Medulloblastoma (MB) is the most common malignant primary pediatric brain tumor and is currently divided into 4 subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH), Group 3 and Group 4. The extensive heterogeneity has made it difficult to assess the relevance of genes to malignant progression. For example, expression of the transcription factor, OTX2, is frequently dysregulated in multiple MB variants; however, it's role may be subtype specific. Here, we utilized human embryonic stem cell-derived neural precursors to determine the role of OTX2 in MB tumor progression using gain and loss of function studies.
OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells.
Specimen part
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Characterization of a novel OTX2-driven stem cell program in Group 3 and Group 4 medulloblastoma.
Cell line
View SamplesMedulloblastoma (MB) is the most common malignant primary pediatric brain cancer. Among the most aggressive subtypes, Group 3 and Group 4 originate from stem/progenitor cells, frequently metastasize, and often display the worst prognosis, yet, as the names imply, we know the least about the molecular mechanisms driving their progression. Here, we show that the transcription factor orthodenticle homeobox 2 (OTX2) promotes self-renewal while inhibiting differentiation in vitro and increases tumor-initiating capacity from MB stem cell populations in vivo. Characterization of the OTX2 regulatory network revealed a novel relationship between OTX2 and genes associated with multiple axon guidance signaling pathways in Group 3 and Group 4 MB stem/progenitor cells. In particular, OTX2 levels were negatively correlated with semaphorin (SEMA) signaling, as expression of 9 SEMA pathway genes is upregulated following OTX2 knockdown with some being potential direct OTX2 targets. Importantly, this negative correlation between OTX2 and SEMA pathway genes was also observed in patient samples, with lower expression of SEMA4D associated with poor outcome in Group 3 and 4 tumors. Functional studies using established and newly derived MB cell lines demonstrated that increased levels of SEMA pathway genes are associated with decreased self-renewal and growth, and that RHO signaling, known to mediate the effects of SEMA genes, is contributing to the OTX2 KD phenotype. Our study provides critical mechanistic insight into the networks controlled by OTX2 in self-renewing MB cells and reveals novel roles for axon guidance genes and their downstream effectors as putative tumor suppressors and therapeutic targets in Group 3 and Group 4 MB.
Characterization of a novel OTX2-driven stem cell program in Group 3 and Group 4 medulloblastoma.
Cell line
View SamplesDNA methylation is thought to induce a transcriptional silencing through the combination of two mechanisms: the repulsion of transcriptional activators that do not recognize their binding sites when methylated, and the recruitment of transcriptional repressors that specifically bind methylated DNA. Methyl CpG Binding Domain proteins MeCP2, MBD1 and MBD2 belong to the latter category. However, the exact contribution of each protein in the DNA methylation dependent transcriptional repression occurring during development and diseases remains elusive. Here we present MBD2 ChIPseq data generated from the endogenous protein in an isogenic cellular model of human mammary oncogenic transformation. In immortalized or transformed cells, MBD2 was found in one fourth of methylated regions and associated with transcriptional silencing. Depletion of MBD2 induces upregulations of genes bound by MBD2 and methylated in their transcriptional start site regions. MBD2 was partially redistributed on methylated DNA during oncogenic transformation, independently of DNA methylation changes. Genes downregulated during this transformation preferentially gained MBD2 binding sites on their promoter. Depletion of MBD2 in transformed cells induced the upregulation of some of these repressed genes, independently of the strategy used for the abrogation of oncosuppressive barriers. Our data confirm that MBD2 is a major interpret of DNA methylation, and show an unreported dynamic in this interpretation during oncogenic transformation. Overall design: RNAseq of untreated HMEC-hTERT cells, siCtrl, siMBD2 or DAC treated HMLER cells, siCtrl or siMBD2 treated HME-ZEB1-RAS and HME-shP53-RAS cells, in duplicates.
Dynamics of MBD2 deposition across methylated DNA regions during malignant transformation of human mammary epithelial cells.
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View Samplesc-Myc controls more than 15% of genes responsible for proliferation, differentiation, and cellular metabolism in pancreatic as well as other cancers making this transcription factor a prime target for treating patients. The transcriptome of 55 patient derived xenografts show that 30% of them share an exacerbated expression profile of MYC transcriptional targets (MYC-high). This cohort is characterized by a high level of Ki67 staining, a lower differentiation state and a shorter survival time compared to the MYC-low subgroup. To define classifier expression signature, we selected a group of 10 MYC targets transcripts which expression is increased in the MYC-high group and 6 transcripts increased in the MYC-low group. We validated the ability of these markers panel to identify MYC-high patient-derived xenografts from both: discovery and validation cohorts as well as primary cells cultures from the same patients. We then showed that cells from MYC-high patients are more sensitive to JQ1 treatment compared to MYC-low cells, in both monolayer and 3D cultured spheroids, due to cell cycle arrest followed by apoptosis. Therefore, these results provide new markers and potentially novel therapeutic modalities for distinct subgroups of pancreatic tumors and may find application to the future management of these patients within the setting of individualized medicine clinics.
Gene expression profiling of patient-derived pancreatic cancer xenografts predicts sensitivity to the BET bromodomain inhibitor JQ1: implications for individualized medicine efforts.
Disease
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Chronic mucocutaneous candidiasis and connective tissue disorder in humans with impaired JNK1-dependent responses to IL-17A/F and TGF-β.
Specimen part, Disease, Disease stage, Treatment, Time
View SamplesPrecise localization of the histone H3 variant CENP-A(Cse4) to centromeres is essential for accurate chromosome segregation. In budding yeast, CENP-A(Cse4) is regulated by ubiquitin-mediated proteolysis to ensure its exclusive localization to the centromere. Overexpression of CENP-A(Cse4) is lethal when the CENP-A(Cse4) E3 ubiquitin ligase, Psh1, is deleted. CENP-A(Cse4) mislocalizes to promoters in this condition, so we investigated if there was an effect on gene expression of downstream genes using RNA-seq. Overall design: RNA-seq from two or three biological replicates each, at t0 and t2 hours after adding galactose for each of 6 experimental genotypes.
Regulation of Budding Yeast CENP-A levels Prevents Misincorporation at Promoter Nucleosomes and Transcriptional Defects.
Subject, Time
View SamplesEngineered abiotic stress resistance is an important target for increasing agricultural productivity.There are concerns, however, regarding possible ecological impacts of transgenic crops. In contrast to the first wave of transgenic crops, many abiotic stress resistance genes can initiate
Comparison of salt stress resistance genes in transgenic Arabidopsis thaliana indicates that extent of transcriptomic change may not predict secondary phenotypic or fitness effects.
Age, Specimen part, Treatment
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Cross-study homogeneity of psoriasis gene expression in skin across a large expression range.
Sex, Specimen part, Time
View SamplescDNA and cRNA hybridization technologies have different, probe-specific sensitivities. We used samples from an etanercept trial (GSE11903) to explore in a real-life setting the uniqueness of each platform.
Cross-study homogeneity of psoriasis gene expression in skin across a large expression range.
Specimen part, Time
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