Neuroblastoma and other pediatric tumors show a paucity of gene mutations, which has sparked an interest in their epigenetic regulation. Several tumor types include phenotypically divergent cells, ...resembling cells from different lineage development stages. It has been proposed that super-enhancer-associated transcription factor (TF) networks underlie lineage identity, but the role of these enhancers in intratumoral heterogeneity is unknown. Here we show that most neuroblastomas include two types of tumor cells with divergent gene expression profiles. Undifferentiated mesenchymal cells and committed adrenergic cells can interconvert and resemble cells from different lineage differentiation stages. ChIP-seq analysis of isogenic pairs of mesenchymal and adrenergic cells identified a distinct super-enhancer landscape and super-enhancer-associated TF network for each cell type. Expression of the mesenchymal TF PRRX1 could reprogram the super-enhancer and mRNA landscapes of adrenergic cells toward a mesenchymal state. Mesenchymal cells were more chemoresistant in vitro and were enriched in post-therapy and relapse tumors. Two super-enhancer-associated TF networks, which probably mediate lineage control in normal development, thus dominate epigenetic control of neuroblastoma and shape intratumoral heterogeneity.
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IJS, NUK, SBMB, UL, UM, UPUK
Two types of stem cells are currently defined in small intestinal crypts: cycling crypt base columnar (CBC) cells and quiescent ‘+4’ cells. Here, we combine transcriptomics with proteomics to define ...a definitive molecular signature for Lgr5+ CBC cells. Transcriptional profiling of FACS‐sorted Lgr5+ stem cells and their daughters using two microarray platforms revealed an mRNA stem cell signature of 384 unique genes. Quantitative mass spectrometry on the same cell populations identified 278 proteins enriched in intestinal stem cells. The mRNA and protein data sets showed a high level of correlation and a combined signature of 510 stem cell‐enriched genes was defined. Spatial expression patterns were further characterized by mRNA in‐situ hybridization, revealing that approximately half of the genes were expressed in a gradient with highest levels at the crypt bottom, while the other half was expressed uniquely in Lgr5+stem cells. Lineage tracing using a newly established knock‐in mouse for one of the signature genes, Smoc2, confirmed its stem cell specificity. Using this resource, we find—and confirm by independent approaches—that the proposed quiescent/‘+4’ stem cell markers Bmi1, Tert, Hopx and Lrig1 are robustly expressed in CBC cells.
Transcriptome and proteome analyses of Lgr5‐positive intestinal cells define the signature of bona fide intestinal stem cells (ISCs) population. These results offer further insight into the nature of ISCs and will instruct further research on this therapeutically highly relevant topic.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Blastemal histology in chemotherapy-treated pediatric Wilms tumors (nephroblastoma) is associated with adverse prognosis. To uncover the underlying tumor biology and find therapeutic leads for this ...subgroup, we analyzed 58 blastemal type Wilms tumors by exome and transcriptome sequencing and validated our findings in a large replication cohort. Recurrent mutations included a hotspot mutation (Q177R) in the homeo-domain of SIX1 and SIX2 in tumors with high proliferative potential (18.1% of blastemal cases); mutations in the DROSHA/DGCR8 microprocessor genes (18.2% of blastemal cases); mutations in DICER1 and DIS3L2; and alterations in IGF2, MYCN, and TP53, the latter being strongly associated with dismal outcome. DROSHA and DGCR8 mutations strongly altered miRNA expression patterns in tumors, which was functionally validated in cell lines expressing mutant DROSHA.
