Methylation Detection Of HIC-1 And SLIT2 In Cell-free DNA And Its Significance In Diagnosis Of Breast Cancer

Background and ObjectiveAs the most common malignant tumor in women,breast cancer is harmful to women's health.Early diagnosis and treatment is the key to improve the survival rate of breast cancer patients.As a liquid biopsy technique,cell-free DNA methylation detection has been paid more and more attention.Many experiments have shown that the degree of cell-free DNA methylation is closely related to the occurrence and development of malignant tumors.In this study,BSP(Bisulfite sequencing PCR)was used to detect HIC-1(Hypermethylated In Cancer 1)and SLIT2(Slit Guidance Ligand 2)gene methylation in cell-free DNA,and to evaluate its clinical significance in the diagnosis of breast diseases.MethodsBlood samples were collected from 25 patients with breast cancer,10 patients with breast benign tumour and 10 healthy volunteers admitted to the ninth people's hospital of Shanghai jiaotong university school of medicine from May 1,2017 to September 30,2018.Free DNA in plasma was isolated and extracted.Methylation levels of CpG sites in promoter regions of genes HIC-1 and SLIT2 were detected by bisulfite sequencing(BSP).Results1.Among the 16 CpG sites in the promoter region of HIC-1,the methylation trend of sites 1-4 was significant.2.According to the analysis of the average methylation rate at sites 1-4 of HIC-1,the average methylation rate of breast cancer group was 22.55%,which was significantly different from that of the benign breast tumor group(8.5%)and the healthy control group(8.25%)(P < 0.05).3.The ROC(receiver operating characteristic)curve was plotted at the mean methylation rate of the 1-4 CpG sites of HIC-1,indicating its certain clinical value in the diagnosis of breast cancer.4.There was no significant difference in average methylation rate of HIC-1 between breast cancer patients with different clinical pathology(P > 0.05).5.The level of SLIT2 methylation in breast cancer patients was higher than that in benign breast tumor patients and healthy volunteers,but there was no statistical difference(P > 0.05).conclusionBreast cancer patients have a higher level of methylation in the promoter region of HIC-1,and the detection of methylation in the promoter region of HIC-1 gene in cell-free DNA has certain clinical value in the diagnosis of breast cancer.