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• Complex genotype-phenotype relationships shape the response to treatment of Down Syndrome Childhood Acute Lymphoblastic Leukaemia

  Extensive genetic and epigenetic variegation has been demonstrated in many malignancies. Importantly, their interplay has the potential to contribute to disease progression and treatment resistance. To shed light on the complex relationships between these different sources of intra-tumour heterogeneity, we explored their relative contributions to the evolutionary dynamics of Acute Lymphoblastic Leukaemia (ALL) in children with Down syndrome, which has particularly poor prognosis. We quantified the tumour propagating potential of genetically distinct sub-clones using serial transplantation assays and SNP-arrays. While most leukaemias were characterized by a single dominant subclone, others were highly heterogeneous. Importantly, we provide clear and direct evidence that genotypes and phenotypes with functional relevance to leukemic progression and treatment resistance can co-segregate within the disease. Hence, individual genetic lesions can be restricted to well-defined cell immunophenotypes, corresponding to different stages of the leukemic differentiation hierarchy and varied proliferation potentials. As a result of this difference in fitness, which can be accurately quantified via competitive transplantation assays, matching diagnostic, post-treatment, and relapse leukaemias can be dominated by different genotypes, including pre-leukemic clones persisting throughout the disease progression and treatment. Intriguingly, plasticity also appears to be a temporally defined property that can segregate with genotype. These results suggest that Down Syndrome ALL should be viewed as a complex matrix of cells exhibiting genetic and epigenetic heterogeneity that foster extensive clonal evolution and competition. Therapeutic intervention reshapes this ‘eco-system’ and may provide the right conditions for the preferential expansion of selected compartments and subsequently relapse.

  Study EGAS50000001287

• Identification of driver oncogenes in scirrhous-type gastric cancer cell lines

  Scirrhous type gastric cancer (SGC) is one of the most intractable cancer subtypes in human, and its therapeutic targets have been rarely identified to date. Exploration of somatic mutations in the SGC genome with the next generation sequencers has been hampered by low tumor contents by the markedly increased fibrous tissues. Thus, SGC cell lines may be useful resources to search for novel oncogenes in. Here we have conducted whole exome sequencing and RNA sequencing on two SGC cell lines, OCUM-8 and OCUM-9. Interestingly, most of the mutations thus identified have not been reported. In OCUM-8 cells, a novel CD44-IGF1R fusion gene is discovered, the protein product of which ligates the amino-terminus of CD44 to the transmembrane and the tyrosine-kinase domains of IGF1R. Further, both of CD44 and IGF1R are markedly amplified in the OCUM-8 genome and abundantly expressed. CD44-IGF1R has a transforming ability, and the suppression of its kinase activity leads to rapid cell death of OCUM-8. On the other hand, OCUM-9 seems to possess multiple oncogenic events in its genome. The MET gene is highly amplified, and the treatment of OCUM-9 with crizotinib, a MET inhibitor, results in cell death. Further, a novel BORCS5-ETV6 fusion gene is identified in the OCUM-9 genome. BORCS5-ETV6 possesses oncogenic activity, and suppression of its message partially inhibits cell growth. Prevalence of these novel fusion genes among SGC awaits further investigation, but we validate the significance of cell lines as appropriate reagents for detailed genomic analyses of SGC.

