title: NDRG1 promotes growth of hepatocellular carcinoma cells by directly interacting with GSK-3β and Nur77 to prevent β-catenin degradation.
abstract: The N-myc downstream regulated gene 1 (NDRG1) is significantly associated with advanced tumor stages and poor survival of hepatocellular carcinoma (HCC), thereby implicating it as a potential target for HCC treatment. We aim to further understand its biological roles in hepatocarcinogenesis, as a means to exploit it for therapeutic purposes. By screening using the ProtoArray® Human Protein Microarrays, we identified glycogen synthase kinase 3β (GSK-3β) and the orphan nuclear receptor (Nur77) as potential interaction partners of NDRG1. These interactions were confirmed in HCC cell lines in vitro by co-immunoprecipitation; and co-localizations of NDRG1 with GSK-3β and Nur77 were observed by immunofluorescence staining. Additionally, high levels of NDRG1 competitively bind to GSK-3β and Nur77 to allow β-catenin to escape degradation, with consequent elevated levels of downstream oncogenic genes. In vivo, we consistently observed that NDRG1 suppression in HCC xenografts decreased β-catenin levels and its downstream target Cyclin D1, with concomitant tumor growth inhibition. Clinically, the over-expression of NDRG1 in HCC patient samples is positively correlated with GSK-3β-9ser (| R | = 0.28, p = 0.01), Nur77 (| R | = 0.42, p < 0.001), and β-catenin (| R |= 0.32, p = 0.003) expressions. In conclusion, we identified GSK-3β and Nur77 as novel interaction partners of NDRG1. These protein-protein interactions regulate the turnover of β-catenin and subsequent downstream signaling mediated by β-catenin in HCC cells, and provides potential targets for future therapeutic interventions.
authors.affiliation: Asian Liver Center, Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Lu
authors.affiliation: Asian Liver Center, Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Mei-Sze
authors.initials: MS
authors.lastname: Chua
authors.affiliation: Asian Liver Center, Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Asian Liver Center, Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: So
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D019938:Cyclin D1 / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D056945:Hep G2 Cells; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000378:metabolism*; D010671:Phenylurea Compounds / Q000494:pharmacology; D011485:Protein Binding; D059748:Proteolysis; D034622:RNA Interference; D000077157:Sorafenib; D047368:Tumor Burden / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays; D051176:beta Catenin / Q000378:metabolism*; D000099259:N-myc Downstream-Regulated Gene 1 Protein
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D019938:Cyclin D1; D004318:Doxycycline; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D047908:Intracellular Signaling Peptides and Proteins; D009536:Niacinamide; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D010671:Phenylurea Compounds; D000077157:Sorafenib; D051176:beta Catenin; D000099259:N-myc Downstream-Regulated Gene 1 Protein; C539821:NR4A1 protein, human; C000605506:GSK3B protein, human; C000605507:Gsk3b protein, mouse
keywords: GSK-3β; NDRG1; Nur77; liver cancer; β-catenin