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: Jennifer E Hrabe, Brianne R O'Leary, Melissa A Fath, Samuel N Rodman, Anna M Button, Frederick E Domann, Douglas R Spitz, James J Mezhir
• Journal: Redox biology (Redox Biol) Vol. 5 Pg. 319-327 (Aug 2015) ISSN: 2213-2317 [Electronic] Netherlands
• PMID: 26114584 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 Published by Elsevier Ltd.

Chemical References

• 7-oxozeanol
• Antineoplastic Agents
• Auranofin
• Thioredoxins
• Zearalenone
• Thioredoxin-Disulfide Reductase
• MAP Kinase Kinase Kinases
• MAP kinase kinase kinase 7
• ras Proteins
• Glutathione

Topics

• Animals
• Antineoplastic Agents (chemistry, therapeutic use, toxicity)
• Auranofin (chemistry, therapeutic use, toxicity)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Colonic Neoplasms (drug therapy, metabolism, pathology)
• Female
• Glutathione (metabolism)
• HCT116 Cells
• Humans
• MAP Kinase Kinase Kinases (antagonists & inhibitors, metabolism)
• Mice
• Mice, Nude
• Mutation
• Oxidative Stress (drug effects)
• Thioredoxin-Disulfide Reductase (antagonists & inhibitors, metabolism)
• Thioredoxins (metabolism)
• Transplantation, Heterologous
• Zearalenone (analogs & derivatives, chemistry, therapeutic use, toxicity)
• ras Proteins (genetics, metabolism)