Wang Yu, Guan Hua, Xie Da-Fei, Xie Yi, Liu Xiao-Dan, Wang Qi, Sui Li, Song Man, Zhang Hong, Zhou Jianhua, Zhou Ping-Kun
Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China.
Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
PLoS One. 2016 Oct 6;11(10):e0163896. doi: 10.1371/journal.pone.0163896. eCollection 2016.
Radiotherapy with heavy ions is considered advantageous compared to irradiation with photons due to the characteristics of the Braggs peak and the high linear energy transfer (LET) value. To understand the mechanisms of cellular responses to different LET values and dosages of heavy ion radiation, we analyzed the proteomic profiles of mouse embryo fibroblast MEF cells exposed to two doses from different LET values of heavy ion 12C. Total proteins were extracted from these cells and examined by Q Exactive with Liquid Chromatography (LC)-Electrospray Ionization (ESI) Tandem MS (MS/MS). Using bioinformatics approaches, differentially expressed proteins with 1.5 or 2.0-fold changes between different dosages of exposure were compared. With the higher the dosage and/or LET of ion irradiation, the worse response the cells were in terms of protein expression. For instance, compared to the control (0 Gy), 771 (20.2%) proteins in cells irradiated at 0.2 Gy of carbon-ion radiation with 12.6 keV/μm, 313 proteins (8.2%) in cells irradiated at 2 Gy of carbon-ion radiation with 12.6 keV/μm, and 243 proteins (6.4%) in cells irradiated at 2 Gy of carbon-ion radiation with 31.5 keV/μm exhibited changes of 1.5-fold or greater. Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Munich Information Center for Protein Sequences (MIPS) analysis, and BioCarta analysis all indicated that RNA metabolic processes (RNA splicing, destabilization and deadenylation) and proteasome pathways may play key roles in the cellular response to heavy-ion irradiation. Proteasome pathways ranked highest among all biological processes associated with heavy carbon-ion irradiation. In addition, network analysis revealed that cellular pathways involving proteins such as Col1a1 and Fn1 continued to respond to high dosages of heavy-ion irradiation, suggesting that these pathways still protect cells against damage. However, pathways such as those involving Ikbkg1 responded better at lower dosages than at higher dosages, implying that cell damage would occur when the networks involving these proteins stop responding. Our investigation provides valuable proteomic information for elucidating the mechanism of biological effects induced by carbon ions in general.
由于布拉格峰的特性和高线性能量转移（LET）值，与光子辐射相比，重离子放疗被认为具有优势。为了了解细胞对不同LET值和重离子辐射剂量的反应机制，我们分析了暴露于不同LET值的重离子12C两种剂量下的小鼠胚胎成纤维细胞（MEF）的蛋白质组图谱。从这些细胞中提取总蛋白，并通过配备液相色谱（LC）-电喷雾电离（ESI）串联质谱（MS/MS）的Q Exactive进行检测。使用生物信息学方法，比较了不同暴露剂量之间变化1.5倍或2.0倍的差异表达蛋白。离子辐射的剂量和/或LET越高，细胞在蛋白质表达方面的反应就越差。例如，与对照（0 Gy）相比，在12.6 keV/μm的碳离子辐射0.2 Gy照射的细胞中有771种（20.2%）蛋白质、在12.6 keV/μm的碳离子辐射2 Gy照射的细胞中有313种（8.2%）蛋白质以及在31.5 keV/μm的碳离子辐射2 Gy照射的细胞中有243种（6.4%）蛋白质表现出1.5倍或更大的变化。基因本体（GO）分析、京都基因与基因组百科全书（KEGG）分析、慕尼黑蛋白质序列信息中心（MIPS）分析和BioCarta分析均表明，RNA代谢过程（RNA剪接、去稳定化和腺苷酸化）和蛋白酶体途径可能在细胞对重离子辐射的反应中起关键作用。在与重碳离子辐射相关的所有生物学过程中，蛋白酶体途径排名最高。此外，网络分析表明，涉及Col1a1和Fn1等蛋白质的细胞途径在高剂量重离子辐射下仍持续做出反应，这表明这些途径仍在保护细胞免受损伤。然而，涉及Ikbkg1等的途径在较低剂量下的反应比在较高剂量下更好，这意味着当涉及这些蛋白质的网络停止反应时，细胞会发生损伤。我们的研究为阐明碳离子诱导的生物学效应机制提供了有价值的蛋白质组学信息。
