title: Suppressing N-Myc downstream regulated gene 1 reactivates senescence signaling and inhibits tumor growth in hepatocellular carcinoma.
abstract: Hepatocellular carcinoma (HCC) is the fifth most lethal malignancy worldwide with no curative therapies. To discover potentially novel therapeutic targets for HCC, we previously studied the gene expression profiles of HCC patients and identified that significant upregulation of N-Myc downstream regulated gene 1 (NDRG1) is associated with more aggressive phenotypes and poorer overall survival of HCC patients. In this study, we further used a loss-of-function approach (RNA interference) to understand the role of NDRG1 in hepatocarcinogenesis. We found that suppression of NDRG1 significantly impaired HCC cell growth through inducing extensive cellular senescence of HCC cells both in vitro and in vivo, accompanied by cell cycle arrest at the G1 phase. The observed antitumor effects of NDRG1 suppression were correlated with activation of major senescence-associated signaling pathways, such as upregulation of tumor suppressors p53, p21 and p16, and decreased phosphorylated Rb. To obtain further insights into the clinical significance of NDRG1-modulated senescence in HCC patients, immunohistochemistry staining of 92 cases of HCC patients was done. We found that high NDRG1 expression (n = 66) is associated with low p21 (n = 82; P < 0.001) and low p16 (n = 86; P < 0.001) levels. In conclusion, this study demonstrated that NDRG1 is a potential therapeutic target for HCC because its suppression triggers senescence of HCC cells through activating glycogen synthase kinase-3β-p53 pathway, thereby inhibiting tumor progression.
authors.affiliation: Asian Liver Center, Department of Surgery, Stanford University School of Medicine, P228, MSLS Building, 1201 Welch Road, Stanford, CA 94305, USA.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Lu
authors.forename: Mei-Sze
authors.initials: MS
authors.lastname: Chua
authors.forename: Samuel K
authors.initials: SK
authors.lastname: So
mesh_terms: D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division; D045744:Cell Line, Tumor; D016922:Cellular Senescence; D016193:G1 Phase; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D034741:RNA, Small Interfering; D015398:Signal Transduction; D000099259:N-myc Downstream-Regulated Gene 1 Protein
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D000099259:N-myc Downstream-Regulated Gene 1 Protein