Determination And Clinical Significance Of SLIT2Gene And DAPK Gene Methylation Of Peripheral Plasma In Hepatocellular Carcinoma

Objective To evaluate the effect of methylation determination about the peripheralplasma DNA in the diagnose of Hepatocellular Carcinoma and select the highlysensitive and specific methylated cancer suppressor genes. MethodsMethylation-specific PCR(MSP) was used to detect the degree of methylation of genepromoter of SLIT2gene and DAPK gene in the peripheral plasma and associated cancertissues of34patients confirmed by pathology, then analyzed their relationship toclinical data. Results The positive rate of the promoter methylation of SLIT2geneand DAPK gene in cancer tissues are70.5%(24/34) and79.4%(27/34) respectively,while the relevant promoter methylation rate in the peripheral plasma are44.1%(15/34)and50%(17/34) respectively. Promoter hypermethylation of SLIT2gene and DAPKgene was not found in plasma and tumor tissue samples from the healthy volunteercontrols. The sensitivity of DNA methylation about SLIT2gene and DAPK gene in theperipheral plasma are62.5%and63%respectively, the specificity of them are both100%. The negative predicted value are52.6%and41.2%, while the positive predictedvalue are both100%. There are no significant correlations between methylation rate andclinical data in cancer tissues and peripheral plasma. The sensitivity of SLIT2gene andDAPK gene promoter hypermethylation detection in34HCC patients is61.8%（21/34）. If AFP≥400ug/L, is considered as positive, AFP-positive rate was47.1%(16/34). Thepositive rate of the promoter methylation of SLIT2gene and DAPK gene in plasma ofpatients whose AFP<400ug/L are38.9%(7/18) and50%(9/18) respectively. Thesensitivity of detection of DNA methylation combining SLIT2gene and DAPK genearrived at61.1%（11/18）. If AFP≥20ug/L, is considered as positive, AFP-positive ratewas67.4（23/34）. The positive rate of the promoter methylation of SLIT2gene andDAPK gene in plasma of patients whose AFP<20ug/L are36.4%(4/11) and45.5%（5/11） respectively. The sensitivity of detection of DNA methylation combiningSLIT2gene and DAPK gene arrived at63.6%（7/11）.Conclusions Methylation ofSLIT2gene and DAPK gene in the plasma of patiens with HCC can be detected,andthere is a significant concordance between the DNA methylation in the tissue andplasma, basing on MSP method. DNA methylation in the plasma combining with AFPas an non-invasive method, may be used to diagnose HCC.