肝细胞肝癌中外周血浆DNA基因甲基化检测及意义

Detection and Clinical Significance of Methylation of Peripheral Plasma DNA in Patients with Hepatocellular Carcinoma

目的评估外周血浆DNA甲基化检测在肝细胞肝癌(HCC)诊断中的作用,筛选血浆灵敏度及特异性高的甲基化抑癌基因。方法采用甲基化特异性PCR(MSP)检测34例经病理检查证实的HCC患者血浆及其配对癌组织中的SLIT2及DAPK基因启动子甲基化状态,并分析其与HCC临床病理特征的关系。结果 34例HCC患者癌组织中SLIT2和DAPK基因甲基化率分别为70.6%(24/34)和79.4%(27/34),相应外周血浆中SLIT2和DAPK基因甲基化率分别为44.1%(15/34)和50.0%(17/34)。血浆SLIT2和DAPK基因甲基化检测的灵敏度分别为62.5%和63.0%,特异度均为100%,阴性预测值分别为52.6%和41.2%,阳性预测值均为100%。HCC癌组织和外周血浆中SLIT2及DAPK甲基化检出率与HCC各临床病理特征无关(P>0.05)。在AFP<400μg/L患者中SLIT2和DAPK基因甲基化联合检出率达61.1%(11/18)。结论基于MSP方法,血浆中SLIT2及DAPK基因甲基化仍有较高的检出率,HCC癌组织和血浆中SLIT2及DAPK基因甲基化具有明显的一致性。血浆DNA甲基化可作为一种独立非侵入性诊断HCC的标志物,尤其对AFP阴性者可提高HCC的诊断率。HBV感染可能仅与部分抑癌基因甲基化相关。

Objective To evaluate the effect of methylation determination about the peripheral plasma DNA in diagnose of hepatocellular carcinoma （HCC） and select the highly sensitive and specific methylated cancer suppressor genes. Methods Methylation-specific PCR （MSP） was used to detect the degree of methylation about SLIT2 and DAPK genes in peripheral plasma and associated cancer tissues of 34 patients with HCC confirmed by pathology, then analyzed their relationship to clinicopathologic feature. Results The positive rate of the promoter methylation of SLIT2 and DAPK genes in cancer tissues in 34 cases were 70. 6% （24/34） and 79. 4% （27/34）, while the relevant pro- moter methylation rate in plasma were 44. 1% （15/34） and 50. 0% （17/34） correspondingly. The sensitivity of detection ofDNA methylation about SLIT2 and DAPK genes in plasma was 62. 5% and 63.0%, respectively; both of the specific- ity for them were 100%. The negative predicted value was 52.6% and 41.2%, respectively; while both of the positive predicted value were 100%. There were no significant correlation between the clinicopathologic features and the meth- ylation rate in cancer tissues and plasma （P〉0.05）. In plasma of patients whose AFP〈400 μg/L, the positive rate of combined detection ofDNA methylation of SLIT2 and DAPK was 61.1% （11/18）. Conclusions The detection rate ofDNA methylation of SLIT2 and DAPK genes in plasma is higher, and there is a significant correlation between the DNA methylation in HCC tissue and plasma, based on MSP method. DNA methylation in plasma, as an non-invasive method, could be used to diagnose HCC, especially for the patients whose AFP is negative. HBV infection may be only associate with DNA methylation of part gene.