关键词: 结直肠癌, 甲基化, miR-204, 表观遗传学

Abstract:

【Abstract】Objective  To investigate the clinical significance of miR-204 promoter methylation in colorectal cancer (CRC). Methods From January 2018 to March 2020，the blood samples, tumor tissue samples and paracarcinoma normal colon mucosal tissue samples were collected from 69 CRC patients admitted to the department of gastroenterology of our hospital. Another 68 healthy volunteers were recruited as the normal control group. The plasma samples were collected. Methylation levels of CpG sites identified in tumor and normal tissue were analyzed using the Tumor Gene Atlas Project (TCGA) database and gene-on-a-chip data (Methyl450K). The gene expression and promoter methylation status of miR-204 were detected by quantitative methylation-specific PCR (qMSP) and quantitative real-time PCR (qPCR). Results The TCGA data indicated that the expression of miR-204 was coordinately down-regulated with the expression of host gene TRPM3, and two CpG islands around the miR-204 promoter were identified. Compared with the paracancer tissues, the miR-204 promoter methylation reference percentage (PMR) was increased in CRC tissues[1.78 (0.35, 16.61) vs. 1.51 (0.45, 2.98), P＜0.001]. And the methylation level of miR-204 promoter was negatively correlated with the expression level of miR-204 (r=-0.324, P＝0.007), and positively correlated with DNA methyltransferase 1 mRNA (r=0.502, P＜0.001). Moreover, compared with the normal control group, the PMR of miR-204 promoter was significantly higher in plasma cfDNA of CRC patients[6.57 (0.76, 12.45) vs. 1.60 (0.59, 3.4), P＝0.015]. And PMR of miR-204 promoter in plasma cfDNA of CRC patients was positively correlated with PMR of miR-204 promoter in CRC tissues (r=0.418, P＜0.001).The area under receiver operating characteristic curve of PMR of miR-204 promoter in plasma cfDNA for CRC diagnosis was 0.701 (95%CI: 0.610-0.791), the sensitivity and specificity were 56.5% and 94.1%. In addition, further stratified analysis was conducted according to clinical stage and differentiation degree, there was no significant correlation between the hypermethylation of miR-204 promoter and the main clinical characteristics of CRC patients (P＞0.05). Conclusion miR-204 promoter methylation is significantly correlated with CRC, and the status of miR-204 promoter methylation in plasma cfDNA may be used as potential biomarkers for CRC diagnosis and monitoring.

Key words: Colorectal cancer, Methylation, miR-204, Epigenetics