CHAF1B induces radioresistance by promoting DNA damage repair in nasopharyngeal carcinoma
CHAF1B induces radioresistance by promoting DNA damage repair in nasopharyngeal carcinoma
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CHAF1B通过促进鼻咽癌DNA损伤修复诱导放射抗性
DOI：
10.1016/j.biopha.2019.109748
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发表时间：
2020-03-01
影响因子：
7.5
通讯作者：
Zhao, Chong
中科院分区：
文献类型：
--
作者：
Di, Muping;Wang, Meng;Zhao, Chong
背景：放射治疗是鼻咽癌的主要治疗手段，但放射抵抗限制了其疗效。因此，需要新的分子调节剂来提高鼻咽癌的放射敏感性。染色质组装因子1亚基B（CHAF 1 B）在DNA合成和修复中发挥作用，并参与多种恶性肿瘤的进展。方法：采用实时荧光定量PCR和免疫印迹法检测CHAF 1B在鼻咽癌中的表达。采用免疫组化法检测160例鼻咽癌组织中CHAF 1B的表达。分析CHAF 1B表达与鼻咽癌临床病理特征的关系。采用MTT法和集落形成实验检测CHAF 1B对鼻咽癌细胞放射敏感性的影响。采用流式细胞术分析细胞凋亡率。应用裸鼠皮下移植瘤模型和活体荧光成像来评价体内肿瘤消退。结果：CHAF 1B在鼻咽癌组织中的表达水平明显升高，与鼻咽癌放射抵抗和预后不良呈正相关。此外，CHAF 1B在放射抗性NPC细胞系中上调。CHAF 1B过表达降低鼻咽癌细胞的放射敏感性，而沉默CHAF 1B则增强鼻咽癌细胞的放射敏感性。CHAF 1B通过促进DNA损伤修复抑制鼻咽癌细胞凋亡。结论：CHAF 1B通过DNA依赖性蛋白激酶（DNA-PK）途径促进DNA损伤修复，抑制细胞凋亡，从而增强细胞的辐射抗性。CHAF 1B可作为预测放射敏感性的新因子。此外，DNA依赖性蛋白激酶抑制剂可作为CHAF 1B高表达的NPC患者的放射增敏剂。
Background: Radiotherapy is the main treatment for nasopharyngeal carcinoma (NPC); however radioresistance restricts its efficacy. Therefore, new molecular regulators are required to improve the radiosensitivity of NPC. Chromatin assembly factor 1 subunit B (CHAF1B) plays a role in DNA synthesis and repair, and participates in the progression of various malignancies. However, the expression and function of CHAF1B in NPC is unclear.Methods: The expression of CHAF1B was determined using real-time PCR and western blotting. CHAF1B expression in 160 human NPC tissue samples was evaluated using immunochemistry (IHC). The correlations between CHAF1B expression and NPC clinicopathological features were determined. The effect of CHAF1B on the radiosensitivity of NPC cells was detected using 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and colony formation assays. Apoptosis rates were analyzed using flow cytometry. A nude mouse subcutaneous xenograft model and living fluorescence imaging were applied to evaluate tumor regression in vivo. The molecular mechanisms of radioresistance were confirmed by bioinformatics analysis and detection of phosphorylated H2A histone family member X (gamma H2AX) foci.Results: Significantly increased CHAF1B levels were observed in NPC tissues, which correlated positively with radioresistance and poor prognosis. In addition, CHAF1B was upregulated in radioresistant NPC cell lines. Overexpression of CHAF1B reduced, while silencing of CHAF1B enhanced, the radiosensitivity of NPC cells in vitro and in vivo. Mechanistically, CHAF1B inhibited NPC cell apoptosis by promoting DNA damage repair. Finally, the DNA-dependent protein kinase (DNA-PK) pathway was observed to be essential for CHAF1B promotion of DNA damage repair-mediated radioresistance.Conclusion: The results suggested CHAF1B enhances radioresistance by promoting DNA damage repair and inhibiting cell apoptosis, in a DNA-PK pathway-dependent manner. CHAF1B may serve as a novel factor for predicting radiorsensitivity. Besides, DNA-dependent protein kinase inhibitor could serve as a radiosensitizer for patients with NPC and high CHAF1B expression.