Figure 2. DNA damaging effects of climacostol in melanoma cells and absence of additive effects with DNA binding agents.

(a) Confocal immunofluorescence imaging of phospho-histone H2A.X in B16-F10 cells cultured in the presence of 30 μg/ml climacostol or vehicle (control) for 1 or 6 h. DAPI (blue) was used for nuclei detection. The images are representative of 4 independent experiments. Scale bar: 20 μm. (b) MTT assay of B16-F10 cells treated for 24 h in the absence (control) or in the presence of increasing concentrations of cisplatin (0.1, 0.3, and 1 μg/ml) and climacostol (1, 3, and 10 μg/ml). Compounds were administered alone or in combination. Data are expressed by setting the absorbance of the reduced MTT in control samples as 100%. Each histogram represent the results obtained from 4–8 independent experiments.