Objective To investigate the methylation status of multiple genes in plasma and tumor tissues and its application in molecular diagnosis of esophageal squamous cell carcinoma (ESCC).Methods Methylation specific polymerase chain reaction (MSP) was used to detect methylation status of 5 tumor suppressor genes,such as adenomatous polyposis coli ( APC ),retinoic acid receptor-beta2 ( RARβ2 ),E-cadherin (CDH1),cyclin-dependent kinase inhibitor4A (p16INK4α) and ras association domain family member 1 A (RASSF1A) in tumour tissues,adjacent normal tissues and plasma which obtained 1 d preoperative and 7 d postoperative in 76 cases with ESCC.60 healthy volunteers were randomly selected as a control which were age-matched and sex-matched.Chi square test was used to analyze DNA methylation rates of 5 genes in various groups of tissue and plasma samples; Kappa test was used to compare the consistency of DNA methylation in the plasma samples and tissue samples,and their correlation was analyzed by Spearman correlation test; Receiver operating characteristic curve (ROC) was used to evaluate the sensitivity and specificity for single gene detection and 5 genes joint detection for diagnosis of esophageal squamous cell carcinoma.Results The methylation rates of APC,RARβ2,CDH1,p16INK4α and RASSF1A in tumour tissues of patients with ESCC were 44.7％ ( 34/76),72.4％ ( 55/76 ),72.4％ (55/76),86.8％ ( 66/76 ),55.3％ (42/76),respectively,which were significantly higher than that in the corresponding adjacent normal tissues [ 6.6％ ( 5/76 ),3.9％ ( 3/76 ),3.9％ ( 3/76 ),3.9％ ( 3/76 ),2.6％ ( 2/76 ),x2 =29.01,75.39,75.39,105.34,57.18,all P ＜ 0.001 ].The methylation rates of above 5 genes in patients' plasma were 42.1％ ( 32/76 ),63.2％ ( 48/76 ),63.2％ ( 48/76 ),71.1％ ( 54/76 ),50.0％ ( 38/76 ),respectively,which were significantly higher than that of control group [3.3％ (2/60),3.3％ (2/60),1.7％ ( 1/60),3.3％ (2/60),1.7％ (1/60),x2 =26.88,51.62,55.01,63.48,38.30,all P ＜ 0.001 ].The methylation consistency was favorable or well between plasma and tumour tissues in patients with ESCC ( Kappa value was 0.679,0.791,0.791,0.542 and 0.895,respectively.all P ＜0.001 ).In single-gene detection for patients' plasma,methylation,the sensitivity of 5 genes was 42.1％ ( 32/76 ),63.2％ ( 48/76 ),63.2％ ( 48/76 ),71.1％ ( 54/76 ),50.0％ ( 38/76 ),respectively.The specificity was 96.7％ ( 58/60 ),96.7％ ( 58/60 ),98.3％ (59/60),96.7％ (58/60),98.3％ (59/60),respectively.The area under curve (AUC) of ROC was 0.694 [95％ confidence interval( CI)0.606 - 0.782 ) ],0.799 ( 95％ CI 0.723 - 0.875 ),0.807 ( 95％CI 0.733 - 0.882),0.839 ( 95 ％ CI 0.769 - 0.908 ) and 0.742 ( 95 ％ CI 0.659 - 0.824 ),respectively.In united