Search Results - EGA European Genome-Phenome Archive

Single Chromatin Fiber Profiling in the Human Brain

We developed a human postmortem brain-applicable ‘Fiber-seq' protocol for genome-scale, PCR-free single molecule sequencing of on average 8-10kb long chromatin fibers, to map nucleosome positioning and nucleosome-depleted regions which include, for example, active promoters and enhancers. We generated two Fiber-seq reference sets, one from sorted non-neuronal NeuN- prefrontal cortex (PFC) nuclei from a 32 year old female donor, with total of 11,143,795 reads/fibers, and median of 30-fold genomic coverage. The other reference set was generated on sorted prefrontal NeuN+ neurons, from two 24 year old brain donors (1 female/1 male), with a combined total read/fiber count of 4,749,556 and median of 20-fold genomic coverage. Each of the peaks in the Fiber-seq libraries seq signal correlated with the ATAC peak levels in the neuronal and non-neuronal ATAC-seq libraries, respectively (promoters, clusters 1, 3; NeuN+, r = 0.574; NeuN-, r=0.683, PHowever, Fiber-seq detected 19,978 highly significant peaks which, while showing some non-significant/near-background ATAC-Seq alignments, lacked a corresponding site-specific enrichment in conventional short-read ATAC- and ChIP-seq datasets. However, 60% of these peaks were in repetitive DNA elements. Therefore, long read single chromatin fiber sequencing, which exceed the base pair length of conventional short-read libraries by two orders of magnitude, could capture many actively regulated repeat elements at the site of specific gene loci, that otherwise would remain unmappable by conventional ATAC-, and histone- ChiP-seq.

Study phs003771

PCPT and SELECT Cohorts: Core Infrastructure Support for Cancer Research

SELECT study: SELECT was a phase III, double-blind, placebo-controlled 4-arm study of selenium, vitamin E, selenium and vitamin E together, and placebo designed to assess the effect of these supplements on the incidence of prostate cancer. Funded by the National Cancer Institute and conducted by SWOG, the study opened in August 2001 and quickly exceeded its accrual goal of 35,533 men.In the fall of 2008, the trial's Data Safety and Monitoring Committee recommended that participants discontinue taking study supplements due to convincing evidence (planned interim futility analysis) that neither vitamin E nor selenium supplements were associated with the prevention of prostate cancer. A subsequent analysis in 2011 showed a significant 17% increase in prostate cancer incidence in participants who were on the vitamin E only arm. Approximately 17,000 participants from the original trial recently completed an additional four years of centralized follow-up. This follow-up ended on May 31, 2014 and SELECT is now closed. PCPT study: The Prostate Cancer Prevention Trial (PCPT) was a SWOG Cancer Research Network-coordinated study designed to test whether the drug finasteride (Proscar®) would prevent prostate cancer in men ages 55 and older. This study was closed on June 24, 2003 because the study objective had been reached. The results of the study, which did find a preventive benefit for the drug, were published as "The Influence of Finasteride on the Development of Prostate Cancer," in the New England Journal of Medicine on July 17, 2003.

Study phs003382

Impact of Glycolysis Inhibition on the Epigenome of Synovial Fluid T Cells in Juvenile Idiopathic Arthritis

Juvenile Idiopathic Arthritis (JIA) encompasses a group of childhood-onset autoimmune conditions characterized by joint inflammation and mononuclear cell infiltration, especially of activated CD4+ memory/effector T (Tmem/Teff) cells in synovial fluid (SF). JIA CD4+ T cells exhibit a distinct inflammation-associated epigenomic profile, though the underlying molecular mechanisms remain unclear. This study investigates the role of glycolysis in shaping the epigenomic landscape of JIA SF CD4+ T cells, with a focus on H3K27ac histone modifications. Using an ex vivo model of antigen stimulation, CD4+ T cells were isolated from peripheral blood (PB) of healthy controls (HC) and synovial fluid from JIA patients. Cells were activated in vitro with anti-CD3/CD28 for 24 hours, and changes in H3K27ac were assessed by chromatin immunoprecipitation followed by sequencing (ChIP-seq). To explore the specific role of glycolysis, cells were also treated with 2-deoxyglucose (2DG), an inhibitor of glucose-6-phosphate production. This inhibition impacted both H3K27ac acetylation patterns and gene expression associated with the activated epigenomic regions. Additionally, HC CD4+ T cells were activated in vitro in the presence of 30% SF or 30% plasma from JIA patients. RNA sequencing (RNA-seq) was performed to examine SF-induced transcriptional changes, providing insight into the metabolic dysregulation and epigenomic alterations observed in JIA SF CD4+ T cells. This dataset includes ChIP-seq and RNA-seq data that collectively advance our understanding of how glycolysis and the SF environment contribute to the epigenetic and transcriptional regulation in JIA CD4+ T cells.

Study EGAS50000000808

DNA demethylation is associated with malignant progression of low-grade gliomas

To elucidate the mechanisms of tumor progression is key to discovering strategies for treating patients with lower-grade glioma. Thus to characterize the changes in the molecular profile during malignant progression, we performed methylation array analysis (122 tumors), whole-exome sequencing (36 tumors and matched normal samples), and RNA sequencing (31 tumors). This cohort included 24 matched pairs of initial lower-grade gliomas and recurrent tumors, most of which showed malignant progression when they recurred. Nearly half of IDH-mutant glioblastomas that had progressed from lower-grade gliomas exhibited characteristic partial DNA demethylation in previously methylated genomic regions of their corresponding initial tumors, which had the glioma CpG island methylator phenotype (G-CIMP). In these glioblastomas, cell cycle-related genes were upregulated, RB and PI3K-AKT pathway genes were frequently altered. Notably, bioinformatics analysis revealed that late-replicating domain was significantly enriched in the demethylated regions that were mostly located in non-regulatory regions, suggesting that the loss of DNA methylation during malignant transformation may involve mainly passive demethylation due to a delay in maintenance of methylation during accelerated cell division. Nonetheless, a limited number of genes including IGF2BP3, which potentially drives cell proliferation, were presumed to be upregulated due to demethylation of their promoter. Thus, cell proliferation was further promoted by passive demethylation in the promoter region of these oncogenic genes. Our data indicated that demethylation of the G-CIMP profile found in a subset of recurrent gliomas reflects accelerated cell divisions accompanied by malignant transformation. Oncogenic genes activated by such epigenetic change represent potential therapeutic targets.

Study JGAS000146

Breast cancer DNA repair

Tumors of germline BRCA1/2 mutated carriers show homologous recombination (HR) deficiency (HRD), resulting in impaired DNA double strand break (DSB) repair and high sensitivity to Poly-(ADP-Ribose)-Polymerase (PARP) inhibitors. Although this therapy is expected to be effective beyond germline BRCA1/2 mutated carriers, a robust validated test to detect HRD tumors is lacking. In the present study we therefore evaluated a functional HR assay exploiting the formation of RAD51 foci in proliferating cells after ex vivo irradiation of fresh breast cancers (BrC) tissue: the RECAP test.Methods Fresh samples of 170 primary BrC were analyzed using the RECAP test. The molecular explanation for the HRD phenotype was investigated by exploring BRCA deficiencies, mutational signatures, tumor infiltrating lymphocytes (TILs) and microsatellite instability (MSI).Results RECAP was completed successfully in 148 out of 170 samples (87%). 24 tumors showed HRD (16%), while 6 tumors were HR intermediate (HRi) (4%). HRD was explained by BRCA deficiencies (mutations, promoter hypermethylation, deletions) in 16 cases. Several non-BRCA deficient HRD tumors showed BRCAness mutational signatures, suggesting that they are also bona fide HRD cases. HRD tumors showed an increased incidence of high TIL counts (p=0.023) compared to HR proficient (HRP) tumors and MSI was more frequently observed in the HRD group (2/20, 10%) than expected in BrC (1%) (p=0.017).Conclusion The RECAP test is a robust assay detecting both BRCA1/2 deficient and BRCA1/2 proficient HRD tumors, suggesting that this test identifies approximately 50% more patients that may benefit from PARPi treatment than BRCA gene testing only.

Study EGAS00001002792

Detection of ctDNA in Plasma of Patients with Clinically Localised Prostate Cancer is Associated with Rapid Disease Progression

Purpose: DNA originating from degenerate tumour cells can be detected in the circulation in many tumour types, where it can be used as a marker of disease burden as well as to monitor treatment response. Although circulating tumour DNA (ctDNA) measurement has prognostic/predictive value in metastatic prostate cancer, its utility in localised disease is unknown. Patients and Methods: We performed whole genome sequencing of tumour-normal pairs in eight patients with clinically localised disease undergoing prostatectomy, identifying high confidence genomic aberrations. A bespoke DNA capture and amplification panel against the highest prevalence, highest confidence aberrations for each individual was designed and used to interrogate ctDNA isolated from plasma prospectively obtained pre- and post- (24 hours and 6 weeks) surgery. In a separate cohort (n=189) we identified the presence of ctDNA TP53 mutations in pre-operative plasma in a retrospective cohort, and determined its association with biochemical- and metastasis-free survival. Results: Tumour variants in ctDNA were positively identified pre-treatment in two of eight patients, which in both cases remained detectable postoperatively. Patients with tumour variants in ctDNA had extremely rapid disease recurrence and progression compared to those where variants could not be detected. In terms of aberrations targeted, single nucleotide and structural variants outperformed indels and copy number aberrations. Detection of ctDNA TP53 mutations was associated with a significantly shorter metastasis-free survival (6.2 vs. 9.5 years (HR 2.4; 95% CIs 1.2-4.8, p = 0.014)). Conclusions: CtDNA is uncommonly detected in localised prostate cancer but its presence portends more rapidly progressive disease.

