Genome wide assessment of RNA Pol II and Myc ChIP profiles in response to drug treatments in MYC-driven medulloblastoma
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE164696 | GEO | 2022/01/12
REPOSITORIES: GEO
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Project description:Genome wide assessment of RNA Pol II and Myc ChIP profiles in response to drug treatments in MYC-driven medulloblastoma
| PRJNA691579 | ENA
Project description:Deregulation of N-myc is a leading cause of malignant brain tumors in children. To target N-myc-driven medulloblastoma, most research has focused on identifying genomic alterations or on the analysis of the medulloblastoma transcriptome. Here, we have broadly characterized the translatome of medulloblastoma and shown that N-myc unexpectedly drives selective translation of transcripts that promote protein homeostasis. Cancer cells are constantly exposed to proteotoxic stress associated with alterations in protein production or folding. It remains poorly understood how cancers cope with proteotoxic stress to promote their growth. Here, our data unexpectedly revealed that N-myc regulates the expression of specific components (~5%) of the protein folding machinery at the translational level through the major cap binding protein, eukaryotic initiation factor eIF4E. Reducing eIF4E levels in mouse models of medulloblastoma blocked tumorigenesis. Importantly, targeting Hsp70, a protein folding chaperone translationally regulated by N-myc, suppressed tumor growth in mouse and human medulloblastoma xenograft models. These findings reveal a previously hidden molecular program that promotes medulloblastoma formation and identify new therapies that may have impact in the clinic.
2022-10-18 | GSE215298 | GEO
Project description:In this experiment, we identify MYC binding sites in the medulloblastoma cell line ONS76. The purpose of this experiment was to identify genes bound by MYC and compare MYC bound genes to genes differentially expressed when SOX2 or omomyc were elevated in ONS76 cells.
2022-08-22 | GSE186834 | GEO
Project description:Medulloblastoma (MB) is the most common malignant brain tumor in children. Patients whose tumors exhibit overexpression or amplification of the MYC oncogene (c-MYC) usually have an extremely poor prognosis, but there are no animal models of this subtype of the disease. Here we show that cerebellar stem cells expressing Myc and mutant Trp53 (p53) generate aggressive tumors following orthotopic transplantation. These tumors consist of large, pleiomorphic cells and resemble human MYC-driven MB at a molecular level. Notably, antagonists of PI3K/mTOR signaling, but not Hedgehog signaling, inhibit growth of tumor cells. These findings suggest that cerebellar stem cells can give rise to MYC-driven MB, and identify a novel model that can be used to test therapies for this devastating disease. To gain insight into the pathways that control growth of MYC-driven MB, we compared gene expression profiles of murine Myc/DNp53 (MP) tumor cells to those of freshly isolated cerebellar stem cells (Prom1+Lin- cells) and of tumors from Ptch1 mutant mice (a model for Sonic Hedgehog-associated MB). RNA was isolated from stem cells and tumor cells using the RNAqueous kit (Ambion). RNA was labeled and hybridized to Affymetrix Mouse Genome 430 2.0 arrays. 19 mouse cell samples (stem cells and tumor cells) were analyzed. There are four groups of samples, three with five biological replicates and the last with four (one outlier was removed). To gain insight into the mechanisms of transformation into tumors, we compared the gene expression profiles of MP tumor cells derived from stem cells (Myc/DNp53-infected Prom1+Lin- cells, designated MP-pl) or progenitors (Myc/DNp53-infected Prom1+ cells, designated MP-p) to gene expression profiles of uninfected stem cells (designated NSC) and profiles from a distinct model of medulloblastoma, the patched mutant mouse (designated ptch1).
2011-12-05 | E-GEOD-34126 | biostudies-arrayexpress
Project description:Aberrant oncogenic activation of MYC drives tumorigenesis in the most aggressive subset of medulloblastoma, the most common malignant brain tumor in childhood. Metastatic dissemination at diagnosis and at recurrence is commonly observed in MYC-driven medulloblastomas. Since these tumors display remarkable resistance to standard multimodal therapeutic approaches, epigenetic modulators commonly altered in these tumors are highly promising targets for novel therapeutic approaches. Here, we report on a cross-entity, high-throughput epigenetic drug screen to evaluate therapeutic vulnerabilities in the most common malignant primary brain tumors. Specifically, we performed a primary screen including 78 epigenetic inhibitors and a secondary screen including 20 histone deacetylase inhibitors (HDACi) to compare response profiles in atypical teratoid/rhabdoid tumor (AT/RT, n=11), medulloblastoma (n=14), and glioblastoma (n=14). This unbiased approach revealed preferential activity of HDACi in MYC-driven medulloblastoma. Importantly, the class I selective HDACi CI-994 showed significant cell viability reduction mediated by induction of apoptosis in MYC-driven medulloblastoma, with little to no activity in non-MYC-driven medulloblastoma, AT/RT, and glioblastoma in vitro. Notably, CI-994 displayed antitumoral effects at the primary site and the metastatic compartment in two orthotopic mouse models of MYC-driven medulloblastoma. Furthermore, synergistic drug screening and RNA sequencing revealed NFκB pathway induction as a mechanism of resistance to CI-994 treatment. Taken together, our findings identified MYC pathway activation as a predictive biomarker for epigenetic treatment intervention in high-risk medulloblastoma and provide a preclinical rationale for further exploration of CI-994 combined with NFκB pathway inhibitors in the treatment of MYC-driven medulloblastoma.
