HSP90 inhibitor, DMAG, synergizes with radiation of lung cancer cells by interfering with base excision and ATM-mediated DNA repair.
HSP90 inhibitor, DMAG, synergizes with radiation of lung cancer cells by interfering with base excision and ATM-mediated DNA repair.
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DOI：
10.1158/1535-7163.mct-07-2104
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发表时间：
2008-07
影响因子：
5.7
通讯作者：
Varticovski L
中科院分区：
文献类型：
--
作者：
Koll TT;Feis SS;Wright MH;Teniola MM;Richardson MM;Robles AI;Bradsher J;Capala J;Varticovski L
抑制热休克蛋白90 （HSP90）导致不适当的蛋白质加工参与细胞存活途径。我们发现，HSP90抑制剂17-（二甲氨基乙胺）-17-demethoxygeldanamycin （DMAG）对非小细胞肺癌细胞系NCI-H460和A549具有协同作用。为了确定这种组合的最佳时间表，在DMAG之前、之后或同时对细胞进行辐射，并通过克隆测定对存活进行评分。DMAG给药顺序对与辐射的协同作用至关重要，预处理16 h可产生最大的协同作用。在RNA干扰使野生型p53表达沉默的等基因细胞中也观察到类似的放射致敏作用，尽管p53缺失使细胞总体上降低了放射敏感性。通过Western blotting、细胞周期分析、碱性彗星试验和直接测量关键碱基切除修复酶的活性来研究协同作用的机制基础。无论给药计划如何，DMAG都会导致辐射后参与细胞存活途径激活的蛋白质降解，这并不能解释在致克隆试验中观察到的给药计划的差异。除了先前报道的ATM激活降低外，DMAG预处理阻断了碱基切除修复机制的激活和关键酶，无尿嘧啶/无嘧啶内切酶和DNA聚合酶-β的活性。同样，用特异性无嘌呤/无嘧啶核酸内切酶抑制剂CRT0044876预处理，可以再现DMAG的作用。因此，放射前给药HSP90抑制剂对于优化其作为放射增敏剂的使用至关重要。
Inhibition of heat shock protein 90 (HSP90) leads to inappropriate processing of proteins involved in cell survival pathways. We found that HSP90 inhibitor, 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (DMAG), is synergistic with radiation for non-small cell lung cancer cell lines, NCI-H460 and A549. To establish the optimal schedule for this combination, cells were radiated before, after, or simultaneously with DMAG, and survival was scored by clonogenic assay. The sequence of DMAG administration was critical for synergy with radiation, and pretreatment for 16 h led to maximal synergy. Similar radiosensitization was observed in isogenic cells in which expression of wild-type p53 was silenced by RNA interference, although p53 loss rendered cells overall less radiosensitive. The mechanistic basis for synergy was studied by Western blotting, cell cycle analysis, alkaline comet assay, and direct measurement of the activities of key base excision repair enzymes. Regardless of schedule of administration, DMAG led to degradation of proteins involved in activation of cell survival pathways after radiation, which did not explain the differences in the schedule of administration observed in clonogenic assays. In addition to previously reported decrease in activation of ATM, pretreatment with DMAG blocked activation of base excision repair machinery and activity of key enzymes, apurinic/apyrimidinic endonuclease, and DNA polymerase-β. Similarly, pretreatment with specific apurinic/apyrimidinic endonuclease inhibitor, CRT0044876, reproduced the effects of DMAG. Thus, administration of HSP90 inhibitors before radiation is critical for optimizing their use as radiosensitizers.