Therapeutic radiation drives leptomeningeal dissemination of medulloblastoma [scRNA-seq]
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ABSTRACT: In this study, we examine the effect of radiation on the transcriptional profile of medulloblastoma tumor cells and its microenvironment that could potentially be leading to metastatic dissemination.
Project description:In this study, we examine the effect of radiation on the transcriptional profile of medulloblastoma tumor cells and its microenvironment that could potentially be leading to metastatic dissemination.
Project description:The main cause of death in medulloblastoma is recurrence associated with leptomeningeal dissemination. Although the molecular basis of medulloblastoma has received considerable attention over the past decade, the role of microRNAs (miRNAs) in the acquisition of metastatic phenotype remains poorly understood. This study aimed to identify miRNA involved in leptomeningeal dissemination and to elucidate its target mechanisms. We analyzed miRNA expression profiles of 29 medulloblastomas according to the presence of cerebrospinal fluid (CSF) seeding. The differential expressed miRNAs (DEmiRNAs) were validated on 29 medulloblastoma tissues and three medulloblastoma cells. The biological function of the selected miRNA was evaluated using in vitro studies. A total of 12 DEmiRNAs were identified including miRNA-192 in medulloblastoma with seeding. The reduced expression of miRNA-192 was confirmed in tumor seeding group and the medulloblastoma cells. Overexpression of miRNA-192 inhibited cellular proliferation targeting dihydrofolate reductase (DHFR). MiRNA-192 decreased cellular anchoring via repression of integrin subunits (αV, β1, and β3) and CD47. Medulloblastoma with seeding showed specific DEmiRNAs compared with those without seeding. MicroRNA-192 suppresses leptomeningeal dissemination of medulloblastoma through modulating cell proliferation and anchoring ability. leptomeningeal dissemination in 29 pediatric medulloblastoma patients
Project description:Medulloblastoma, the most common malignant pediatric brain tumour, disseminates by shedding cells into the cerebrospinal fluid, which then re-implant to cover the surface of the brain and spinal cord. Metastases are a very poor prognostic sign at presentation and are usually lethal at recurrence. Mechanisms driving dissemination have been described in the bulk primary tumour, with the underlying assumption that primary tumour and metastases are biologically similar. Here we show that in both mouse and human medulloblastoma, multiple metastases from a single animal are extremely similar, but are genetically highly divergent from the primary tumour. Clonal genetic events in the metastases can be demonstrated in a restricted sub-clone of the primary tumour, suggesting that only rare cells within the primary tumour have the ability to metastasize. Failure to account for the bicompartmental nature of primary and metastatic medulloblastoma represents a major barrier to the development of effective targeted therapies. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from cryopreserved human medulloblastoma tissue samples. Copy number analysis of Affymetrix SNP6 arrays was performed for 17 pediatric medulloblastoma samples. Samples comprise a series of 7 patient-matched primary/metastatic cases.
Project description:Medulloblastoma, the most common malignant pediatric brain tumour, disseminates by shedding cells into the cerebrospinal fluid, which then re-implant to cover the surface of the brain and spinal cord. Metastases are a very poor prognostic sign at presentation and are usually lethal at recurrence. Mechanisms driving dissemination have been described in the bulk primary tumour, with the underlying assumption that primary tumour and metastases are biologically similar. Here we show that in both mouse and human medulloblastoma, multiple metastases from a single animal are extremely similar, but are genetically highly divergent from the primary tumour. Clonal genetic events in the metastases can be demonstrated in a restricted sub-clone of the primary tumour, suggesting that only rare cells within the primary tumour have the ability to metastasize. Failure to account for the bicompartmental nature of primary and metastatic medulloblastoma represents a major barrier to the development of effective targeted therapies. DNA methylation analysis of 15 pediatric medulloblastoma samples consisting of 6 primary-metastatic pairs and 4 normal cerebella samples profiled in Illumina Infinium HumanMethylation27 Beadchip v1.2
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.
Project description:The main cause of death in medulloblastoma is recurrence associated with leptomeningeal dissemination. Although the molecular basis of medulloblastoma has received considerable attention over the past decade, the role of microRNAs (miRNAs) in the acquisition of metastatic phenotype remains poorly understood. This study aimed to identify miRNA involved in leptomeningeal dissemination and to elucidate its target mechanisms. We analyzed miRNA expression profiles of 29 medulloblastomas according to the presence of cerebrospinal fluid (CSF) seeding. The differential expressed miRNAs (DEmiRNAs) were validated on 29 medulloblastoma tissues and three medulloblastoma cells. The biological function of the selected miRNA was evaluated using in vitro studies. A total of 12 DEmiRNAs were identified including miRNA-192 in medulloblastoma with seeding. The reduced expression of miRNA-192 was confirmed in tumor seeding group and the medulloblastoma cells. Overexpression of miRNA-192 inhibited cellular proliferation targeting dihydrofolate reductase (DHFR). MiRNA-192 decreased cellular anchoring via repression of integrin subunits (αV, β1, and β3) and CD47. Medulloblastoma with seeding showed specific DEmiRNAs compared with those without seeding. MicroRNA-192 suppresses leptomeningeal dissemination of medulloblastoma through modulating cell proliferation and anchoring ability.
Project description:Medulloblastoma (MB) is the most common malignant brain tumor in children. Despite recent improvements in overall survival, only a modest percentage of patients survive high-risk MB. The devastating side effects of radiation and chemotherapy substantially reduce qualify of life for surviving patients. We identified a novel tumor suppressor miRNA that sensitizes both ionizing radiation and vincristine responses in medulloblastoma. To understand the mechanism by which the tumor suppressor miR-584-5p may act as a tumor suppressor and therapy sensitizer, we performed microarray analysis in D425Med and D458Med medulloblastoma cells transfected with scrambled (miR-NC) or miR-584-5p mimic (miR-584-5p).