  Study JGAS000179

• Sequencing data from triple-negative breast cancer tumors

  Autoimmunity and anti-cancer immunity lie on the same biological continuum1,2, but their link remains obscure. The paraneoplastic neurological syndrome anti-NMDA receptor (NMDAR) encephalitis (ANRE) is a paradigm for their connectivity3 given that intratumoral NMDAR expression correlates with the generation of anti-NMDAR antibodies4,5. Here, we verify ectopic expression of GluN1 and GluN2B NMDAR sub-units in triple-negative breast cancer (TNBC)6 and model this using orthotopic TNBC tumors with inducible expression of GluN1-GluN2B NMDARs. We show that NMDAR expression is sufficient to induce B cell recruitment and their affinity maturation, consistent with an integrated adaptive immune response. Reconstruction of extended intratumoral B cell phylogenies and cryo-EM structural analyses demonstrated that affinity-matured hypermutated and class-switched antibodies emerged from pre-existing germline-configuration lower-affinity anti-NMDAR antibodies. Distinct matured antibodies targeted specific epitopes and induced conformational rearrangements within the NMDAR amino-terminal domain, predictive of their functional effects, ranging from inhibition to potentiation. Passive transfer of an NMDAR-potentiating antibody caused autonomic dysregulation and lowered the seizure threshold in healthy female mice, recapitulating key diagnostic criteria of ANRE4,5. We further identify a correlation between intratumoral NMDAR expression and anti-NMDAR antibody titers in TNBC patients. Taken together, our data establish a direct connection between intratumoral NMDAR expression, antibody maturation, and the onset of autoimmunity. These findings suggest that germline-encoded anti-NMDAR antibodies contribute to immune surveillance but can also trigger autoimmune disease upon maturation, revealing a mechanistic tradeoff between cancer immunity and neurotoxicity.

  Study EGAS50000001585

• Sequencing data from triple-negative breast cancer tumors

  Autoimmunity and anti-cancer immunity lie on the same biological continuum1,2, but their link remains obscure. The paraneoplastic neurological syndrome anti-NMDA receptor (NMDAR) encephalitis (ANRE) is a paradigm for their connectivity3 given that intratumoral NMDAR expression correlates with the generation of anti-NMDAR antibodies4,5. Here, we verify ectopic expression of GluN1 and GluN2B NMDAR sub-units in triple-negative breast cancer (TNBC)6 and model this using orthotopic TNBC tumors with inducible expression of GluN1-GluN2B NMDARs. We show that NMDAR expression is sufficient to induce B cell recruitment and their affinity maturation, consistent with an integrated adaptive immune response. Reconstruction of extended intratumoral B cell phylogenies and cryo-EM structural analyses demonstrated that affinity-matured hypermutated and class-switched antibodies emerged from pre-existing germline-configuration lower-affinity anti-NMDAR antibodies. Distinct matured antibodies targeted specific epitopes and induced conformational rearrangements within the NMDAR amino-terminal domain, predictive of their functional effects, ranging from inhibition to potentiation. Passive transfer of an NMDAR-potentiating antibody caused autonomic dysregulation and lowered the seizure threshold in healthy female mice, recapitulating key diagnostic criteria of ANRE4,5. We further identify a correlation between intratumoral NMDAR expression and anti-NMDAR antibody titers in TNBC patients. Taken together, our data establish a direct connection between intratumoral NMDAR expression, antibody maturation, and the onset of autoimmunity. These findings suggest that germline-encoded anti-NMDAR antibodies contribute to immune surveillance but can also trigger autoimmune disease upon maturation, revealing a mechanistic tradeoff between cancer immunity and neurotoxicity.

  Study EGAS50000001598

• High-Resolution Spatial Transcriptomics Uncover Epidermal-Dermal Divergences in Merkel Cell Carcinoma: Spatial Context Reshapes the Gene Expression Landscape

  Merkel cell carcinoma (MCC) is an aggressive malignancy with neuroendocrine differentiation marked by high plasticity, often manifesting as rapid therapy resistance. Although the cell-of-origin is presumed to be epithelial, epidermal localization of MCC is rarely observed, largely because in situ MCC is typically an incidental finding. Nevertheless, a subset of MCC tumors exhibits epidermotropism, wherein tumor cells are present in the epidermis. The behavior of cancer cells is profoundly influenced by the tumor microenvironment and interactions with neighboring cells. Notably, the normal counterparts of the cancer’s cell-of-origin have been shown to attenuate tumor aggressiveness. Thus, epidermotropic MCC presents a unique opportunity to explore the potential role of surrounding keratinocytes in modulating tumor cell behavior. While the epidermotropic tumor nests share histological resemblance with their dermal counterparts, their transcriptomic profiles remain unexplored. Here, we employed high-definition spatial and single cell transcriptomics to dissect the gene expression profiles of epidermotropic MCC cells, comparing them to MCC cells in the tumor core and those adjacent to blood vessels. Notably, epidermotropic MCC cells exhibit a transcriptomic signature reminiscent of cutaneous squamous cell carcinoma, characterized by upregulation of genes encoding keratins, S100A proteins, as well as calmodulin-like proteins 3 and 5. Mechanistically, this keratinocytic differentiation is associated with enhanced p63 activity, leading to the upregulation of PERP. Collectively, our study demonstrates that MCC cells can adopt a keratinocytic differentiation program in response to microenvironmental cues, underscoring the remarkable phenotypic plasticity of this malignancy and the importance of the tumor microenvironment for tumor characteristics.

