Search Results - EGA European Genome-Phenome Archive

Fragmentation signatures in cancer patients are similar to those in patients with vascular and autoimmune diseases

The analysis of fragmentation patterns in plasma cell-free DNA (cfDNA) has been shown to distinguish individuals with cancer from healthy controls in multiple case-controlled studies. However, there have been few studies that investigate various types cfDNA fragmentomics patterns in individuals with other diseases. For this purpose, we developed a comprehensive metric, called fragmentation signatures, that integrated the distributions of fragment positioning, fragment length, and fragment end-motifs. Using this metric, we found that individuals with venous thromboembolism, systemic lupus erythematosus, dermatomyositis, or scleroderma had cfDNA fragmentation signatures that closely mimicked those found in individuals with advanced cancers. Furthermore, these signatures were highly correlated with increases in inflammatory markers in the blood. Though these data put substantial limitations on the specificity of fragmentomics-based tests for cancer diagnostics, they also offer ways to improve the interpretability of such tests. Moreover, they should lead to a better understanding of the cells – most likely inflammatory cells - from which plasma cfDNA is derived.

Study EGAS00001008004

STimage: Robust and interpretable prediction of gene markers and cell types from spatial transcriptomics data

Spatial transcriptomics (ST) links tissue morphology with gene expression values, opening new avenues for digital pathology. Deep learning models are used to predict gene expression or classify cell types directly from images, offering significant clinical potential but still requiring improvements in interpretability and robustness. We present STimage as a comprehensive suite of models to predict spatial gene expression and classify cell types directly from standard H\&E images. STimage enhances robustness by estimating gene expression distributions and quantifying both data-driven (aleatoric) and model-based (epistemic) uncertainty using ensemble approach with foundation models. Interpretability is achieved through attribution analysis at single-cell resolution integrated with histopathological annotations, functional genes, and latent representations. We validated STimage across diverse datasets, demonstrating its performance across various platforms. STimage-predicted gene expression can stratify patient survival and predict drug response. By enabling molecular and cellular prediction from routine histology, STimage offers a powerful tool to advance digital pathology.

Study EGAS50000001503

Whole_genome_sequencing_in_a_multiplex_Crohn_s_disease_family

In 2009 we identified a four-generation family with over 700 members and 41 affected with Crohn's disease (CD). At the time we sequenced the exome of 6 affected individuals but did not identify any coding variants which appear to explain the high prevalence of disease. Since then we have collected DNA from a large number of additional family members, genotyped linkage arrays on the entire family to refine genomic regions shared by identity by descent and genotyped affected and unaffected members at known CD risk loci identified by Genome Wide Association Studies (GWAS). These analyses have confirmed that a significant unexplained excess of disease remains after accounting for all known genetic factors, and that several regions of the genome are shared by a large fraction of affected individuals. We therefore perform whole genomes sequencing from 8 individuals which will allow us to impute the complete sequence of nearly all the members of the two largest and most severely affected branches of the family.

Study EGAS00001000060

Inferring expressed genes by whole-genome sequencing of plasma DNA

The analysis of cell-free DNA (cfDNA) in plasma represents a rapidly advancing field in medicine. cfDNA consists predominantly of nucleosome-protected DNA shed into the bloodstream by cells undergoing apoptosis. We performed whole-genome sequencing (WGS) of plasma DNA and identified two discrete regions at transcription start sites (TSS) where the nucleosome occupancy results in different read-depth coverage patterns in expressed and silent genes. By employing machine learning for gene classification we found that the plasma DNA read depth patterns from healthy donors reflected the expression signature of hematopoietic cells. In cancer patients with metastatic disease, we were able to classify expressed cancer driver genes in regions with somatic copy number gains with high accuracy. We could even determine the expressed isoform of genes with several TSSs as confirmed by RNA-Seq of the matching primary tumor. Our analyses provide functional information about the cells releasing their DNA into the circulation.

Study EGAS00001001754

Inactivation of TGFβ receptors in stem cells drives cutaneous squamous cell carcinoma - 30 whole exomes

Melanoma patients treated with oncogenic BRAF inhibitors can develop cutaneous squamous cell carcinoma (cSCC) within weeks of treatment, driven by paradoxical RAS/RAF/MAPK pathway activation. Here, we identify frequent TGFBR1 and TGFBR2 mutations in human vemurafenib-induced skin lesions and in sporadic cSCC. Functional analysis reveals these mutations ablate canonical TGFβ Smad signaling which is localised to bulge stem cells in both normal human and murine skin. MAPK pathway hyperactivation (through BrafV600E or KrasG12D knockin) and TGFβ signaling ablation (through Tgfbr1 deletion) in LGR5+ve stem cells enables rapid cSCC development in the mouse. Mutation of Tp53 (which is commonly mutated in sporadic cSCC) coupled with Tgfbr1 deletion in LGR5+ve cells also results in cSCC development. These findings indicate that LGR5+ve stem cells can act as cells of origin for cSCC and that RAS/RAF/MAPK pathway hyperactivation or Tp53 mutation, coupled with loss of TGFβ signaling, are driving events of skin tumorigenesis.

Study EGAS00001001892

Chordoma_Sequencing_Project_Whole_Genome

This is a continuation of the Chordoma Sequencing Project, prelim #G0175-122-CF. All cancers arise due to somatically acquired abnormalities in DNA sequence. Systematic sequencing of cancer genomes allows acquisition of complete catalogues of all classes of somatic mutation present in cancer. These mutation catalogues will allow identification of the somatically mutated cancer genes that are operative and characterise patterns of somatic mutation that may reflect previous exogenous and endogenous mutagenic exposures. In this application, we aim to perform whole genome sequencing on 10 chordoma matched genome pairs. The Chordoma Foundation will fund the RNA Sequencing/Methylation and SNP6 costs for this project while the whole genome and library sequencing will be covered under the CGP, 2012-2013 core WTSI internal funding. An additional sequencing of three cancer cell lines will be added to this work, financed by the Chordoma Foundation. In this project, the Chordoma foundation will pay for the additional costs of methylation, RNA Seq,

Study EGAS00001000409

CD74-NRG1 fusions in lung adenocarcinoma

We discovered a novel somatic gene fusion, CD74-NRG1, by transcriptome sequencing of 25 lung adenocarcinomas of never smokers. By screening 102 lung adenocarcinomas negative for known oncogenic alterations we found four additional fusion-positive tumors, all of which were of the invasive mucinous subtype. Mechanistically, CD74-NRG1 leads to extracellular expression of the EGF-like domain of NRG1 III-beta3, thereby providing the ligand for ERBB2-ERBB3 receptor complexes. Accordingly, ERBB2 and ERBB3 expression was high in the index case and expression of phospho-ERBB3 was specifically found in tumors bearing the fusion (p<0.0001). Ectopic expression of CD74-NRG1 in lung cancer cell lines expressing ERBB2 and ERBB3 activated ERBB3 and the PI3K-AKT pathway, and led to increased colony formation in soft agar. Thus, CD74-NRG1 gene fusions are activating genomic alterations in invasive mucinous adenocarcinomas and may offer a therapeutic opportunity for a lung tumor subtype with, so far, no effective treatment.

