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目的研究抑制磷脂酰肌醇3激酶和(或)蛋白激酶B(PI3K/AKT)生存传导路径是否改变乳腺癌细胞的放射敏感性。方法用乳腺癌细胞细胞株MCF7为实验对象,分别接受单纯放射、Ly294002(PI3K抑制剂)和二者结合处理。通过Western印记法证实Ly294002可下调AKT活性。采用成克隆法定量分析细胞增殖性死亡。通过半胱天冬酶-3(caspase-3)活性评估细胞凋亡。结果单纯Ly294002(5μmol/L)可抑制AKT的磷酸化,而单纯放射对AKT的活性无明显影响,二者结合可提高对AKT活性的抑制作用。Ly294002(5μmol/L)在放射前与细胞作用1h及放射后作用10d均可提高MCF7细胞对放射的敏感性。Ly294002结合放射可增加MCF7细胞增殖性死亡,SF_4值的放射增敏比为1．25,D_o值的放射增敏比为1．42。Ly294002可增加MCF7细胞放射后诱导的细胞凋亡。结论抑制PI3K通过降低AKT活性,增加MCF7细胞对放射的敏感性,为筛选放射敏感剂进行临床实验提供了依据。
Objective To investigate whether inhibiting the survival pathway of phosphatidylinositol 3 kinase and / or protein kinase B (PI3K / AKT) alters the radiosensitivity of breast cancer cells. Methods The breast cancer cell line MCF7 was used as the experimental subject and received radioimmunotherapy alone, Ly294002 (PI3K inhibitor) and the combination of the two. Western blotting confirmed that Ly294002 down-regulated AKT activity. Quantitative analysis of cell proliferative death using cloning method. Apoptosis was assessed by caspase-3 activity. Results Ly294002 (5μmol / L) inhibited the phosphorylation of AKT. However, radiotherapy alone did not affect the activity of AKT. The combination of the two could increase the inhibition of AKT activity. Ly294002 (5μmol / L) before irradiation and the role of cells 1h and 10d after irradiation can increase the sensitivity of MCF7 cells to radiation. Ly294002 combined with radiation can increase the proliferation of MCF7 cell death, SF_4 value of the radiosensitization ratio of 1.25, D_o value of the radiosensitization ratio of 1.42. Ly294002 increases the apoptosis induced by radiation after MCF7 cells. Conclusion Inhibition of PI3K can reduce the AKT activity and increase the sensitivity of MCF7 cells to radiation, which provides the basis for screening radiosensitizers for clinical trials.