Search Results - EGA European Genome-Phenome Archive

Sézary Syndrome Originates from Heavily Mutated Hematopoietic Progenitors

The pathogenesis of cutaneous T cell lymphoma (CTCL) remains unclear. To study the malignant transformation of CTCL, we collected matched hematopoietic stem cell (HSC) extracts from bone marrow, CD4+CD26- malignant T cells, CD4+CD26+ normal T cells, and CD34+ HSCs from apheresis performed on 4 patients. To establish the baseline for calling true mutations without using hematopoietic cells, we also cultured bone marrow fibroblasts from each patient to use as normal controls. Whole exome sequencing (WES) was performed on all samples for somatic mutation calling. We identified >200 mutations in CD34+ HSCs derived from either bone marrow or apheresis. Previously reported key oncodrivers in Sezary Syndrome were identified in autologous HSCs and malignant peripheral cells, but not in progenitor (bone marrow HSCs) cells. Also, we identified specific mutations shared by autologous HSCs and malignant peripheral cells in every patient. WES data of bone marrow HSCs, apheresis HSCs, CD4+CD26- T cells, CD4+CD26+ T cells, and fibroblasts will be available through dbGaP.

Study phs003158

Targeted Long-Read Sequencing of the Ewing Sarcoma 6p25.1 Susceptibility Locus

Ewing Sarcoma (EwS) is rare but the second most common cancer in children, adolescents and young adults. Recent studies suggest germline variation in or around GGAA microsatellites may interact with fusion oncoprotein binding causing changes in binding affinity and potentially impacting enhancer activity on nearby target genes. This study aims to better understand germline variation around EwS susceptibility regions by performing long-range haplotype sequencing of these regions using PacBio sequencing. Our analysis focused on characterizing variation in GGAA microsatellite length as well as germline variants in or around the microsatellite and their association with EwS risk.

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Molecular Subtyping Reveals Immune Alterations Associated with Progression of Bronchial Premalignant Lesions

Exposure to cigarette smoke creates a field of injury throughout the entire respiratory tract inducing genomic alterations that lead to an "at-risk" airway where lung cancers develop. Lung squamous cell carcinoma (SCC) arises in the epithelial layer of the bronchial airways and is often preceded by the development of premalignant lesions (PMLs). Effective tools to identify and treat premalignant lesions at highest risk of progression to invasive carcinoma are not available. Endobronchial biopsies and brushings were obtained from high-risk subjects undergoing lung cancer screening at approximately 1-year intervals by white light and auto-fluorescence bronchoscopy and computed tomography at the Roswell Park Cancer Institute in Buffalo, NY. Subjects were selected that had biopsies collected in repeat locations via serial bronchoscopies. mRNA sequencing was performed on a discovery cohort (DC) of samples comprising endobronchial biopsies and brushes collected between 2010 and 2012 (n=30 subjects, n=197 biopsies, and n=91 brushings). mRNA sequencing was subsequently performed on a validation cohort (VC) of samples comprising endobronchial biopsies and brushes collected between 2010 and 2015 (n=20 subjects, n=111 biopsies, and n=49 brushings). Data analysis identified four distinct molecular subtypes (Proliferative, Inflammatory, Secretory, and Normal) in the bronchial biopsies that correspond to a spectrum of biological and morphological alterations. The Proliferative subtype was enriched with dysplastic PMLs from current smokers that exhibit up-regulation of metabolic and cell cycle pathways and down-regulation of cilium-associated processes. Molecular subtype classification in the validation cohort biopsies replicated these significant clinical and biological associations. Airway brushes from normal fluorescing areas of the large airway classified as the Proliferative subtype specifically predict the presence of biopsies of this same subtype. Within the Proliferative subtype, genes associated with interferon signaling and antigen processing and presentation were observed to be down-regulated among dysplastic biopsies that persist or progress in the future. Innate and adaptive immune cells were computationally predicted to be depleted in these biopsies and this was confirmed via immunofluorescence staining of adjacent biopsies. These findings provide a proof of concept that molecular biomarkers of endobronchial biopsies can enhance histopathological grading and that immunoprevention strategies are an important future direction in intercepting the progression of PMLs to lung cancer.FASTQ files from the RNA sequencing of these biopsies and brushings will be available via dbGaP.

