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Updated: Jun 28, 2026
Isolation, Enrichment, and Maintenance of Medulloblastoma Stem Cells
Published on: September 1, 2010
Defining a role for Sonic hedgehog pathway activation in desmoplastic medulloblastoma by identifying GLI1 target
Joon Won Yoon1, Richard Gilbertson, Stephen Iannaccone
1Developmental Biology Program, Children's Memorial Research Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Abstract:
A subgroup of medulloblastomas shows constitutive activation of the Sonic hedgehog pathway with expression of GLI1. We identified the subset of GLI1 transforming target genes specifically expressed in medulloblastomas by comparing GLI1 targets in RK3E cells transformed by GLI1 with the gene expression profile of Sonic hedgehog signature medulloblastomas. We identified 1,823 genes whose expression was altered more than 2-fold in 2 independent RK3E + GLI1 cell lines. We identified 25 whose expression was altered similarly in medulloblastomas expressing GLI1. We identified potential GLI binding elements in the regulatory regions of 10 of these genes, confirmed that GLI1 binds the regulatory regions and activates transcription of select genes, and showed that GLI1 directly represses transcription of Krox-20. We identified upregulation of CXCR4, a chemokine receptor that plays roles in the proliferation and migration of granule cell neuron precursors during development, supporting the concept that reinitiation of developmental programs may contribute to medulloblastoma tumorigenesis. In addition, the targets suggest a pathway through which GLI1 may ultimately affect medulloblastoma cell proliferation, survival and genomic stability by converging on p53, SGK1, MGMT and NTRK2. We identify a p53 mutation in RK3E + GLI1 cells, suggesting that p53 mutations may sometimes shift the balance toward dysregulated tumor cell survival.
Insights
Sonic hedgehog pathway activation in medulloblastoma involves GLI1 target genes. Researchers identified specific GLI1-regulated genes contributing to tumor development and survival, offering new therapeutic targets.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Medulloblastoma, a pediatric brain tumor, can exhibit constitutive activation of the Sonic hedgehog (SHH) signaling pathway.
- GLI1 is a key transcription factor downstream of the SHH pathway, driving tumor growth.
Purpose of the Study:
- To identify GLI1-target genes specifically involved in medulloblastoma.
- To understand the molecular mechanisms by which GLI1 contributes to medulloblastoma tumorigenesis.
Main Methods:
- Comparative gene expression profiling of GLI1-transformed RK3E cells and medulloblastoma samples.
- Identification and validation of GLI1 binding sites in regulatory regions.
- Analysis of gene expression changes and pathway involvement.
Main Results:
- Identified 25 GLI1 target genes commonly altered in medulloblastomas.
- Confirmed GLI1 binding and transcriptional regulation of specific target genes, including repression of Krox-20.
- Observed upregulation of CXCR4, suggesting reinitiation of developmental programs.
- Identified potential GLI1 targets converging on pathways regulating cell proliferation, survival, and genomic stability (p53, SGK1, MGMT, NTRK2).
- Found a p53 mutation in GLI1-transformed cells, indicating a role in dysregulated cell survival.
Conclusions:
- GLI1 directly regulates a specific set of genes in medulloblastoma.
- Reactivation of developmental pathways and alterations in cell survival mechanisms contribute to medulloblastoma.
- These findings provide insights into SHH-driven medulloblastoma pathogenesis and potential therapeutic strategies.
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