MTORC1 promotes malignant large cell/anaplastic histology and is a therapeutically targetable vulnerability in SHH-TP53 mutant medulloblastoma
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA762305 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR15838441.fastq.gz | Fastqsanger.gz | |||
| SRR15838442.fastq.gz | Fastqsanger.gz | |||
| SRR15838443.fastq.gz | Fastqsanger.gz | |||
| SRR15838444.fastq.gz | Fastqsanger.gz | |||
| SRR15838445.fastq.gz | Fastqsanger.gz |
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Project description:Distinct molecular subgroups and subtypes have been identified for medulloblastoma (MB), one of the most malignant brain tumors of childhood, with the sonic hedgehog (SHH)-activated subgroup of patients with mutations in p53 having a very severe outcome, associated with unfavorable histological large cell/anaplastic (LC/A) features. Aim of this study was to determine whether hyperactivation of mechanistic Target Of Rapamycin Complex 1 (mTORC1) pathway, whose role in molecular subtypes of MB is currently undefined, underlies the acquisition of LC/A histology in this subtype. MBs developing in p53-deficient Ptch+/- SHH mice show LC/A features that correlate with mTORC1 hyperactivation, which, mechanistically, is mediated by a decrease in the p53-dependent expression of the negative mTORC1 regulator Tsc2. Ectopic mTORC1 activation in mouse MB cancer stem cells (CSCs) promotes the acquisition of the LC/A phenotype. Furthermore, mTORC1 inhibition in both autochthonous p53-mutant SHH MBs and CSC-derived LC/A MBs results in reduced tumor burden and enhanced survival. Most remarkably, mTORC1 hyperactivation in tumor cells is detected only in human p53-mutant SHH MB samples and treatment with rapamycin of a human preclinical model phenocopying this subgroup decreases tumor growth and malignancy. As such, mTORC1 may act as a new and specific druggable target for this subset of SHH MB, thus resulting in the implementation of a more stringent MB risk stratification and in the potentially rapid translation of this precision medicine approach into the clinical setting.
2021-10-21 | GSE183901 | GEO
Project description:Medulloblastoma (MB), one of the most malignant brain tumors of childhood, comprises distinct molecular subgroups, with p53 mutant sonic hedgehog-activated (SHH-activated) MB patients having a very severe outcome that is associated with unfavorable histological large cell/anaplastic (LC/A) features. To identify the molecular underpinnings of this phenotype, we analyzed a large cohort of MB developing in p53-deficient Ptch+/- SHH mice that, unexpectedly, showed LC/A traits that correlated with mTORC1 hyperactivation. Mechanistically, mTORC1 hyperactivation was mediated by a decrease in the p53-dependent expression of mTORC1 negative regulator Tsc2. Ectopic mTORC1 activation in mouse MB cancer stem cells (CSCs) promoted the in vivo acquisition of LC/A features and increased malignancy; accordingly, mTORC1 inhibition in p53-mutant Ptch+/- SHH MB and CSC-derived MB resulted in reduced tumor burden and aggressiveness. Most remarkably, mTORC1 hyperactivation was detected only in p53-mutant SHH MB patient samples, and treatment with rapamycin of a human preclinical model phenocopying this subgroup decreased tumor growth and malignancy. Thus, mTORC1 may act as a specific druggable target for this subset of SHH MB, resulting in the implementation of a stringent risk stratification and in the potentially rapid translation of this precision medicine approach into the clinical setting.