Study EGAS00001000653

Biallelic DICER1 mutations in sporadic pleuropulmonary blastoma

Pleuropulmonary blastoma (PPB) is an extremely rare pediatric malignancy in the lung, whose pathogenesis is poorly understood, except for recent reports of frequent germline heterozygous DICER1 mutations. To investigate the genetic basis of PPB, we performed whole-exome sequencing in 7 representative PPB cases, followed by targeted deep sequencing in 12 cases with PPB. DICER1 mutations were found in 11/12 cases. Biallelic DICER1 mutations were common in PPB, in which RNase IIIb domain mutations were found in all cases with or without nonsense/frameshift mutations and were somatic in all evaluable cases. A majority of cases had mutated DICER1 alleles in germline with or without an additional somatic mutation in the remaining allele, while other cases had exclusively somatic mutations involving the RNase IIIb domain. TP53 deletions/mutations were detected in 8/12 cases. Our results highlight a unique role of the RNase IIIb domain mutations and TP53 inactivation in PPB pathogenesis.

Study EGAS00001000662

Tracking the origins and drivers of subclonal metastatic expansion in prostate cancer

Tumour heterogeneity in primary prostate cancer is a well-established phenomenon. However, how the subclonal diversity of tumours changes during metastasis and progression to lethality is poorly understood. Here we reveal the precise direction of metastatic spread across four lethal prostate cancer patients using whole-genome and ultra-deep targeted sequencing of longitudinally collected primary and metastatic tumours. We find one case of metastatic spread to the surgical bed causing local recurrence, and another case of cross-metastatic site seeding combining with dynamic remoulding of subclonal mixtures in response to therapy. By ultra-deep sequencing end-stage blood, we detect both metastatic and primary tumour clones, even years after removal of the prostate. Analysis of mutations associated with metastasis reveals an enrichment of TP53 mutations, and additional sequencing of metastases from 19 patients demonstrates that acquisition of TP53 mutations is linked with the expansion of subclones with metastatic potential which we can detect in the blood.

Study EGAS00001000942

Origins and functional consequence of somatic mitochondrial DNA mutations

Recent sequencing studies have extensively explored the somatic alterations present in the nuclear genomes of cancers. Although mitochondria control energy metabolism and apoptosis, the origins and impact of cancer-associated mutations in mitochondrial DNA (mtDNA) are unclear. Here, we analysed somatic alterations in mtDNA from 1,675 tumors across 31 histologies. We identified 1,907 somatic substitutions, which exhibited dramatic replicative strand bias, predominantly C>T and A>G on the mitochondrial heavy strand. This strand-asymmetric signature differs from those found in nuclear cancer genomes but matches the inferred germline process shaping primate mtDNA sequence content. Numbers of mtDNA mutations showed considerable heterogeneity across tumor types. Missense mutations were selectively neutral and often gradually drifted towards homoplasmy over time. In contrast, mutations resulting in protein truncation undergo negative selection and were almost exclusively heteroplasmic. Our findings indicate that the endogenous mutational mechanism has far greater impact than any other external mutagens in mitochondria, and is fundamentally linked to mtDNA replication.

Study EGAS00001000968

Clinical Implications of Genomic Alterations in the Tumor and Circulation of Pancreatic Cancer Patients

Pancreatic adenocarcinoma has the worst mortality of any solid cancer. To evaluate the clinical implications of genomic alterations in this tumor type, we performed whole-exome analyses of 24 tumors, targeted genomic analyses of 77 tumors, and used non-invasive approaches to examine tumor-specific mutations in the circulation of these patients. These analyses reveal somatic mutations in chromatin regulating genes MLL, MLL2, MLL3, and ARID1A in 20% of patients that were associated with improved survival. We observe alterations in genes with potential clinical utility in over a third of cases. Liquid biopsy analyses demonstrate that 43% of patients with localized disease have detectable circulating tumor DNA (ctDNA) at diagnosis. Detection of ctDNA after resection predicts clinical relapse and poor outcome, and recurrence by ctDNA is detected 6.5 months earlier than with CT imaging. These observations provide genetic predictors of outcome in pancreatic cancer and have implications for new avenues of therapeutic intervention.

Study EGAS00001001257

Searching for variants associated with endometriosis

We explored regulatory mechanism of a SNP on chromosome 9p21 associated with endometriosis by leveraging “allele-specific” functional genomic approaches. By re-sequencing 1.29 Mb of 9p21 region and scrutinizing DNase-seq data from the ENCODE project, we prioritized rs17761446 as a candidate functional variant that was in perfect linkage disequilibrium with the original GWAS SNP (rs10965235) and located on DNase I hypersensitive site. Chromosome conformation capture followed by high-throughput sequencing revealed that the protective G allele of rs17761446 exerted stronger chromatin interaction with ANRIL promoter. We demonstrated that the protective allele exhibited preferential binding affinities to TCF7L2 and EP300 by bioinformatics and chromatin immunoprecipitation (ChIP) analyses. ChIP assays for histone H3 lysine 27 acetylation and RNA polymerase II reinforced the enhancer activity of the SNP site. The allele specific expression analysis for eutopic endometrial tissues and endometrial carcinoma cell lines showed that rs17761446 was a cis-regulatory variant where G allele was associated with increased ANRIL expression.

Study EGAS00001001741

A Genomic History of Aboriginal Australia

The population history of Aboriginal Australians remains largely uncharacterised. We generated high-coverage genomes for 83 Aboriginal Australians (speakers of Pama-Nyungan languages) and 25 Papuans from the New Guinea Highlands. We find that Papuan and Aboriginal Australian ancestors diversified 25-40 thousand years ago (kya), suggesting early population structure in the ancient continent of Sahul (Australia, New Guinea and Tasmania). However, all studied Aboriginal Australians descend from a single founding population that differentiated ~10-32 kya. We infer a population expansion in northeast Australia during the Holocene (past c.10 kya) associated with limited gene flow from this region to the rest of Australia consistent with the spread of the Pama-Nyungan languages. We estimate that Aboriginal Australians and Papuans diverged from Eurasians 51-72 kya, following a single out of Africa dispersal, and subsequently admixed with different archaic populations. Finally, we report evidence of selection in Aboriginal Australians potentially associated with living in the desert.

Study EGAS00001001766

Rare disruptive mutations in ciliary function genes contribute to testicular cancer susceptibility

Testicular germ cell tumor (TGCT) is the most common cancer in young men1,2. Here we aimed to identify novel risk factors for TGCT using whole-exome sequencing, which was performed on 328 affected individuals from 153 families, 634 sporadic cases and 1,644 controls. We searched for genes that were recurrently affected by rare variants (minor allele frequency <0.01) with potentially damaging effects and evidence of segregation in families. 8.7% of families carried rare disruptive mutations in the cilia-microtubule genes (CMG) as compared to 0.5% of controls3 (P=2.1x10-8). The most significantly mutated CMG was DNAAF1 with biallelic inactivation and loss of DNAAF1 expression shown in tumors from carriers. DNAAF1 as a cause of TGCT was supported by a DNAAF1Hu255h(+/-) zebrafish model with 94% penetrance for TGCT compared to 14% in wildtype fish. These data implicate cilia-microtubule inactivation as a cause of TGCT development and are the first evidence for CMGs as cancer susceptibility genes.

Study EGAS00001001789

Recurrent somatic mutations in POLR2A define a distinct subset of meningiomas

RNA polymerase II mediates the transcription of all protein-coding genes in eukaryotic cells, a process that is fundamental to life. Genomic mutations in this enzyme have not been previously linked to any pathology in humans, a testament to its indispensable role in cell biology. Based on a combination of next-generation genomic analyses of 775 meningiomas, we report that recurrent somatic p.Gln403Lys or p.Leu438_His439del mutations in POLR2A, which encodes the catalytic subunit of RNA polymerase II1, are sufficient to hijack this essential enzyme and drive neoplasia. POLR2A mutant tumors reveal dysregulation of key meningeal identity genes, including WNT6 and ZIC1/ZIC42,3. In addition to POLR2A, NF2, SMARCB1, TRAF7, KLF4, AKT1, PIK3CA and SMO4-8, we also report somatic mutations in AKT3, PIK3R1, PRKAR1A, and SUFU in meningiomas. Our results identify a role for essential transcriptional machinery in driving tumorigenesis and define mutually exclusive meningioma subgroups with distinct clinical and pathological features.

Study EGAS00001001916

Divergence between high metastatic tumor burden and low circulating tumor DNA concentration in metastasized breast cancer

Circulating tumor DNA (ctDNA) was reported to represent a highly sensitive biomarker of metastatic cancer disease directly reflecting tumor burden and dynamics. Here we investigated the role of ctDNA in patients with metastatic breast cancer. In an index patient with more than 100,000 circulating tumor cells (CTCs) in serial blood analyses, whole genome, exome, or targeted deep sequencing of the primary tumor, metastases, and 551 CTCs were consistent with a genetically homogeneous cancer. However, the allele fractions (AFs) of ctDNA were only 2-3% in each analysis, which did neither reflect the tumor burden nor the dynamics of this progressive disease by far. Indeed, plasma analyses of 71 further patients demonstrated highly variable AFs of mutant fragments, which frequently did not correspond to the tumor burden. These results provide insights into mechanisms involved in CTC and ctDNA release into the circulation and have important implications for diagnostic tests based on liquid biopsies.

Study EGAS00001000625

Transcriptional and functional profiling defines human small intestinal macrophage subsets

Macrophages (Mf) are instrumental in maintaining immune homeostasis in the intestine, yet studies on origin and heterogeneity of human intestinal Mf are scarce. Here, we identified four distinct Mf subpopulations in human small intestine (SI). Assessment of their turnover in duodenal transplants revealed that all Mf subsets were completely replaced over time; Mf1 and Mf2, phenotypically similar to peripheral blood monocytes (PBMo), were largely replaced within 3 weeks, whereas two subsets with features of mature Mf, Mf3 and Mf4, exhibited significantly slower replacement. Mf3 and Mf4 localized differently in SI; Mf3 formed a dense network in mucosal lamina propria, whereas Mf4 was enriched in submucosa. Transcriptomic analysis showed that all Mf subpopulations subsets were markedly distinct from PBMo and dendritic cells (DC). Compared to PBMo, Mf subpopulations showed reduced responsiveness to proinflammatory stimuli, but were proficient at endocytosis of particulate and soluble material. These data provide a comprehensive analysis of human SI Mf population and suggest a precursor-progeny relationship with PBMo.

Study EGAS00001002093

Myelodysplastic cells in patients re-program mesenchymal stromal cells to establish a transplantable stem cell-niche disease unit.

Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid neoplasms with defects in hematopoietic stem/progenitor cells (HSPCs) and possibly the HSPC niche. Here we show that patient-derived mesenchymal stromal cells (MDS MSCs) display a disturbed differentiation program and are essential for the propagation of MDS-initiating lin-CD34+CD38- stem cells in orthotopic xenografts. Overproduction of niche factors such as N-Cadherin, IGFBP2, VEGFA and LIF is associated with the ability of MDS MSCs to enhance MDS expansion. These factors represent putative therapeutic targets to disrupt critical hematopoietic-stromal interactions in MDS. Finally, healthy MSCs adopt "MDS-MSC like" molecular features when exposed to hematopoietic MDS cells, indicative of an instructive remodeling of their microenvironment. This patient-derived xenograft model therefore provides functional and molecular evidence that MDS is a complex disease involving both the hematopoietic and stromal compartments. The resulting deregulated expression of niche factors may well also be a feature of other hematopoietic malignancies.

Study EGAS00001000716

Whole exome sequencing for gallbladder cancer in Xinhua Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine

Patients with gallbladder carcinoma (GBC), the most aggressive malignancy of the biliary tract, have a poor prognosis. Here, we report our identification of somatic mutations of GBCs in 57 tumor-normal pairs by use of a combination of exome sequencing and ultra-deep sequencing of cancer-related genes. The mutation pattern is defined by a dominative prevalence of C>T mutations at TCN sites. Genes with a significant frequency of non-silent mutations include TP53 (47.1%), KRAS (7.8%), and ERBB3 (11.8%). Moreover, ErbB signaling (including EGFR, ERBB2, ERBB3, ERBB4 and their downstream genes) is the most extensively mutated pathway, affecting 36.8% (21 of 57) of the GBC samples. Multivariate analyses further reveal that patients with ErbB pathway mutations have a worse outcome (P = 0.001). These findings provide insight into the somatic mutational landscape in GBC and highlight the key role of the ErbB signaling pathway in the pathogenesis of GBCs.

Study EGAS00001000853

Genetic Basis of Hepatosplenic T Cell Lymphoma (HSTL)

Hepatosplenic T cell lymphoma (HSTL) is a rare and lethal lymphoma; the genetic drivers of this disease are unknown. Through whole exome sequencing of 68 HSTLs, we define recurrently mutated driver genes and copy number alterations in the disease. Chromatin modifying genes including SETD2, INO80 and ARID1B were commonly mutated in HSTL, affecting 62% of cases. HSTLs manifest frequent mutations in STAT5B (31%), STAT3 (9%), and PIK3CD (9%) for which there currently exist potential targeted therapies. In addition, we noted less frequent events in EZH2, KRAS and TP53. SETD2 was the most frequently silenced gene in HSTL. We experimentally demonstrated that SETD2 acts as a tumor suppressor gene. In addition, we found that mutations in STAT5B and PIK3CD activate critical signaling pathways important to cell survival in HSTL. Our work thus defines the genetic landscape of HSTL and implicates novel gene mutations linked to HSTL pathogenesis and potential treatment targets.

Study EGAS00001002182

miR-200-regulated CXCL12β promotes fibroblast heterogeneity and immunosuppression in ovarian cancers

High-grade serous epithelial ovarian cancer (HGSOC) has been recently subdivided into molecular subgroups, including the mesenchymal HGSOC associated with partial tumor-debulking surgery and poor patient survival. Consistent with stromal-related genes signatures defining mesenchymal HGSOC, we show here that stroma plays a key function in this HGSOC molecular subtype. We first highlight stromal heterogeneity in HGSOC by identifying 4 subsets of Carcinoma-Associated Fibroblast (CAF-S1-4). Mesenchymal HGSOC significantly accumulate the activated CAF-S1 subset, which exhibits immunosuppressive functions by promoting attraction, survival and activation of regulatory T-lymphocytes. The CXCL12β chemokine reliably characterizes mesenchymal HGSOC and specifically accumulates in the CAF-S1 subset through a regulation mediated by the miR-141/200a. CXCL12β promotes attraction of T-lymphocytes and is thus a key actor in CAF-S1-mediated immunosuppressive functions. In conclusion, we highlight here for the first time stromal heterogeneity and immunosuppression in mesenchymal HGSOC that could participate in the poor patient prognosis.

Study EGAS00001002184

Genomic analyses of gynecologic carcinosarcomas reveal frequent mutations in chromatin remodeling genes

Malignant Mixed Müllerian Tumors, also known as carcinosarcomas, are rare tumors of gynecological origin. Here we perform whole exome analyses of 22 tumors using massively parallel sequencing to determine the mutational landscape of this tumor type. On average, we identify 43 mutations per tumor, excluding four cases with a mutator phenotype that harbored inactivating mutations in mismatch repair genes. In addition to mutations in TP53 and KRAS, we identify genetic alterations in chromatin remodeling genes, ARID1A and ARID1B, in histone methyltransferase MLL3, in histone deacetylase modifier SPOP, and in chromatin assembly factor BAZ1A, in nearly two thirds of cases. Alterations in genes with potential clinical utility are observed in more than three quarters of the cases and included members of the PI 3-kinase and homologous DNA repair pathways. These findings highlight the importance of the dysregulation of chromatin remodeling in carcinosarcoma tumorigenesis and suggest new avenues for personalized therapy.

Study EGAS00001000941

Data from the paper Context-specific Effects of TGFβ/SMAD3 in Cancer Are Modulated by the Epigenome. Tufegdzic et al, Cell Reports 2015

The transforming growth factor beta (TGFβ) signalling pathway exerts opposing effects on cancer cells, acting either as a tumor-promoter or as a tumor-suppressor. Here we show these opposing effects are a result of the synergy between SMAD3, a downstream effector of TGFβ signalling, and the distinct epigenomes of breast tumor initiating cells (BTICs). These effects of TGFβ are associated with distinct gene expression programs, but genomic SMAD3 binding patterns are highly similar in the BTIC-promoting and BTIC- suppressing contexts. Our data show cell type-specific epigenetic configurations provide a modulatory layer by determining accessibility of genes to regulation by TGFβ/SMAD3. LBH, one such context-specific target gene, is regulated according to its DNA methylation status, and is crucial for TGFβ-dependent promotion of BTICs. Overall, these results reveal that the epigenome plays a central and previously overlooked role in shaping the context-specific effects of TGFβ in cancer.

Study EGAS00001001570

The spatial organization of intratumor heterogeneity andevolutionary trajectories of metastases in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has one of the poorest survival amongst cancers. Using multi-regional sampling of nine resected HCC with different etiologies, we find that phylogenetic relationships of these sectors show diverse levels of genetic sharing spanning early to late diversification. Unlike the variegated pattern found in colorectal cancers, a large proportion of HCC display a clear Isolation-By-Distance pattern where spatially closer sectors are genetically more similar. Two resected intra-hepatic metastases showed genetic divergence occurring before and after primary tumor diversification respectively. Interestingly, metastatic tumors had much higher variability than their primary tumors, suggesting that intra-hepatic metastasis is accompanied by rapid diversification at the distant location. The presence of co-existing mutations offers the possibility of drug repositioning for HCC treatment. Taken together, these insights into intra-tumor heterogeneity allow for a comprehensive understanding of the evolutionary trajectories of HCC and suggest novel avenues for personalized therapy.

