Project description:We explore cellular heterogeneity in 28 childhood medulloblastoma (MB) (1 WNT, 9 SHH, 7 GP3 and 11 GP4) using single-cell RNA sequencing (scRNA-seq), immunohistochemistry and deconvolution of bulk transcriptomic data. Neoplastic cells are broadly clustered according to subgroup, and within subgroups discrete sample clustering is associated with chromosomal copy number variance. Each subgroup contains subpopulations exhibiting mitotic , undifferentiated and neuronal differentiated transcript profiles , corroborating other recent medulloblastoma scRNA-seq studies and identifying new subpopulations. We identify a photoreceptor-differentiated subpopulation that is predominantly found in GP3 medulloblastoma, and in SHH, a subpopulation that constitutes differentiating nodules . Deconvolution of a large transcriptomic dataset shows that neoplastic subpopulations are associated with major and minor subgroup subdivisions, for example, photoreceptor subpopulation cells are more abundant in GP3-alpha. This scRNA-seq dataset also demonstrates medulloblastoma subgroup-specific differences in the tumor microenvironment and immune landscape, and reveals an SHH nodule -associated myeloid subpopulation. Additionally, we perform scRNA-seq on genetically engineered mouse (GEM) models of GP3 and SHH medulloblastoma. These models specifically matched the corresponding human subgroup-specific neoplastic subpopulations. We provide an interactive online resource that facilitates exploration of these MB single cell datasets. Collectively, our findings advance our understanding of the neoplastic and immune landscape of the main medulloblastoma subgroups in both humans and GEM models.
Project description:A hallmark of high-risk childhood medulloblastoma is the dysregulation of RNA translation. Currently, it is unknown whether medulloblastoma dysregulates the translation of putatively oncogenic non-canonical open reading frames. To address this question, we performed ribosome profiling of 32 medulloblastoma tissues and cell lines and observed widespread non-canonical ORF translation. We then developed a step-wise approach using multiple CRISPR-Cas9 screens to elucidate non-canonical ORFs and putative microproteins implicated in medulloblastoma cell survival. We determined that multiple lncRNA-ORFs and upstream open reading frames (uORFs) exhibited selective functionality independent of the main coding sequence. A microprotein encoded by one of these ORFs, ASNSD1-uORF or ASDURF, was upregulated, associated with the MYC family oncogenes, and was required for medulloblastoma cell survival through engagement with the prefoldin-like chaperone complex. Our findings underscore the fundamental importance of non-canonical ORF translation in medulloblastoma and provide a rationale to include these ORFs in future studies seeking to define new cancer targets.
Project description:A high throughput microRNA expression profiles was performed in human primary medulloblastoma specimens and relative controls to investigate microRNA involvement in medulloblastoma carcinogenesis. Medulloblastoma is an aggressive brain malignancy with high incidence in childhood. MicroRNA expression analysis has emerged as a powerful tool to identify candidate molecules playing an important role in a large number of malignancies. A high throughput microRNA expression profiles was performed in human primary medulloblastoma specimens and relative controls to investigate microRNA involvement in medulloblastoma carcinogenesis. Keywords: RT-PCR
Project description:These methylation arrays were performed as part of a project aiming to integrate quantitative proteomic, gene expression and epigenetic data from the childhood brain tumor medulloblastoma.
Project description:These gene expression microarrays were performed as part of a project aiming to integrate quantitative proteomic, gene expression and epigenetic data from the childhood brain tumor medulloblastoma.
Project description:KDM5A/LSD1 is an important epigenetic regulator in medulloblastoma, the most frequent brain tumor of childhood. Here, the response of ONS76 medulloblastoma cells upon siRNA-mediated knockdown of KDM5A is analysed.
Project description:KDM5A/LSD1 is an important epigenetic regulator in medulloblastoma, the most frequent brain tumor of childhood. Here, the response of ONS76 medulloblastoma cells upon siRNA-mediated knockdown of KDM5A is analysed. The expression profile of ONS76 cells upon KDM5A knockdown was compared to mock control. Both conditions were run in triplicate.
Project description:Medulloblastoma encompasses a collection of clinically and molecularly diverse tumor subtypes that together comprise the most common malignant childhood brain tumor. These tumors are thought to arise within the cerebellum, with approximately 25% originating from granule neuron precursor cells (GNPCs) following aberrant activation of the Sonic Hedgehog pathway (hereafter, SHH-subtype). The pathological processes that drive heterogeneity among the other medulloblastoma subtypes are not known, hindering the development of much needed new therapies. Here, we provide evidence that a discrete subtype of medulloblastoma that contains activating mutations in the WNT pathway effector CTNNB1 (hereafter, WNT-subtype), arises outside the cerebellum from cells of the dorsal brainstem. We found that genes marking human WNT-subtype medulloblastomas are more frequently expressed in the lower rhombic lip (LRL) and embryonic dorsal brainstem than in the upper rhombic lip (URL) and developing cerebellum. Magnetic resonance imaging (MRI) and intra-operative reports showed that human WNT-subtype tumors infiltrate the dorsal brainstem, while SHH-subtype tumors are located within the cerebellar hemispheres. Activating mutations in Ctnnb1 had little impact on progenitor cell populations in the cerebellum, but caused the abnormal accumulation of cells on the embryonic dorsal brainstem that included aberrantly proliferating Zic1+ precursor cells. These lesions persisted in all mutant adult mice and in 15% of cases in which Tp53 was concurrently deleted, progressed to form medulloblastomas that recapitulated the anatomy and gene expression profiles of human WNT-subtype medulloblastoma. We provide the first evidence that subtypes of medulloblastoma have distinct cellular origins. Our data provide an explanation for the marked molecular and clinical differences between SHH and WNT-subtype medulloblastomas and have profound implications for future research and treatment of this important childhood cancer. A total of 16 samples are analyzed, repsresenting 4 experimental groups: Ctnnb1 medulloblastoma (3 samples); Ptch1 medulloblastoma (6 samples); embryonic dorsal brainstem (4 samples); and postnatal granule neuron precursor cells (3 samples). Every sample was prepared from a different mouse.