Related Experiment Video
Updated: Sep 18, 2025
A Data Integration Workflow to Identify Drug Combinations Targeting Synthetic Lethal Interactions
Published on: May 27, 2021
Targeting synthetic lethality between non-homologous end joining and radiation in very-high-risk medulloblastoma
Alexandria DeCarlo1, Graham MacLeod2, Carolina Fernandes da Silva3
1Developmental, Stem Cell and Cancer Biology Programme, Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada.
Abstract:
Specific and biologically informed treatments for medulloblastoma, especially for the highly lethal TP53-mutant SHH subgroup, remain elusive, where radiotherapy is the primary treatment modality. Leveraging genome-wide CRISPR-Cas9 dropout screening in combination with lethal doses of radiotherapy, we identify loss of p53 as the main driver of radiation resistance in SHH medulloblastoma. A negative-selection CRISPR-Cas9 screen across multiple models of Trp53-deficient SHH medulloblastoma reveals a strong synthetic lethal interaction between components of the non-homologous end-joining pathway and radiation, particularly DNA-dependent protein kinase (DNA-PK) and its binding partners. Both genetic and pharmacological perturbation of DNA-PK enhance radiosensitivity in TP53-deficient SHH medulloblastoma, leading to cell death. In vivo treatment of both somatic and germline TP53-mutant SHH medulloblastoma models with peposertib, a small-molecule inhibitor of DNA-PK, significantly improves survival when combined with radiotherapy, strongly supporting further clinical investigation.
Insights
Loss of p53 drives radiation resistance in SHH medulloblastoma. Targeting DNA-PK, a key DNA repair enzyme, with inhibitors like peposertib enhances radiosensitivity and improves survival in preclinical models.
Area of Science:
- Oncology
- Molecular Biology
- Radiation Oncology
Background:
- Medulloblastoma, particularly the SHH subgroup with TP53 mutations, lacks effective targeted treatments, relying heavily on radiotherapy.
- Radiation resistance is a major challenge in treating aggressive medulloblastoma subtypes.
- Identifying specific vulnerabilities in cancer cells can lead to novel therapeutic strategies.
Purpose of the Study:
- To identify genetic drivers of radioresistance in TP53-mutant SHH medulloblastoma.
- To discover synthetic lethal interactions that can be targeted to enhance radiotherapy efficacy.
- To evaluate the therapeutic potential of targeting DNA-PK in preclinical models of medulloblastoma.
Main Methods:
- Genome-wide CRISPR-Cas9 dropout screening was employed in combination with radiotherapy.
- Negative-selection screens were performed across various Trp53-deficient SHH medulloblastoma models.
- Genetic and pharmacological inhibition of DNA-dependent protein kinase (DNA-PK) was investigated.
- In vivo studies utilized somatic and germline TP53-mutant SHH medulloblastoma models treated with peposertib and radiotherapy.
Main Results:
- Loss of p53 was identified as a primary driver of radiation resistance in SHH medulloblastoma.
- A synthetic lethal interaction was discovered between non-homologous end-joining (NHEJ) pathway components, specifically DNA-PK, and radiation.
- Both genetic and pharmacological inhibition of DNA-PK significantly increased radiosensitivity and induced cell death in TP53-deficient cells.
- Combined treatment with peposertib and radiotherapy markedly improved survival in preclinical medulloblastoma models.
Conclusions:
- Targeting DNA-PK represents a promising strategy to overcome radioresistance in TP53-mutant SHH medulloblastoma.
- Pharmacological inhibition of DNA-PK in combination with radiotherapy shows significant therapeutic potential.
- Further clinical investigation of DNA-PK inhibitors for medulloblastoma treatment is warranted.
Related Concept Videos
02:57Targeted Cancer Therapies
There are several types of targeted therapies against...
02:50Combination Therapies and Personalized Medicine
The combination of the drug acetazolamide and sulforaphane is a good example of combination therapy to treat cancer. The cells in the interior of a large tumor often die due to the hypoxic and...