  Study EGAS00001008157

• Microsatellite data show recent demographic expansions in sedentary but not in nomadic human populations in Africa and Eurasia.

  The transition from hunting and gathering to plant and animal domestication was one of the most important cultural and technological revolutions in human history. According to archeologists and paleoanthropologists, this transition triggered major demographic expansions. However, few genetic studies have found traces of Neolithic expansions in the current repartition of genetic polymorphism, pointing rather toward Paleolithic expansions. Here, we used microsatellite autosomal data to investigate the past demographic history of 87 African and Eurasian human populations with contrasted lifestyles (nomadic hunter-gatherers, semi-nomadic herders and sedentary farmers). Likely due to the combination of a higher mutation rate and the possibility to analyze several loci as independent replicates of the coalescent process, the analysis of microsatellite data allowed us to infer more recent expansions than previous genetic studies, potentially resulting from the Neolithic transition. Despite the variability in their location and environment, we found consistent expansions for all sedentary farmers, while we inferred constant population sizes for all hunter-gatherers and most herders, which could result from constraints linked to a nomadic or semi-nomadic lifestyle and/or competition for land between herders and farmers. As an exception, we inferred expansions for Central Asian herders. This might be linked with the arid environment of this area, which may have been more favorable to nomadic herders than to sedentary farmers. Alternatively, current Central Asian herders may descent from populations who have first experienced a transition from hunter-gathering to sedentary agropastoralism, and then a second transition to nomadic herding.

  Study EGAS00001000652

• Aging and genome-wide patterns of DNA methylation in an African rainforest hunter-gathering population

  Aging is associated with widespread changes in genome-wide patterns of DNA methylation. Thousands of CpG sites whose tissue-specific methylation levels are strongly correlated with chronological age have been previously identified. However, the majority of these studies have focused primarily on cosmopolitan populations living in the developed world; it is not known if age-related patterns of DNA methylation at these loci are similar across a broad range of human genetic and ecological diversity. We investigated genome-wide methylation patterns using saliva derived DNA from a traditionally hunting and gathering African populations: the Baka of the western Central African rainforest, together with the ≠Khomani San of the South African Kalahari Desert. We identify hundreds of CpG sites whose methylation levels are significantly associated with age, thousands that are significant in a meta-analysis, and replicate trends previously reported in populations of non-African descent. We confirm that an age associated site in the gene ELOVL2 shows a remarkably congruent relationship with aging in humans, despite extensive genetic and environmental variation across populations. We also demonstrate that genotype state at methylation quantitative trait loci (meQTLs) can affect methylation trends at some known age-associated CpG sites. Our study explores the relationship between CpG methylation and chronological age in populations of African hunter-gatherers, who rely on different diets across diverse ecologies. While many age-related CpG sites replicate across populations, we show that considering common genetic variation at meQTLs further improves our ability to detect previously identified age associations.

