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Inhibition of DNA-PK activity and radio-sensitization induced by single strand DNA

单链 DNA 诱导的 DNA-PK 活性抑制和放射增敏作用

基本信息

批准号：
15390357
负责人：
HOSOI Yoshio
金额：
$ 8.77万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15390357/
关键词：
ionizing radiation DNA-PK single strand DNA DNA double strand breaks suramin EGF受容体 2重鎖切断 DNA修復癌

项目摘要

Phosphorothioate oligonucleotides and suramin bind to heparin binding proteins including DNA polymerases, and inhibit their functions. In the present study, we report inhibition of DNA-dependent protein kinase (DNA-PK) activity by phosphorothioate oligonucleotides and suramin. Inhibitory effect of phosphorothioate oligonucleotides on DNA-PK activity was increased with length and reached a plateau at 36-mer. The base composition of phosphorothioate oligonucleotides did not affect the inhibitory effect. The inhibitory effect by phosphorothioate oligodeoxycytidine 36-mer can be about 200-fold greater than that by the phosphodiester oligodeoxycytidine 36-mer. The inhibitory effect was also observed with purified DNA-PK, which suggests direct interaction between DNA-PK and phosphorothioate oligonucleotides. DNA-PK will have different binding positions for double-stranded DNA and phosphorothioate oligodeoxycytidine 36-mer because they were not competitive in DNA-PK activation. Suramin sensit … More ized cells to X-radiation in a dose-dependent fashion and longer exposure to suramin before X-irradiation resulted in more efficient sensitization. The dose-modifying factors calculated from the survival curves were 1.18 in LM217 cells and 1.37 in MDA-MB-468 cells. Suramin did not sensitized scid cells that had no DNA-dependent protein kinase activity. Suramin inhibited DNA-dependent protein kinase activity in vitro and in vivo. The concentration of suramin resulting in 50% inhibition in vitro was 1.7 μM in LM217 cells and 2.4 μM in MDA-MB-468 cells. Exposure of LM217 and MDA-MB-468 cells to suramin did not affect the level of Ku70 or Ku80, but it increased the level of DNA-PKcs. Suramin did not sensitize LM217 or MDA-MB-468 cells to UV radiation. Exposure to suramin inhibited the repair of DNA double-strand breaks caused by 50 Gy irradiation. Suramin's effects were not caused by accumulation of cells in a specific phase of the cell cycle. These results suggest that suramin sensitizes cells to ionizing radiation by inhibiting DNA-dependent protein kinase activity. Less

硫代磷酸酯寡核苷酸和苏拉明与包括 DNA 聚合酶在内的肝素结合蛋白结合，并抑制其功能。在本研究中，我们报告了硫代磷酸寡核苷酸和苏拉明对 DNA 依赖性蛋白激酶 (DNA-PK) 活性的抑制作用。硫代磷酸寡核苷酸对 DNA-PK 活性的抑制作用随着长度的增加而增加，并在 36 聚体处达到稳定水平。硫代磷酸寡核苷酸的碱基组成不影响抑制效果。硫代磷酸酯寡脱氧胞苷36聚体的抑制效果可以比磷酸二酯寡脱氧胞苷36聚体的抑制效果大约200倍。纯化的 DNA-PK 也观察到了抑制作用，这表明 DNA-PK 和硫代磷酸酯寡核苷酸之间存在直接相互作用。 DNA-PK 对于双链 DNA 和硫代磷酸寡脱氧胞苷 36 聚体将具有不同的结合位置，因为它们在 DNA-PK 激活中不具有竞争性。苏拉明以剂量依赖性方式使细胞对 X 辐射敏感，并且在 X 辐射之前较长时间接触苏拉明会导致更有效的敏化。从生存曲线计算出的剂量修改因子在LM217细胞中为1.18，在MDA-MB-468细胞中为1.37。苏拉明不会使不具有 DNA 依赖性蛋白激酶活性的 scid 细胞致敏。苏拉明在体外和体内抑制 DNA 依赖性蛋白激酶活性。在 LM217 细胞中产生 50% 体外抑制的苏拉明浓度为 1.7 μM，在 MDA-MB-468 细胞中为 2.4 μM。将 LM217 和 MDA-MB-468 细胞暴露于苏拉明不会影响 Ku70 或 Ku80 的水平，但会增加 DNA-PKcs 的水平。苏拉明不会使 LM217 或 MDA-MB-468 细胞对紫外线辐射敏感。暴露于苏拉明可抑制 50 Gy 辐射引起的 DNA 双链断裂的修复。苏拉明的作用不是由细胞周期特定阶段的细胞积累引起的。这些结果表明，苏拉明通过抑制 DNA 依赖性蛋白激酶活性使细胞对电离辐射敏感。较少的