AIM:To investigate the effects of 3-phosphoinositide-dependent protein-1(PDK1)on the biologi-cal characteristics of non-small-cell lung cancer cell line A549 and the underlying mechanisms.METHODS:The expres-sion levels of PDK1 in lung normal epithelial cell line BEAS-2B and different lung cancer cell lines H 460, SPCA1 and A549 were determined by Western blot and real-time PCR.Small interfering RNA was used to down-regulated PDK1 ex-pression in the A549 cells,and then cell viability and apoptosis were measured by CCK-8 assay and flow cytometry,respec-tively.The expression of cell cycle-and apoptosis-related molecules at protein level and the activation of Akt /FoxO1 path-way were measured by Western blot.Insulin-like growth factor-1(IGF-1,one of the most potent Akt activators)was used to evaluate the interaction between PDK 1 and Akt/FoxO1 pathway.RESULTS:Compared with lung normal epithelial cell line BEAS-2B,PDK1 expression in the lung cancer cell lines was obviously increased(P<0.05).Knockdown of PDK1 suppressed cell viability and cell cycle,but promoted the apoptosis of the A 549 cells.The results of Western blot showed that the protein levels of cyclin D1,CDK4,p-Rb,Bcl-2,p-Akt and cytoplasmic p-FoxO1 were significantly decreased after knockdown of PDK1,with increases in the protein levels of P27, cleaved caspase-3 and nuclear FoxO1.Pre-incubation with IGF-1 partly reversed the effect of PDK1 knockdown on Akt/FoxO1 pathway and increased the viability of A 549 cells. CONCLUSION:In human non-small-cell lung cancer A549 cells,knockdown of PDK1 suppresses cell viability and pro-motes cell apoptosis by regulating the expression of cell cycle-and apoptosis-related molecules via Akt/FoxO1 pathway, suggesting that PDK1 may be a potential target for diagnosis and theatment of lung cancer.%目的:探讨3-磷酸肌醇依赖性蛋白激酶1(PDK1)对肺癌细胞株A549生物学特性的影响及其潜在的作用机制.方法:采用Western blot和real-time PCR检测肺正常上皮细胞BEAS-2B和肺癌细胞(H460、SPCA1和A549)中PDK1的表达水平.利用RNA干扰技术下调肺癌A549细胞中PDK1的表达,然后分别采用CCK-8法和流式细胞术检测细胞活力及凋亡的变化;Western blot检测增殖及周期相关蛋白的表达和Akt/FoxO1信号通路的活性.最后通过Akt信号通路特异性激动剂胰岛素样生长因子1(insulin-like growth factor-1, IGF-1)进一步验证PDK1和Akt/FoxO1信号通路的相互作用.结果:相较于肺正常上皮细胞BEAS-2B,肺癌细胞中的PDK1均呈高表达(P<0.05).干扰A549细胞中PDK1的表达后,细胞活力显著降低,周期进程缓慢,而细胞凋亡显著增加.Western blot实验结果显示,干扰PDK1后,细胞中cyclin D1、CDK4、p-Rb、Bcl-2、p-Akt及胞浆中p-FoxO1的含量显著下降,P27、cleaved caspase-3及核内FoxO1的蛋白水平显著升高(P<0.05).预先给予Akt激动剂IGF-1可部分逆转干扰PDK1对Akt/FoxO1信号通路的影响,并增加A549细胞的活力(P<0.05).结论:干扰人肺癌细胞株A549的PDK1可通过抑制Akt/FoxO1信号通路而调控周期及凋亡相关因子的表达,发挥生长抑制及凋亡促进作用,提示PDK1可作为肺癌的潜在诊疗靶点.
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