Inhibition of Hsp90 compromises the DNA damage response to radiation
Inhibition of Hsp90 compromises the DNA damage response to radiation
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DOI：
10.1158/0008-5472.can-06-2181
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发表时间：
2006-09-15
期刊：
影响因子：
11.2
通讯作者：
Tofilon, Philip J.
中科院分区：
文献类型：
--
作者：
Dote, Hideaki;Burgan, William E.;Tofilon, Philip J.
分子伴侣 Hsp90 的抑制剂已被证明可以增强肿瘤细胞的放射敏感性。为了开始解决相关机制，我们确定了 Hsp90 抑制剂 17-(二甲基氨基乙基氨基)-17-去甲氧基格尔德霉素 (17DMAG) 对辐射 DNA 损伤反应的影响。根据 γ H2AX 病灶扩散和中性彗星测定，将 MiaPaCa 肿瘤细胞暴露于 17DMAG 会导致放射增敏，从而抑制 DNA 双链断裂的修复。这种修复抑制与辐射后 DNA-PK 催化亚基 (DNA-PKcs) 磷酸化的减少以及 DNA-PKcs/ ErbBI 相互作用的破坏有关。这些数据表明，先前确定的 17DMAG 介导的 ErbBI 活性降低减少了其与 DNA-PKcs 的相互作用，从而解释了辐射诱导的 DNA-PK 激活的减弱。 17DNIAG 还被发现可以消除 G(2) 期和 S 期细胞周期检查点的激活。与这些事件相关的是 17DMAG 处理的细胞中辐射诱导的共济失调毛细血管扩张突变 (ATM) 激活和病灶形成的减少。虽然没有检测到 ATM 和 Hsp90 之间的相互作用，但发现 Hsp90 与 MREII/Rad5O/NBSI (MRN) 复合物相互作用。 17DMAG 暴露降低了 MRN 成分在辐射后形成核灶的能力。此外，尽管没有检测到 MRN 复合物的降解，但 17DMAG 暴露减少了 NBSI 和 ATM 之间的相互作用。这些结果表明，17DMAG 处理的细胞中辐射诱导的 ATM 激活减弱是 MRN 复合物功能受损的结果。这些数据表明，Hsp90 可以促进对辐射的 DNA 损伤反应，影响 DNA 修复和细胞周期检查点激活。
Inhibitors of the molecular chaperone Hsp90 have been shown to enhance tumor cell radiosensitivity. To begin to address the mechanism responsible, we have determined the effect of the Hsp90 inhibitor 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17DMAG) on the DNA damage response to radiation. Exposure of MiaPaCa tumor cells to 17DMAG, which results in radiosensitization, inhibited the repair of DNA double-strand breaks according to gamma H2AX foci dispersal and the neutral comet assay. This repair inhibition was associated with reduced DNA-PK catalytic subunit (DNA-PKcs) phosphorylation after irradiation and a disruption of DNA-PKcs/ ErbBI interaction. These data suggest that the previously established 17DMAG-mediated reduction in ErbBI activity reduces its interaction with DNA-PKcs and thus accounts for the attenuation of radiation-induced DNA-PK activation. 17DNIAG was also found to abrogate the activation of the G(2)- and S-phase cell cycle checkpoints. Associated with these events was a reduction in radiation-induced ataxia-telangiectasia mutated (ATM) activation and foci formation in 17DMAG-treated cells. Although no interaction between ATM and Hsp90 was detected, Hsp90 was found to interact with the MREII/Rad5O/NBSI (MRN) complex. 17DMAG exposure reduced the ability of the MRN components to form nuclear foci after irradiation. Moreover, 17DMAG exposure reduced the interaction between NBSI and ATM, although no degradation of the MRN complex was detected. These results suggest that the diminished radiation-induced activation of ATM in 17DMAG-treated cells was the result of a compromise in the function of the MRN complex. These data indicate that Hsp90 can contribute to the DNA damage response to radiation affecting both DNA repair and cell cycle checkpoint activation.