Oxidative RNA damage has been found to be associated with a variety of diseases, and 8-hydroxyguanosine (8-OHG) is a typical marker of oxidative modification of RNA. This guanosine modification is an emerging biomarker for disease detection and determination of 8-OHG in human urine is favored because it is noninvasive to patients. However, due to its poor ionization efficiency in mass spectrometry and trace amount in urine, accurate quantification of this modified nucleoside is still challenging. Herein, a rapid, accurate, sensitive and robust method using solid-phase extraction (SPE) combined with isotope dilution ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for detection of this oxidative RNA modification in human urine. The limit of detection can reach 1.5 fmol and the method exhibits good precision on intra-day (1.8-3.3%) and inter-day (0.6-1.2%) analyses. Satisfactory recovery (87.5-107.2%) at three spiked levels was achieved by using HLB cartridge for urine pretreatment. Using this method, we quantified 8-OHG in urine from 65 colorectal cancer (CRC) patients and 76 healthy volunteers. The measured level of urinary 8-OHG for CRC patients and healthy controls is 1.91 ± 0.63 nmol/mmol creatinine and 1.33 ± 0.35 nmol/mmol creatinine, respectively. We found the content of 8-OHG in urine was raised in CRC patients patients, implying this oxidative RNA modification marker could act as a potential noninvasive indicator for early screening of CRC. In addition, this study will make contributions to the investigations of the influences of oxidative stress on the formation and development of CRC.

中文翻译：

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8-羟基鸟苷作为大肠癌患者尿液中可能的RNA氧化修饰标记：超高效液相色谱-串联质谱法评估。

已经发现氧化性RNA损伤与多种疾病有关，而8-羟基鸟苷（8-OHG）是RNA氧化修饰的典型标志。鸟嘌呤修饰是一种用于疾病检测的新兴生物标志物，人尿中8-OHG的测定是受欢迎的，因为它对患者无创。然而，由于其在质谱中的电离效率差和尿中的痕量，该修饰的核苷的准确定量仍然具有挑战性。本文中，开发了一种快速，准确，灵敏且可靠的方法，该方法使用固相萃取（SPE）结合同位素稀释超高效液相色谱串联质谱（UPLC-MS / MS）来检测人尿中的这种氧化RNA修饰。检测下限可以达到1。5 fmol，该方法在日内（1.8-3.3％）和日间（0.6-1.2％）分析中显示出良好的精度。通过使用HLB滤筒进行尿液预处理，可以在三个加标水平上获得满意的恢复率（87.5％至107.2％）。使用这种方法，我们对来自65位结直肠癌（CRC）患者和76位健康志愿者的尿液中的8-OHG进行了定量。CRC患者和健康对照者的尿中8-OHG的测量水平分别为1.91±0.63 nmol / mmol肌酐和1.33±0.35 nmol / mmol肌酐。我们发现CRC患者患者尿液中的8-OHG含量升高，这暗示该氧化性RNA修饰标记物可作为CRC早期筛查的潜在非侵入性指标。此外，本研究将为研究氧化应激对CRC形成和发展的影响做出贡献。