title: The iron chelators Dp44mT and DFO inhibit TGF-β-induced epithelial-mesenchymal transition via up-regulation of N-Myc downstream-regulated gene 1 (NDRG1).
abstract: The epithelial-mesenchymal transition (EMT) is a key step for cancer cell migration, invasion, and metastasis. Transforming growth factor-β (TGF-β) regulates the EMT and the metastasis suppressor gene, N-myc downstream-regulated gene-1 (NDRG1), could play a role in regulating the TGF-β pathway. NDRG1 expression is markedly increased after chelator-mediated iron depletion via hypoxia-inducible factor 1α-dependent and independent pathways (Le, N. T. and Richardson, D. R. (2004) Blood 104, 2967-2975). Moreover, novel iron chelators show marked and selective anti-tumor activity and are a potential new class of anti-metabolites. Considering this, the current study investigated the relationship between NDRG1 and the EMT to examine if iron chelators can inhibit the EMT via NDRG1 up-regulation. We demonstrated that TGF-β induces the EMT in HT29 and DU145 cells. Further, the chelators, desferrioxamine (DFO) and di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), inhibited the TGF-β-induced EMT by maintaining E-cadherin and β-catenin, at the cell membrane. We then established stable clones with NDRG1 overexpression and knock-down in HT29 and DU145 cells. These data showed that NDRG1 overexpression maintained membrane E-cadherin and β-catenin and inhibited TGF-β-stimulated cell migration and invasion. Conversely, NDRG1 knock-down caused morphological changes from an epithelial- to fibroblastic-like phenotype and also increased migration and invasion, demonstrating NDRG1 knockdown induced the EMT and enhanced TGF-β effects. We also investigated the mechanisms involved and showed the TGF-β/SMAD and Wnt pathways were implicated in NDRG1 regulation of E-cadherin and β-catenin expression and translocation. This study demonstrates that chelators inhibit the TGF-β-induced EMT via a process consistent with NDRG1 up-regulation and elucidates the mechanism of their activity.
authors.affiliation: General Surgery Department of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Iron Metabolism and Chelation Program, Department of Pathology, Bosch Institute, University of Sydney, New South Wales 2006, Australia.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Iron Metabolism and Chelation Program, Department of Pathology, Bosch Institute, University of Sydney, New South Wales 2006, Australia.
authors.forename: Daohai
authors.initials: D
authors.lastname: Zhang
authors.affiliation: General Surgery Department of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Yue
authors.affiliation: General Surgery Department of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. Electronic address: zmhtiger@yeah.net.
authors.forename: Minhua
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Iron Metabolism and Chelation Program, Department of Pathology, Bosch Institute, University of Sydney, New South Wales 2006, Australia.
authors.forename: Zaklina
authors.initials: Z
authors.lastname: Kovacevic
authors.affiliation: General Surgery Department of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Iron Metabolism and Chelation Program, Department of Pathology, Bosch Institute, University of Sydney, New South Wales 2006, Australia. Electronic address: d.richardson@med.usyd.edu.au.
authors.forename: Des R
authors.initials: DR
authors.lastname: Richardson
mesh_terms: D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D003676:Deferoxamine / Q000494:pharmacology*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D055785:Gene Knockdown Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D017262:Siderophores / Q000494:pharmacology*; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism; D013882:Thiosemicarbazones / Q000493:pharmacokinetics* / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects*; D060449:Wnt Signaling Pathway / Q000187:drug effects; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism; D000099259:N-myc Downstream-Regulated Gene 1 Protein
chemical_list: D015820:Cadherins; D018797:Cell Cycle Proteins; D003676:Deferoxamine; D047908:Intracellular Signaling Peptides and Proteins; D016271:Proto-Oncogene Proteins c-myc; D017262:Siderophores; D051785:Smad Proteins; D013882:Thiosemicarbazones; D053773:Transforming Growth Factor beta1; D051176:beta Catenin; D000099259:N-myc Downstream-Regulated Gene 1 Protein; C489427:MYC protein, human; C539263:di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone