ID #715 Exploring and targeting therapy-induced cellular senescence in medulloblastoma

Abstract

Medulloblastoma is the most common malignant brain tumour in children, accounting for ∼20% of paediatric brain cancers. Although chemotherapy is essential for treatment, its toxicity is associated within long-term morbidity and aggressive tumour recurrences. Emerging evidence implicates cellular senescence, a growth-arrest state triggered by DNA damage, in therapy resistance and disease relapse across multiple cancers. However, the role of therapy-induced senescence (TIS) in medulloblastoma remains poorly understood. If present, targeting senescent tumour cells may represent a strategy to enhance treatment outcomes. This study investigated whether standard-of-care medulloblastoma therapies induce cellular senescence in preclinical medulloblastoma models.

Four cell lines from molecular Group 3 (D341, MED-411) and Group 4 (CHLA-01, CHLA-01R) were treated with varying concentrations of vincristine or cisplatin for 24 h, followed by assessment of cell viability and analysis of senescence-associated biomarkers. Nuclear area, cell area, SA-β-galactosidase activity, p21, p16, and EdU incorporation were assessed 7 and 14 days post-treatment using single-cell high-content fluorescence imaging. Senolytic agent ABT-263 was subsequently evaluated for its ability to enhance post-treatment cell elimination following vincristine exposure.

Both chemotherapies induced a senescence-like phenotype characterised by marked temporal heterogeneity, with increased p16 and/or p21 expression and a concentration-dependent reduction in EdU incorporation across all cell lines. Classical morphological senescence markers were more variable, with a significant increase in nuclear and cell area observed only in D341. Notably, combined treatment with vincristine and senolytic ABT-263 synergistically reduced D341 viability.

These findings suggest that vincristine and cisplatin can induce a senescence-like state in medulloblastoma cells and provide preliminary support for exploring senolytic–chemotherapy combinations as a strategy to enhance treatment responses. Ongoing studies will further explore various medulloblastoma-specific treatments and patient-derived models to define the molecular characteristics and therapeutic relevance of TIS in medulloblastoma using transcriptomic profiling, organoids, and orthotopic mouse models, alongside evaluation of senotherapeutic approaches.