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Subgroup specific somatic copy number aberrations in the medulloblastoma genome

ABSTRACT: Medulloblastoma, the most common malignant pediatric brain tumour is currently treated with non-specific cytotoxic therapies including surgery, whole brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, prior attempts to identify targets for therapy have been underpowered due to small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1087 unique medulloblastomas. SCNAs are more common than SNVs in medulloblastoma, and are predominantly subgroup enriched. The most common region of focal copy number gain is a tandem duplication of the Parkinson's disease gene SNCAIP, which is exquisitely restricted to Subgroup 4alpha. Recurrent translocations of PVT1, including PVT1-MYC and PVT1-NDRG1 that arise through localized chromosomal shattering (topochromothripsis) are restricted to Group 3 tumours. Numerous actionable SCNAs, including recurrent events targeting TGFbeta signaling in Group 3, and NF-kappaB signaling in Group 4 suggest future avenues for rational, targeted therapy This SuperSeries is composed of the SubSeries listed below.

OTHER RELATED OMICS DATASETS IN: PRJNA161099PRJNA161101PRJNA161029

ORGANISM(S): Homo sapiens

PROVIDER: GSE37385 | GEO | 2012/07/27

SECONDARY ACCESSION(S): PRJNA161029

REPOSITORIES: GEO

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Project description:Recent genomic approaches have suggested the existence of multiple distinct subtypes of medulloblastoma. We studied a large cohort of medulloblastomas to determine how many subgroups of the disease exist, how they differ, and the extent of overlap between subgroups. We determined gene expression profiles and DNA copy number aberrations for 103 primary medulloblastomas. Bioinformatic tools were used for class discovery of medulloblastoma subgroups based on the most informative genes in the dataset. Immunohistochemistry for subgroup-specific ‘signature’ genes was used to determine subgroup affiliation for 294 non-overlapping medulloblastomas on two independent tissue microarrays (TMAs). Multiple unsupervised analyses of transcriptional profiles identified four distinct, non-overlapping molecular variants: WNT, SHH, Group C, and Group D. Supervised analysis of these four subgroups revealed significant subgroup-specific demographics, histology, metastatic status, and DNA copy number aberrations. Immunohistochemistry for DKK1 (WNT), SFRP1 (SHH), NPR3 (Group C), and KCNA1 (Group D) could reliably and uniquely classify formalin fixed medulloblastomas in ~98% of cases. Group C patients (NPR3 +ve tumors) exhibited a significantly diminished progression free and overall survival irrespective of their metastatic status. Our integrative genomics approach to a large cohort of medulloblastomas has identified four disparate subgroups with distinct demographics, clinical presentation, transcriptional profiles, genetic abnormalities, and clinical outcome. Medulloblastomas can be reliably assigned to subgroups through immunohistochemistry, thereby making medulloblastoma sub-classification widely available. Future research on medulloblastoma and the development of clinical trials should take into consideration these four distinct types of medulloblastoma. A total of 103 primary medulloblastoma specimens were profiled by Affymetrix exon array and gene-level analysis was performed.

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Subgroup specific somatic copy number aberrations in the medulloblastoma genome

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