Retrospective study of the roles of NDRG1 expression in gastric cancer: a meta- and bioinformatics analysis

NDRG1 (N-myc downstream-regulated gene 1) is the first member discovered in the NDRG family. It is believed to function as an inhibitor gene of tumors. This study performed a detailed and retrospective document retrieval through PubMed, Web of Science, and CNKI updated through July 10, 2017. It was found that levels of NDRG1 expression were decreased in gastric cancer, compared to normal mucosa (p<0.05). Expression of NDRG1 was negatively correlated with depth of invasion, lymph node metastasis, distant metastasis, TNM staging, and dedifferentiation of gastric cancer (p<0.05). A positive association between NDRG1 expression and favorable overall survival was detected in patients with gastric cancer (p<0.0001). Bioinformatics analysis demonstrated that NDRG1 mRNA expression was higher in gastric cancer than in homologous normal tissues, evenly stratified into different type of intestinal-, diffuse-, mixed-, tubular-, and mucinous-type carcinomas (p<0.05). Moreover, less invasion and lighter TNM staging had hyperexpression of NDRG1 mRNA (p<0.05). According to KM plotter database, expression of NDRG1 was significantly correlated with overall survival or progression-free survival rates of patients with gastric cancer, depending on the subgrouping (p<0.05). These consequences indicate that NDRG1 expression might be employed as a potential biomarker to indicate gastric carcinogenesis and subsequent progression, even prognosis.