Clinicopathological Significances Of NDRG1 Expression In Gastric Cancer

ObjectiveN-myc downstream regulatory gene 1(NDRG1)has been reported to be down-regulated in a variety of cancers and was positively associated with malignant biological behavior and poor prognosis in these cancers.The purpose of this study was to investigate NDRG1 expression in gastric cancer(GC)and the relationship between its expression and the clinicopathological parameters,DNA methylation,prognosis and related signaling pathways in gastric cancer.Methods1.Articles related to NDRG1 were downloaded from Pub Med,Web of Science and CNKI respectively.After screened under some criteria,those articles were used for meta-analysis by Review Manager 5.2 software.2.Western blot(WB)was used to detect NDRG1 protein expression level in sixteen pairs of gastric cancer and adjacent normal tissues.3.NDRG1 m RNA expression level was detected by q RT-PCR in eighteen pairs of gastric cancer and adjacent normal tissues.4.Tissue microarraies were constructed to detect NDRG1 protein expression level in 160 gastric cancer and eighty-six adjacent normal tissues in immunohistochemistry staining(IHC),and to study the relationship between NDRG1 protein expression and clinicopathological parameters.5.Transcriptome,clinical and methylation data of gastric cancer was downloaded from The Cancer Genome Atlas(TCGA)database respectively,and the raw data were processed with perl and R software.The data was used to compare NDRG1 m RNA expression difference in normal and gastric cancer groups,and analyze the relationship between NDRG1 m RNA expression and the clinicopathological characteristics,promoter methylation,and methylationsites in gastric cancer.6.The prognosis data of NDRG1 m RNA in gastric cancer was downloaded from Kaplan-Meier Plotter database,which was used to investigate the relationship between NDRG1 m RNA expression and the prognosis.7.Transcriptome data of TCGA-GC patients was used to conduct NDRG1-related gene set enrichment analysis(GSEA)by gsea-3.0 software.Results1.Meta-analysis result showed that NDRG1 protein was down-regulated in gastric cancer.NDRG1 protein expression was negatively correlated with local infiltration,lymph node metastasis,distant metastasis and TNM stage(P<0.05),but positively correlated with differentiation and prognosis(P<0.05),not with gender or age(P>0.05).2.TCGA and q RT-PCR results showed that NDRG1 m RNA expression was decreased in gastric cancer(P<0.05).3.WB and IHC results showed that NDRG1 was down-regulated in protein level(P<0.05).4.IHC results showed that NDRG1 protein expression was negatively correlated with tumor diameter,invasion depth,lymph node metastasis and lymphatic infiltration(P<0.05),positively associated with differentiation(P<0.05),and associated with Lauren’s classification(P<0.05),but not with age,gender or distant metastasis(P>0.05).5.In TCGA data,NDRG1 m RNA expression was negatively correlated with the depth of invasion and TNM staging of gastric cancer(P<0.05).6.NDRG1 m RNA expression was negatively correlated with promoter methylation(Cor=-0.3,P=8.282e-08)and partial methylation sites(Cor≤-0.3).7.Kaplan-Meier Plotter results indicated that NDRG1 m RNA hypoexpression was positively associated with poor prognosis of gastric cancer(P<0.05).8.The GSEA results showed that NDRG1 could be enriched in Cancer,Notch,PPAR,ERBB,adherent connection and tight connection signal pathways(P<0.05).Conclusions1.NDRG1 was down-regulated in gastric cancer,which might be related to gene promoter methylation.2.NDRG1 was negatively correlated with the malignant pathobiological behavior and poor prognosis in gastric cancer,and played an anti-cancer role through Notch,PPAR,ERBB,adhesion and tight junction signal pathways.3.NDRG1 could be used as a molecular marker for the development,progression and prognosis of gastric cancer.