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Genome-Wide CRISPR Screen for Unveiling Radiosensitive and Radioresistant Genes
Published on: May 23, 2025
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Cryptic developmental events determine medulloblastoma radiosensitivity and cellular heterogeneity without altering
Daniel Shiloh Malawsky1, Seth J Weir1, Jennifer Karin Ocasio1,2
1Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
Communications Biology
|May 22, 2021
Summary
Medulloblastoma treatment outcomes vary due to developmental timing of mutations. Early mutations trigger radioresistant tumors, while later mutations yield radiation-curable tumors, revealing developmental events as key to prognosis.
Area of Science:
- Neuro-oncology
- Developmental biology
- Cancer genomics
Background:
- Medulloblastoma patient outcomes differ despite similar treatments.
- Transcriptomic profiling identifies prognostic subgroups but doesn't explain individual recurrence risk.
- Understanding variable tumor behavior requires investigating early developmental influences.
Purpose of the Study:
- To explore how the timing of oncogenic mutation during brain development impacts medulloblastoma progression, radiosensitivity, and cellular composition.
- To identify developmental determinants of tumor heterogeneity and treatment response.
Main Methods:
- Genetically engineered mice to express oncogenic SmoM2 in either multipotent stem cells or committed neural progenitors.
- Compared medulloblastoma progression, radiosensitivity, and cellular heterogeneity using single-cell transcriptomic analysis (scRNA-seq).
- Analyzed tumor microenvironment composition, including macrophage and microglia populations.
Main Results:
- Stem cell-triggered medulloblastomas showed faster progression, radioresistance, and higher levels of stem-like OLIG2+ cells.
- Progenitor-triggered medulloblastomas exhibited slower progression, reduced stem-like cells, and were sensitive to radiation.
- Developmental timing influenced tumor microenvironment, with progenitor-triggered tumors having diverse stromal populations and altered macrophage/microglia ratios.
- Reduced mTORC1 activity and differential IGF1 signaling were observed in stem cell-triggered tumors.
Conclusions:
- The developmental stage at which a driver mutation occurs significantly influences medulloblastoma phenotype, heterogeneity, and treatment response.
- Transcriptomic profiles alone may not capture the full picture of medulloblastoma pathogenesis.
- Resolving cellular heterogeneity through methods like scRNA-seq is crucial for understanding medulloblastoma prognosis and developing effective therapies.
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