Study EGAS00001004636

PD-L1 blockade in combination with carboplatin as immune induction in metastatic lobular breast cancer: the GELATO-trial

Invasive lobular breast cancer (ILC) is the second most common histological breast cancer subtype but published data on trials specific for ILC are so far lacking. Translational research revealed that a subset of ILCs may be immune-related and more sensitive to DNA-damaging agents such as platinum. In murine ILC models, synergy between immune checkpoint blockade and platinum has been observed. Here, we tested this concept in the phase II, GELATO-trial (NCT03147040), in which patients with metastatic ILC were treated with weekly carboplatin (AUC 1.5) as immune induction treatment for 12 weeks and atezolizumab (PD-L1 blockade; every three weeks) from the third week onwards until disease progression. Four out of 23 evaluable patients had a partial response (17%, 95%CI 5-39%) and two patients had stable disease for at least 24 weeks, resulting in a clinical benefit rate of 26% (95%CI 10-48%). Out of these six patients, four patients had triple-negative ILC (TN-ILC). In serial biopsies of metastatic lesions, we observed higher CD8 T-cell infiltration, expression of immune checkpoints, and exhausted T cells upon carboplatin/PD-L1 blockade. This is the first report of a clinical trial specifically for ILC and we demonstrate promising anti-tumor activity of atezolizumab with carboplatin as immune induction, in particular for TN-ILC. While activity of carboplatin/PD-L1 blockade in classical ER+ ILC was limited, our translational data yield important insights for the design of highly needed clinical trials in ILC.

Study EGAS00001006902

Sperm sequencing reveals extensive positive selection in the human germline -WGS

Mutations that occur during human ageing in the cell lineages of sperm or eggs have the potential to be transmitted to offspring. In males, positive selection of driver mutations during spermatogenesis is known to increase the birth prevalence of certain developmental disorders and cancer predisposition syndromes. However, direct observation of the scope of this selection in sperm has been limited by the error rates of sequencing technologies. Using the duplex sequencing method known as NanoSeq, we sequenced bulk sperm samples from individuals aged 24 to 75 years. Our findings revealed a linear accumulation mutations per year and mutational signatures consistent with pedigree studies. Deep targeted and deep exome NanoSeq of sperm samples identified genes subject to significant positive selection in the male germline, which are linked to diverse cellular pathways including RAS/MAPK and BMP signaling. Strikingly, nearly all positively selected genes are associated with developmental or cancer predisposition disorders in children. We find that this effect drives an elevated risk of known likely disease-causing mutations in sperm across a wide age range. This implies that the disorders attributed to these genes likely exhibit elevated birth prevalence in human populations, particularly among older fathers. These findings shed light on the dynamics of germline mutations and highlight an increased disease risk for children born to fathers of advanced age.

Dataset EGAD00001015592

Sperm sequencing reveals extensive positive selection in the human germline -NanoSeq

Mutations that occur during human ageing in the cell lineages of sperm or eggs have the potential to be transmitted to offspring. In males, positive selection of driver mutations during spermatogenesis is known to increase the birth prevalence of certain developmental disorders and cancer predisposition syndromes. However, direct observation of the scope of this selection in sperm has been limited by the error rates of sequencing technologies. Using the duplex sequencing method known as NanoSeq, we sequenced bulk sperm samples from individuals aged 24 to 75 years. Our findings revealed a linear accumulation mutations per year and mutational signatures consistent with pedigree studies. Deep targeted and deep exome NanoSeq of sperm samples identified genes subject to significant positive selection in the male germline, which are linked to diverse cellular pathways including RAS/MAPK and BMP signaling. Strikingly, nearly all positively selected genes are associated with developmental or cancer predisposition disorders in children. We find that this effect drives an elevated risk of known likely disease-causing mutations in sperm across a wide age range. This implies that the disorders attributed to these genes likely exhibit elevated birth prevalence in human populations, particularly among older fathers. These findings shed light on the dynamics of germline mutations and highlight an increased disease risk for children born to fathers of advanced age.

Dataset EGAD00001015590

scRNA-seq of HSPC treated with gemcitabine and carboplatin

4 samples of 2000000 HSPCs in 2 ml media each were then prepared and treated for 24 hours: carboplatin-high: 150 µg/ml carboplatin carboplatin-low: 18.75 µg/ml carboplatin gemcitabine: 25 ng/ml gemcitabine control: no drug Single-cells were subsequently extracted using the ddSEQ™ Single-Cell Isolator (Bio-Rad) and later sequenced using the SureCell™ Whole Transcriptome Analysis 3' Library Prep Kit (Illumina) on the NextSeq 500 System (Illumina) using the NextSeq 500/550 High Output Kit v2.5 150 Cycles (Illumina) all following the manufacturer's instructions. The raw FASTQ-files are available as read 1 and read 2 files from 4 lanes for each sample giving a total of 16 FASTQ-files. The FASTQ-files were also processed following the ddSeeker (Romagnoli, D., et al., BMC Genomics 2018, doi:10.1186/s12864-018-5249-x) and Drop-seq (Macosko, E.Z., et al., Cell 2015, doi:10.1016/j.cell.2015.05.002) protocols for processing scRNA-seq data to yield the final digital gene expression (dge) for each cell of each sample. This has resulted in one dge text file and one dge summary text file per sample. These 8 text-files with dge data are found in the zip-compressed analysis data-file.

Dataset EGAD00001006080

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