Cytotoxic Activity of Curcumin towards CCRF-CEM Leukemia Cells and Its Effect on DNA Damage

The cytotoxic activity of curcumin towards CCRF-CEM human T-cell leukemia cells was measured by the MTT assay. Tumor cells were more sensitive to the cytotoxic activity of curcumin or curcumin-Cu (II) compared to normal cells, and the IC50 of curcumin towards CCRF-CEM cells was 8.68 mu M, and that of curcumin-Cu (II) was 8.14 mu M. The cell cycle distribution of curcumin-treated CCRF-CEM cells was analyzed by flow cytometry. DNA damage induced by oxidants such as curcumin-Cu (II) ions is considered as one of the main causes of cell inactivation. Therefore, we analyzed the effect of curcumin on DNA damage by agarose gel electrophoresis and atomic force microscopy (AFM). Gel electrophoresis analyses showed that curcumin or Cu (II) alone failed to cause DNA damage in pBR322 plasmid DNA as compared with the normal plasmid. However, DNA plasmids were mostly damaged after treatment with curcumin of different concentrations in the presence of Cu (II). Two forms were observed by means of AFM: closed circular plasmids and linear plasmids. DNA damage induced by a combination of curcumin and Cu (II) was also found by agarose gel electrophoresis, which was applied as control method to verify the results obtained by AFM.