The involvement of c-Myc in the DNA double-strand break repair via regulating radiation-induced phosphorylation of ATM and DNA-PKcs activity
The involvement of c-Myc in the DNA double-strand break repair via regulating radiation-induced phosphorylation of ATM and DNA-PKcs activity
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c-Myc 通过调节辐射诱导的 ATM 磷酸化和 DNA-PKcs 活性参与 DNA 双链断裂修复
DOI：
10.1007/s11010-015-2422-2
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发表时间：
2015-08-01
影响因子：
4.3
通讯作者：
Zhou, Ping-Kun
中科院分区：
文献类型：
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作者：
Cui, Fengmei;Fan, Rong;Zhou, Ping-Kun
c-Myc的失调经常发生在各种人类癌症中，这不仅有助于癌症的发生和进展，而且还影响癌症放疗或化疗的结果。在这项研究中，我们研究了c-Myc在γ射线照射诱导的DNA双链断裂（DSB）修复中的功能。利用RNA干扰技术从HeLa细胞中获得c- myc沉默的HeLa -630细胞系。采用γ - h2ax聚焦法、中性彗星法和脉冲场凝胶电泳法检测DNA dsb。我们发现，与对照Hela-NC细胞相比，Hela-630细胞的DNA DSB修复能力明显降低，DSB修复动力学延迟。c-myc的沉默使细胞对电离辐射的敏感性增强。在辐照细胞中，磷酸化的c-Myc （Thr58/pSer62）与γ - h2ax以及磷酸化的DNA-PKcs/S2056形成一致的共定位灶。此外，c-Myc的抑制在很大程度上减弱了电离辐射诱导的共济失调毛细血管扩张突变体（ATM）的磷酸化，并降低了DNA-PKcs的体外激酶活性。综上所述，我们的研究结果表明，c-Myc蛋白在DNA双链断裂修复过程中至少部分地通过影响ATM磷酸化和DNA- pkcs激酶活性发挥作用。肿瘤中c-Myc的过度表达可以解释某些肿瘤细胞类型的放射抗性。
Deregulation of c-Myc often occurs in various human cancers, which not only contributes to the genesis and progression of cancers but also affects the outcomes of cancer radio- or chemotherapy. In this study, we have investigated the function of c-Myc in the repair of DNA double-strand break (DSB) induced by gamma-ray irradiation. A c-Myc-silenced Hela-630 cell line was generated from HeLa cells using RNA interference technology. The DNA DSBs were detected by gamma-H2AX foci, neutral comet assay and pulsed-field gel electrophoresis. We found that the capability of DNA DSB repair in Hela-630 cells was significantly reduced, and the repair kinetics of DSB was delayed as compared to the control Hela-NC cells. Silence of c-myc sensitized the cellular sensitivity to ionizing radiation. The phosphorylated c-Myc (Thr58/pSer62) formed the consistent co-localisation foci with gamma-H2AX as well as the phosphorylated DNA-PKcs/S2056 in the irradiated cells. Moreover, depression of c-Myc largely attenuated the ionizing radiation-induced phosphorylation of the ataxia telangiectasia mutated (ATM) and decreased the in vitro kinase activity of DNA-PKcs. Taken together, our results demonstrated that c-Myc protein functions in the process of DNA double-strand break repair, at least partially, through affecting the ATM phosphorylation and DNA-PKcs kinase activity. The overexpression of c-Myc in tumours can account for the radioresistance of some tumour cell types.