Clonal Selection Drives Genetic Divergence of Metastatic Medulloblastoma
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE34356 | GEO | 2011/12/13
SECONDARY ACCESSION(S): PRJNA151451
REPOSITORIES: GEO
Similar Datasets
Project description:Medulloblastoma, the most common malignant paediatric brain tumour, arises in the cerebellum and disseminates through the cerebrospinal fluid in the leptomeningeal space to coat the brain and spinal cord. Dissemination, a marker of poor prognosis, is found in up to 40% of children at diagnosis and in most children at the time of recurrence. Affected children therefore are treated with radiation to the entire developing brain and spinal cord, followed by high-dose chemotherapy, with the ensuing deleterious effects on the developing nervous system. The mechanisms of dissemination through the cerebrospinal fluid are poorly studied, and medulloblastoma metastases have been assumed to be biologically similar to the primary tumour. Here we show that in both mouse and human medulloblastoma, the metastases from an individual are extremely similar to each other but are divergent from the matched primary tumour. Clonal genetic events in the metastases can be demonstrated in a restricted subclone 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 metastatic medulloblastoma could be a major barrier to the development of effective targeted therapies.
| S-EPMC3288636 | biostudies-literature
Project description:This SuperSeries is composed of the following subset Series: GSE34280: Clonal Selection Drives Genetic Divergence of Metastatic Medulloblastoma [Affymetrix SNP6 Arrays] GSE34355: Clonal Selection Drives Genetic Divergence of Metastatic Medulloblastoma [Illumina Infinium HumanMethylation27 Beadchip v1.2] Refer to individual Series
2011-12-13 | E-GEOD-34356 | biostudies-arrayexpress
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.
2011-12-09 | E-GEOD-34280 | biostudies-arrayexpress
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.
2011-12-13 | GSE34355 | GEO
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
2011-12-13 | E-GEOD-34355 | biostudies-arrayexpress
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.
2011-12-09 | GSE34280 | GEO
Project description:The development of targeted anti-cancer therapies through the study of cancer genomes is intended to increase survival rates and decrease treatment-related toxicity. We treated a transposon-driven, functional genomic mouse model of medulloblastoma with 'humanized' in vivo therapy (microneurosurgical tumour resection followed by multi-fractionated, image-guided radiotherapy). Genetic events in recurrent murine medulloblastoma exhibit a very poor overlap with those in matched murine diagnostic samples (<5%). Whole-genome sequencing of 33 pairs of human diagnostic and post-therapy medulloblastomas demonstrated substantial genetic divergence of the dominant clone after therapy (<12% diagnostic events were retained at recurrence). In both mice and humans, the dominant clone at recurrence arose through clonal selection of a pre-existing minor clone present at diagnosis. Targeted therapy is unlikely to be effective in the absence of the target, therefore our results offer a simple, proximal, and remediable explanation for the failure of prior clinical trials of targeted therapy.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2018-04-10 | GSE112877 | GEO
Project description:Chromosome gains and losses are a frequent feature of human cancers. However, how these aberrations can outweigh the detrimental effects of aneuploidy remains unclear. An initial comparison of existing chromosomal instability (CIN) mouse models suggests that aneuploidy accumulates to low levels in these animals. We therefore developed a novel mouse model that enables unprecedented levels of chromosome missegregation in the adult animal. At the earliest stages of T-cell development, cells with random chromosome gains and/or losses are selected against, but CIN eventually results in the expansion of progenitors with clonal chromosomal imbalances. Clonal selection leads to the development of T-cell lymphomas with stereotypic karyotypes in which chromosome 15, containing the Myc oncogene, is gained with high prevalence. Expressing human MYC from chromosome 6 (MYC Chr6) is sufficient to change the karyotype of these lymphomas to include universal chromosome 6 gains. Interestingly, while chromosome 15 is still gained in MYC Chr6 tumors after genetic ablation of the endogenous Myc locus, this chromosome is not efficiently gained after deletion of one copy of Rad21, suggesting a synergistic effect of both MYC and RAD21 in driving chromosome 15 gains. Our results show that the initial detrimental effects of random missegregation are outbalanced by clonal selection, which is dictated by the chromosomal location and nature of certain genes and is sufficient to drive cancer with high prevalence.
| S-EPMC8336892 | biostudies-literature
Project description:Phenotypic adaptations may be the result of changes in gene structure or gene regulation, but little is known about the evolution of gene expression. In addition, it is unclear whether the same selective forces may operate at both levels simultaneously. Reproductive proteins evolve rapidly, but the underlying selective forces promoting such rapid changes are still a matter of debate. In particular, the role of sexual selection in driving positive selection among reproductive proteins remains controversial, whereas its potential influence on changes in promoter regions has not been explored. Protamines are responsible for maintaining DNA in a compacted form in chromosomes in sperm and the available evidence suggests that they evolve rapidly. Because protamines condense DNA within the sperm nucleus, they influence sperm head shape. Here, we examine the influence of sperm competition upon protamine 1 and protamine 2 genes and their promoters, by comparing closely related species of Mus that differ in relative testes size, a reliable indicator of levels of sperm competition. We find evidence of positive selection in the protamine 2 gene in the species with the highest inferred levels of sperm competition. In addition, sperm competition levels across all species are strongly associated with high divergence in protamine 2 promoters that, in turn, are associated with sperm swimming speed. We suggest that changes in protamine 2 promoters are likely to enhance sperm swimming speed by making sperm heads more hydrodynamic. Such phenotypic changes are adaptive because sperm swimming speed may be a major determinant of fertilization success under sperm competition. Thus, when species have diverged recently, few changes in gene-coding sequences are found, while high divergence in promoters seems to be associated with the intensity of sexual selection.
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