Peroxiredoxin 3 Is a Redox-Dependent Target of Thiostrepton in Malignant Mesothelioma Cells

• Type of Material: Article
• Authors: Kheng Newick, University of Vermont; Brian Cunniff, University of Vermont; Kelsey Preston, University of Vermont; Paul Held, BioTek Instruments; Jack Arbiser, Emory University; Harvey Pass, New York University Langone Medical Center; Brooke Mossman, University of Vermont; Arti Shukla, University of Vermont; Nicholas Heintz, University of Vermont
• Language: English
• Date: 2012-06-25
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2012 Newick et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0039404
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 7
• Issue: 6
• Start Page: e39404
• End Page: e39404
• Grant/Funding Information: The John Sterling Family Memorial grant from the Mesothelioma Applied Research Foundation, the Lake Champlain Cancer Research Organization, the Vermont Cancer Center, the Vermont Ladies Auxiliary of the Veterans of Foreign Wars, and a training grant in Environmental Pathology from the NIEHS (T32 ES007122-29).; The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.; The website for the Mesothelioma Applied Research Foundation is curemeso.org. There is no website for the Lake Champlain Cancer Research Organization, a charitable organization that funds cancer research at the Vermont Cancer Center, which has the web address vermontcancer.org.; The MARF, LCCRO and VFW grants supporting this work do not have federal grant numbers, only internal numbers associated with UVM accounting.
• Keywords: Science & Technology; BREAST-CANCER CELLS; MULTIDISCIPLINARY SCIENCES; N-TERMINAL-DOMAIN; Science & Technology - Other Topics; Multidisciplinary Sciences; FORKHEAD BOX M1; FLUORESCENT PROTEIN INDICATORS; PLEURAL MESOTHELIOMA; TRANSCRIPTION FACTOR; THIAZOLE ANTIBIOTICS; HEPATOCELLULAR-CARCINOMA; UP-REGULATION; FOXM1 EXPRESSION
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Pathology

Abstract

Thiostrepton (TS) is a thiazole antibiotic that inhibits expression of FOXM1, an oncogenic transcription factor required for cell cycle progression and resistance to oncogene-induced oxidative stress. The mechanism of action of TS is unclear and strategies that enhance TS activity will improve its therapeutic potential. Analysis of human tumor specimens showed FOXM1 is broadly expressed in malignant mesothelioma (MM), an intractable tumor associated with asbestos exposure. The mechanism of action of TS was investigated in a cell culture model of human MM. As for other tumor cell types, TS inhibited expression of FOXM1 in MM cells in a dose-dependent manner. Suppression of FOXM1 expression and coincidental activation of ERK1/2 by TS were abrogated by pre-incubation of cells with the antioxidant N-acetyl-L-cysteine (NAC), indicating its mechanism of action in MM cells is redox-dependent. Examination of the mitochondrial thioredoxin reductase 2 (TR2)-thioredoxin 2 (TRX2)-peroxiredoxin 3 (PRX3) antioxidant network revealed that TS modifies the electrophoretic mobility of PRX3. Incubation of recombinant human PRX3 with TS in vitro also resulted in PRX3 with altered electrophoretic mobility. The cellular and recombinant species of modified PRX3 were resistant to dithiothreitol and SDS and suppressed by NAC, indicating that TS covalently adducts cysteine residues in PRX3. Reduction of endogenous mitochondrial TRX2 levels by the cationic triphenylmethane gentian violet (GV) promoted modification of PRX3 by TS and significantly enhanced its cytotoxic activity. Our results indicate TS covalently adducts PRX3, thereby disabling a major mitochondrial antioxidant network that counters chronic mitochondrial oxidative stress. Redox-active compounds like GV that modify the TR2/TRX2 network may significantly enhance the efficacy of TS, thereby providing a combinatorial approach for exploiting redox-dependent perturbations in mitochondrial function as a therapeutic approach in mesothelioma.