右美托咪定对神经胶质瘤细胞PTEN/Akt/mTOR介导自噬及放疗敏感性的影响

Effects of Dexmedetomidine on PTEN/Akt/mTOR-mediated Autophagy and Radiosensitivity of Glioma Cells

目的探究右美托咪定(DEX)通过第10号染色体缺失的磷酸酶及张力蛋白同源物基因/蛋白激酶B/哺乳动物雷帕霉素靶蛋白(PTEN/Akt/mTOR)通路对神经胶质瘤U251细胞自噬及放疗敏感性的影响。方法检测0、5、10、25、50、100、200、500 ng/ml DEX对U251细胞增殖的影响,检测10 ng/ml DEX与不同剂量放射剂量(0、2、4、6、8 Gy)联合处理后细胞克隆形成率。随后将U251细胞分为对照组、放疗组(6 Gy剂量射线)、DEX组(10 ng/ml DEX)、DEX+放疗组(10 ng/ml DEX+6 Gy剂量射线),检测并比较各组细胞凋亡、自噬相关蛋白微管相关蛋白1轻链3(LC3)、自噬相关蛋白(Beclin-1)及PTEN/Akt/mTOR通路相关蛋白的表达情况。结果DEX处理U251细胞24 h的半数抑制浓度(IC_(50))约为50 ng/ml;10 ng/ml DEX与6 Gy放射剂量联合处理可以明显增加U251细胞的放疗敏感性。与对照组比较,放疗组Akt、mTOR蛋白磷酸化水平显著降低,细胞凋亡率、LC3、Beclin-1、PTEN蛋白水平均显著升高(P<0.05)。与放疗组比较,DEX+放疗组Akt、mTOR蛋白磷酸化水平显著降低,细胞凋亡率、LC3、Beclin-1、PTEN蛋白水平均显著升高(P<0.05)。结论DEX可增加神经胶质瘤U251细胞自噬与放疗的敏感性,可能与抑制PTEN/Akt/mTOR信号通路有关。

Objective To investigate effects of Dexmedetomidine(DEX)on autophagy and radiosensitivity of glioma U251 cells through homologous deletion phosphatase and tensin on chromosome ten/protein kinase B/mammalian target of rapamycin(PTEN/Akt/mTOR)pathways.Methods Effects of 0,5,10,25,50,100,200 and 500 ng/ml of DEX on U251 cell proliferation were detected,and formation rates of cell clone treated by 10 ng/ml DEX combined with different radiation doses(0,2,4,6,8 Gy)were also detected.U251 cells were divided into control group,irradiation group(IR group,6 Gy dose radiation treatment),DEX group(10 ng/ml DEX treatment)and DEX+IR group(combined treatment of 10 ng/ml DEX+6 Gy dose radiation),and conditions of apoptosis and expressions of autophagy-related proteins microtubule-associated protein 1 light chain 3(LC3),autophagy-related proteins(Beclin-1)and PTEN/Akt/mTOR pathway-related proteins were detected among 4 groups.Results The inhibitory concentration 50(IC_(50))of U251 cells treated by DEX for 24 h was approximately 50 ng/ml,and 10 ng/ml DEX combined with 6 Gy radiation dose could significantly increase the radiosensitivity of U251 cells.Compared with those in control group,phosphorylation levels of Akt and mTOR proteins were significantly decreased,while values of apoptosis rate,protein levels of LC3,Beclin-1 and PTEN were significantly increased in IR group(P<0.05).Compared with those in IR group,phosphorylation levels of Akt and mTOR proteins were significantly decreased,while values of apoptosis rate,protein levels of LC3,Beclin-1 and PTEN were significantly increased in DEX+IR group(P<0.05).Conclusion DEX may increase the autophagy and sensitivity to radiotherapy of U251 glioma cells,which may be related to the inhibition of PTEN/Akt/mTOR signaling pathway.