Radiotherapy is the most important adjuvant treatment for glioma; however, radioresistance is the major cause for inevitable recurrence and poor survival of glioma patients. Thus, this study aims to investigate the effect of astrocyte elevated gene-1 (AEG-1) on the radiosensitivity of glioma cells. Immunohistochemistry assay found that AEG-1 was generally overexpressed in glioma tissues and was correlated with poor clinicopathological features of glioma patients. AEG-1 knockdown inhibited proliferation of glioma cells. And γ-H2AX foci assay, colony formation assay, and flow cytometry analysis demonstrated that AEG-1 depletion enhanced radiosensitivity and promoted apoptosis as well as cell cycle arrest in G2 phase of glioma cells treated by ionizing radiation. Moreover, replication factor C5 (RFC5) was screened as the target of AEG-1 by using Affymetrix human gene expression array, and RFC5 expression was downregulated in AEG-1 knockdown glioma cells. Mechanistically, AEG-1 knockdown impaired homologous recombination repair activity induced by radiation through inhibiting RFC5 expression. Furthermore, the Kaplan–Meier analysis and multivariate Cox regression analysis indicated that high levels of AEG-1 and RFC5 were related to poor prognosis of glioma patients treated with radiotherapy. Taken together, our findings indicate that AEG-1 may serve as a reliable radiosensitizing target for glioma radiotherapy.

中文翻译：

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AEG-1 敲低通过靶向 RFC5 削弱同源重组，使胶质瘤细胞对辐射敏感

放射治疗是胶质瘤最重要的辅助治疗；然而，放射抗性是胶质瘤患者不可避免的复发和生存率低的主要原因。因此，本研究旨在探讨星形胶质细胞升高基因1（AEG-1）对神经胶质瘤细胞放射敏感性的影响。免疫组化分析发现AEG-1在胶质瘤组织中普遍过表达，与胶质瘤患者临床病理特征较差有关。AEG-1敲低抑制了胶质瘤细胞的增殖。γ-H2AX 病灶测定、集落形成测定和流式细胞术分析表明AEG-1耗竭增强放射敏感性并促进细胞凋亡以及电离辐射治疗的胶质瘤细胞 G2 期的细胞周期停滞。此外，通过使用Affymetrix人类基因表达阵列筛选复制因子C5（RFC5）作为AEG-1的靶标，并且RFC5在AEG-1敲低的胶质瘤细胞中表达下调。从机制上讲，AEG-1敲低通过抑制RFC5表达来削弱辐射诱导的同源重组修复活性。此外，Kaplan-Meier 分析和多变量 Cox 回归分析表明，高水平的AEG-1和RFC5与接受放疗的胶质瘤患者预后不良有关。总之，我们的研究结果表明AEG-1可以作为神经胶质瘤放疗的可靠放射增敏靶标。