testing of 5 genes,the sensitivity was 80.3％ and the specificity was 88.3％,AUC was 0.843 (95％CI 0.773 -0.913 ).The sensitivity of united testing was significantly higher than that of single-gene detection of APC and RASSF1A(x2 =23.30,15.33 ; P ＜ 0.001 ),except RARβ2,CDH1 and p16INK4α (x2 =5.48,5.48,1.75; P =0.019,0.019,0.186);There was no significant differences in specificity between united testing and single-gene detection (x2 =1.922,1.922,3.348,1.922,3.348,all P ＞ 0.05 ).Conclusions The methylation consistency is favorable or well between tumour tissues and plasma in patients with ESCC.There is no significant superior in diagnosing ESCC with united testing of multiple tumor suppressor genes methylation in plasma than with single-gene detection.But the sensitivity of the former is better than the latter.%目的 研究食管鳞癌患者肿瘤组织和血浆多基因甲基化状态及其对食管鳞癌诊断的应用价值.方法 用甲基化特异性聚合酶链反应(methylation specific polymerase chain reaction,MSP)检测76例食管鳞癌患者肿瘤组织、配对癌旁正常组织、患者术前1d、术后7d血浆游离DNA中腺瘤性息肉瘤基因(adenomatous polyposis coli,APC)、维甲酸受体β2基因(retinoic acid receptor-beta2,RARβ2)、上皮细胞钙黏蛋白基因(E-cadherin,CDH1)、细胞周期蛋白依赖激酶抑制剂4A家族p16基因(cyclin-dependent kinase inhibitor4A,p16INK4α)、Ras相关家族蛋白1A基因(ras association domain family member 1A,RASSF1 A)甲基化,选取同期60名年龄、性别匹配的健康志愿者血浆DNA作对照.用x2检验分析各类组织与血浆标本中5个基因DNA甲基化率的差异；血浆与食管鳞癌组织标本DNA甲基化的相关性用Spearman相关分析；绘制受试者操作特征(receive operating characteristic,ROC)曲线评价单基因与5个基因联合检测诊断食管鳞癌的敏感度、特异度.结果 食管鳞癌组肿瘤组织中的APC、RARβ2、CDH1、p16INK4α、RASSF1A基因甲基化阳性率分别为44.7％ (34/76)、72.4％(55/76)、72.4％( 55/76)、86.8％( 66/76)、55.3％ (42/76),均显著高于对应癌旁正常组织[6.6％(5/76)、3.9％ (3/76)、3.9％ (3/76)、3.9％ (3/76)、2.6％( 2/76),x2值分别为29.01、75.39、75.39、105.34、57.18,P均＜0.001].食管鳞癌组术前血浆中5个基因的甲基化阳性率分别为42.1％(32/76)、63.2％ (48/76)、63.2％ (48/76)、71.1％ (54/76)、50.0％( 38/76),均显著高于健康对照组[3.3％ (2/60)、3.3％(2/60)、1.7％( 1/60)、3.3％ (2/60)、1.7％ (1/60),x2值分别为26.88、51.62、55.01、63.48、38.30,P均＜0.001].食管鳞癌患者血浆与肿瘤组织中5个基因甲基化的符合率均较高(Kappa值分别为0.679、0.791、0.791、0.542、0.895,P均＜0.001).血浆中APC、RARβ2、CDH1、p16INK4α、RASSF1A基因甲基化单项诊断食管鳞癌的敏感度分别为42.1％( 32/76)、63.2％(48/76)、63.2％( 48/76)、71.1％ (54/76)、50.0％( 38/76),特异度分别为96.7％( 58/60)、96.7％(58/60)、98.3％ (59/60)、96.7％( 58/60)、98.3％( 59/60)；ROC曲线下面积(AUC)分别为0.694[95％可信限(CI)0.606～0.782]、0.799( 95％ CI 0.723 ～0.875)、0.807( 95％ CI 0.733～0.882)、0.839(95％ CI0.769～0.908)、0.742(95％ CI 0.659～0.824)；5个基因联合检测血浆甲基化的敏感度为80.3％ (61/76),特异度88.3％ (53/60),ROC曲线AUC为0.843(95％ CI 0.773～0.913).联合检测的敏感度显著高于APC、RASSF1A单项检测(x2值分别为23.30、15.33,P均＜0.001),但与RARβ2、CDH1、p16INK4α的敏感度差异无统计学意义(x2值分别为5.48、5.48、1.75,P值分别为0.019、0.019、0.186)；联合检测与单项检测的特异度差异无统计学意义(x2值分别为1.922、1.922、3.348、1.922、3.348,P均＞0.05).结论 食管鳞癌患者血浆与肿瘤组织中抑癌基因甲基化符合率均较高,血浆中5个基因甲基化联合检测诊断食管鳞癌与单基因检测相比无显著优势,但前者敏感度高于后者.
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