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

AIM: To study the antitumor action of elemene (Ele) and its mechanism. METH ODS: Inhibition of proliferation was measured with a colorimetric 3-[4,5-di methyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide ( MTT) assay. Morpholo gical assessment of apoptosis was performed with fluorescence microscope. D NA fragmentation was assessed by agarose gel electrophoresis and flow cytom etry. The levels of bcl-2 protein was measured with flow cytometry. RESULTS : Exposure of exponentially growing K562 cells to Ele 65 - 520 mu mol L-1 f or 48 h resulted in growth arrest. The values of IC50 and 95 % confidence l imits were 220 (152 - 319) mu mol.L-1 After treatment of K562 cells with El e 130 mu mol.L-1, marked morphological changes including "Apo bodies reduct ion in volume were observed with fluorescence microscope. Agarose gel elect rophoresis of DNA from cells treated with Ele for 48 h revealed "ladder" pa ttern. Toe levels of bcl-2 protein in K562 cells treated with Ele for 48 h were obviously decreased. CONCLUSION: Ele induces apoptosis of K562 cells, which is related with the down-regulation of bcl-2 protein in K562 cells.