Faculty Collaboration Database

The iron-chelating drug triapine causes pronounced mitochondrial thiol redox stress. Toxicol Lett 2011 Mar 05;201(2):130-6

Date

01/05/2011

Pubmed ID

21195754

DOI

10.1016/j.toxlet.2010.12.017

Scopus ID

2-s2.0-79651473123 (requires institutional sign-in at Scopus site)   22 Citations

Abstract

Triapine (Tp) is an iron chelator with activity against several types of cancer. Iron-Tp [Fe(III)(Tp)(2)] can be redox-cycled to generate reactive oxygen species that may contribute to its cytotoxicity. However, evidence for this mechanism in cells is limited. The cytosolic and mitochondrial thioredoxins (Trx1 and Trx2, respectively) are essential for cell survival. They are normally maintained in the reduced state, and support the function of many intracellular proteins including the peroxiredoxins (Prxs). Their redox status can indicate oxidant stress in their respective subcellular compartments. Tp treatment of human lung A549 cells caused almost complete oxidation of Trx2 and its dependent peroxiredoxin (Prx3), but there was no effect on Trx1 redox status. Significant inhibition of total TrxR activity did not occur until Tp levels were 4-fold above those needed to cause Trx2 oxidation. While Tp caused a 36-45% decline in reduced glutathione (GSH) levels, GSH accounted for >99% of the total glutathione in the absence and presence of Tp. In vitro studies demonstrated that cysteine reduces Fe(III)(Tp)(2) to Fe(II)(Tp)(2), and cysteine was faster and more efficient than reduced glutathione (GSH) in this regard. Fe(III)(Tp)(2) also mediated the oxidation of purified Trx2 in vitro. Thus, Fe(III)(Tp)(2) itself, and/or various reactive species that may result from its redox cycling, could account for Trx2 and Prx3 oxidation in Tp-treated cells. The striking difference between the effects on Trx2 and Trx1 implies a pronounced thiol redox stress that is largely directed at the mitochondria. These previously unrecognized effects of Tp could contribute to its overall cytotoxicity.

Author List

Myers JM, Antholine WE, Zielonka J, Myers CR

Author

Jacek M. Zielonka PhD Assistant Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cells, Cultured
Glutathione
Humans
Iron Chelating Agents
Mitochondria
Oxidation-Reduction
Peroxiredoxins
Pyridines
Stress, Physiological
Sulfhydryl Compounds
Thioredoxins
Thiosemicarbazones