中文摘要：

目的：观察DNA甲基化酶（ DNMT1、DNMT3a和DNMT3b）与肺癌危险性的关系。方法：采用酶联免疫吸附法检测136例肺癌患者（肺癌组）、141例肺良性疾病患者（对照组）血清DNMT1、DNMT3a和DNMT3b的水平。分析性别、年龄、吸烟史、肺癌组织学类型和临床分期对血清DNMT1、DNMT3a和DNMT3b的影响，以及血清DN-MT1、DNMT3a和DNMT3b表达水平与肺癌危险性的关系。结果：肺癌组DNMT1、DNMT3a表达水平（μg/L）[12．64（9．67～17．07），0．74（0．61～1．05）]高于对照组[11．07（7．85～17．59），0．66（0．49～1．00）（Z ＝1．884， P＝0．002；Z＝1．788，P＝0．003）]，DNMT3b差异无统计学意义。按3种DNMTs水平的百分位数25％、50％、75％为分界点分别将肺癌组和对照组分为4层，结果显示随着DNMT1、DNMT3a表达水平增加，患肺癌的危险性增加（χ^2趋势＝4．062和7．853，P＜0．05）。结论：肺癌患者血清中DNMT1、DNMT3a表达水平显著升高，检测血清DNMTs的变化可预测患肺癌的风险。

英文摘要：

Aim： To explore the association of DNA methyltransferases （ DNMT1, DNMT3a and DNMT3b） and the risk of lung cancer .Methods：The levels of DNMT1, DNMT3a and DNMT3b in serum of 136 patients with lung cancer （ cancer group ） and 141 patients with benign pulmonary diseases （ control group ） were tested by ELISA .The impact of gen-der, age, smoking history, tumor histological type and stage on serum DNMT 1, DNMT3a and DNMT3b and associations between DNMT1, DNMT3a or DNMT3b and lung cancer risk were analyzed .Results：The levels of DNMT1 and DNMT3a （μg/L） in cancer group were[12.64（9.67-17.07）, 0.74（0.61-1.05）], significantly higher than the control group [11.07（7.85-17.59）, 0.66（0.49-1.00）（Z=1.884,P=0.002;Z=1.788,P=0.003）].The levels of DNMT3b had no significant difference between the 2 groups.When the subjects were categorized into four layers based on the 25%, 50%, 75%cut-off point of three DNA methyltransferases , it was shown that overexpressing of DNMT 1 and DNMT3a had increased risk of lung cancer （χ^2trend=4.062 and 7.853,P〈0.05）.Conclusion：DNMT1 and DNMT3a are overexpressed in serum of lung cancer patients and detection the DNMTs levels could predict the risk of lung cancer .