Project description:Medulloblastoma is a malignant childhood cerebellar tumour comprised of distinct molecular subgroups. Whereas genomic characteristics of these subgroups are well defined, the extent to which cellular diversity underlies their divergent biology and clinical behaviour remains largely unexplored. We used single-cell transcriptomics to investigate intra- and inter-tumoural heterogeneity in twenty-five medulloblastomas spanning all molecular subgroups. WNT, SHH, and Group 3 tumours comprised subgroup-specific undifferentiated and differentiated neuronal-like malignant populations, whereas Group 4 tumours were exclusively comprised of differentiated neuronal-like neoplastic cells. SHH tumours closely resembled granule neurons of varying differentiation states that correlated with patient age. Group 3 and Group 4 tumours exhibited a developmental trajectory from primitive progenitor-like to more mature neuronal-like cells, whose relative proportions distinguished these subgroups. Cross-species transcriptomics defined distinct glutamatergic populations as putative cells-of-origin for SHH and Group 4 subtypes. Collectively, these data provide novel insights into the cellular and developmental states underlying subtype-specific medulloblastoma biology.
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:Here, we studied the effects of oHSV C134 in two syngeneic medulloblastoma mouse models, one that aligns with the sonic hedgehog (SHH) subtype (MYCN) and another that aligns with tumors of the group 3 subtype (CMYC).We harvested tumor tissue two and six days post-injection of C134 and performed single cell RNA-sequencing (scRNA-seq).