Sensitization of breast carcinoma cells to ionizing radiation by small molecule inhibitors of DNA-dependent protein kinase and ataxia telangiectsia mutated
Sensitization of breast carcinoma cells to ionizing radiation by small molecule inhibitors of DNA-dependent protein kinase and ataxia telangiectsia mutated
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DOI：
10.1016/j.bcp.2005.09.029
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发表时间：
2005-12-19
影响因子：
5.8
通讯作者：
Tilby, MJ
中科院分区：
文献类型：
--
作者：
Cowell, IG;Durkacz, BW;Tilby, MJ
DNA- pk和ATM是磷脂酰肌醇t激酶样激酶（PIKK）家族丝氨酸/苏氨酸蛋白激酶的成员，在细胞对DNA双链断裂的反应中起关键作用。任何一种活性的基因缺失都会导致对电离辐射（IR）的明显敏感性。因此，这些酶是增强肿瘤细胞放射敏感性的潜在靶标。我们发现新的DNA-PK或ATM抑制剂使乳腺癌细胞对IR敏感。放射致敏伴随着明显的DNA修复缺陷，这是通过红外诱导的磷酸化组蛋白H2AX灶（γ H2AX灶）的持久性来测量的。这些特异性抑制剂还允许我们探测组蛋白H2AX在乳腺癌细胞γ辐照后磷酸化的生物化学和动力学，目的是验证H2AX作为体内DNA-PK或ATM抑制的生物标志物。ATM抑制降低了H2AX γ病灶的初始平均强度，而DNA-PK抑制对H2AX初始磷酸化的影响很小。然而，同时使用这两种化合物可显著降低γ - H2AX聚焦强度，这与报道的ATM和DNA-PK在IR诱导的H2AX磷酸化中的作用一致。(c) 2005爱思唯尔公司版权所有。
DNA-PK and ATM are members of the phosphatidylinositol T-kinase like kinase (PIKK) family of serine/threonine protein kinases and have critical roles in the cellular response to DNA double-strand breaks. Genetic loss of either activity leads to pronounced sensitivity to ionizing radiation (IR). Hence, these enzymes are potential targets to confer enhanced radio sensitivity on tumour cells. We show that novel inhibitors of either DNA-PK or ATM sensitize breast carcinoma cells to IR. Radiosensitization was accompanied by an apparent DNA repair deficit as measured by the persistence of IR-induced foci of phosphorylated histone H2AX (gamma H2AX foci). These specific inhibitors also allowed us to probe the biochemistry and kinetics of histone H2AX phosphorylation following gamma-irradiation in breast cancer cells with the aim of validating H2AX as a biomarker for DNA-PK or ATM inhibition in vivo. ATM inhibition reduced the initial average intensity of gamma H2AX foci while inhibition of DNA-PK had only a small effect on the initial phosphorylation of H2AX. However, simultaneous treatment with both compounds dramatically reduced gamma H2AX focus intensity, consistent with the reported role of ATM and DNA-PK in IR induced phosphorylation of H2AX. (c) 2005 Elsevier Inc. All rights reserved.