interestingly, our results suggest that DNA derived from pathological tissues makes a minor contribution to the increased cfDNA in many clinical cases. Finally, we have identified a tissue-specific hypermethylated cfDNA marker located in the intragenic regions of tissue-specifichighlyexpressed genes. This study represents valuable progress in the field of cfDNA and offers promise for clinical research and medical diagnostics using the described method.
2019-07-01 | GSE118690 | GEO
Project description:Nucleosomes are the basic unit of packaging of eukaryotic chromatin, and nucleosome positioning can differ substantially between cell types. Here, we sequence 14.5 billion plasma-borne cell-free DNA (cfDNA) fragments (700-fold coverage) to generate genome-wide maps of in vivo nucleosome occupancy. We identify 13 million local maxima of nucleosome protection, spanning 2.53 gigabases (Gb) of the human genome, whose positions and spacings correlate with nuclear architecture, gene structure and gene expression. We further show that short cfDNA fragments - poorly recovered by standard protocols - directly footprint the in vivo occupancy of DNA-bound transcription factors such as CTCF. The sequence composition of cfDNA has previously been used to noninvasively monitor cancer, pregnancy and organ transplantation, but a key limitation of this paradigm is its dependence on genotypic differences to distinguish between contributing tissues. We show that nucleosome spacing in gene bodies and cis-regulatory elements, inferred from cfDNA in healthy individuals, correlates most strongly with transcriptional and epigenetic features of lymphoid and myeloid cells, consistent with hematopoietic cell death as the normal source of cfDNA. We build on this observation to show how in vivo nucleosome footprints can be used to infer the cell types that contribute to circulating cfDNA in pathological states such as cancer. Because it does not rely on genotypic differences, this strategy may enable the noninvasive cfDNA-based monitoring of a much broader set of clinical conditions than is currently possible. Sequencing of cfDNA libraries from healthy individuals, pooled healthy individuals and individuals with disease for the identification of nucleosomes and protection from other DNA binding proteins.
2015-11-04 | E-GEOD-71378 | biostudies-arrayexpress
Project description:Background: Liquid biopsies analyzing cell-free DNA methylation in plasma offer a non-invasive diagnostic for diseases, with aging biomarker potential underexplored. Methods: Utilizing enzymatic methyl-seq (EM-seq), this study assessed cfDNA methylation patterns in aging with blood from 35 healthy individuals. Results: It found aging signatures, including higher cfDNA levels and variations in fragment sizes, plus over 2 million age-related differentially methylated CpG sites. A biological age predictive model based on 41 CpG sites showed a strong correlation with chronological age, verified by two datasets. Age-specific epigenetic shifts linked to inflammation were revealed through differentially methylated regions profiling and Olink proteomics. Conclusion: These findings indicate cfDNA methylation as a potential biomarker for aging, and it might exacerbate immunoinflammatory reactivity in older individuals.
2024-05-23 | GSE259312 | GEO
Project description:We use mice containing a gene trap in the first intron of the Rest gene, which effectively eliminates transcription from all coding exons, to prematurely remove REST from neural progenitors. We find catastrophic DNA damage that occurs during S-phase of the cell cycle, with consequences including abnormal chromosome separation, apoptosis, and smaller brains. Further support for persistent effects is the latent appearance of proneural glioblastomas in adult mice also lacking the tumor suppressor, p53. A Rest deficient mouse line generated previously, using a conventional gene targeting approach, does not exhibit these phenotypes, likely due to a remaining C terminal peptide that still binds chromatin and recruits REST chromatin modifiers.Our results indicate that REST-mediated chromatin remodeling is required for proper S-phase dynamics, prior to its well-established role in relieving repression of neuronal genes at terminal differentiation.
2015-08-01 | GSE68368 | GEO
Project description:We performed all stimulatory experiments using THP1 cell line as a representative of primary human monocytes to show fundamental role of the cfDNA in healthy organisms. The experiments were conducted in duplicates using plasma containing cfDNA (NP) and the reference one with cfDNA removed by DNase (TP) to recognize unequivocally the effect of plasma cfDNA on transcriptome and proteome of monocytes. We used native human plasma samples obtained from healthy volunteers with no animal serum addition to cultivation medium in order to avoid the presence of uncharacterized animal cfDNA in the experiments.
2021-05-18 | PXD017285 | Pride