Study phs003185

Temporal Evolution Reveals Bifurcated Lineages in Aggressive Neuroendocrine Small Cell Prostate Cancer Trans-Differentiation

Trans-differentiation from adenocarcinoma to small cell neuroendocrine (SCN) cancer is an adverse consequence of treatment escape in various cancers, including prostate, lung, and bladder cancers (Balanis and Sheu et al., 2019 Cancer Cell). Expression of dominant negative p53 (TP53DN), myrAkt1, RB1-shRNA, c-Myc, and Bcl2(PARCB forward transformation) using human naïve prostate basal epithelial cells recapitulated both transcriptional and histological characteristics of small cell neuroendocrine prostate cancer (NEPC) (Park et al., 2018 Science). To study the temporal transcriptional landscape during this trans-differentiation process, we conducted a time course study using a PARCB model by integrating multi-omics sequencing, including bulk RNA-sequencing and ATAC-sequencing on samples taken at different time point, as well as single cell RNA sequencing on serial xenograft tumors. We found a common SCN pathway that resulted in two distinct end states defined by mutually exclusive expression of ASCL1 and ASCL2. Further investigation using CUT&RUN sequencing identified TFAP4 as a potential epigenetic regulator of both proteins. Our study reveals temporal and transcriptional changes from prostate adenocarcinoma to NEPC trans-differentiation.

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ARST17B2-Q Germline and Somatic Genetic Landscape of Pediatric Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. While these malignancies display aberrant myogenic differentiation, relatively little is known about genetic susceptibility to RMS, or how genetic variants influence subsequent somatic events and may be used in risk stratification strategies. A small percentage of cases are associated with mutations in TP53 (Li-Fraumeni syndrome), HRAS (Costello syndrome), and PTCH1 (nevoid basal cell carcinoma syndrome/Gorlin syndrome), suggesting the genetic origins of childhood RMS. In spite of this, little work has been done to characterize genetic susceptibility to this malignancy. We plan to leverage samples collected as part of D9902 to conduct one of the largest germline genomic studies of RMS. We anticipate that once genetic associations are identified, researchers can use the information to develop better strategies to detect, treat, and prevent childhood RMS.

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Comprehensive Omics Analysis of Pediatric Solid Tumors and Establishment of a Repository for Related Biologic Studies (10C0086)

This study (10-C-0086) collected and analyzed tumor and circulating tumor omics of pediatric and young adult patients with relapsed rhabdomyosarcoma who were co-enrolled in and receiving treatment on the interventional study 17-C-0049. We sought to describe the summary genomic findings of tumors, and report on the detection of circulating tumor DNA (ctDNA) in serial samples. Tumor tissue and blood were collected and analyzed. Tumor samples were subjected to whole exome and/or whole genome sequencing paired with RNA-Seq. Cell free DNA (cfDNA) was extracted from serially collected blood samples and sequenced. Fusion status, mutations, and IGF1R and YES1 expression from tumor samples revealed the presence of a PAX3 fusion in most samples, a number of common mutations, and universal but heterogeneous expression of IGF-1R and YES1. ctDNA was detected above the 3% threshold in a majority of patients and analysis of cfDNA demonstrated an ability to monitor tumor clonal evolution.

