粪便中SOX21基因甲基化检测在结直肠癌诊断中应用价值

Aberrant methylation of SOX21 gene as a potential marker for stool-based detection of colorectal cancer

目的 Y染色体性别决定区域相关高迁移率族盒21基因(sex-determining regio of Y chromosome related high-mobility-group box 21,SOX21)在结直肠癌组织中发生异常甲基化,然而该基因在结肠癌粪便标本中是否发生异常甲基化及其意义尚不清楚。本研究检测组织和粪便标本中SOX21基因启动子区甲基化水平,旨在评估甲基化的SOX21基因作为结直肠癌粪便基因检测标志物价值。方法选取2014-05-20-2015-02-26中山大学附属第六医院胃肠外科收治的105例结直肠癌患者的癌与癌旁正常组织,分别组成结直肠癌组和癌旁正常组。以及2014-04-03-2016-10-10收治的240例患者粪便标本,其中结直肠癌80例为结直肠癌组,腺瘤77例为腺癌组,正常83例为正常组。采用定量甲基化特异性聚合酶链式反应(quantitative methylation specific polymerase chain reaction,qMSP)技术检测SOX21基因甲基化水平,计算敏感性、特异性和ROC曲线下面积,并分析SOX21基因甲基化与结直肠癌患者临床病理特征之间关系。结果组织标本结果显示,肿瘤组织SOX21基因甲基化水平高于其对应癌旁组织,Z=8.679,P<0.001;当甲基化的SOX21特异性为97.1%(102/105)时,结直肠癌检出率为84.8%(89/105);ROC曲线下面积为0.930,95%CI为0.889～0.971;SOX21甲基化与年龄、性别、部位、TNM分期、肿瘤大小和分化程度无关联,均P>0.05。粪便标本结果显示,结直肠癌组和腺瘤组SOX21甲基化水平高于正常组,P<0.05。当甲基化的SOX21特异性为97.6%(81/83)时,对结直肠癌敏感性为80.0%(64/80),对腺瘤敏感性为33.8%(26/77);SOX21检测结直肠癌的ROC曲线下面积为0.926,95%CI为0.885～0.968,检测腺瘤的ROC曲线下面积为0.667,95%CI为0.583～0.751;SOX21基因对肿瘤检出率与肿瘤近、远端发生位置有关联,远端肿瘤检出率高,χ2=17.372,P<0.001,但与年龄、性别、TNM分期、肿瘤大小和分化程度无关联,P>0.05。结论在结直肠癌组织和粪便标本中,SOX21基因启动子区均发生异常高甲基化。甲基化的SOX21基因是结直肠癌粪便基因检测的潜在良好标志物。

OBJECTIVE Abnormal methylation of SRY-related HMG-box 21(SOX21)gene has been investigated in colorectal cancer(CRC)tissue.However,this gene's methylation status in stool sample of CRC has not been reported.We examined SOX21 gene promoter methylation level in tissue and stool samples simultaneously to assess the value of SOX21 methylation as a stool-based CRC detection marker.METHODS All tissue and stool samples were collected from Department of Gastroenterology,Sixth Affiliated Hospital of Sun Yat-sen University.Totally 105 pairs of CRC and adjacent normal tissues collected from 2014-05-20 to 2015-02-26 were assigned to CRC group and adjacent normal group respectively. Totally 240 stool samples collected form 2014-04-03 to 2016-10-10 were allocated to CRC group (80 CRCs),adenoma group (adenomas)and normal group (83 normal indiriduals)respectively.Quantitative methylation specific PCR(qMSP) was applied to measure the methylation level of SOX21 gene.Sensitivity,specificity and the area under ROC curve were calculated.The association between SOX21 methylation and the elinicopatbological features of CRC patients was also ana- lyzed.RESULTS Methylation level of SOX21 was significantly higher in tumor tissues as compared to the adjacent normal tissues(P<0.001).In tissue samples,84.8%tumor could be detected by the methylated SOX21 at a specificity of 97.1%.The detection rate was independent of the cIinicopathological features of the tumors.Methylated SOX21 was noticeably upregulated in the stool samples from CRC or adenoma patients compared to the normal samples(P<0.05).The stool sample analyses showed that the sensitivity of methylated SOX21 was 80.0%to CRC and 33.8M to adenoma respectively,at a specificity of 97.6 %.The CRC detection rate in stool was only related to tumor location,but not to age, gender,TNM stage,dysplasia and tumor size.CONCLUSIONS The promoter region of SOX21 was aberrantly hypermethylated in cancer tissue and fecal samples from CRC patients.The methylated SOX21 is a potential biomarker for stoolbased noninvasive CRC detection.