Correlation Of RASSF1A And MINT31 Promoter Hypermethylation With Esophageal Intraepithelial Neoplasia And Esophageal Squamous Cell Carcinoma

Background:Esophageal intraepithelial neoplasia (EIN) is the crucial step when normal or chronic inflammatory esophageal tissue evolving to esophageal squamous cell carcinoma (ESCC), however, no practical molecular biomarkers are available for the early appraisal of EIN in clinical practice.Aims:To investigate the correlation of RASSF1A and MINT31 (tumor-related genes) promoter hypermethylation, as well as expression of DNA methyltransferase (DNMT1), with the development and progression of EIN and ESCC.Methods:Methylation-specific PCR (MSP) was used to determine the methylation patterns of RASSF1A and MINT31 in 30 ESCC,80 EIN and 20 normal esophageal tissues, and the results were verified by bisulfite sequencing PCR (BSP). Expression of DNMT1 protein in EIN and ESCC was measured by immunohistochemistry.Results:RASSF1A and MINT3I promoter methylation rates were increased gradually from normal esophageal tissue, EIN to ESCC (5.0% and 5.0% vs.32.5% and 26.2% vs.60.0% and 46.7%), significant difference was observed between any two stepwise groups (P＜0.05). In EIN and ESCC with MSP-proved RASSF1A promoter methylation, methylation loci could be detected in RASSF1A promoter by BSP. The positivity rates of DNMT1 in low-grade, high-grade EIN and ESCC were 32.5%,55.0% and 76.7%, respectively, with significant difference between any two stepwise groups (P<0.05). Overexpression of DNMT1 was positively correlated with RASSF1A promoter methylation, but not MIXT31 promoter methylation.Conclusions:RASSF1A and MINT31 promoter hypermethylation, as well as overexpression of DNMT1, play important roles in the development and progression of EIN and ESCC. Their measurements might be useful for the appraisal of EIN.