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•SIX1/2 mutations in blastemal type Wilms tumors induce a proliferation signature•DROSHA/DGCR8 microprocessor mutations lead to a broad decrease in miRNA processing•TP53 mutations are associated with aneuploidy, chromothripsis, and high lethality•IGF2 and MYCN/FBXW7 alterations are frequent in blastemal type tumors
Blastemal type Wilms tumors are associated with poor prognosis. Wegert et al. identify recurrent mutations in SIX1 and SIX2 that correlate with high proliferation and in DROSHA and DGCR8 that affect miRNA biogenesis, as well as a high frequency of IGF2 overexpression in these tumors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Transition between differentiation states in development occurs swift but the mechanisms leading to epigenetic and transcriptional reprogramming are poorly understood. The pediatric cancer ...neuroblastoma includes adrenergic (ADRN) and mesenchymal (MES) tumor cell types, which differ in phenotype, super-enhancers (SEs) and core regulatory circuitries. These cell types can spontaneously interconvert, but the mechanism remains largely unknown. Here, we unravel how a NOTCH3 intracellular domain reprogrammed the ADRN transcriptional landscape towards a MES state. A transcriptional feed-forward circuitry of NOTCH-family transcription factors amplifies the NOTCH signaling levels, explaining the swift transition between two semi-stable cellular states. This transition induces genome-wide remodeling of the H3K27ac landscape and a switch from ADRN SEs to MES SEs. Once established, the NOTCH feed-forward loop maintains the induced MES state. In vivo reprogramming of ADRN cells shows that MES and ADRN cells are equally oncogenic. Our results elucidate a swift transdifferentiation between two semi-stable epigenetic cellular states.
Telomere maintenance by telomerase activation or alternative lengthening of telomeres (ALT) is a major determinant of poor outcome in neuroblastoma. Here, we screen for ALT in primary and relapsed ...neuroblastomas (n = 760) and characterize its features using multi-omics profiling. ALT-positive tumors are molecularly distinct from other neuroblastoma subtypes and enriched in a population-based clinical sequencing study cohort for relapsed cases. They display reduced ATRX/DAXX complex abundance, due to either ATRX mutations (55%) or low protein expression. The heterochromatic histone mark H3K9me3 recognized by ATRX is enriched at the telomeres of ALT-positive tumors. Notably, we find a high frequency of telomeric repeat loci with a neuroblastoma ALT-specific hotspot on chr1q42.2 and loss of the adjacent chromosomal segment forming a neo-telomere. ALT-positive neuroblastomas proliferate slowly, which is reflected by a protracted clinical course of disease. Nevertheless, children with an ALT-positive neuroblastoma have dismal outcome.
Fibrodysplasia Ossificans Progressiva (FOP) is a very rare genetic disease characterized by progressive heterotopic ossification (HO) of soft tissues, leading to immobility and premature death. FOP ...is caused by a mutation in the Activin receptor Type 1 (ACVR1) gene, resulting in altered responsiveness to Activin-A. We recently revealed that Activin-A induces fewer, but larger and more active, osteoclasts regardless of the presence of the mutated ACVR1 receptor. The underlying mechanism of Activin-A-induced changes in osteoclastogenesis at the gene expression level remains unknown. Transcriptomic changes induced by Activin-A during osteoclast formation from healthy controls and patient-derived CD14-positive monocytes were studied using RNA sequencing. CD14-positive monocytes from six FOP patients and six age- and sex-matched healthy controls were differentiated into osteoclasts in the absence or presence of Activin-A. RNA samples were isolated after 14 days of culturing and analyzed by RNA sequencing. Non-supervised principal component analysis (PCA) showed that samples from the same culture conditions (e.g., without or with Activin-A) tended to cluster, indicating that the variability induced by Activin-A treatment was larger than the variability between the control and FOP samples. RNA sequencing analysis revealed 1480 differentially expressed genes induced by Activin-A in healthy control and FOP osteoclasts with
(adj) < 0.01 and a Log2 fold change of ≥±2. Pathway and gene ontology enrichment analysis revealed several significantly enriched pathways for genes upregulated by Activin-A that could be linked to the differentiation or function of osteoclasts, cell fusion or inflammation. Our data showed that Activin-A has a substantial effect on gene expression during osteoclast formation and that this effect occurred regardless of the presence of the mutated ACVR1 receptor causing FOP.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Neuroblastoma is an embryonal tumour of the peripheral sympathetic nervous system (SNS). One of the master regulator genes for peripheral SNS differentiation, the homeobox transcription factor
...PHOX2B, is mutated in familiar and sporadic neuroblastomas. Here we report that inducible expression of
PHOX2B in the neuroblastoma cell line SJNB-8 down-regulates
MSX1, a homeobox gene important for embryonic neural crest development. Inducible expression of
MSX1 in SJNB-8 caused inhibition of both cell proliferation and colony formation in soft agar. Affymetrix micro-array and Northern blot analysis demonstrated that
