Medulloblastoma is the most common malignant brain tumour in children, constituting about 20% of paediatric brain cancers. Although chemotherapy is essential for treatment, its toxicity often results in long-term disabilities and more aggressive tumour recurrences. A growing body of evidence links cellular senescence, a growth-arrest state triggered by DNA damage, to therapy resistance and relapse in cancers. However, chemotherapy-induced senescence in medulloblastoma remains poorly understood. If such senescence is present, eliminating senescent cells could enhance treatment outcomes.
This study investigates whether vincristine, a chemotherapy drug used specifically for medulloblastoma, induces senescence in medulloblastoma cells.
Two cell lines, D341 and CHLA-01R-MED, were treated with varying vincristine concentrations (1-100nM) for 24 hours, followed by viability assessments and senescence biomarker analyses. To evaluate senescence, six biomarkers including nuclear area, cell area, SA-β-galactosidase activity, Interleukin-6 (IL-6), p21, and EdU incorporation were assessed 7 days post- vincristine using fluorescence imaging (PerkinElmer Phenix High Content Microscope). Additionally, a senolytic agent (ABT-263) was tested to determine its effect on eliminating senescent cells.
Vincristine treatment significantly reduced cell viability in both cell lines, with CHLA-01R-MED cells exhibiting greater sensitivity. While no significant changes were observed in nuclear area, cell area, or SA-β-gal activity in either cell line, IL-6 expression significantly increased in both cell lines, with CHLA-01R-MED showing a 2.6-2.8-fold increase, and D341 displaying a 2-fold increase at higher concentrations. p21 levels were significantly elevated only in D341. EdU incorporation decreased in a concentration-dependent manner in both lines, suggesting reduced cell proliferation. Combination treatment with ABT-263 and vincristine produced a synergistic effect, significantly reducing D341 cell viability.
Overall, the data suggest that vincristine induces senescence in medulloblastoma cells, particularly in D341. Moreover, the findings indicate that combining senolytics with existing medulloblastoma chemotherapeutics is a novel approach that may enhance treatment efficacy. Future studies should investigate additional biomarkers and extended incubation periods to improve senescence identification, as well as explore combinations with different senolytics and chemotherapeutics, potentially leading to more effective therapies targeting senescent cells.