mTORC1 promotes malignant large cell/ anaplastic histology and is a targetable vulnerability in SHH-TP53 mutant medulloblastoma

V. Conti, M. Cominelli, V. Pieri, A.L. Gallotti, I. Pagano, M. Zanella, S. Mazzoleni, F. Pivetta, M. Patanè, G.M. Scotti, I.S. Piras, B. Pollo, A. Falini, A. Zippo, A. Castellano, R. Maestro, P.L. Poliani, R. Galli

Research output: Contribution to journalArticlepeer-review


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. © 2021, Conti et al.
Original languageEnglish
Article numbere153462
Number of pages23
JournalJCI Insight
Issue number23
Publication statusPublished - 2021


  • mammalian target of rapamycin complex 1
  • protein p53
  • sonic hedgehog protein
  • animal cell
  • animal experiment
  • animal model
  • animal tissue
  • apoptosis
  • Article
  • controlled study
  • correlation analysis
  • gene mutation
  • human
  • human cell
  • immunomodulation
  • immunophenotyping
  • immunoreactivity
  • immunoregulation
  • large cell carcinoma
  • medulloblastoma
  • molecular dynamics
  • mouse
  • nonhuman
  • oncogene
  • phenotype
  • protein analysis
  • protein expression
  • protein function
  • SHH TP53 gene
  • tumor volume


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