Expression of N-myc downstream-regulated gene 1 in primary gallbladder carcinoma and its correlation with clinicopathological features and clinical outcome.

N-myc downstream-regulated gene 1 (NDRG1), a member of the N-myc downstream-regulated gene family, is induced under a wide variety of stress and cell growth-regulatory conditions. In several cancers, recent studies have shown its association with inhibition of tumor metastasis and suggested it to be a tumor suppressor gene. However, its significance in primary gallbladder carcinoma (PGC) has not been studied. Therefore, the aim of this study was to investigate NDRG1 expression in PGC and its prognostic significance. We examined NDRG1 expression in tumor specimens from 138 patients with PGC by immunohistochemistry and analyzed the correlation between NDRG1 expression and clinicopathologic factors or survival. NDRG1 was expressed in 63.8% of PGC but not in the normal epithelium of the gallbladder, remarkably at the invasive front of the tumors. In addition, NDRG1 expression was significantly associated with high histologic grade, advanced pathologic T stage and clinical stage, positive nodal metastasis and venous/lymphatic invasion. Moreover, Kaplan-Meier curves showed that NDRG1 over-expression was significantly related to poor overall and disease-free survival (both P = 0.02). Furthermore, multivariate analyses showed that NDRG1 expression (hazard ratio, 3.338; P = 0.02) and clinical stage (hazard ratio, 3.128; P = 0.03) were independent risk factors for disease-free survival. Our data demonstrate for the first time that NDRG1 expression in PGC was significantly correlated with unfavorable clinicopathologic features and an independent poor prognostic factor for disease-free survival in patients. Taken together, our findings suggest that NDRG1 expression could be used as a novel prognostic factor for patient survival and might be a potential therapeutic target in PGC.