Down-regulation of Cdc25c, CDK1 and Cyclin B1 and Up-regulation of Wee1 by Curcumin Promotes Human Colon Cancer Colo 205 Cell Entry into G2/M-phase of Cell Cycle.

Curcumin (diferuloylmethane) exhibited potent inhibitory activities against proliferation and induced apoptosis in several tumor cell lines. It was recently reported that curcumin induced cell cycle arrest in several human cancer cell lines. However, the exact mechanisms are unclear.Flow cytometry was used to analyze the cell cycle in human colon cancer colo 205 cells treated with various concentrations of curcumin for 48 h. In order to further understand the mechanism of curcumin-induced G2/M arrest, the checkpoint associated with enzymes of the cell cycle were also investigated by Western blotting methods.Curcumin induced G2/M arrest in the examined cells and these effects were dose- and time-dependent. Futhermore, curcumin induced Wee1 expression and decreased the Cdc25c, cyclin B1 and CDK1 expressions, resulting in the induction of G2/M cell cycle arrest in the colo 205 cells. The cDNA microarray assay was also employed to confirm gene expressions (mRNA Wee1, Cdc25c, cyclin B1 and CDK1).The results indicate that curcumin promoted the gene expression of Wee1 and inhibited that of Cdc25c, CDK1 and cyclin B1.