Li Yong, Han Wei, Ni Ting-Ting, Lu Liang, Huang Min, Zhang Yu, Cao Hui, Zhang Han-Qun, Luo Wen, Li Hang
Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China.
Department of Occupational and Environmental Health, School of Public Health, Ningxia Medical University, Ningxia 750004, P.R. China.
Oncol Rep. 2015 Jun;33(6):2821-8. doi: 10.3892/or.2015.3884. Epub 2015 Mar 30.
Resistance to radiation is a major problem in cancer treatment. The mechanisms of radioresistance remain poorly understood; however, mounting evidence supports a role for microRNAs (miRNAs) in the modulation of key cellular pathways mediating the response to radiation. The present study aimed to identify specific miRNAs and their effect on radioresistant cells. The global miRNA profile of an established radioresistant lung cancer cell line and the corresponding control cells was determined. Differential expression of the miRNAs was confirmed by quantitative real-time PCR (qRT-PCR). The binding effect of identical novel miRNAs and target mRNAs was determined by luciferase assay. Lung cancer cells were transfected with miRNA-specific mimics or inhibitors. The DNA-dependent protein kinase (DNA-PKcs) protein level was tested by western blot analysis. Radiosensitivity of cancer cells was determined using colony formation assay. Among the differentially expressed miRNAs, 25 miRNAs were overexpressed while 18 were suppressed in the radioresistant cells, both basally and in response to radiation compared to their control. An miRNA signature miR-1323 exhibited a >5-fold increase in the radioresistant cells. miR-1323 was demonstrated to bind to PRKDC 3'UTR, which is involved in DNA repair. Ectopic expression of miR-1323 significantly increased the survival fraction of irradiated cancer cells. Inhibition of miR-1323 reversed the radioresistance of cancer cells and subsequently suppressed the expression of miR-1323-regulated DNA-PKcs protein. The present study indicated that miRNAs are involved in the radioresistance of human lung cancer cells. A possible mechanism for resistance to radiation was via enhanced DNA repair. The present study demonstrated a role for miR-1323 in modulating radioresistance and highlights the need for further study investigating the potential role of miR-1323 as both a predictive marker of response and a novel therapeutic agent with which to enhance the efficacy of radiotherapy.
辐射抗性是癌症治疗中的一个主要问题。辐射抗性的机制仍知之甚少；然而，越来越多的证据支持微小RNA（miRNA）在调节介导辐射反应的关键细胞通路中发挥作用。本研究旨在鉴定特定的miRNA及其对辐射抗性细胞的影响。测定了一种已建立的辐射抗性肺癌细胞系及其相应对照细胞的整体miRNA谱。通过定量实时PCR（qRT-PCR）确认了miRNA的差异表达。通过荧光素酶测定确定了相同的新型miRNA与靶mRNA的结合作用。用miRNA特异性模拟物或抑制剂转染肺癌细胞。通过蛋白质印迹分析检测DNA依赖性蛋白激酶（DNA-PKcs）蛋白水平。使用集落形成试验测定癌细胞的放射敏感性。在差异表达的miRNA中，与对照相比，在辐射抗性细胞中，无论是基础状态还是对辐射的反应，有25种miRNA过表达，18种被抑制。一种miRNA特征性分子miR-1323在辐射抗性细胞中表现出超过5倍的增加。已证明miR-1323与参与DNA修复的PRKDC 3'非翻译区结合。miR-1323的异位表达显著增加了受辐照癌细胞的存活分数。抑制miR-1323可逆转癌细胞的辐射抗性，并随后抑制miR-1323调节的DNA-PKcs蛋白的表达。本研究表明，miRNA参与了人肺癌细胞的辐射抗性。辐射抗性的一种可能机制是通过增强DNA修复。本研究证明了miR-1323在调节辐射抗性中的作用，并强调需要进一步研究miR-1323作为反应预测标志物和增强放疗疗效的新型治疗剂的潜在作用。
