抑制生存传导路径可增加肿瘤细胞化疗敏感性

Inhibition of survival pathway could sensitize the tumor cells to chemotherapy

目的:研究抑制磷酸酰肌醇3激酶(PI3K)/Akt生存传导路径是否可增加肿瘤细胞对一些化疗药物的敏感性。方法:采用Akt亚型特异抑制剂结合多柔比星(阿霉素ADM)或喜树碱治疗各种肿瘤细胞系;检测细胞凋亡蛋白激酶3活性,来定量评估细胞凋亡程度;免疫沉淀+Werstern印迹法测定药物对磷酸化各类Akt亚型的抑制作用。结果:①各类Akt亚型抑制剂可阻断Akt1或Akt2蛋白序列上的第308位点苏氨酸(pAkt308)和第473位点丝氨酸(pAkt473)磷酸化,并表现出相应的Akt亚型抑制特异性;②单独抑制某一类Akt亚型并不足以增加肿瘤细胞对化疗药物的敏感性,只有同时抑制Akt1和Akt2才能增敏药物对肿瘤细胞的杀灭效应;③药物的增敏效应可能和肿瘤细胞内源性PTEN脱磷酸酶的表达有一定的关联。结论:临床应用化疗结合PI3K/Akt生存传导路径抑制剂应选择具有阻断2种Akt亚型功能的药物以达到最大的肿瘤杀灭效应。

Purpose:To study whether the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt survival pathway could sensitize the response of tumor cells to some chemotherapyeutic agents. Methods:The different tumor cells has been treated with the combination of isoform specific Akt inhibitor and either adriamycin or camptothecin; the quantitation of the induction of apoptosis by drugs has been estimated with caspase 3 assay; immunoprecipitation western blotting has been used to evaluate the inhibition of the phosphorylation of different isoforms of Akt after the treatment. Results:①The inhibitors could reduce the phosphorylation of Threonine 308 and Serine 473 of isoform specific Akt. ②The inhibition of any one isoform specific Akt could not reverse the resistance of tumor cells tested to chemotherapeutic drugs, but it is not the same case if blocking of two isoforms of both Akt1 and Akt2 was done at the same time. ③The synergistic effects of Akt inhibitors is maybe relative to the level of endogenous PTEN(phosphatase and tensin homolog deleted on chromosome 10) expression. Conclusions:It is required to inhibit two isoforms of both Akt1 and Akt2 in order to maximally sensitize the tumor cells to chemotherapy.