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Structurally Complex Osteosarcoma Genomes Exhibit Limited Heterogeneity within Individual Tumors and across Evolutionary Time

A key characteristic of osteosarcoma is extensive and complex genomic rearrangements. However, published models explaining how these genomic rearrangements occur disagree about if these rearrangements occur early in tumor progression and then are stable afterwards, or if there is ongoing genomic instability. Previous studies have employed bulk sequencing technologies to characterize genomic alterations. A limitation of this approach is that it averages all changes within the bulk sample, essentially masking intra-sample heterogeneity and making evaluation of ongoing genomic instability difficult. To overcome this limitation and compliment previous work, we utilized single-cell whole genome sequencing to quantify somatic copy number alterations (SCNA). By interrogating individual cells within a sample, we were able to examine intra-sample heterogeneity. We found that the SCNA patterns between cells within a single sample were remarkably consistent, which supports the concept that the genomes of osteosarcoma tumors are relatively stable after early genome fragmentation events.

Study phs003209

Melbourne Collaborative Cohort Study DNA Methylation Studies

This dataset contains raw Illumina 450K blood DNA methylation data from a subset of participants in the Melbourne Cohort Study (MCCS), a prospective study of 41,513 healthy adult volunteers (24,469 women) aged between 27 and 76 years when recruited between 1990 and 1994. Nested case-control studies: DNA methylation data were generated as part of cancer case-control studies nested in the MCCS. Participants were cancer-free at blood draw; blood samples were taken at baseline (1990-1994) for 97% of participants; and for 3% of participants at the second wave of follow-up (2003-2007). Eight separate studies were conducted of breast, prostate, colorectal, lung, kidney, urothelial and gastric cancer and B-cell lymphoma, for a total of > 3,500 cancer cases. Controls were individually matched to cases on age, sex, and country of birth using incidence density sampling. Additional matching on smoking history was made for the study of lung cancer. Longitudinal study: For a subset of 1,100 participants with baseline DNA methylation measures (from dried blood spots) who were selected as controls in the nested case-control studies, repeated methylation measures were made using wave 2 follow-up samples (also from dried blood spots) to study longitudinal DNA methylation changes. Project aims: 1. Nested case-control studies: To assess prospective associations between peripheral blood DNA methylation and risk of eight cancer types (breast, prostate, colorectal, lung, kidney, urothelial cell and gastric cancer, and mature B-cell neoplasms). 2. Longitudinal study: To assess associations between lifestyle changes and changes in peripheral blood DNA methylation.

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Molecular Determinants of Esophageal Cancer in Tanzania

We describe the genomic profiles of 61 esophageal squamous cell carcinoma (ESCC) cases from Tanzania and compare them to profiles from an existing cohort of ESCC cases from Malawi. We also provide a comparison to ESCC tumors in The Cancer Genome Atlas Program (TCGA). Despite a high burden of ESCC in Eastern Africa, investigations into the genomics in this region are nascent. This represents the largest comprehensive genomic analysis of ESCC from sub-Saharan Africa to date. We observed substantial transcriptional overlap with other squamous histologies via comparison with TCGA PanCan dataset. DNA analysis revealed known mutational patterns, both genome-wide as well as in genes known to be commonly mutated in ESCC. TP53 mutations were the most common somatic mutation in tumors from both Tanzania and Malawi but were detected at lower frequencies than previously reported in ESCC cases from other settings. In a combined analysis, two unique transcriptional clusters were identified: a proliferative/epithelial cluster and an invasive/migrative/mesenchymal cluster. Mutational signature analysis of the Tanzanian cohort revealed common signatures associated with aging and cytidine deaminase activity and an absence of signature 29, which was previously reported in the Malawi cohort.

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TREM2+ Cells in Human Basal Cell Carcinomas

To explore the tumor immune microenvironment heterogeneity in sporadic human basal cell carcinoma tumors, we profiled two individual patient tumors by scRNA-Seq. We identified a population of TREM2+ macrophages, which have been implicated in promoting an immunosuppressive tumor microenvironment. We identify that TREM2+ can promote tumor epithelial proliferation in an immunosuppressive independent manner.

Study phs003242

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