DNA 依赖性蛋白激酶抑制剂 NU7026 对辐射胃癌细胞系 N87 中 DNA 修复和细胞存活的影响。
Effects of dna-dependent protein kinase inhibition by NU7026 on dna repair and cell survival in irradiated gastric cancer cell line N87.
机构信息
Segal Cancer Centre, Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC.
Department of Oncology, Division of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, QC.
出版信息
Curr Oncol. 2014 Apr;21(2):91-6. doi: 10.3747/co.21.1509.
UNLABELLED
Repair of radiation-induced dna double-strand breaks is a key mechanism in cancer cell radio-resistance. The synthesized compound NU7026 specifically inhibits dna-dependent protein kinase (dna-pk) within the non-homologous end-joining repair mechanism. Earlier studies demonstrated increased radiosensitivity in dna-pk deficient cells compared with wild-type cells. In chronic leukemia cells, NU7026 appears to enhance the cytotoxic effect of chlorambucil. The radio-modifying effects of NU7026 on cell survival, cell cycle, apoptosis, and dna double-strand break repair have yet to be studied in gastric cancer cells.
METHODS
The gastric cancer cell line N87 was treated with 0 Gy or 4 Gy in the presence of NU7026 at a dose range of 0-20 μmol/L. Clonogenic assays were used to assess cell survival after treatment. Cell-cycle distribution was analyzed using propidium iodide with fluorescence-activated cell sorting. Apoptosis was detected using annexin-V and propidium iodide with fluorescence-activated cell sorting. The γH2AX assay was used to measure dna double-strand breaks.
RESULTS
Statistically significant increases in G2/M arrest were observed in N87 cells treated with radiation and NU7026 compared with those treated with radiation alone (p = 0.0004). Combined treatment also led to an increase in apoptosis (p = 0.01). At 24 hours, the γH2AX analysis revealed more dna double-strand breaks in N87 cells treated with radiation and NU7026 than in those treated with radiation alone (p = 0.04). Clonogenic assays demonstrated declining cell survival as both the radiation and the NU7026 dose increased. The dose enhancement factor at 0.1 survival fraction was 1.28 when N87 cells were treated with 4 Gy radiation and 5 μmol/L NU7026.
CONCLUSIONS
In gastric cancer cells, NU7026 appears to enhance the cytotoxic effect of irradiation as assessed by clonogenic assays. This increased cytotoxicity might be the result of an increase in dna double-strand breaks resulting in G2/M cell arrest and possibly higher levels of apoptosis.
未加标签
修复辐射诱导的 DNA 双链断裂是癌细胞放射抗性的关键机制。合成化合物 NU7026 特异性抑制非同源末端连接修复机制中的 DNA 依赖性蛋白激酶（DNA-PK）。早期的研究表明，与野生型细胞相比，DNA-PK 缺陷细胞的放射敏感性增加。在慢性白血病细胞中，NU7026 似乎增强了氯苯丁酸的细胞毒性作用。NU7026 对细胞存活、细胞周期、细胞凋亡和 DNA 双链断裂修复的放射修饰作用尚未在胃癌细胞中进行研究。
方法
用 0Gy 或 4Gy 处理胃癌细胞系 N87，同时用 0-20μmol/L 的 NU7026 处理。克隆形成实验用于评估处理后细胞的存活率。用碘化丙啶通过荧光激活细胞分选分析细胞周期分布。用 Annexin-V 和碘化丙啶通过荧光激活细胞分选检测细胞凋亡。用 γH2AX 测定法测量 DNA 双链断裂。
结果
与单独用辐射处理的细胞相比，用辐射和 NU7026 处理的 N87 细胞中观察到 G2/M 期阻滞显著增加（p=0.0004）。联合治疗也导致细胞凋亡增加（p=0.01）。在 24 小时时，γH2AX 分析显示，与单独用辐射处理的细胞相比，用辐射和 NU7026 处理的 N87 细胞中的 DNA 双链断裂更多（p=0.04）。克隆形成实验表明，随着辐射和 NU7026 剂量的增加，细胞存活率下降。当用 4Gy 辐射和 5μmol/L NU7026 处理 N87 细胞时，在 0.1 存活分数时的剂量增强因子为 1.28。
结论
在胃癌细胞中，NU7026 似乎通过克隆形成实验增强了照射的细胞毒性作用。这种增加的细胞毒性可能是由于 DNA 双链断裂增加导致 G2/M 期细胞阻滞和可能更高水平的细胞凋亡所致。
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