奥拉帕尼对CNE-2细胞不同剂量率照射的生物效应影响

目的 研究人鼻咽癌细胞CNE-2在不同剂量率照射下给予PARP抑制剂奥拉帕尼后的生物效应变化。方法 采用奥拉帕尼IC₁₀为实验用药浓度。分4个照射组(均0、1、2、3、5、7、10 Gy剂量):急速照射组(RT,各剂量点4 min内完成)、分次照射组(FRT,各剂量点30 min内完成)、奥拉帕尼+RT组、奥拉帕尼+FRT组。克隆分析法测得各剂量点存活分数,多靶单击模型拟合细胞存活曲线。蛋白印迹法检测0、1、2 Gy点RT、FRT组细胞PARP-1和各组细胞γH₂AX的表达水平,免疫荧光验证各组细胞γH₂AX焦点数。4个组间比较使用单因素方差分析,两两比较采用SNK-q检验。结果 奥拉帕尼对CNE-2细胞 IC₁₀值为4.0μmol/L。1、2 Gy点FRT组细胞PARP-1表达均高于RT组(P=0.029、0.022),FRT组γH₂AX蛋白和焦点均低于其余3个组(P均<0.05)。FRT组较RT组D₀、D_q、SF₂值分别增加了11.67%、15.78%、23.61%,奥拉帕尼+FRT组较FRT组D₀、D_q、SF₂值分别降低了11.19%、6.44%、13.26%;RT组、奥拉帕尼+RT组、奥拉帕尼+FRT组间相近。

Radiobiological effects of irradiation plus olaparib with different dose rates on CNE-2 cell line

Objective To investigate the radiobiological effects of radiation with different dose rates on human nasopharyngeal carcinoma cell line CNE-2 treated with or without a poly ADP-ribose polymerase (PARP) inhibitor,olaparib.Methods The concentration of olaparib used to treat cells equaled to the inhibition concentration IC10 of olaparib to CNE-2 cells.The CNE-2 cells were divided into acute radiotherapy (RT) group,fractionated radiotherapy (FRT) group,olaparib + RT group,and olaparib + FRT group.All groups were exposed to radiation of 0,1,2,3,5,7,and 10 Gy at a dose rate of 3 Gy/min.The delivery time for each dose point was 4 min in RT and 30 min in FRT.The colony forming assay was used to evaluate the survival of CNE-2 cells at each dose point.The multi-target,single-hit model was used to fit the cell survival curves and the parameters,D0,Dq,and SF2,were calculated.At dose points of 0.1,and 2 Gy,western blot was used to determine the expression of PARP-1 in the RT group and the FRT group and γH2AX in each group.Immunofluorescence was used to evaluate the γH2AX focus formation.A single factor analysis of variance was used to compare the 4 groups,and two two compared with SNK-q test.Results The IC10 value of olaparib to CNE-2 cells was 4.0 μmoL/L.At dose points of 1 and 2 Gy,the PARP-1 expression was significantly higher in the FRT group than in the RT group (P=0.029,0.022),while the γH2AX focus number was significantly smaller in the FRT group than in the other three groups (all P＜0.05);compared with the RT group,the D0,Dq,and SF2 values in the FRT group were increased by 11.67％,15.78％,and 23.61％,respectively;compared with the FRT group,the D0,Dq,and SF2 values in the Olaparib+ FRT group decreased by 11.19％,6.44％,and 13.26％,respectively;there were no significant differences in above indices between the RT group,the Olaparib+RT group,and the Olaparib+FRT group.Conclusions For the same radiation dose,fractionation reduces the relative dose rate and weakens the radiobiological effects.lowdose olaparib can compromise the single strand break repair induced by the decline of the relative dose rate in a fractionated irradiation mode,which promotes the formation of double-strand break and improves the radiobiological effects.