纳米氧化铈颗粒对人肺腺癌耐顺铂细胞辐射敏感性的影响

目的：研究纳米氧化铈颗粒对人肺腺癌耐顺铂细胞（A549/DDP）辐射敏感性的影响。方法：采用细胞增殖抑制实验确定γ射线半数抑制剂量和纳米氧化铈的使用浓度，细胞集落形成实验检测γ射线和纳米氧化铈处理后的细胞存活情况。将细胞分为阴性对照，γ射线照射组，纳米氧化铈低、中、高浓度组（分别加入0.000 5、0.05和5 μmol/L的纳米氧化铈处理后，再进行照射），采用流式细胞术进行细胞凋亡率、细胞周期和胞内pH值检测。结果：通过细胞增殖抑制实验，确定γ射线诱导A549/DDP细胞半数抑制剂量为25 Gy。细胞集落形成实验观察发现，与照射组相比，纳米氧化铈低浓度组细胞的SF₂降低、a/b比值和增敏比升高。流式细胞术检测发现，纳米氧化铈低浓度组细胞凋亡率增加（t=5.42，P < 0.05）；纳米氧化铈低、中、高浓度组的S期阻滞明显（t=3.14、4.08、6.81，P < 0.05）；纳米氧化铈低、高浓度组的胞内pH值升高（t=2.86、4.93，P < 0.05）。结论：低浓度纳米氧化铈对于体外培养的A549/DDP细胞具有一定的辐射增敏作用。

Effect of cerium oxide nanoparticles on radiosensitivity of a drug-resistant human lung adenocarcinoma cell line

OBJECTIVE: To study the effect of cerium oxide nanoparticles (CeO₂) on radiosensitivity of A549/DDP. METHODS: The half maximal inhibitory exposure dose and concentration of CeO₂ were determined by inhibitory rate of proliferation of A549/DDP. The cell colony-forming experiment was performed to observe changes of cellular surviving fractions between the radiation group after treated with different concentration of CeO₂ groups and radiation only group. A549/DDP cells were grouped as negative control(control),radiation control (rad),and the low,medium and high concentration of CeO₂ groups (final concentrations were 0.000 5,0.05 and 5 μmol/L). Apoptosis,cell cycle and intracellular pH were determined using by flow cytometry. RESULTS: The half maximal inhibitory exposure dose of A549/DDP induced by γ-rays was 25 Gy,which was determined by inhibitory rate of A549/DDP proliferation. At the survival fraction of 2 Gy (SF₂),the ratios of a/b and the sensitive enhancement ratios (SER) were obtained by the cell colony-forming experiment. Comparing with the rad group,the value SF₂ of low concentration CeO₂ group was decreased. The ratio of a/b and the value of SER of the low concentration CeO₂ group were both increased. From the flow cytometry analyses,the percent of apoptosis in the low concentration CeO₂ group was increased (t=5.42,P < 0.05);S-phase arrest of the low,medium and high concentration CeO₂ groups were obvious (t=3.14,4.08,6.81,P < 0.05). The value of pH in cells of the low and high concentration CeO₂ groups were raised (t=2.86,4.93,P < 0.05). CONCLUSION: All the results indicate that low concentrations of CeO₂ enhanced radiosensitivity of A549/DDP.