PI3K-AKT-mTOR通路对骨肉瘤细胞顺铂耐药性的影响及其机制

Effect of the PI3K-AKT-mTOR pathway on the drug resistance of osteosarcoma cells and its mechanism

目的探讨磷脂酰肌醇3-激酶(PI3K)-蛋白激酶B(AKT)-哺乳动物雷帕霉素靶蛋白(mTOR)通路对骨肉瘤细胞顺铂耐药性的影响及其机制,为骨肉瘤的靶向治疗提供新的思路。方法体外培养MG-63细胞,予2μg/mL顺铂重复给药建立MG-63耐药细胞株,向MG-63耐药细胞株中转染miRNA-22高表达质粒建立miRNA-22高表达的MG-63耐药细胞株。以MG-63细胞为对照组,MG-63耐药细胞为耐药组,用2μg/mL顺铂处理后的MG-63耐药细胞和转染miRNA-22的MG-63耐药细胞分别为耐药DDP组、耐药miRNA-22+DDP组。采用噻唑兰(MTT)法检测细胞增殖能力。采用荧光定量逆转录聚合酶链反应(RT-PCR)法检测细胞内PI3K、AKT以及mTOR mRNA的表达。采用Western blot检测细胞内PI3K、AKT以及mTOR蛋白的表达。结果(1)MTT法检测结果显示,对照组、耐药组、耐药DDP组和耐药miRNA-22+DDP组的吸光度分别为1.097±0.039、1.157±0.065、0.870±0.014和0.737±0.029,差异有统计学意义(F=67.731,P<0.01):与对照组比较,耐药DDP组、耐药miRNA-22+DDP组吸光度均明显下降,差异均有统计学意义(P值均<0.01);耐药组、耐药DDP组、耐药miRNA-22+DDP组3组间比较,吸光度呈下降趋势,差异均有统计学意义(P值均<0.01)。(2)荧光定量RT-PCR结果显示,与对照组比较,耐药组、耐药DDP组PI3K、AKT的相对表达量均增多,尤其以耐药组增多明显(P值均<0.01),耐药miRNA-22+DDP组与对照组差异均无统计学意义(P值均>0.01);而mTOR相对表达量耐药组增高,耐药DDP组、耐药miRNA-22+DDP组均降低,差异均有统计学意义(P值均<0.01)。耐药DDP组、耐药miRNA-22+DDP组PI3K、AKT、mTOR的相对表达量均低于耐药组,差异均有统计学意义(P值均<0.01);而耐药miRNA-22+DDP组仅PI3K、mTOR的相对表达量低于耐药DDP组,差异均有统计学意义(P值均<0.01)。(3)Western blot检测结果显示,与对照组比较,耐药组PI3K、AKT、mTOR蛋白的相对表达量均明显增加,耐药DDP组、耐药miRNA-22+DDP组PI3K、AKT蛋白的相对表达量均明显降低,差异均有统计学意义(P值均<0.01)。耐药组、耐药DDP组、耐药miRNA-22+DDP组3组间两两比较,耐药DDP组、耐药miRNA-22+DDP组PI3K、AKT、mTOR蛋白的相对表达量均明显低于耐药组,耐药miRNA-22+DDP组PI3K、AKT蛋白的相对表达量均明显低于耐药DDP组,差异均有统计学意义(P值均<0.01)。结论PI3K-AKT-mTOR通路参与了骨肉瘤细胞对顺铂耐药性的产生,miRNA-22通过下调PI3K-AKT-mTOR通路中PI3K、AKT以及mTOR的表达降低骨肉瘤细胞对顺铂的耐药性。

Objective This study aims to investigate the effect of the phosphatidylinositol 3-hydroxy kinase(PI3K)-protein kinase B(AKT)-mammalian target of rapamycin(mTOR)pathway on the drug resistance of osteosarcoma cells and its mechanism to provide new ideas for the targeted therapy of osteosarcoma.Methods MG-63 cells were cultured in vitro,and MG-63 drug-resistant cell lines were established using the repeated administration of 2μg/mL cisplatin.The high-expression plasmids of miRNA-22 were transfected into MG-63 drug-resistant cell lines to establish MG-63 drug-resistant cell lines with high miRNA-22 expression.MG-63 cells were the control group,and the MG-63 drug-resistant cells were the drug-resistant group.MG-63 frug-resistant cells treated with 2μg/mL cisplatin and the drug-resistant MG-63 cells transfected with miRNA-22 were the drug-resistant DDP and the drug-resistant miRNA-22+DDP groups,respectively.The cell proliferation was detected using the thiazoline(MTT)assay.The expression levels of PI3K,AKT,and mTOR mRNA were detected using fluorescence quantitative RT-PCR.The protein expressions of PI3K,AKT,pAKT,mTOR,and p-mTOR were detected using the Western blot.Results(1)The MTT results showed that the absorbance values of the control,drug-resistant,drug-resistant DDP,and drug-resistant miRNA-22+DDP groups were 1.097±0.039,1.157±0.065,0.870±0.014,and 0.737±0.029,respectively.The differences were statistically significant(F=67.731,P<0.01).Compared with that of the control group,the absorbance of the drug-resistant DDP and the drug-resistant miRNA-22+DDP groups decreased significantly(all P values<0.01).For the drug-resistant,drug-resistant DDP group,and drug-resistant miRNA-22+DDP group,the absorbance showed a downward trend,and the differences were statistically significant(all P values<0.01).(2)The results of fluorescence quantitative RT-PCR showed that compared with that in the control group,the relative expression of PI3K and AKT in the drug-resistant and the drug-resistant DDP groups increased especially in the drug-resistant group(all P values<0.01).No significant difference was observed between the drug-resistant miRNA-22+DDP and the control groups(all P values>0.01).The relative expression of mTOR significantly increased in the drug-resistant group and significantly decreased in the drug-resistant DDP and the drug-resistant miRNA-22+DDP groups(all P values<0.01).The relative expression levels of PI3K,AKT,and mTOR in the drug-resistant DDP and drug-resistant miRNA-22+DDP groups were lower than those in the drug-resistant group,and all differences were statistically significant(all P values<0.01).The relative expression levels of PI3K and mTOR in the drug-resistant miRNA-22+DDP group were lower than those in the drug-resistant DDP group,and the differences were statistically significant(all P values<0.01).(3)The results of Western blot showed that compared with that in the control group,the relative expression levels of PI3K,AKT,and mTOR proteins in the drug-resistant group increased significantly and that the relative expression levels of PI3K and AKT proteins in the drug-resistant DDP and drug-resistant miRNA-22+DDP groups were significantly reduced.The differences were statistically significant(all P values<0.01).The pairwise comparison among three groups revealed that the relative expression levels of PI3K,AKT,and mTOR proteins in the drug-resistant DDP and drug-resistant miRNA-22+DDP groups were significantly lower than those in the drug-resistant group.The relative expression levels of PI3K and AKT proteins in the drug-resistant miRNA-22+DDP group were significantly lower than those in the drug-resistant DDP group(all P values<0.01).Conclusions The PI3K-AKT-mTOR pathway was involved in the development of osteosarcoma cells'resistance to cisplatin.miRNA-22 reduced the resistance of osteosarcoma cells to cisplatin by downregulating the expression levels of PI3K,AKT,and mTOR in the PI3K-AKT-mTOR pathway.