title: Disruption of thioredoxin metabolism enhances the toxicity of transforming growth factor β-activated kinase 1 (TAK1) inhibition in KRAS-mutated colon cancer cells.
abstract: Transforming growth factor β-activated kinase 1 (TAK1) is critical for survival of many KRAS mutated colorectal cancer cells, and TAK1 inhibition with 5Z-7-oxozeaenol has been associated with oxidative stress leading to tumor cell killing. When SW 620 and HCT 116 human colon cancer cells were treated with 5µM 5Z-7-oxozeaenol, cell viability, growth, and clonogenic survival were significantly decreased. Consistent with TAK1 inhibition being causally related to thiol-mediated oxidative stress, 10mM N-acetylcysteine (NAC) partially reversed the growth inhibitory effects of 5Z-7-oxozeaenol. In addition, 5Z-7-oxozeaenol also increased steady-state levels of H2DCFDA oxidation as well as increased levels of total glutathione (GSH) and glutathione disulfide (GSSG). Interestingly, depletion of GSH using buthionine sulfoximine did not significantly potentiate 5Z-7-oxozeaenol toxicity in either cell line. In contrast, pre-treatment of cells with auranofin (Au) to inhibit thioredoxin reductase activity significantly increased levels of oxidized thioredoxin as well as sensitized cells to 5Z-7-oxozeaenol-induced growth inhibition and clonogenic cell killing. These results were confirmed in SW 620 murine xenografts, where treatment with 5Z-7-oxozeaenol or with Au plus 5Z-7-oxozeaenol significantly inhibited growth, with Au plus 5Z-7-oxozeaenol trending toward greater growth inhibition compared to 5Z-7-oxozeaenol alone. These results support the hypothesis that thiol-mediated oxidative stress is causally related to TAK1-induced colon cancer cell killing. In addition, these results support the hypothesis that thioredoxin metabolism is a critical target for enhancing colon cancer cell killing via TAK1 inhibition and could represent an effective therapeutic strategy in patients with these highly resistant tumors.
authors.affiliation: Department of Surgery, Division of Surgical Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA; Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Hrabe
authors.affiliation: Department of Surgery, Division of Surgical Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Brianne R
authors.initials: BR
authors.lastname: O'Leary
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Fath
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Rodman
authors.affiliation: Department of Biostatistics, University of Iowa, Iowa City, IA, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Button
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Frederick E
authors.initials: FE
authors.lastname: Domann
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.affiliation: Department of Surgery, Division of Surgical Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA; Department of Radiation Oncology, Free Radical and Radiation Biology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA. Electronic address: james-mezhir@uiowa.edu.
authors.forename: James J
authors.initials: JJ
authors.lastname: Mezhir
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000627:therapeutic use / Q000633:toxicity; D001310:Auranofin / Q000737:chemistry / Q000627:therapeutic use / Q000633:toxicity; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D005260:Female; D005978:Glutathione / Q000378:metabolism; D045325:HCT116 Cells; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects; D013880:Thioredoxin-Disulfide Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*; D014183:Transplantation, Heterologous; D015025:Zearalenone / Q000031:analogs & derivatives / Q000737:chemistry / Q000627:therapeutic use / Q000633:toxicity / Q000008:administration & dosage; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7; D007783:Lactones; D012118:Resorcinols
chemical_list: D000970:Antineoplastic Agents; D001310:Auranofin; D005978:Glutathione; D020930:MAP Kinase Kinase Kinases; D013880:Thioredoxin-Disulfide Reductase; D013879:Thioredoxins; D015025:Zearalenone; D018631:ras Proteins; D000099151:MAP Kinase Kinase Kinase 7; C505734:7-oxozeanol; D007783:Lactones; D012118:Resorcinols
keywords: Colorectal cancer; KRAS; TAK1; Thioredoxin; Treatment resistance