中文摘要：

利用多重监测反应模式（MRM），通过对液相色谱及质谱条件的优化，建立了人体结肠癌组织样品中基因组DNA甲基化的高效液相色谱-电喷雾质谱（HPLC—ESIMS／MS）检测方法，对结肠癌组织及癌旁组织中基因组DNA甲基化进行了检测。结果表明，5-甲基脱氧胞苷（5mdC）的检出限是1Pg，线性范围为0．0375～0．5mg／L，工作曲线相关系数大于0．9990，该方法的相对标准偏差为2．32％～9．21％。结肠癌病人样品检测结果表明，结肠癌组织基因组DNA甲基化水平低于相应的癌旁组织（P〈0．05）。

英文摘要：

A sensitive and precise method for the quantification of global DNA methylation level in human colon cancer tissues was developed by liquid chromatography - electrospray ionization tandem mass spectrometry with multiple reaction monitoring（MRM） mode under optimized conditions. This method was used to detect the global DNA methylation level of the colon cancer tissues and non-cancerous tissues from colon cancer patients. Results showed that the detection limit was 1 pg for 5mdC （S/N = 5.6） , the linear range of calibration curve was 0. 037 5 - 0. 5 mg/L for 5mdC with the correlation coefficient higher than 0. 999 0. The relative standard deviations（RSD） ranged from 2.32% to 9.21% . Results also indicated that the global DNA methylation level in colon cancer tissues was significantly less than that of non-cancerous tissues（P 〈0. 05）.