2019-12-13 | GSE123760 | GEO
Project description:Myc-driven Group 3 medulloblastoma (MB) is the most aggressive tumor among the four subgroups classified by transcriptome, genomic landscape and clinical outcomes. So far in all available mouse Group 3 models, the constitutive ectopic Myc expression was under control of LTR element or other exogenous promoters within the vectors, which were randomly inserted into the genome with multiple copies. Here we are deploying nuclease deficient CRISPR/dCas9-based transactivator that is targeted to promoter DNA sequences by specific guide RNA to force the transcriptional activation of endogenous Myc in p53-/-;cdkn2c-/- neurospheres cells. A combination of three sgRNAs together with dCas9-VP64 induced the highest expression of endogenous Myc. When the targeted cells were transplanted to the cortex of recipients, tumors arose fully recapitulate the Group 3 MB in human. This novel mouse model should significantly strengthen our understanding and treatment of the Myc-driven Group 3 medulloblastoma.
2018-06-19 | GSE102037 | GEO
Project description:Medulloblastoma is one of the most common malignant pediatric brain tumors. Group 3 is the most aggressive molecular subgroup, showing the highest rate of metastasis at diagnosis. To date, very few long noncoding RNAs have been implicated in Group 3 Medulloblastoma biology. Here, we identified the long noncoding RNAs dependent on the activity of the MYC oncogene, the major driver gene of Group 3 Medulloblastoma.
2021-08-11 | GSE171117 | GEO
Project description:Group 3 medulloblastoma is one of the most aggressive types of childhood brain tumors. Roughly 30% of cases carry genetic alterations in MYC, SMARCA4, or both genes combined. While overexpression of MYC has previously been shown to drive medulloblastoma formation in mice, the functional significance of SMARCA4 mutations and their suitability as a therapeutic target remain largely unclear. To address this issue, we combined overexpression of MYC with a loss of SMARCA4 in granule cell precursors. Both alterations did not increase proliferation of granule cell precursors in vitro. However, combined MYC overexpression and SMARCA4 loss successfully induced tumor formation in vivo after orthotopic transplantation in recipient mice. Resulting tumors displayed anaplastic histology and exclusively consisted of SMARCA4 negative cells although a mixture of recombined and non-recombined cells was injected. These observations provide first evidence for a tumor-promoting role of a SMARCA4 deficiency in the development of medulloblastoma. In comparing the transcriptome of tumors to the cells of origin and an established Sonic Hedgehog medulloblastoma model, we gathered first hints on deregulated gene expression that could be specifically involved in SMARCA4/MYC driven tumorigenesis. Finally, an integration of RNA sequencing and DNA methylation data of murine tumors with human samples revealed a high resemblance to human Group 3 medulloblastoma on the molecular level. Altogether, the development of SMARCA4-deficient medulloblastomas in mice paves the way to deciphering the role of frequently occurring SMARCA4 alterations in Group 3 medulloblastoma with the perspective to explore targeted therapeutic options.
2023-09-26 | GSE235924 | GEO
Project description:Group 3 medulloblastoma is one of the most aggressive types of childhood brain tumors. Roughly 30% of cases carry genetic alterations in MYC, SMARCA4, or both genes combined. While overexpression of MYC has previously been shown to drive medulloblastoma formation in mice, the functional significance of SMARCA4 mutations and their suitability as a therapeutic target remain largely unclear. To address this issue, we combined overexpression of MYC with a loss of SMARCA4 in granule cell precursors. Both alterations did not increase proliferation of granule cell precursors in vitro. However, combined MYC overexpression and SMARCA4 loss successfully induced tumor formation in vivo after orthotopic transplantation in recipient mice. Resulting tumors displayed anaplastic histology and exclusively consisted of SMARCA4 negative cells although a mixture of recombined and non-recombined cells was injected. These observations provide first evidence for a tumor-promoting role of a SMARCA4 deficiency in the development of medulloblastoma. In comparing the transcriptome of tumors to the cells of origin and an established Sonic Hedgehog medulloblastoma model, we gathered first hints on deregulated gene expression that could be specifically involved in SMARCA4/MYC driven tumorigenesis. Finally, an integration of RNA sequencing and DNA methylation data of murine tumors with human samples revealed a high resemblance to human Group 3 medulloblastoma on the molecular level. Altogether, the development of SMARCA4-deficient medulloblastomas in mice paves the way to deciphering the role of frequently occurring SMARCA4 alterations in Group 3 medulloblastoma with the perspective to explore targeted therapeutic options.
2023-09-26 | GSE235625 | GEO
Project description:Group 3 medulloblastoma is often associated with MYC amplification or overexpression, while whether MYC overexpression alone is sufficient to induce tumorigenesis is unknown and the cell type(s) which can be transformed by MYC is unclear. Here, by generating a new mouse model, we demonstrated that overexpression of Myc alone is sufficient to transform astrocyte progenitors and granule neuron progenitors (GNP) in the early postnatal cerebellum following orthotopic transplantation. The resulting tumors resemble human Group 3 medulloblastoma in terms of both histology and gene expression profiles. Using these models we found that inhibition of lactate dehydrogenase A (LDHA) significantly reduced both murine and human MYC-driven tumor growth, but did not affect SHH medulloblastoma, indicating that LDHA is potential and specific therapeutic target for MYC-driven medulloblastoma.
2019-04-25 | GSE114760 | GEO