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目的 :研究紫草素对DNA拓扑异构酶I催化活性和K5 6 2白血病细胞凋亡的影响。方法 :从K5 6 2白血病细胞提取拓扑异构酶I,通过DNA解螺旋试验评价该药对拓扑异构酶I催化活性的抑制作用。用MTT法测定了该药对K5 6 2白血病细胞增殖的抑制作用。应用流式细胞术和琼脂糖凝胶电泳观察了该药对细胞凋亡的诱导作用。结果 :紫草素可显著抑制拓扑异构酶I的解螺旋活性 (IC50 =75 0 μmol/L)。该药能显著抑制K5 6 2的细胞增殖 ,并随剂量增大而抑制作用增强。紫草素 0 3～ 3μmol/L对K5 6 2细胞作用 2 4h后 ,其凋亡率为 2 0 %～ 70 %。琼脂糖凝胶电泳出现典型的DNA“lad der”。结论 :紫草素显著抑制拓扑异构酶I的催化活性 ,并能诱导K5 6 2白血病细胞凋亡
Objective: To study the effect of shikonin on DNA topoisomerase I catalytic activity and apoptosis of K562 cells. Methods: Topoisomerase I was extracted from K562 cells and the inhibitory effect of this drug on the catalytic activity of topoisomerase I was evaluated by DNA decolonization assay. The inhibitory effect of this drug on the proliferation of K562 cells was determined by MTT assay. Flow cytometry and agarose gel electrophoresis were used to observe the induction of apoptosis by this drug. Results: Shikonin significantly inhibited the topoisomerase I helicase activity (IC50 = 750 μmol/L). The drug can significantly inhibit K562 cell proliferation, and the inhibitory effect increases with increasing dose. Shikonin 0 3 ~ 3μmol / L on K562 cells after 24h, its apoptotic rate was 20% to 70%. Agarose gel electrophoresis shows the typical DNA “lad der”. Conclusion: Shikonin significantly inhibits the catalytic activity of topoisomerase I and induces apoptosis in K562 cells.