Ciprofloxacin-mediated induction of S-phase cell cycle arrest and apoptosis in COLO829 melanoma cells.

Background: Low effectiveness of anti-melanoma therapies makes it necessary to search for new drugs that could improve or replace the standard chemotherapy. Fluoroquinolones are a group of synthetic antibiotics, used in the treatment of wide range of bacterial infections. Moreover, this class of antibiotics has shown promising anti-tumor activity in several cancer cell lines. The aim of this study was to examine the effect of ciprofloxacin on cell viability, apoptosis and cell cycle distribution in COLO829 melanoma cells.

Methods: Cell viability was evaluated by the WST-1 assay. Cell cycle distribution and apoptosis in cells exposed to ciprofloxacin was analyzed by the use of fluorescence image cytometer NucleoCounter NC-3000.

Results: Ciprofloxacin decreased the cell viability in a dose- and time-dependent manner. For COLO829 cells treated with ciprofloxacin for 24 h, 48 h and 72 h the values of IC were found to be 0.74 mM, 0.17 mM and 0.10 mM, respectively. The oligonucleosomal DNA fragmentation was observed when the cells were exposed to ciprofloxacin in concentration of 1.0 mM for 48 h and 72 h. At lower ciprofloxacin concentrations (0.01 mM and 0.1 mM) cells were arrested in S-phase suggesting a mechanism related to topoisomerase II inhibition. Moreover, it was demonstrated that ciprofloxacin induced apoptosis as a result of mitochondrial membrane breakdown.

Conclusions: The obtained results for COLO829 melanoma cells were compared with data for normal dark pigmented melanocytes and the use of ciprofloxacin as a potential anticancer drug for the treatment of melanoma in vivo was considered.