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Updated: Jan 3, 2026
Isolation, Enrichment, and Maintenance of Medulloblastoma Stem Cells
Published on: September 1, 2010
Sox2+ cells in Sonic Hedgehog-subtype medulloblastoma resist p53-mediated cell-cycle arrest response and drive
Daniel M Treisman1,2,3,4,5, Yinghua Li3,4,5, Brianna R Pierce3,4,5
1Cellular and Molecular Biology Graduate Program, Ann Arbor, Michigan.
Background:
High-intensity therapy effectively treats most TP53 wild-type (TP53-WT) Sonic Hedgehog-subgroup medulloblastomas (SHH-MBs), but often cause long-term deleterious neurotoxicities in children. Recent clinical trials investigating reduction/de-escalation of therapy for TP53-WT SHH-MBs caused poor overall survival. Here, we investigated whether reduced levels of p53-pathway activation by low-intensity therapy potentially contribute to diminished therapeutic efficacy.
Methods:
Using mouse SHH-MB models with different p53 activities, we investigated therapeutic efficacy by activating p53-mediated cell-cycle arrest versus p53-mediated apoptosis on radiation-induced recurrence.
Results:
Upon radiation treatment, p53WT-mediated apoptosis was sufficient to eliminate all SHH-MB cells, including Sox2+ cells. The same treatment eliminated most Sox2- bulk tumor cells in SHH-MBs harboring p53 R172P, an apoptosis-defective allele with cell-cycle arrest activity, via inducing robust neuronal differentiation. Rare quiescent Sox2+ cells survived radiation-enhanced p53R172P activation and entered a proliferative state, regenerating tumors. Transcriptomes of Sox2+ cells resembled quiescent Nestin-expressing progenitors in the developing cerebellum, expressing Olig2 known to suppress p53 and p21 expression. Importantly, high SOX2 expression is associated with poor survival of all four SHH-MB subgroups, independent of TP53 mutational status.
Conclusions:
Quiescent Sox2+ cells are efficiently eliminated by p53-mediated apoptosis, but not cell-cycle arrest and differentiation. Their survival contributes to tumor recurrence due to insufficient p53-pathway activation.
Insights
Quiescent Sox2+ cells in medulloblastoma recur after therapy due to insufficient p53 activation. Apoptosis effectively eliminates these cells, unlike cell-cycle arrest or differentiation, preventing tumor recurrence.
Area of Science:
- Pediatric oncology
- Cancer biology
- Molecular genetics
Background:
- High-intensity therapy for TP53 wild-type (TP53-WT) Sonic Hedgehog-subgroup medulloblastomas (SHH-MBs) causes neurotoxicity.
- Reduced therapy intensity in TP53-WT SHH-MBs led to poor survival in clinical trials.
- Investigating the role of p53-pathway activation levels in therapeutic efficacy for SHH-MBs.
Purpose of the Study:
- To investigate the impact of reduced p53-pathway activation on the efficacy of low-intensity therapy for SHH-MBs.
- To determine if p53-mediated apoptosis or cell-cycle arrest is more critical for eliminating SHH-MB cells, including therapy-resistant populations.
- To understand the mechanisms underlying tumor recurrence in SHH-MBs after radiation treatment.
Main Methods:
- Utilized mouse SHH-MB models with varying p53 activities.
- Assessed therapeutic efficacy by activating p53-mediated cell-cycle arrest versus p53-mediated apoptosis.
- Analyzed the response to radiation treatment and characterized surviving cell populations.
Main Results:
- p53WT-mediated apoptosis eradicated all SHH-MB cells, including Sox2+ cells, after radiation.
- In p53R172P (apoptosis-defective) models, neuronal differentiation eliminated most Sox2- bulk cells, but rare quiescent Sox2+ cells survived and repopulated tumors.
- Sox2+ cells exhibited progenitor-like characteristics and expressed Olig2, which suppresses p53 and p21.
- High SOX2 expression correlated with poor survival across all SHH-MB subgroups, irrespective of TP53 status.
Conclusions:
- Quiescent Sox2+ cells are eliminated by p53-mediated apoptosis but not by cell-cycle arrest or differentiation.
- Incomplete p53-pathway activation allows survival of Sox2+ cells, leading to tumor recurrence.
- Targeting p53-mediated apoptosis is crucial for durable responses in SHH-MBs.
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