目的 探讨藤黄酸对白血病细胞系K562增殖、凋亡、细胞周期的影响,并观察藤黄酸对hERG 钾通道蛋白的调控作用。方法 K562细胞以不同浓度藤黄酸(0.125-8.0μmol/L)处理0-72h后,MTT 法观察藤黄酸对K562细胞生长抑制的情况,Annexin-V/PI 双标法及透射电镜检测细胞凋亡,PI 单染法检测细胞周期分布,Western blotting、RT-PCR 法分别检测藤黄酸对K562细胞内hERG 通道的调控作用。结果 藤黄酸能明显抑制K562细胞增殖,具有时间-剂量依赖性,其24h的IC₅₀为(2.637±0.208)μmol/L。此外,藤黄酸以浓度依赖性方式诱导K562细胞凋亡,并伴随明显的凋亡细胞形态学改变,而藤黄酸的凋亡诱导效应可能与其诱导K562细胞周期阻滞于G₀/G₁ 期有关。hERG 钾通道蛋白在人白血病K562细胞中表达量较高,藤黄酸对hERG 钾通道蛋白及其表达水平均有不同程度的抑制作用,该抑制作用呈明显的量效关系(P<0.01)。结论 藤黄酸可通过下调hERG 钾通道蛋白的表达发挥较强的抗白血病效应,hERG 钾通道有望成为白血病诊治的新靶标。

Objective To explore the effects of gambogic acid(GA) on proliferation,apoptosis,and cell cycle distribution of leukemia cells K562,as well as to observe its regulation on the expression of human ether-à-go-go related genes(hERG) protein.Methods K562 Cells were treated with various concentration of GA(0.125-8.0μmol/L) for 0-72h.MTT Assay was used to evalute the inhibition of GA on the growth of K562 cells.Cell apoptosis was detected through both Annexin-V/PI double-labeled cytometry and transmission electron microscopy(TEC).Cell cycle regulation was studied by a propidium iodide method.Western blotting and RT-PCR technologies were applied to assess the regulation on the expression level of hERG in K562 cells.Results GA presented striking growth inhibition on the proliferation of K562 cells in vitro in a time-and dose-dependent manner. The IC₅₀ value of GA for 24h was (2.637±0.208)μmol/L.Moreover,GA induced K562 cells apoptosis in a dose-dependent manner and companied with the obvious morphological changes of apoptosis.Meanwhile,the apoptosis induction potency of GA on K562 cells might correlate well with its effect on the G₀/G₁ cell cycle arrest.Overexpression of hERG potassium channel protein was found in K562 cells,while GA could downregulate it at both protein and mRNA level in a dose-dependent manner(P<0.01).Conclusion GA could exhibit its anti-leukemia effects partially through the downregulation of the protein expression level of hERG potassium channel in K562 cells,which suggests that hERG potassium channel might be a new target for future therapy of leukemia.

国家自然科学基金资助项目(30472267)