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

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 down-regulated in GC, and was negatively correlative to DNMT1 (r = −0.11, p = 0.03), DNMT3A (r = −0.10, p = 0.01), DNMT3B (r = −0.01, p = 0.88), respectively, whereas the DNA methylation of NDRG1 was positively correlative to DNMT family (DNMT1 r = 0.20, p < 0.01; DNMT3A r = 0.26, p < 0.001; DNMT3B r = 0.03, p = 0.57, respectively). NDRG1 expression was significantly inverse correlated with invasion depth ( p = 0.023), but DNMT1 was significantly positive correlated with invasion depth ( p = 0.049). DNMT3B was significantly correlated with the degree of tumor cell differentiation ( p = 0.030). However, there was no association between the expression of DNMT3A and clinicopathological features. The KM plotter showed that NDRG1 (HR = 0.95, 95% CI [0.8–1.12], p = 0.53) and DNMT1 (HR = 1.04, 95% CI [0.88–1.23], p = 0.67) had no association with prognosis of GC patients, while, DNMT3A ( p = 0.0064) and DNMT3B ( p = 0.00025) displayed significantly association. But the overall survival of high expression of NDRG1 tended to be prolonged. Conclusion These data suggest that down-regulation of NDRG1expression in GC may be due to its promoter DNA methylation via DNMT family. The demethylating agent maybe a potential target drug for GC patients.