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Project description:We undertook a comprehensive clinical and biological investigation of serial medulloblastoma biopsies obtained at diagnosis and relapse. Combined MYC gene family amplifications and P53 pathway defects commonly emerged at relapse, and all patients in this molecular group died of rapidly progressive disease post-relapse. To study this genetic interaction, we investigated a transgenic model of MYCN-driven medulloblastoma and found spontaneous development of Trp53 inactivating mutations. Abrogation of Trp53 function in this model produced aggressive tumors that mimicked the characteristics of relapsed human tumors with combined P53–MYC dysfunction. Restoration of p53 activity, genetic and therapeutic suppression of MYCN all reduced tumor growth and prolonged survival. Our findings identify P53–MYC interactions which emerge at medulloblastoma relapse as biomarkers of clinically aggressive disease that may be targeted therapeutically. There are currently no effective therapies for children with relapsed medulloblastoma. While clinical and biological features of the disease at diagnosis are increasingly well understood, biopsy is rarely performed at relapse and few biological data are available to guide more effective treatments. Here, we show that medulloblastomas develop altered biology at relapse which is predictive of disease course and cannot be detected at diagnosis. We have discovered the emergence of P53–MYC interactions at relapse, as biomarkers of clinically aggressive relapsed disease, which can be modelled and targeted therapeutically in genetically-engineered mice. These data provide clear precedent for the incorporation of biopsy at relapse into routine clinical practice, to direct palliative care and the development of improved treatment strategies. mouse model expression profiles from various mouse Medulloblastoma models MYCN/MYC overexpressing with/without p53 Mutations were compared to human MB expression profiles using Non-negative Matrix Factorization projection in order to sub-type the mouse models
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Project description:The outcome of patients with anaplastic gliomas varies considerably depending on histology and single molecular markers such as codeletion of 1p/19q and mutations of the isocitrate dehydrogenase (IDH) gene. Whether a molecularly-based classification of anaplastic gliomas based on large scale genomic or epigenomic analyses is superior to histopathology, may reflect distinct biological subtypes, predict outcome and guide therapy decisions had yet to be determined. Epigenome-wide DNA methylation analysis, which also allows for the detection of copy-number aberrations, was performed in a cohort of 228 patients with anaplastic gliomas (astrocytomas, oligoastrocytomas and oligodendrogliomas), including 115 patients of the NOA-04 trial. We further compared these tumors with a group of 55 glioblastomas. Unsupervised clustering demonstrated two main groups based on IDH mutation status: CpG island methylator phenotype (CIMP) positive (77.5%) or negative (22.5%). CIMP+ (IDH mutant) tumors showed a further separation based on copy-number status of chromosome arms 1p and 19q, but not based on histopathology. CIMP- (IDH wild type) tumors on the other hand showed hallmark copy-number alterations of glioblastomas. These tumors clustered together with CIMP- glioblastomas without forming separate groups based on WHO grade. There was no Tumor classification based on CIMP and 1p/19q status was significantly associated with survival allowing a better prediction of outcome than the current histopathological classification alone: Patients with CIMP+ tumors with 1p/19q codeletion had the best prognosis, followed by patients with CIMP+ but intact 1p/19q status. Patients with CIMP- anaplastic gliomas had the worst prognosis. Collectively, our data suggest that anaplastic gliomas can be grouped into three molecular subtypes with clear association to underlying biology and clinical outcome based on IDH and 1p/19q status. The data do not provide a molecular basis for the diagnosis of anaplastic oligoastrocytoma. We investigated a subset of 228 anaplastic gliomas using the Illumina 450k methylation array.
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Project description:The outcome of patients with anaplastic gliomas varies considerably depending on histology and single molecular markers such as codeletion of 1p/19q and mutations of the isocitrate dehydrogenase (IDH) gene. Whether a molecularly-based classification of anaplastic gliomas based on large scale genomic or epigenomic analyses is superior to histopathology, may reflect distinct biological subtypes, predict outcome and guide therapy decisions had yet to be determined. Epigenome-wide DNA methylation analysis, which also allows for the detection of copy-number aberrations, was performed in a cohort of 228 patients with anaplastic gliomas (astrocytomas, oligoastrocytomas and oligodendrogliomas), including 115 patients of the NOA-04 trial. We further compared these tumors with a group of 55 glioblastomas. Unsupervised clustering demonstrated two main groups based on IDH mutation status: CpG island methylator phenotype (CIMP) positive (77.5%) or negative (22.5%). CIMP+ (IDH mutant) tumors showed a further separation based on copy-number status of chromosome arms 1p and 19q, but not based on histopathology. CIMP- (IDH wild type) tumors on the other hand showed hallmark copy-number alterations of glioblastomas. These tumors clustered together with CIMP- glioblastomas without forming separate groups based on WHO grade. There was no Tumor classification based on CIMP and 1p/19q status was significantly associated with survival allowing a better prediction of outcome than the current histopathological classification alone: Patients with CIMP+ tumors with 1p/19q codeletion had the best prognosis, followed by patients with CIMP+ but intact 1p/19q status. Patients with CIMP- anaplastic gliomas had the worst prognosis. Collectively, our data suggest that anaplastic gliomas can be grouped into three molecular subtypes with clear association to underlying biology and clinical outcome based on IDH and 1p/19q status. The data do not provide a molecular basis for the diagnosis of anaplastic oligoastrocytoma.
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