Medulloblastoma group 3 and 4 tumors comprise a clinically and biologically significant expression continuum reflecting human cerebellar development

• Published in: Cell reports (Cambridge) 2022-08, Vol.40 (5), p.111162-111162, Article 111162
• Main Authors: Williamson, Daniel, Schwalbe, Edward C., Hicks, Debbie, Aldinger, Kimberly A., Lindsey, Janet C., Crosier, Stephen, Richardson, Stacey, Goddard, Jack, Hill, Rebecca M., Castle, Jemma, Grabovska, Yura, Hacking, James, Pizer, Barry, Wharton, Stephen B., Jacques, Thomas S., Joshi, Abhijit, Bailey, Simon, Clifford, Steven C.
• Format: Article
• Language: English
• Subjects: Cerebellar Neoplasms - genetics; Cerebellar Neoplasms - pathology; development; DNA Methylation - genetics; genomics; Humans; medulloblastoma; Medulloblastoma - genetics; Medulloblastoma - pathology; pediatrics
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2022.111162

Medulloblastoma is currently subclassified into distinct DNA methylation subgroups/subtypes with particular clinico-molecular features. Using RNA sequencing (RNA-seq) in large, well-annotated cohorts of medulloblastoma, we show that transcriptionally group 3 and group 4 medulloblastomas exist as intermediates on a bipolar continuum between archetypal group 3 and group 4 entities. Continuum position is prognostic, reflecting a propensity for specific DNA copy-number changes, and specific switches in isoform/enhancer usage and RNA editing. Examining single-cell RNA-seq (scRNA-seq) profiles, we show that intratumoral transcriptional heterogeneity along the continuum is limited in a subtype-dependent manner. By integrating with a human scRNA-seq reference atlas, we show that this continuum is mirrored by an equivalent continuum of transcriptional cell types in early fetal cerebellar development. We identify distinct developmental niches for all four major subgroups and link each to a common developmental antecedent. Our findings show a transcriptional continuum arising from oncogenic disruption of highly specific fetal cerebellar cell types, linked to almost every aspect of group 3/group 4 molecular biology and clinico-pathology. [Display omitted] •Group 3 and group 4 medulloblastoma exist along a transcriptomic continuum•Position on the continuum is prognostic and reflects key molecular aberrations•Intratumoral transcriptional heterogeneity is limited according to subtype•This continuum maps to early fetal development, implicating cells of origin The childhood brain tumor medulloblastoma is classified into multiple DNA methylation-based subtypes. Using RNA-seq, Williamson et al. show that group 3 and group 4 tumors manifest as intermediates on a transcriptomic continuum. Position on the continuum is associated with molecular pathology and disease course. The continuum mirrors early cerebellar development, implicating cells of origin.