The Synergistic Effects of the Combination of Ciprofloxacin and Temozolomide on Human Glioblastoma A-172 Cell Line

Background: Combination therapy has generated remarkable motivation in the clinical setting since it boosts the therapeutic potential of anticancer drugs. Glioblastoma multiforme is the most common, aggressive malignant brain tumor which affects patients of all ages. This brain tumor is principally resistant to treatment. Methods: In this study, we combined temozolomide as a standard chemotherapeutic drug for human glioblastoma multiforme, with ciprofloxacin in an attempt to determine whether ciprofloxacin could potentiate the cytotoxic effects of temozolomide. The glioblastoma A-172 cell line was exposed to ciprofloxacin and temozolomide either alone or in combination for 24, 48 and 72 h. Cytotoxicity was measured by the MTT assay. Results: Ciprofloxacin and temozolomide induced tumor cell death in a dosedependent manner with an IC50 value of 259.3 μM for ciprofloxacin and 62.5 μM for temozolomide at 72 h. These values shifted to 22.8 μM for ciprofloxacin and 8.6 μM for temozolomide in the presence of the IC50 of the other drug. The combination index values were