Enhanced Anticancer Effect of Temozolomide through Synergistic Combination with Diltiazem in Neuroblastoma (SH-SY5Y) Cell Line

Objective: This study aimed to assess the enhanced anticancer effect of Temozolomide (TMZ) through a synergistic combination with Diltiazem (DTZ) in the neuroblastoma cell line (SH-SY5Y). Material and Methods: The SH-SY5Y neuroblastoma cell line was cultured in a DMEM medium. TMZ and DTZ stock solutions were prepared and diluted to obtain different concentrations. The XTT assay was performed to evaluate cell viability. Cells were treated with TMZ alone or with DTZ for 24 and 48 hours. Viability was measured using the XTT-formazan product, and statistical analysis was performed. Results: The viability of neuroblastoma cells treated with TMZ alone and TMZ+DTZ combination was assessed. At 24 hours, TMZ showed no cytotoxic effect, while DTZ showed a low cytotoxic impact. At 48 hours, TMZ and TMZ+DTZ combination exhibited significant cytotoxic effects. The cytotoxic effects were concentration-dependent and time-dependent. DTZ alone showed significant cytotoxic effects on neuroblastoma cells at specific concentrations. Conclusion: The study demonstrated that TMZ alone and combined with DTZ had a significant cytotoxic effect on neuroblastoma cells. The combination of TMZ and DTZ may enhance the anticancer effect of TMZ and overcome drug resistance in neuroblastoma treatment. DTZ, a P-glycoprotein inhibitor, could prevent the efflux of TMZ from cancer cells, increasing its concentration and effectiveness.