Elemene induces apoptosis and regulates expression of bcl-2 protein in human leukemia K562 cells.

OBJECTIVE

To study the antitumor action of elemene (Ele) and its mechanism.

METHODS

Inhibition of proliferation was measured with a colorimetric 3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological assessment of apoptosis was performed with fluorescence microscope. DNA fragmentation was assessed by agarose gel electrophoresis and flow cytometry. The levels of bcl-2 protein was measured with flow cytometry.

RESULTS

Exposure of exponentially growing K562 cells to Ele 65-520 mumol. L-1 for 48 h resulted in growth arrest. The values of IC50 and 95% confidence limits were 220 (152-319) mumol.L-1. After treatment of K562 cells with Ele 130 mumol.L-1, marked morphological changes including "Apo bodies" reduction in volume were observed with fluorescence microscope. Agarose gel electrophoresis of DNA from cells treated with Ele for 48 h revealed "ladder" pattern. The levels of bcl-2 protein in K562 cells treated with Ele for 48 h were obviously decreased.

CONCLUSIONS

Ele induces apoptosis of K562 cells, which is related with the down-regulation of bcl-2 protein in K562 cells.