DNMT family induced down-regulation of NDRG1 via DNA methylation and clinicopathological significance in gastric cancer

Abstract

Background Aberrant DNA methylation of tumor suppressor genes is a common event in the development and progression of gastric cancer(GC). Our previous study showed NDRG1, which could suppress cell invasion and migration, was frequently down-regulated by DNA methylation of its promoter in GC. Purpose and Methods To analyze the relationship between the expression and DNA methylation of NDRG1 and DNA methyltransferase (DNMT) family. We performed a comprehensive comparison analysis using 407 patients including sequencing analysis data of GC from TCGA. Results NDRG1 was negatively correlative to DNMT1 (p =0.03), DNMT3A(p =0.01), DNMT3B(p =0.88), respectively. Whereas, the DNA methylation of NDRG1 was positively correlative to DNMT family(DNMT1 p<0.01, DNMT3A p<0.001, DNMT3B p=0.57, respectively). NDRG1 expression was significantly inverse correlated with invasion depth (p =0.023), and DNMT1 was significantly positive correlated with the degree of tumor cell differentiation (p =0.049). DNMT3B was significantly correlated with tumor cell differentiation (p =0.030). However, there was no association between the expression of DNMT3A and clinicopathological features. The univariate analysis showed that NDRG1and DNMTs had no association with prognosis of GC patients. But, multivariate analysis showed DNMT1 was significantly correlated with prognosis of GC patients. Conclusion These data suggest that down-regulation of NDRG1 in gastric cancer is due to DNA methylation of NDRG1 gene promoter via DNMT family. The demethylating agent maybe a potential target drug for GC patients.