[Apoptosis-inducing effects of brucine on human chronic myeloid leukemia cell line K562]

To investigate the apoptosis-induction effect of brucine on human chronic myeloid leukemia cell line K562 cells, K562 cells were exposed to various dosages of brucine. MTT method was used to assayed the growth inhibition effect of brucine on K562 cells. The apoptosis of K562 cells was detected by acridine orange/ethidium bromide (AO/EB) double staining, Annexin-V/PI double labeling method and DNA agarose gel electrophoresis. The results showed that brucine could remarkably inhibit the K562 cell growth in a concentration-dependent and time-dependent manners at the range of 50 to 400 µg/ml, and its most significant inhibition was observed at 400 µg/ml for 72 hours and the inhibition rate was 94.0%. Staining of cells with AO-EB revealed that brucine induced nuclear chromatin condensation. After the K562 cells were treated with the brucine of 400 µg/ml for 72 hours, the most of the nucleus were orange stained and condensation-like or bead-like showing apoptotic morphology. The K562 cells treated with brucine of different concentrations (50, 100, 200, 400, 800 µg/ml) for 72 hours, Annexin-V/PI detection showed brucine could induce apoptosis of K562 cells, and apoptosis rate increased gradually with increasing concentration of drugs. The K562 cells treated with brucine of 400 µg/ml for 72 hours displayed typical ladder strap in DNA gel electrophoresis. It is concluded that brucine can efficiently inhibit cell growth and induce apoptosis of K562 cells with dose-dependent manner in concentrations of 50 - 400 µg/ml.