Development of an Orthotopic Medulloblastoma Zebrafish Model for Rapid Drug Testing

Pediatrics Neurology Oncology Medicine
medulloblastoma zebrafish model drug testing neural stem cells tumor growth

Academic Background

Medulloblastoma (MB) is one of the most common malignant brain tumors in children. Although recent advances in molecular characterization and multimodal treatment have significantly improved patient survival rates, the prognosis of medulloblastoma remains closely related to molecular subtypes, particularly for patients with Group 3 MB, who have the worst prognosis. Currently, preclinical research primarily relies on mouse models, which are time-consuming and costly, making them unsuitable for large-scale drug screening. Therefore, developing a rapid and efficient in vivo model is crucial for accelerating research into medulloblastoma treatment.

Zebrafish (Danio rerio) embryos have gradually become an ideal model for studying various human cancers due to their high fecundity, ex utero embryogenesis, small size, rapid development, and low maintenance costs. In particular, zebrafish embryos can mimic tumor growth and metastasis after transplantation of human tumor cells, displaying characteristics similar to patient tumors. However, the application of zebrafish models in medulloblastoma research has not been fully explored. The aim of this study was to develop a zebrafish-based medulloblastoma model for rapid drug testing and tumor growth research.

Source of the Paper

This research was conducted by Niek van Bree, Ann-Sophie Oppelt, Susanne Lindström, and others from Karolinska Institutet, and was published in the journal Neuro-Oncology, with an early online release on October 9, 2024. The study was supported by multiple grants, including those from Cancerfonden and Barncancerfonden.

Research Process and Results

1. Establishment of the Zebrafish Embryo Transplantation Model

Researchers transplanted nine different medulloblastoma cell lines or patient-derived cells into the blastula stage of zebrafish embryos. Tumor development and migration were monitored using live imaging techniques. To enhance the homing ability of tumor cells, the cells were pre-conditioned in a neural stem cell-like medium, and transcriptomic changes were analyzed via RNA sequencing.

Key Results:

  • Transplanted medulloblastoma cells formed orthotopic tumors within 24 hours, primarily homing to the hindbrain region of zebrafish embryos.
  • Pre-conditioning in a neural stem cell-like medium significantly enhanced the homing ability and aggressiveness of tumor cells.
  • Transcriptomic analysis revealed that pre-conditioned cells exhibited a more migratory and neuronal phenotype, particularly with the upregulation of Sema3A and Efnb1 genes, which are associated with lower survival rates in medulloblastoma patients.

2. Validation of the Drug Testing Model

To validate the model’s drug testing capability, researchers conducted drug treatment experiments in a 96-well format. Transplanted zebrafish embryos were treated with drugs 24 hours post-transplantation, and drug efficacy was assessed via fluorescence imaging and luciferase activity assays 48 hours later.

Key Results:

  • Sonidegib (an SMO inhibitor) and 4-HCP (the active metabolite of cyclophosphamide) significantly inhibited tumor cell growth and survival.
  • The model allowed for rapid evaluation of drug efficacy, particularly during the early embryonic stage when the blood-brain barrier is not yet formed, providing a unique window for drug screening.

3. Impact of Neural Stem Cell Medium on Tumor Cells

Researchers cultured two medulloblastoma cell lines (UW228-3 and D425 Med) in a neural stem cell-like medium to observe its effects on tumor cell homing and invasiveness.

Key Results:

  • The neural stem cell-like medium significantly improved the homing ability and invasiveness of tumor cells, particularly in the hindbrain region.
  • Transcriptomic analysis revealed that the medium change led to the upregulation of genes associated with cell migration and neuronal development, such as Col6A1, Sema3A, and Efnb1.

4. Comparison of Different Medulloblastoma Subtypes

Researchers also compared the behavior of different medulloblastoma subtypes in the zebrafish model, including SHH, Group 3, and Group 4 subtypes.

Key Results:

  • All medulloblastoma subtypes exhibited high brain homing ability, particularly in the hindbrain region.
  • Non-brain tumor cells (such as breast cancer cells MDA-MB-231 and colon cancer cells HCT116 p53+/+) primarily localized to non-brain regions, such as the yolk sac.

Conclusions and Significance

This study successfully developed a zebrafish embryo-based medulloblastoma model capable of rapidly evaluating tumor cell growth, homing ability, and drug efficacy. Compared to traditional mouse models, this model offers advantages such as simplicity, low cost, and short experimental cycles, making it particularly suitable for large-scale drug screening and personalized treatment research. Additionally, the study revealed the important role of neural stem cell-like medium in enhancing tumor cell homing and invasiveness, providing new insights into the molecular mechanisms of medulloblastoma.

Research Highlights

  1. Rapid Drug Screening: The model allows for quick evaluation of drug efficacy, providing a new tool for medulloblastoma treatment.
  2. Role of Neural Stem Cell Medium: The study found that neural stem cell-like medium significantly enhances the homing ability and invasiveness of tumor cells, highlighting the importance of the tumor microenvironment in tumor behavior.
  3. Multi-Subtype Research: The model is applicable to the study of various medulloblastoma subtypes, offering potential for personalized treatment across different subtypes.

Other Valuable Information

This study is the first to report the application of zebrafish embryos in medulloblastoma research, providing a new direction for future tumor studies. Additionally, the transcriptomic analysis in the study identified several key genes associated with tumor migration and invasion, offering potential candidate targets for molecular targeted therapy in medulloblastoma.

Through this research, the team not only developed an efficient experimental model but also provided important theoretical and practical tools for personalized treatment and drug development in medulloblastoma.