Abstract:

Abstract:Objective
To investigate the influence of Meconopsis racemosa Maxim.of a traditional Tibetan medicine in the biological activity of human leukemia cell line K562 cells in vitro and  to clarify its related mechanism.Methods The K562 cells were treated with different concentrations (30,60,90,120,150 mg?L-1) of Meconopsis racemosa Maxim.alcohol extract in vitro,meanwhile blank control group was set up.MTT assay was used to detect the growth inhibitory rates of K562 cells treated with Meconopsis racemosa Maxim.alcohol extract.The  morphological changes of K562 cells were observed by inverted microscope.DNA injury was evaluated by single cell gel electrophoresis assay (SCGE).The changes of cell cycle were detected using flow cytometry.Results The inhibitory rates of K562 cells proliferation in Meconopsis racemosa Maxim.alcohol extract groups were significantly higher than those in blank control group  after 24,48 and 72 h(P＜0.01) in dose-dependent and time-dependent manner.The numbers of K562 cells was reduced,and the cells shapes were irregular with cuntour fuzzy under inverted  microscope.The SCGE results showed that nucleus DNA fragmentation and TailDNA% were increased after treated with 60,90,and 120 mg•L^-1 Meconopsis racemosa Maxim.alcohol extract,there were significant differences compared with blank control group(P＜0.05,P＜0.01). The cell cycle detection results showed that in 60,90 and 120 mg•L^-1 Meconopsis racemosa Maxim. alcohol extract groups,the percentages of K562 cells at G0/G1 phase and S  phase were  decreased,the percentages of K562 cells at G2/M phase were increased(1.88%±0.30%,5.46%±0.57%,19.8%±1.03%),they were significantly higher than that in blank control group(1.10%±0.12%)（P＜0.05）,which suggested a G2/M cell cycle arresting in Meconopsis racemosa Maxim.alcohol extract groups.Conclusion Meconopsis racemosa Maxim.alcohol extract could obviously inhibit the proliferation of K562 cells,and the mechanism may be related to inducing DNA injury of K562 cells and arresting cell cycle in G2/ M phase.

Key words: Meconopsis racemosa Maxim., K562 cells, proliferation inhibition, DNA injury, cell cycle arrest