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Thrombospondin-1 mimetics are promising novel therapeutics for MYC-associated medulloblastoma
Tiffany S Y Chan1,2, Daniel Picard1, Cynthia E Hawkins2,3
1Department of Pediatrics, Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
Background:
Medulloblastoma (MB) comprises four subtypes of which group 3 MB are the most aggressive. Although overall survival for MB has improved, the outcome of group 3 MB remains dismal. C-MYC (MYC) amplification or MYC overexpression which characterizes group 3 MB is a strong negative prognostic factor and is frequently associated with metastases and relapses. We previously reported that MYC expression alone promotes highly aggressive MB phenotypes, in part via repression of thrombospondin-1 (TSP-1), a potent tumor suppressor.
Methods:
In this study, we examined the potential role of TSP-1 and TSP-1 peptidomimetic ABT-898 in MYC-amplified human MB cell lines and two distinct murine models of MYC-driven group 3 MBs.
Results:
We found that TSP-1 reconstitution diminished metastases and prolonged survival in orthotopic xenografts and promoted chemo- and radio-sensitivity via AKT signaling. Furthermore, we demonstrate that ABT-898 can recapitulate the effects of TSP-1 expression in MB cells in vitro and specifically induced apoptosis in murine group 3 MB tumor cells.
Conclusion:
Our data underscore the importance of TSP-1 as a critical tumor suppressor in MB and highlight TSP-1 peptidomimetics as promising novel therapeutics for the most lethal subtype of MB.
Insights
Thrombospondin-1 (TSP-1) acts as a tumor suppressor in aggressive group 3 medulloblastoma (MB). Restoring TSP-1 or using its peptidomimetic ABT-898 combats MB progression and enhances treatment sensitivity.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Group 3 medulloblastoma (MB) is the most aggressive subtype with poor outcomes.
- MYC amplification/overexpression in group 3 MB correlates with poor prognosis, metastasis, and relapse.
- MYC overexpression suppresses thrombospondin-1 (TSP-1), a known tumor suppressor.
Purpose of the Study:
- To investigate the therapeutic potential of TSP-1 and its peptidomimetic ABT-898 in MYC-amplified group 3 MB.
- To evaluate the role of TSP-1 in mitigating aggressive phenotypes associated with MYC-driven MB.
Main Methods:
- Examined TSP-1 and ABT-898 in MYC-amplified human MB cell lines.
- Utilized two distinct murine models of MYC-driven group 3 MB.
- Assessed effects on metastasis, survival, chemo- and radio-sensitivity, and apoptosis.
Main Results:
- TSP-1 reconstitution reduced metastases and improved survival in xenografts.
- TSP-1 enhanced chemo- and radio-sensitivity through AKT signaling.
- ABT-898 mimicked TSP-1 effects in vitro and induced apoptosis in murine group 3 MB cells.
Conclusions:
- TSP-1 is a critical tumor suppressor in medulloblastoma.
- TSP-1 peptidomimetics like ABT-898 show promise as novel therapeutics for aggressive group 3 MB.