MSX1 strongly up-regulated the Delta–Notch pathway genes
DLK1,
NOTCH3, and
HEY1. In addition, the proneural gene
NEUROD1 was down-regulated. Western blot analysis showed that
MSX1 induction caused cleavage of the NOTCH3 protein to its activated form, further confirming activation of the Delta–Notch pathway. These experiments describe for the first time regulation of the Delta–Notch pathway by
MSX1, and connect these genes to the
PHOX2B oncogene, indicative of a role in neuroblastoma biology. Affymetrix micro-array analysis of a neuroblastic tumour series consisting of neuroblastomas and the more benign ganglioneuromas showed that
MSX1,
NOTCH3 and
HEY1 are more highly expressed in ganglioneuromas. This suggests a block in differentiation of these tumours at distinct developmental stages or lineages.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Abstract The c-Myc and MYCN oncogenes strongly induce cell proliferation. Although a limited series of cell cycle genes were found to be induced by the myc transcription factors, it is still unclear ...how they mediate the proliferative phenotype. We therefore analysed a neuroblastoma cell line with inducible MYCN expression. We found that all members of the minichromosome maintenance complex (MCM2–7) and MCM8 and MCM10 were up-regulated by MYCN. Expression profiling of 110 neuroblastoma tumours revealed that these genes strongly correlated with MYCN expression in vivo . Extensive chromatin immunoprecipitation experiments were performed to investigate whether the MCM genes were primary MYCN targets. MYCN was bound to the proximal promoters of the MCM2 to -8 genes. These data suggest that MYCN stimulates the expression of not only MCM7, which is a well defined MYCN target gene, but also of the complete minichromosome maintenance complex.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Whole-genome sequencing detected structural rearrangements of TERT in 17 of 75 high-stage neuroblastomas, with five cases resulting from chromothripsis. Rearrangements were associated with increased ...TERT expression and targeted regions immediately up- and downstream of TERT, positioning a super-enhancer close to the breakpoints in seven cases. TERT rearrangements (23%), ATRX deletions (11%) and MYCN amplifications (37%) identify three almost non-overlapping groups of high-stage neuroblastoma, each associated with very poor prognosis.
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IJS, NUK, SBMB, UL, UM, UPUK
Abstract
Given the complexity, omics data like RNA-seq are often analyzed by bioinformaticians, and not the wetlab researchers that performed the experiments. With the biomedical researcher (with ...limited or no bioinformatics skills) in mind as the end-user, we developed the user-friendly, publicly accessible R2 platform (http://r2.amc.nl), enabling biomedical scientists to work with their own data from anywhere at any time. R2 (cited in >850 peer-reviewed scientific publications) consists of an omics database, coupled to an extensive set of interactive tools to analyze/visualize the datasets. Interactive analyses within the software are highly connected, allowing quick navigation between various aspects of the datamining process. Besides password protected private data, R2 also contains an extensive body of publicly available omics data, enabling users to relate their findings to other diseases / tissues, or as validation in integrative analyses. Next to gene expression (bulk as well as single cell), R2 is also being employed for the integration, analysis and visualization of copynumber, SNP, methylation, miRNA, drug response, ChIP-seq, and NGS exome/WGS DNA sequencing data. Analyses include correlation, differential expression, gene sets, gene ontology, transcription factor binding sites, tSNE, PCA, k-means, Kaplan Meier survival scans, signature creation etc. Visualizations include various gene oriented plots, heatmaps, Circos plots, embedded genome browser, Venn diagrams, etc. The real power of the platform lies in the chaining of results of analyses; e.g. the results of a differential expression analysis can be further trimmed down using a Kaplan Meier analysis that in turn can be used for a Gene Ontology over-representation analysis. Furthermore, the webserver allows for overviews across different datasets (such as MegaSampler and 2D distribution), where a user can harness the power of thousands of measurements. Recently, integrated analyses for personalized medicine, where copy number, mRNA expression, methylation and mutation data are combined into a comprehensive overview, occasionally supplemented with PDX/organoid drug response data. These serve clinical decision making for a patient, but as growing cohorts also form a treasure trove for scientific discovery. R2 provides a central starting point from where data mining and analysis paths can be followed within one environment. Data/analyses can be shared between R2-users via our community options, making R2 an outstanding environment for discovery, hypothesis testing and scientific collaboration.
Citation Format: Jan Koster, Richard Volckmann, Danny Zwijnenburg, Piet Molenaar, Rogier Versteeg. R2: Genomics analysis and visualization platform abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2490.
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