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.