雷公藤红素对白血病细胞Akt信号通路的影响及在细胞凋亡中的作用

Effect of Celastrol on Akt Signaling Pathway and Apoptosis of Leukemic K562 Cell Line

目的研究雷公藤红素(celastrol)对人类白血病细胞株K562细胞Akt信号通路的影响及其作用。方法应用MTT法检测细胞增殖活性,Annexin V/PI双标法、Hoechst33258染色法和DNA ladder法检测细胞凋亡,Western Blot法检测Caspase家族成员及Akt信号通路相关蛋白在雷公藤红素作用前后的表达或磷酸化情况,并进一步分析其对雷公藤红素诱导细胞凋亡作用的影响。结果雷公藤红素以剂量-时间依赖性方式抑制K562细胞增殖,其24h半数抑制量(IC50)是(2.15±0.11)μmol/L;并以剂量依赖性方式诱导K562细胞凋亡,2.0μmol/L雷公藤红素处理24h后出现明显的DNA剪切现象,伴有典型的细胞凋亡形态学改变。雷公藤红素诱导细胞凋亡过程中伴随Caspase-3、8的活化,50μmol/L Caspase抑制剂z-VAD-fmk可阻断雷公藤红素作用的K562细胞凋亡。雷公藤红素降低K562细胞Akt信号通路中p-Ak,t Survivin和Bcl-2的表达,25μmol/LWORT(PI3K-Akt抑制剂)可显著提高雷公藤红素诱导K562细胞凋亡的作用。结论雷公藤红素显著抑制K562细胞增殖,通过活化Caspase途径诱导K562细胞凋亡。雷公藤红素诱导细胞凋亡过程中伴Akt磷酸化水平的降低,雷公藤红素参与PI3K-Akt抑制剂协同诱导K562细胞的凋亡。

Objective To research the effect and route of celastrol on Akt signaling pathway of human leukemia cell line K562 apoptosis. Methods The activities of K562 proliferation cells were detected by MTT assay; cell apoptosis was detected by Hoechst 33258 staining assay,DNA fragmentation assay,and Annexin V/PI double-labeled cytometry; the expression and phosphorylation level of Caspase family members and AKT signaling pathway related proteins were determined by Western blot before and after celastrol treatment,and further the effect of AKT signaling pathway on celastrol-induced-apoptosis was analyzed. Results K562 cell proliferation was inhibited by celastrol in a time-and dose-dependent manner,with the IC50 value for 24 h of （2.15±0.11） μmol/L. Celastrol induced K562 cells apoptosis in a dose-dependent manner,apparent DNA fragmentation and typical apoptotic morphological changes,and accompanied Caspase-3,8 activation in the apoptosis process were shown after cells were treated with 2.0 μmol/L celastrol for 24 h. And the celastrol induced apoptosis could be blocked by 50 μmol/L z-VAD-fmk （caspase inhibitor）,but augmented by 25 μmol/L WORT （PI3K-Akt inhibitor）. Moreover,Celastrol decreased the expressions of p-Akt,survivin and Bcl-2 in the Akt signaling pathway. Conclusions Celastrol inhibited the proliferation of K562 cells and induced cell apoptosis by way of activating caspase cascade. The decreased level of Akt phosphorylation during celastrol-induced-apoptosis process suggested that celastrol acted synergistically with PI3K-Akt inhibitors in K562 cell apoptosis inducing.