  Study EGAS00001002226

• Exome Sequencing Of 75 Individuals From Multiply Affected Coeliac Families

  Coeliac disease is a highly heritable common autoimmune disease involving chronic small intestinal inflammation in response to dietary wheat. The human leukocyte antigen (HLA) region, and 40 newer regions identified by genome wide association studies (GWAS) and dense fine mapping, account for ~40% of the disease heritability. We hypothesized that in pedigrees with multiple individuals with coeliac disease rare [minor allele frequency (MAF) <0.5%] mutations of larger effect size (odds ratios of ~ 2 – 5) might exist. We sequenced the exomes of 75 coeliac individuals of European ancestry from 55 multiply affected families. We selected interesting variants and genes for further follow up using a combination of: an assessment of shared variants between related subjects, a model-free linkage test, and gene burden tests for multiple, potentially causal, variants. We next performed highly multiplexed amplicon resequencing of all RefSeq exons from 24 candidate genes selected on the basis of the exome sequencing data in 2,248 unrelated coeliac cases and 2,230 controls. 1,335 variants with a 99.9% genotyping call rate were observed in 4,478 samples, of which 939 were present in coding regions of 24 genes (Ti/Tv 2.99). 91.7% of coding variants were rare (MAF <0.5%) and 60% were novel. Gene burden tests performed on rare functional variants identified no significant associations (P<1x10-3) in the resequenced candidate genes. Our strategy of sequencing multiply affected families with deep follow up of candidate genes has not identified any new coeliac disease risk mutations.

  Study EGAS00001001093

• UK10K NEURO ASD SKUSE

  In the UK10K project we propose a series of complementary genetic approaches to find new low frequency/rare variants contributing to disease phenotypes. These will be based on obtaining the genome wide sequence of 4000 samples from the TwinsUK and ALSPAC cohorts (at 6x sequence coverage), and the exome sequence (protein coding regions and related conserved sequence) of 6000 samples selected for extreme phenotypes. Our studies will focus primarily on cardiovascular-related quantitative traits, obesity and related metabolic traits, neurodevelopmental disorders and a limited number of extreme clinical phenotypes that will provide proof-of-concept for future familial trait sequencing. We will analyse directly quantitative traits in the cohorts and the selected traits in the extreme samples, and also use imputation down to 0.1% allele frequency to extend the analyses to further sample sets with genome wide genotype data. In each case we will investigate indels and larger structural variants as well as SNPs, and use statistical methods that combine rare variants in a locus or pathway as well as single-variant approaches. This sample set of UK origin consists of clinically identified subjects with Autism Spectrum Disorders, mostly without intellectual disability (ie. Verbal IQs >70). The subjects represent children and adults with Autism, Asperger syndrome or Atypical Autism, identified according to standardized research criteria (ADI-algorithm, ADOS). A minority has identified comorbid neurodevelopmental disorders (e.g. ADHD). Family histories are available, with measures of broader phenotype in first-degree relatives.For further information on this cohort please contact David Skuse (d.skuse@ucl.ac.uk).

  Study EGAS00001000114

• UK10K_NEURO_MUIR

  In the UK10K project we propose a series of complementary genetic approaches to find new low frequency/rare variants contributing to disease phenotypes. These will be based on obtaining the genome wide sequence of 4000 samples from the TwinsUK and ALSPAC cohorts (at 6x sequence coverage), and the exome sequence (protein coding regions and related conserved sequence) of 6000 samples selected for extreme phenotypes. Our studies will focus primarily on cardiovascular-related quantitative traits, obesity and related metabolic traits, neurodevelopmental disorders and a limited number of extreme clinical phenotypes that will provide proof-of-concept for future familial trait sequencing. We will analyse directly quantitative traits in the cohorts and the selected traits in the extreme samples, and also use imputation down to 0.1% allele frequency to extend the analyses to further sample sets with genome wide genotype data. In each case we will investigate indels and larger structural variants as well as SNPs, and use statistical methods that combine rare variants in a locus or pathway as well as single-variant approaches.The sample selection consists of subjects with schizophrenia (SZ), autism, or other psychoses all with mental retardation (learning disability). The samples were initially collected under the leadership of Walter J Muir (deceased), now with Prof. Blackwood, Dr McKechanie and Prof McIntosh as custodians. These subjects represent the intersection of severe forms of neurodevelopmental disorders, appear to have a higher rate of familiality of SZ than typical, and are likely to have more serious and penetrant forms of mutations.For further information on this cohort please contact Andrew McIntosh (andrew.mcintosh@ed.ac.uk).

  Study EGAS00001000122