Summary Curcumin (1,7-Bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) has exhibited potent inhibitory activities against proliferation and exhibited the induction of apoptosis from several tumor cell lines. Recently it was reported that curcumin induced cell cycle arrest in several human cancer cell lines. However, the exact mechanisms of curcumin induce cell cycle arrest is unclear. In the present study, we used flow cytometry to analyze the cell cycle after human colon cancer colo 205 cells treated with various concentrations of curcumin for 48 hours. The results demonstrated that curcumin induced G2/M arrest in these examined cells and that those effects are dose-and time-dependent. In order to further understand the mechanism of curcumin induced G2/M arrest, we also investigated the checkpoint associated with enzymes of cell cycle based on the Western blotting methods. The results demonstrated that curcumin induced Wee1 expression and decreased the CDC25C, cyclin B1 and CDK2 expression, resulting in the induction of G2/M cell cycle arrest in colon cancer cells (colo 205). We also used cDNA microarray assay to confirm the gene expression(mRNA Wee1, CDC25, cyclin B1 and CDK2). The results indicated that curcumin promoted the gene expression of Wee1 and inhibited the gene expression of CDC25C, CDK2 and cyclin B.?
