Proliferation and apoptosis induced by emodin and its effect on expression of c-myc in leukemia cell line K562

OBJECTIVE:To investigate the effect of emodin on apoptosis and the expression of c-myc mRNA in leukemia cell line K562.METHODS:K562 cells were exposed with emodin at different concentrations.The growth inhibition was measured by MTT assay.Morphological changes were observed by AO fluorescent staining.DNA fragmentation was assessed by agarose gel electrophoresis.Flow cytometry was applied to detect the change of cell cycle.RT-PCR was used to assess the expression of c-myc in K562 cells.RESULTS:MTT showed that emodin could significantly inhibit the proliferation of K562 cells in both time-and concentration-dependant manners,and IC50 value for emodin treatment at 96 h was 53.28 μmol/L.Emodin induced the nuclei of K562 with anomalistic and fragmentized for 96 hours.Agarose gel electrophoresis of DNA revealed a typical DNA ladder map of apoptosis.Emodin could block cell cycle in G0/G1 phase according to the detection of flow cytometry.RT-PCR showed that c-myc expression level was decreased by 54% after 100 μmol/L emodin treatment compared with the control group(P0.01).CONCLUSIONS:Emodin can efficiently inhibit the proliferation and induce apoptosis of K562 cell through blocking the cell cycle at G0/G1 phase.The decrease of c-myc expression level may play an important role in inducing K562 cell apotosis.