Search Results - EGA European Genome-Phenome Archive

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.

Study phs003192

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.

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Genetic Analysis of Skin Cells

Cutaneous squamous cell carcinoma (cSCC) is a form of skin cancer originating from keratinocytes in the skin. They have high mutation burdens, primarily driven by UV-radiation-induced DNA damage. The order in which mutations undergo selection during the evolution of cSCC is not known. A subset of cSCCs grow out of benign neoplasms called actinic keratoses. To better understand the evolution of cSCC, we identified cases of cSCCs adjacent to actinic keratoses. From these cases, we separately microdissected the surrounding normal skin, the actinic keratosis, and the cSCC, and we performed targeted DNA-sequencing on the tissue from each area. We reconstructed tumor phylogenies and performed spatial transcriptomics on the 10X FFPE Visium platform on a subset of cases. Collectively, these studies revealed the mutational and gene expression changes that arise during the evolution of cSCC.

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Maintenance of Brain Tumor Profile on Organotypic Brain Slice Culture (OBSC)

We used uncultured tumor resection tissue from an NF2 mutation-driven grade II meningioma (MG-II) to investigate whether tumors engrafted onto organotypic brain slice cultures (OBSCs) maintained the genetic profile of the parent tumor. We prepared three groups of samples for whole exome sequencing (WES) from the same pool of dissociated MG-II tissue. Group HT is the original uncultured human tumor tissue (n = 3). Group CL is the parent tumor tissue expanded in standard in vitro cell culture until the minimum number of cells required for WES had grown. Because of initial cell loss and subsequent clonal expansion, this required six passages over the span of approximately one month (n = 3). Group BSHT is the uncultured tumor resection tissue engrafted onto OBSCs and subsequently dissected from the OBSCs at the conclusion of our standardized assay length (4 days; n = 4). WES analysis showed that tumor tissue engrafted onto OBSCs maintained a significant genetic resemblance to the parent tumor, while tumor tissue expanded in vitro displayed a distinctly different profile. Furthermore, the mutational profiles of all four BSHT biological replicates were markedly similar, indicating that each OBSC-engrafted tumor indeed contained a representative sample of the original patient tumor. A closer look at the hallmark NF2 mutations existing within all samples revealed that while all samples from the original tumor (HT1-3) and the OBSC-engrafted tumor (BSHT1-4) maintain the frame shift deletion at V24, this mutation was lost in all samples expanded in vitro (CL1-3) and replaced by mutations in other areas. Together, this data suggests that the rapid assay design and tumor-accommodating niche of our OBSC platform enables effective maintenance of the original patient tumor profile. The BBsplit algorithm from the BBtools suite was run on all samples to eliminate rat DNA contamination in the BSHT samples as well as to account for any biases that may result as a part of that process. Only the reads that were binned to the human reference were used for subsequent analysis. Reads were then mapped to the GRCh38 version of the human genome with BWA v0.7.17 and realigned together with ABRA2 v.23. Quality control was implemented using the GATK/Picard v4.1.7.0 toolkit. Somatic variants were called for each sample using the MuTect2 algorithm v4.1.7.0. Variants were merged into a single cohort variant call file and then converted to MAF via vcf2maf v1.6.21 tool. Variants were annotated using VEP v87. To identify mutations with potentially high biological impact, multiple filtering steps were applied to somatic mutation calling. First, we selected only the somatic variants that passed all filters from the MuTect2 FilterMutectCalls algorithm and second, only high/moderate impact (change coding) variants as defined by the VEP annotation were further analyzed. Over 1900 single nucleotide variants (SNVs) were detected across all samples. Figures that summarized the results were generated using maftools.

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Supraphysiologic MDM2 Expression Impacts P53-Independent Chromatin Networks and Therapeutic Responses in Sarcoma

We collected multiple liposarcoma samples from different patients, including different subtypes (DD, WD) and normal adipose tissue as control. This study provides the biggest liposarcoma cohort to date, and examined the molecular regulatory circuits associated with MDM2 overexpression. To this end, we obtained not only RNA-seq data, but also ChIP-seq from Jun, RUNX, MDM2, P53 and H3K27ac, as well as hiChIP from tumor samples and cell lines. We found that MDM2 binds to thousands of genes involved in cellular growth and stress response in a P53-independent manner. Furthermore, we described these active genes engaged in multi-way topological interactions that resemble transcriptional hubs.

Study phs003272

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