Yuan Dexiao, Xu Jinping, Wang Juan, Pan Yan, Fu Jiamei, Bai Yang, Zhang Jianghong, Shao Chunlin
Institute of Radiation Medicine, Fudan University, Shanghai 200032, China.
Oncotarget. 2016 May 31;7(22):32707-22. doi: 10.18632/oncotarget.9017.
MiRNAs in the circulation have been demonstrated to be a type of signaling molecule involved in intercellular communication but little is known about their role in regulating radiosensitivity. This study aims to investigate the effects of extracellular miRNAs induced by ionizing radiation (IR) on cell proliferation and radiosensitivity. The miRNAs in the conditioned medium (CM) from irradiated and non-irradiated A549 lung cancer cells were compared using a microarray assay and the profiles of 21 miRNAs up and down-regulated by radiation were confirmed by qRT-PCR. One of these miRNAs, miR-1246, was especially abundant outside the cells and had a much higher level compared with that inside of cells. The expressions of miR-1246 in both A549 and H446 cells increased along with irradiation dose and the time post-irradiation. By labeling exosomes and miR-1246 with different fluorescence dyes, it was found that the extracellular miR-1246 could shuttle from its donor cells to other recipient cells by a non-exosome associated pathway. Moreover, the treatments of cells with miR-1246 mimic or its antisense inhibitor showed that the extracellular miR-1246 could enhance the proliferation and radioresistance of lung cancer cells. A luciferase reporter-gene transfer experiment demonstrated that the death receptor 5 (DR5) was the direct target of miR-1246, and the kinetics of DR5 expression was opposite to that of miR-1246 in the irradiated cells. Our results show that the oncogene-like extracellular miR-1246 could act as a signaling messenger between irradiated and non-irradiated cells, more importantly, it contributes to cell radioresistance by directly suppressing the DR5 gene.
循环中的微小RNA（miRNA）已被证明是一种参与细胞间通讯的信号分子，但对其在调节放射敏感性中的作用知之甚少。本研究旨在探讨电离辐射（IR）诱导的细胞外miRNA对细胞增殖和放射敏感性的影响。使用微阵列分析比较了照射和未照射的A549肺癌细胞条件培养基（CM）中的miRNA，并通过qRT-PCR确认了21种受辐射上调和下调的miRNA的谱。其中一种miRNA，miR-1246，在细胞外特别丰富，与细胞内相比水平要高得多。miR-1246在A549和H446细胞中的表达均随着照射剂量和照射后时间的增加而增加。通过用不同荧光染料标记外泌体和miR-1246，发现细胞外miR-1246可以通过非外泌体相关途径从其供体细胞穿梭到其他受体细胞。此外，用miR-1246模拟物或其反义抑制剂处理细胞表明，细胞外miR-1246可以增强肺癌细胞的增殖和放射抗性。荧光素酶报告基因转移实验表明，死亡受体5（DR5）是miR-1246的直接靶标，并且在受照射细胞中DR5表达的动力学与miR-1246相反。我们的结果表明，癌基因样细胞外miR-1246可以作为照射细胞和未照射细胞之间的信号信使，更重要的是，它通过直接抑制DR5基因来促进细胞放射抗性。
