Laiakis Evagelia C, Mak Tytus D, Anizan Sebastien, Amundson Sally A, Barker Christopher A, Wolden Suzanne L, Brenner David J, Fornace Albert J
a Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington DC;
Radiat Res. 2014 Apr;181(4):350-61. doi: 10.1667/RR13567.1. Epub 2014 Mar 27.
The emergence of the threat of radiological terrorism and other radiological incidents has led to the need for development of fast, accurate and noninvasive methods for detection of radiation exposure. The purpose of this study was to extend radiation metabolomic biomarker discovery to humans, as previous studies have focused on mice. Urine was collected from patients undergoing total body irradiation at Memorial Sloan-Kettering Cancer Center prior to hematopoietic stem cell transplantation at 4-6 h postirradiation (a single dose of 1.25 Gy) and 24 h (three fractions of 1.25 Gy each). Global metabolomic profiling was obtained through analysis with ultra performance liquid chromatography coupled to time-of-flight mass spectrometry (TOFMS). Prior to further analyses, each sample was normalized to its respective creatinine level. Statistical analysis was conducted by the nonparametric Kolmogorov-Smirnov test and the Fisher's exact test and markers were validated against pure standards. Seven markers showed distinct differences between pre- and post-exposure samples. Of those, trimethyl-l-lysine and the carnitine conjugates acetylcarnitine, decanoylcarnitine and octanoylcarnitine play an important role in the transportation of fatty acids across mitochondria for subsequent fatty acid β-oxidation. The remaining metabolites, hypoxanthine, xanthine and uric acid are the final products of the purine catabolism pathway, and high levels of excretion have been associated with increased oxidative stress and radiation induced DNA damage. Further analysis revealed sex differences in the patterns of excretion of the markers, demonstrating that generation of a sex-specific metabolomic signature will be informative and can provide a quick and reliable assessment of individuals in a radiological scenario. This is the first radiation metabolomics study in human urine laying the foundation for the use of metabolomics in biodosimetry and providing confidence in biomarker identification based on the overlap between animal models and humans.
放射恐怖主义威胁及其他放射事件的出现，使得开发快速、准确且无创的辐射暴露检测方法成为必要。本研究的目的是将辐射代谢组学生物标志物的发现扩展至人类，因为此前的研究主要集中在小鼠身上。在纪念斯隆凯特琳癌症中心，于造血干细胞移植前，在照射后4 - 6小时（单次剂量1.25 Gy）和24小时（每次1.25 Gy，分三次照射），收集接受全身照射患者的尿液。通过超高效液相色谱与飞行时间质谱联用（TOFMS）分析获得全球代谢组学图谱。在进一步分析之前，将每个样本根据其各自的肌酐水平进行标准化。采用非参数柯尔莫哥洛夫 - 斯米尔诺夫检验和费舍尔精确检验进行统计分析，并针对纯标准品验证标志物。七个标志物在暴露前后的样本中显示出明显差异。其中，三甲基 - l - 赖氨酸以及肉碱共轭物乙酰肉碱、癸酰肉碱和辛酰肉碱在脂肪酸跨线粒体转运以进行后续脂肪酸β氧化过程中发挥重要作用。其余代谢物次黄嘌呤、黄嘌呤和尿酸是嘌呤分解代谢途径的终产物，高排泄水平与氧化应激增加和辐射诱导的DNA损伤有关。进一步分析揭示了标志物排泄模式中的性别差异，表明生成性别特异性代谢组学特征将具有参考价值，并可为放射场景中的个体提供快速可靠的评估。这是首次针对人类尿液的辐射代谢组学研究，为代谢组学在生物剂量测定中的应用奠定了基础，并基于动物模型与人类之间的重叠，为生物标志物鉴定提供了信心。
