Department of Radiation Medicine, Institute of Modern physics, Chinese Academy of Sciences, Lanzhou, China; Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China.
J Cell Physiol. 2015 May;230(5):1094-103. doi: 10.1002/jcp.24841.
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a critical role in non-homologous end-joining repair of DNA double-strand breaks (DSB) induced by ionizing radiation (IR). Little is known, however, regarding the relationship between DNA-PKcs and IR-induced angiogenesis; thus, in this study we aimed to further elucidate this relationship. Our findings revealed that lack of DNA-PKcs expression or activity sensitized glioma cells to radiation due to the defective DNA DSB repairs and inhibition of phosphorylated Akt(Ser473) . Moreover, DNA-PKcs deficiency apparently mitigated IR-induced migration, invasion and tube formation of human microvascular endothelial cell (HMEC-1) in conditioned media derived from irradiated DNA-PKcs mutant M059J glioma cells or M059K glioma cells that have inhibited DNA-PKcs kinase activity due to the specific inhibitor NU7026 or siRNA knockdown. Moreover, IR-elevated vascular endothelial growth factor (VEGF) secretion was abrogated by DNA-PKcs suppression. Supplemental VEGF antibody to irradiated-conditioned media was negated enhanced cell motility with a concomitant decrease in phosphorylation of the FAK(Try925) and Src(Try416) . Furthermore, DNA-PKcs suppression was markedly abrogated in IR-induced transcription factor hypoxia inducible factor-1α (HIF-1α) accumulation, which is related to activation of VEGF transcription. These findings, taken together, demonstrate that depletion of DNA-PKcs in glioblastoma cells at least partly suppressed IR-inflicted migration, invasion, and tube formation of HMEC-1 cells, which may be associated with the reduced HIF-1α level and VEGF secretion. Inhibition of DNA-PKcs may be a promising therapeutic approach to enhance radio-therapeutic efficacy for glioblastoma by hindering its angiogenesis.
DNA 依赖性蛋白激酶催化亚基（DNA-PKcs）在电离辐射（IR）诱导的 DNA 双链断裂（DSB）的非同源末端连接修复中发挥关键作用。然而，关于 DNA-PKcs 与 IR 诱导的血管生成之间的关系知之甚少；因此，在这项研究中，我们旨在进一步阐明这种关系。我们的研究结果表明，由于 DNA DSB 修复缺陷和磷酸化 Akt（Ser473）抑制，缺乏 DNA-PKcs 表达或活性使神经胶质瘤细胞对辐射敏感。此外，由于特异性抑制剂 NU7026 或 siRNA 敲低抑制了 DNA-PKcs 激酶活性，DNA-PKcs 缺陷明显减轻了来自照射的 DNA-PKcs 突变体 M059J 神经胶质瘤细胞或 M059K 神经胶质瘤细胞的条件培养基诱导的人微血管内皮细胞（HMEC-1）的 IR 诱导迁移、侵袭和管形成。此外，DNA-PKcs 抑制消除了 IR 升高的血管内皮生长因子（VEGF）分泌。用 IR 处理的条件培养基中的补充 VEGF 抗体被否定了，同时降低了 FAK（Try925）和 Src（Try416）的磷酸化，增强了细胞迁移。此外，IR 诱导的转录因子缺氧诱导因子-1α（HIF-1α）积累被 DNA-PKcs 抑制显著消除，这与 VEGF 转录的激活有关。这些发现表明，神经胶质瘤细胞中 DNA-PKcs 的耗竭至少部分抑制了 HMEC-1 细胞的 IR 诱导的迁移、侵袭和管形成，这可能与 HIF-1α 水平和 VEGF 分泌减少有关。抑制 DNA-PKcs 可能是通过阻碍其血管生成来增强胶质母细胞瘤放射治疗效果的有前途的治疗方法。