Study EGAS00001001603

Comparing nodal versus bony metastatic spread using tumour phylogenies

The role of lymph node metastases in distant prostate cancer dissemination and lethality is ill defined. Patients with metastases restricted to lymph nodes have a better prognosis than those with distant metastatic spread, suggesting the possibility of distinct aetiologies. To explore this, we traced patterns of cancer dissemination using tumour phylogenies inferred from genome-wide copy-number profiling of 48 samples across 3 patients with lymph node metastatic disease and 3 patients with osseous metastatic disease. Our results show that metastatic cells in regional lymph nodes originate from evolutionary advanced extra-prostatic tumour cells rather than less advanced central tumour cell populations. In contrast, osseous metastases do not exhibit such a constrained developmental lineage, arising from either intra or extra-prostatic tumour cell populations, at early and late stages in the evolution of the primary. Collectively, this comparison suggests that lymph node metastases may not be an intermediate developmental step for distant osseous metastases, but rather represent a distinct metastatic lineage.

Study EGAS00001001801

Coverage bias and sensitivity of variant calling for four whole-genome sequencing technologies

Massively parallel sequencing has revolutionized research in cancer genetics and genomics and enhanced our understanding of natural human genetic variation. Recently, Lam et al. have performed a detailed comparison of two next-generation sequencing technologies with respect to their sensitivity to call single nucleotide variants (SNV) and indels. Here, we sequenced two tumor/normal pairs obtained from two paedriatic medulloblastoma patients with Life Technologies’ SOLiD 4 and 5500xl SOLiD, Illumina’s HiSeq2000, and Complete Genomics’ technology. We then compared their ability to call SNVs with high confidence. As gold standard for SNV calling, we used genotypes determined by an Affymetrix SNP array. Additionally, we performed a detailed analysis of how evenly each technology covers the genome and how the reads are distributed across functional genomic regions. Finally, we studied how a combination of data from different technologies might help to overcome the limitations in SNV calling by any of the four technologies alone.

Study EGAS00001000274

Genetic landscape of Early T-cell precursor acute lymphoblastic leukaemia

Early T-cell precursor acute lymphoblastic leukaemia (ETP ALL) is an aggressive malignancy of unknown genetic basis. We performed whole-genome sequencing of 12 ETP ALL cases and assessed the frequency of the identified somatic mutations in 94 T-cell acute lymphoblastic leukaemia cases. ETP ALL was characterized by activating mutations in genes regulating cytokine receptor and RAS signalling (67% of cases; NRAS, KRAS, FLT3, IL7R, JAK3, JAK1, SH2B3 and BRAF), inactivating lesions disrupting haematopoietic development (58%; GATA3, ETV6, RUNX1, IKZF1 and EP300) and histone-modifying genes (48%; EZH2, EED, SUZ12, SETD2 and EP300). We also identified new targets of recurrent mutation including DNM2, ECT2L and RELN. The mutational spectrum is similar to myeloid tumours, and moreover, the global transcriptional profile of ETP ALL was similar to that of normal and myeloid leukaemia haematopoietic stem cells. These findings suggest that addition of myeloid-directed therapies might improve the poor outcome of ETP ALL.

Study EGAS00001000348

Epigenomic alterations define lethal CIMP-positive ependymomas of infancy

Ependymomas are common childhood brain tumours that occur throughout the nervous system, but are most common in the paediatric hindbrain. Current standard therapy comprises surgery and radiation, but not cytotoxic chemotherapy as it does not further increase survival. Whole-genome and whole-exome sequencing of 47 hindbrain ependymomas reveals an extremely low mutation rate, and zero significant recurrent somatic single nucleotide variants. Although devoid of recurrent single nucleotide variants and focal copy number aberrations, poor-prognosis hindbrain ependymomas exhibit a CpG island methylator phenotype. Transcriptional silencing driven by CpG methylation converges exclusively on targets of the Polycomb repressive complex 2 which represses expression of differentiation genes through trimethylation of H3K27. CpG island methylator phenotype-positive hindbrain ependymomas are responsive to clinical drugs that target either DNA or H3K27 methylation both in vitro and in vivo. We conclude that epigenetic modifiers are the first rational therapeutic candidates for this deadly malignancy, which is epigenetically deregulated but genetically bland.

Study EGAS00001000443

Reference epigenomes generated as part of the International Human Epigenomics Consortium (IHEC)

The Centre for Epigenome Mapping Technologies (CEMT) is an epigenome sequencing platform funded by the Canadian Institutes of Health Research (CIHR) and Genome BC as part of the Canadian Epigenetics, Environment and Health Research Consortium (CEEHRC). CEMT aims to produce 100 human reference epigenomes, each comprising the following datasets: whole genome; whole genome bisulfite and oxidative bisulfite; transcriptome; microRNA; and chromatin immunoprecipitation (ChIP)-seq for the core chromatin marks (H3K4me1, H3K4me3, H3K9me3, H3K27me3, H3K36me3, and H3K27ac).CEEHRC is a full member of the International Human Epigenomics Consortium (IHEC), which aims to coordinate the production of 1,000 reference maps of human epigenomes for key cellular states relevant to health and diseases. As such, all datasets submitted by the CEMT platform conform to IHEC assay standards and metadata guidelines.

Study EGAS00001000552

Genomic catastrophes frequently arise in esophageal adenocarcinoma and drive tumorigenesis.

Oesophageal adenocarcinoma (EAC) incidence is rapidly increasing in Western countries. A better understanding of EAC underpins efforts to improve early detection and treatment outcomes. While large EAC exome sequencing efforts to date have found recurrent loss-of-function mutations, oncogenic driving events have been underrepresented. Here we use a combination of whole-genome sequencing (WGS) and single-nucleotide polymorphism-array profiling to show that genomic catastrophes are frequent in EAC, with almost a third (32%, n=40/123) undergoing chromothriptic events. WGS of 22 EAC cases show that catastrophes may lead to oncogene amplification through chromothripsis-derived double-minute chromosome formation (MYC and MDM2) or breakage-fusion-bridge (KRAS, MDM2 and RFC3). Telomere shortening is more prominent in EACs bearing localized complex rearrangements. Mutational signature analysis also confirms that extreme genomic instability in EAC can be driven by somatic BRCA2 mutations. These findings suggest that genomic catastrophes have a significant role in the malignant transformation of EAC.

