Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), is extracted from the plant Curcuma longa. It has cytotoxic effects and induces apoptosis in many human cancer cells but the molecular mechanisms are not fully understood. In the present study, we evaluated the effects of curcumin on human breast cancer MDA-MB-231 cells. The cytotoxic effects of curcumin on MDA-MB-231 cells were measured by MTT assay. The percentages of cell cycle were determined by flow cytometry. The

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... in expressions of p21, 53, Bax and Bcl-2 were examined by Western blotting. The results show that curcumin inhibits the proliferation of MDA-MB-231 cells and induces G2/M arrest in a dosedependent manner. Curcumin increased the protein expressions of p21 and Bax, but decreased the protein expression of p53 and Bcl-2 in MDA-MB-231 cells. Our results show that one molecular mechanism of curcumin inhibits the proliferation of MDA-MB-231 cells either through up-regulating p21 expression and then inducing apoptosis, or through up-regulating the Bax to Bcl-2 ratio and then inducing apoptosis. Our results also show that curcumin inhibits the migratory activity of MDA-MB-231 cells through down-regulating the protein expression of NF-κBp65. Accordingly, the therapeutic potential of curcumin for breast cancer deserves further study.