PI3K/AKT信号在增强乳腺癌细胞对肿瘤坏死因子相关凋亡诱导配体敏感性中的作用及其机制

Role of phosphatidylinositol 3 kinase/protein kinase B signaling pathway in enhancement of sensitivity of breast cancer cells to TNF related apoptosis inducing ligand and relevant mechanism

目的分析磷脂酰肌醇3激酶(phosphatidylinositol 3 kinase,PI3K)/蛋白激酶B(protein kinase B,AKT)通路是否通过长细胞caspase-8样抑制蛋白(cellular FLICE inhibitory protein,c-FLIP-L)的介导来影响乳腺癌细胞对肿瘤坏死因子相关凋亡诱导配体(TNF related apoptosis inducing ligand,TRAIL)的敏感性,并探讨其机制。方法用40 nmol/L wortmannin(AKT活化的特异性抑制剂)、100 ng/ml TRAIL、40 nmol/L wortmannin+100 ng/ml TRAIL处理人乳腺癌MDA-MB-231细胞,并设空白对照组。MTT法检测药物作用24、48、72 h后的细胞增殖抑制率;流式细胞术检测药物作用48 h后的细胞凋亡率;Western blot法检测细胞中磷酸化AKT(pAKT)和c-FLIP-L的表达。结果TRAIL+wortmannin组24、48和72 h细胞增殖抑制率与其他组比较,均明显升高(P<0.05);TRAIL+wortmannin组与TRAIL组和wortmannin组比较,可明显促进细胞凋亡(P<0.05);随着wortmannin作用时间的延长,pAKT的表达水平明显降低,同时c-FLIP-L的表达水平也随之下降,而TRAIL对pAKT和c-FLIP-L的表达无明显影响。结论抑制PI3K/AKT通路可增强乳腺癌细胞对TRAIL的敏感性,这种作用可能是通过c-FLIP-L的介导来实现的。

Objective To analyze whether phosphatidylinositol 3 kinase（PI3K） / protein kinase B（AKT） signaling pathway enhances the sensitivity of breast cancer cells to TNF related apoptosis inducing ligand（TRAIL）in mediation of long cellular FLICE inhibitory protein（c-FLIP-L） and investigate the relevant mechanism. Methods Human breast cancer MDA-MB-231 cells were treated with 40 nmol / L wortmannin（an AKT-activated specific inhibitor）,100 ng / ml TRAIL and 40 nmol / L wortmannin ＋ 100 ng / ml TRAIL respectively,using those untreated as blank control. The inhibitory rates of cell propagation 24,48 and 72 h after treatment were determined by MTT assay,while the cell apoptosis rate 48 h after treatment by flow cytometry,and the expressions of phosphorylated AKT（pAKT）and c-FLIP-L by Western blot. Results The inhibitory rates of propagation of cells 24,48 and 72 h after treatment with TRAIL ＋wortmannin were significantly higher than those in other groups（P 0. 05）. Compared with TRAIL and wortmannin,TRAIL ＋ wortmannin promoted the cell apoptosis significantly（P 0. 05）. The expression levels of pAKT and c-FLIP-L decreased significantly with the increasing time for treatment with wortmannin. However,TRAIL showed no significant effect on the expressions of pAKT and c-FLIP-L. Conclusion The sensitivity of breast cancer cells to TRAIL might be enhanced by inhibiting PI3K / Akt pathway in mediation of c-FLIP-L.