Study EGAS00001000750

Tracking the genomic evolution of esophageal adenocarcinoma through neoadjuvant chemotherapy

Esophageal adenocarcinomas (EACs) are associated with dismal prognosis. Deciphering the evolutionary histories of this disease may shed light on therapeutically tractable targets and reveal changing mutational processes during the disease course and following neoadjuvant chemotherapy (NAC). We exome sequenced 40 tumor regions from 8 patients with operable EACs both before and after platinum-containing NAC. This revealed the evolutionary genomic landscape of EACs with the presence of heterogeneous driver mutations, parallel evolution, early genome doubling events and an association between high intratumor heterogeneity and poor response to NAC. Multi-region sequencing demonstrated a significant reduction in T>G mutations within a CTT context when comparing early and late mutational processes and the presence of a platinum signature with enrichment of C>A mutations within a CpC context following NAC. EACs are characterized by the presence of amplifications containing targetable oncogenes present before and after chemotherapy that may provide a rationale for future therapeutic approaches.

Study EGAS00001001254

RNA_seq_of_Toxoplasma_gondii_response_in_human_macrophages

Toxoplasmosis is a zoonotic disease caused by a ubiquitous protozoan parasite called Toxoplasma gondii, which caninfect all mammal and bird species throughout the world. seroprevalence varies widely between countries. Studieshave estimated that between 7-34% of people in the UK have been infected with T. gondii. The vast majority of thesepeople will not have noticed any symptoms, however about 10% of people develop a mild to moderate self limitingflu-like illness. Following the acute active stage of the infection the parasite persists in the body in the form of cysts,particularly in heart and skeletal muscle and nervous system tissues, for many years, and usually for life. Inimmunocompetent persons these cysts do not pose a health risk. We will use RNA-seq to quantify the transcriptionalresponse of macrophages to T gondii infection.This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/

Study EGAS00001001708

Novel mutational mechanisms and drivers in Pancreatic Neuroendocrine Tumours

Pancreatic neuroendocrine tumours (PanNETs) are increasing in prevalence due to earlier detection, consequently creating challenges in clinical care, as current classification permits unsatisfactory therapeutic stratification. We performed whole genome sequencing of 102 primary PanNETs and defined the genomic events underlying their pathogenesis. We describe the mutational signatures they harbour, including a novel G:C>T:A Base-Excision-Repair-deficiency signature due to MUTYH inactivation. We uncover a larger than expected proportion of germline mutations in clinically sporadic PanNETs. These include previously unreported mutations in DNA repair genes MUTYH, CHEK2, BRCA2, and PALB2, which together with MEN1 and VHL occur in 16% of patients. Somatic mutations (point mutations and structural rearrangements) commonly occurred in genes involved in 4 main pathways: chromatin remodelling, DNA damage repair, activation of mTOR signalling (including novel EWSR1 gene fusions) and telomere maintenance. Aberrations in these mechanisms are associated with subtypes of PanNET with potential clinical application for prognostic and therapeutic stratification.

Study EGAS00001001732

Complete Genomics paired end sequencing; Ovarian cancer

We sequenced the genomes from a monozygotic twin discordant for schizophrenia and a tumor-normal pair of an ovarian cancer patient. Using whole-genome twin data to discriminate between correctly identified single nucleotide variants (SNVs) and errors a strategy for the accurate detection of SNVs was developed. By applying stringent sequencing quality measures, excluding error-prone regions and selecting SNVs identified by different mapping and variation calling algorithms, error rates were ~37-fold reduced. This enabled us to identify the first discordant SNVs in monozygotic twins using whole-genome sequencing. In addition, by showing that novel SNVs are highly enriched in errors, accurate estimates of the number of novel and rare SNVs occurring in unrelated Caucasian individuals were obtained. Finally, somatic mutations in coding and regulatory sequences were reliably identified in the highly rearranged ovarian tumor. Overall, our data demonstrate that strategies to reduce error rates in whole-genomes are required for disease gene discovery.

Study EGAS00001000158

Exome_sequencing_of_blastic_plasmacytoid_dendritic_cell_neoplasms

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive haematological malignancy derived from precursors of plasmacytoid dendritic cells. Due to the rarity of BPDCNs our knowledge of their molecular pathogenesis was until recently confined to observations describing reccurent chromosomal deletions involving chromosomes 5q, 12p, 13q, 6q, 15q and 9. A recent publication went on to delineate the common deleted regions using aCGH and demonstrated that these centred around known tumour suppressor genes including CDKN2A/B (9p21.3), RB1 (12p13.2-14.3), CDKN1B (13q11-q12) and IKZF1 (7p12.2).These mutations are found recurrently in several different cancers and in most cases are thought to be involved in tumour progression rather than initiation. However, the well-defined nature and cellular ontogeny of these neoplasms suggests strongly that they share one or a few characteristic mutations as has been demonstrated for other uncommon but well-defined neoplasms such as Hairy Cell Leukemia (BRAF) and ovarian Granulosa Cell tumours (FOXL2).

Study EGAS00001000171

Association of Age at Diagnosis and Genetic Mutations in Patients with Neuroblastoma

Neuroblastoma is diagnosed over a wide age range from birth through young adulthood, and older age at diagnosis is associated with a decline in survivability. We performed whole genome sequencing of DNA from diagnostic tumors and their matched germlines from 40 patients with metastatic neuroblastoma obtained between 1987 and 2009. To identify genetic lesions that are associated with age at diagnosis in patients with metastatic neuroblastoma. Age groups at diagnosis included infants (0-18 months), children (18 months-12 years), and adolescents and young adults (>12 years). To confirm the findings from this discovery cohort, validation testing using tumors from an additional 64 patients obtained between 1985 and 2009 was also performed. Formalin-fixed paraffin-embedded tumor tissue was used for immunohistochemistry and fluorescent in situ hybridization. Telomere lengths were analyzed using the whole genome sequencing data, quantitative polymerase chain reaction and fluorescent in situ hybridization

Study EGAS00001000213

Genome Landscape of High-Grade Serous Ovarian Cancer

Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.

Study EGAS00001000397

A Genomics-Based Classification of Human Lung Tumors

We characterized genome alterations in 1255 clinically annotated lung tumors of all histological subgroups to identify genetically defined and clinically relevant subtypes. More than 55% of all cases had at least one oncogenic genome alteration potentially amenable to specific therapeutic intervention, including several personalized treatment approaches that are already in clinical evaluation. Marked differences in the pattern of genomic alterations existed between and within histological subtypes, thus challenging the original histomorphological diagnosis. Immunohistochemical studies confirmed many of these reassigned subtypes. The reassignment eliminated almost all cases of large cell carcinomas, some of which had therapeutically relevant alterations. Prospective testing of our genomics-based diagnostic algorithm in 5145 lung cancer patients enabled a genome-based diagnosis in 3863 (75%) patients, confirmed the feasibility of rational reassignments of large cell lung cancer, and led to improvement in overall survival in patients with EGFR-mutant or ALK-rearranged cancers. Thus, our findings provide support for broad implementation of genome-based diagnosis of lung cancer.

