State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University/Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu Province, 215123, P. R. China.
Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Institute of Radiotherapy & Oncology, Soochow University, 1055 Sanxiang Road, Suzhou, Jiangsu Province, 215004, P. R. China.
Int J Biol Sci. 2019 Aug 19;15(10):2240-2255. doi: 10.7150/ijbs.35356. eCollection 2019.
Radiation-induced bystander effect (RIBE), e.g. the biological response occurring in unirradiated cells when their neighboring cells are irradiated, is the consequence of intercellular communication between irradiated and unirradiated cells and intracellular signal transduction of these two cell populations. Although several miRNAs have been found to play an important role in RIBEs, the evidence for the regulatory effects of miRNAs on RIBEs is still limited. In this study, by using a two cell-line co-culture system, we first found that the migration of unirradiated bystander WS1 skin fibroblasts was inhibited after co-culture with irradiated HaCaT skin keratinocytes. Further study revealed that HaCaT cells exposed to α-particles and X-rays quickly showed an elevated miR-27a expression, which was essential for the induction of the bystander effect, resulting in the secretion of miR-27a-containing exosomes as a major RIBE signaling factor. Upon uptake of these exosomes, the recipient unirradiated WS1 cells displayed oxidative stress and increased miR-27a levels. Elevated levels of miR-27a that targets MMP2 in the recipient WS1 cells then led to slowed cell migration, which was dependent upon the redox status of WS1 cells. To summarize, the present study has revealed a critical role of miR-27a in every step of the induction of bystander migration inhibition of unirradiated WS1 fibroblasts co-cultured with irradiated HaCaT keratinocytes, confirming the important regulatory effects of miRNAs in RIBEs. Additionally, we provided direct evidence that RIBEs could affect wound healing.
辐射诱导的旁观者效应（RIBE），例如当相邻细胞受到照射时，未照射细胞中发生的生物学反应，是照射细胞和未照射细胞之间细胞间通讯以及这两种细胞群体的细胞内信号转导的结果。虽然已经发现几种 microRNA（miRNA）在 RIBE 中发挥重要作用，但 miRNA 对 RIBE 的调节作用的证据仍然有限。在这项研究中，我们首先使用两细胞系共培养系统发现，与照射的 HaCaT 皮肤角质形成细胞共培养后，未照射的旁观者 WS1 皮肤成纤维细胞的迁移被抑制。进一步的研究表明，暴露于α粒子和 X 射线的 HaCaT 细胞很快表现出 miR-27a 的表达升高，这对于诱导旁观者效应是必需的，导致含有 miR-27a 的外泌体的分泌作为主要的 RIBE 信号因子。在摄取这些外泌体后，未照射的 WS1 细胞显示出氧化应激和 miR-27a 水平升高。受体内 WS1 细胞中 miR-27a 的靶标 MMP2 的水平升高导致细胞迁移减慢，这依赖于 WS1 细胞的氧化还原状态。总之，本研究揭示了 miR-27a 在与照射的 HaCaT 角质形成细胞共培养的未照射 WS1 成纤维细胞诱导旁观者迁移抑制的每一步中都起着关键作用，证实了 miRNA 在 RIBE 中的重要调节作用。此外，我们提供了直接证据表明 RIBE 可能会影响伤口愈合。
