Unique Cellular and Biochemical Features of Human Mitochondrial Peroxiredoxin 3 Establish the Molecular Basis for Its Specific Reaction with Thiostrepton.

Kimberly J Nelson,Nicholas Heintz,Stacie Beuschel,Uma Gandhi,Alexis Saaman,Brian Cunniff,Terri Messier,Terrence L Smalley,W Todd Lowther,Stephanie Milczarek

doi:10.3390/antiox10020150

Kimberly J Nelson, Nicholas Heintz + Show 8 more

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https://doi.org/10.3390/antiox10020150

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Abstract

A central hallmark of tumorigenesis is metabolic alterations that increase mitochondrial reactive oxygen species (mROS). In response, cancer cells upregulate their antioxidant capacity and redox-responsive signaling pathways. A promising chemotherapeutic approach is to increase ROS to levels incompatible with tumor cell survival. Mitochondrial peroxiredoxin 3 (PRX3) plays a significant role in detoxifying hydrogen peroxide (H2O2). PRX3 is a molecular target of thiostrepton (TS), a natural product and FDA-approved antibiotic. TS inactivates PRX3 by covalently adducting its two catalytic cysteine residues and crosslinking the homodimer. Using cellular models of malignant mesothelioma, we show here that PRX3 expression and mROS levels in cells correlate with sensitivity to TS and that TS reacts selectively with PRX3 relative to other PRX isoforms. Using recombinant PRXs 1–5, we demonstrate that TS preferentially reacts with a reduced thiolate in the PRX3 dimer at mitochondrial pH. We also show that partially oxidized PRX3 fully dissociates to dimers, while partially oxidized PRX1 and PRX2 remain largely decameric. The ability of TS to react with engineered dimers of PRX1 and PRX2 at mitochondrial pH, but inefficiently with wild-type decameric protein at cytoplasmic pH, supports a novel mechanism of action and explains the specificity of TS for PRX3. Thus, the unique structure and propensity of PRX3 to form dimers contribute to its increased sensitivity to TS-mediated inactivation, making PRX3 a promising target for prooxidant cancer therapy.

Highlights

IntroductionThiostrepton (TS) is an FDA-approved, thiazole antibiotic produced by Streptomycetes
The goal of this study was to determine the molecular basis for the specificity of TS for human peroxiredoxin 3 (PRX3), one key component for this candidate redox-based cancer therapy
PRX3 is over-expressed in MM cells and tumors [31], and PRX3 expression levels and mitochondrial reactive oxygen species (mROS) levels correlate with TS sensitivity (Figure 2)

Summary

Introduction

Thiostrepton (TS) is an FDA-approved, thiazole antibiotic produced by Streptomycetes. A recent study reported by Corsello et al tested the ability of 4518 drugs from the Drug. Repurposing Hub at the Broad Institute to kill 578 cancer cells lines [1]. TS showed significant efficacy in 403 tumor cells lines. TS was highlighted as “a drug of greatest interest for mechanistic follow-up.”. Previous work from our groups identified peroxiredoxin 3 (PRX3) as a key molecular target of TS [2,3]. Our data demonstrated that TS irreversibly crosslinks PRX3 through its active site Cys residues to form inactive covalent dimers, leading to increased mROS levels, reduced FOXM1 expression and anti-tumor activity in both in vitro and in vivo malignant mesothelioma (MM) tumor models

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