Study EGAS00001000647

High number of somatic mutations found in the healthy blood compartment of a 115-year-old woman reveals oligoclonal hematopoiesis

The somatic mutation burden in healthy white blood cells (WBCs) is not well known. Based on deep whole genome sequencing, we estimate that ~450 somatic mutations accumulated in the non-repetitive genome within the healthy blood compartment of a 115-year old woman. The detected mutations appear to have been harmless passenger mutations: they were enriched in non-coding, AT-rich regions that are not evolutionarily conserved, and they were depleted for genomic elements where mutations might have favorable or adverse effects on cellular fitness, such as regions with actively transcribed genes.The distribution of variant allele frequencies of these mutations suggests that the majority of the peripheral white blood cells were offspring of two related hematopoietic stem cell (HSC) clones. Moreover, telomere lengths of the WBCs were significantly shorter than telomere lengths from other tissues. Together, this suggests that the finite lifespan of HSCs, rather than somatic mutation effects, may lead to hematopoietic clonal evolution at extreme ages.

Study EGAS00001000660

Germline and somatic SMARCA4 mutations characterize small-cell carcinoma of the ovary, hypercalcemic type.

Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is the most common undifferentiated ovarian malignancy in women under 40 years1. We sequenced the exomes of six individuals from three SCCOHT families. After discovering segregating deleterious germline mutations in SMARCA4 in all three families, we tested DNA from a fourth family, which also possessed a segregating SMARCA4 germline mutation. All familial tumors sequenced harboured either a somatic mutation or loss of the wild-type allele. Immunohistochemical (IHC) analysis of these and additional familial and non-familial cases showed loss of the SMARCA4 protein (BRG1) in 38/40 tumors overall. Sequencing of cases with available DNA revealed at least one germline or somatic deleterious SMARCA4 mutation in 30/32 cases. Additionally, the SCCOHT cell line BIN-67 contained bi-allelic deleterious mutations in SMARCA4. Our findings identify alterations in SMARCA4 as the major cause of SCCOHT, which could lead to genetic counseling and new treatment approaches.

Study EGAS00001000721

Integrated genetic and epigenetic analysis defines novel molecular clusters in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood. To unravel the genetic/epigenetic basis of RMS, we studied 60 RMS cases using whole exome/transcriptome sequencing, copy number (CN) profiling, and DNA methylome analysis. Based on DNA methylation patterns, RMS was clustered into 4 distinct subtypes, which exhibited remarkable correlation with mutation/CN profiles, histological phenotypes, and clinical behaviors. A1 and A2 subtypes, especially A1, largely corresponded to alveolar histology with frequent PAX3/7 fusions and alterations in cell cycle regulators. In contrast, mostly showing embryonal histology, both E1 and E2 subtypes were characterized by high frequency of CN alterations and/or allelic imbalances, FGFR4/RAS/AKT pathway mutations and PTEN mutations/methylation and in E2, also by p53 inactivation. Despite generally poor prognosis in RMS, patients in E1 cluster exceptionally showed excellent prognosis. Our results highlight the close relationship between DNA methylation status and gene mutations and biological behavior in RMS.

Study EGAS00001000884

SeqControl: Process Control for DNA Sequencing

As next-generation sequencing (NGS) continues to increase in speed and throughput, routine clinical and industrial application draws steadily closer. These “production” uses of NGS will require enhanced quality-monitoring and quality-control to optimize output and reduce costs. We therefore developed a framework called SeqControl for predicting sequencing quality and coverage using a set of 15 metrics describing overall coverage, coverage distribution, base-wise coverage and base-wise quality. Using whole-genome sequences of 27 prostate cancers and 26 normal references we derive multivariate models that predict sequencing quality and depth. SeqControl robustly predicts how much sequencing is required to reach a given coverage depth (AUC = 0.993), accurately classifies clinically relevant formalin-fixed paraffin-embedded samples and makes predictions from as little as 1/8 of a lane of sequencing data (AUC = 0.967). These techniques can be immediately incorporated into existing NGS pipelines to monitor data quality in real-time. SeqControl represents a first step towards statistical process-control for NGS.

Study EGAS00001000899

Genetic_profiling_of_mucosal_melanoma

Primary mucosal melanomas (MMs) arise from melanocytes located in mucosal membranes lining the respiratory, gastrointestinal and urogenital tracts. MMs frequently present late and have a poor prognosis; the 5-year survival rate is only 14%. MM makes up only ~1.4% of all melanomas and it is this rarity that makes knowledge of the genetic changes that contribute to its pathogenesis limited to a small number of exome/genome studies and other targeted studies. Thus to investigate the somatic alterations and mutation spectra in MM genomes, we have extracted genomic DNA from formalin-fixed, paraffin-embedded (FFPE) human MMs, and subjected them to whole exome sequencing. Given the propensity of MM to metastasize, we will also be sequencing metastatic MM lesions; primary and metastatic lesions from the same individual represent an excellent opportunity to identify potential drivers of metastasis in MM. Finally we will sequence ‘normal’ DNA from the same individual, where possible, to exclude germline variations.

Study EGAS00001001115

Exome sequencing of hepatocellular carcinomas identifies new mutational signatures and potential therapeutic targets

Genomic analyses promise to improve tumor characterization in order to optimize personalized treatment for patients with hepatocellular carcinoma (HCC). Exome sequencing analysis of 243 liver tumors revealed mutational signatures associated with specific risk factors, mainly combined alcohol/tobacco consumption, aflatoxin B1 and HBV infection. We identified 161 putative driver genes associated with 11 recurrent pathways. Associations of mutations defined 3 groups of genes related to risk factors and centered on CTNNB1 (alcohol), TP53 (HBV) and AXIN1. Analyses according to tumor stage progression revealed TERT promoter mutation as an early event whereas FGF/CCND1 amplification, TP53 and CDKN2A alterations appeared at more advanced stages in aggressive tumors. In 24% of the tumors, we identified genetic alterations potentially targetable by FDA-approved drugs. In conclusion, we identified risk factor–specific mutational signatures and defined the extensive landscape of altered genes and pathways in HCC, which will be useful to design clinical trials for targeted therapy.

Study EGAS00001001002

Whole-genome plasma sequencing reveals focal amplifications as a driving force in metastatic prostate cancer

Genomic alterations in metastatic prostate cancer remain incompletely characterized. Here we analyze 493 prostate cancer cases from the TCGA database and perform whole-genome plasma sequencing on 95 plasma samples derived from 43 patients with metastatic prostate cancer. From these samples, we identify established driver aberrations in a cancer-related gene in nearly all cases (97.7%), including driver gene fusions (TMPRSS2:ERG), driver focal deletions (PTEN, RYBP, SHQ1), and driver amplifications (AR, MYC). In serial plasma analyses, we observe changes in focal amplifications in 40% of cases. The mean time interval between new amplifications was 26.4 weeks (range: 5-52 weeks), suggesting that they represent rapid adaptations to selection pressure. An increase in neuron-specific enolase is accompanied by clonal pattern changes in the tumor genome, most consistent with subclonal diversification of the tumor. Our findings suggest a high plasticity of prostate cancer genomes with newly occurring focal amplifications as a driving force in progression

Study EGAS00001001018

Neuroblastoma relapse trio series from the AMC

The majority of neuroblastoma patients have tumors that initially respond to chemotherapy, but a large proportion of patients will experience therapy-resistant relapses. The molecular basis of this aggressive phenotype is unknown. Whole genome sequencing of 23 paired diagnostic and relapsed neuroblastomas showed clonal evolution from the diagnostic tumor with a median of 29 somatic mutations unique to the relapse sample. Eighteen of the 23 relapse tumors (78%) showed RAS-MAPK pathway mutations. Seven events were detected only in the relapse tumor while the others showed clonal enrichment. In neuroblastoma cell lines we also detected a high frequency of activating mutations in the RAS-MAPK pathway (11/18, 61%) and these lesions predicted for sensitivity to MEK inhibition in vitro and in vivo. Our findings provide a rationale for genetic characterization of relapse neuroblastoma and show that RAS-MAPK pathway mutations may function as a biomarker for new therapeutic approaches to refractory disease.

Study EGAS00001001183

Recurrent mTORC1-activating RRAGC mutations in follicular lymphoma

Follicular lymphoma (FL) is an incurable B-cell malignancy characterized by the t(14;18) and mutations in one or more components of the epigenome. Whilst frequent gene mutations in signaling pathways, including JAK-STAT, NOTCH and NF-κB, have also been defined, the spectrum of these mutations typically overlap with the closely-related diffuse large B cell lymphoma (DLBCL). A combination of discovery exome and extended targeted sequencing revealed recurrent somatic mutations in RRAGC uniquely enriched in FL patients (17%). More than half of the mutations preferentially co-occurred with ATP6V1B2 and ATP6AP1 mutations, components of the vacuolar H+-adenosine triphosphate ATPase (v-ATPase) known to be necessary for amino acid-dependent mTORC1 activation. RagC mutants increased raptor binding whilst rendering mTORC1 signaling resistant to amino acid deprivation through nucleotide-independent mechanisms. Collectively, the activating nature of the RRAGC mutations, their existence within the dominant clone and stability during disease progression supports their potential as an excellent candidate to be therapeutically exploited.

Study EGAS00001001190

Recurrent adeno-associated virus 2-related insertional mutagenesis in human hepatocellular carcinomas

Hepatocellular carcinomas (HCC) are liver tumors related to various etiologies including alcohol intake, hepatitis B (HBV) or C (HCV) virus infection. Additional risk factors remain to be identified, particularly in patients who develop HCC without cirrhosis. We identified clonal integration of adeno-associated virus type 2 (AAV2) in 11 out of 193 HCC. These AAV2 integrations occurred within known cancer driver genes, namely, CCNA2 (Cyclin A2, 4 cases), TERT (Telomerase Reverse-Transcriptase, 1 case), CCNE1 (Cyclin E1, 3 cases), TNFSF10 (Tumor Necrosis Factor member 10, 2 cases) or KMT2B (Lysine (K)-Specific Methyltransferase 2B, 1 case) leading to over-expression of the target genes. Tumors with viral integration mainly developed in non-cirrhotic liver (9 out of 11 cases) and without known risk factors (6 out of 11) suggesting a pathogenic role of AAV2 in these patients. In conclusion, AAV2 is a DNA virus associated with oncogenic insertional mutagenesis in human HCC.

Study EGAS00001001284

Barcoding reveals complex clonal dynamics of de novo transformed human mammary cells

Most human breast cancers have already diversified genomically when they first become clinically evident, by which time extensive heterogeneous histopathologies, transcriptomes and growth patterns are also apparent. Accordingly, important initial events and the cellular context in which they occur have been difficult to characterize. Using DNA barcoding, we now demonstrate the high efficiency with which both purified basal and luminal cells isolated directly from normal adult human mammary tissue can be rapidly transformed by a single oncogene (KRASG12D) resulting in the production within 8 weeks in vivo of serially transplantable, polyclonal, invasive ductal carcinomas that are phenotypically heterogeneous and transcriptionally distinct from the initial cells transduced. Barcoding also revealed a consistent dramatic change in the clonal content of passaged tumours. This system thus provides a powerful new platform for examining early events in the genesis, evolution and treatment response of malignant human mammary cells generated using defined mutations.

Study EGAS00001001310

A comprehensive assessment of somatic mutation detection in cancer using whole genome sequencing

As whole genome sequencing for cancer genome analysis becomes a clinical tool, a full understanding of the variables affecting sequencing analysis output is required. Using tumor-normal sample pairs from two different types of cancer, chronic lymphocytic leukemia and medulloblastoma, we conducted a benchmarking exercise within the context of the International Cancer Genome Consortium. We compare sequencing methods, analysis pipelines, and even validation methods. Here we show that using PCR-free methods and increasing sequencing depth to ~100x showed benefits, as long as the tumor:control coverage ratio remains balanced. We observe widely varying mutation call rates and low concordance among analysis pipelines, reflecting the artifact-prone nature of the raw data and lack of standards for dealing with the artifacts. However, armed with the benchmark mutation set we have created, we show that many issues are in fact easy to remedy and have an immediate positive impact on mutation detection accuracy.

Study EGAS00001001539

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