Inhibition of reductase systems by 2-AAPA modulates peroxiredoxin oxidation and mitochondrial function in A172 glioblastoma cells

• Published in: Toxicology in vitro Vol. 42; pp. 273 - 280
• Main Authors: de Souza, Luiz Felipe, Schmitz, Ariana Ern, da Silva, Luana Caroline Schüler, de Oliveira, Karen Andrinéia, Nedel, Cláudia Beatriz, Tasca, Carla Inês, de Bem, Andreza Fabro, Farina, Marcelo, Dafre, Alcir Luiz
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2017; Elsevier Science Ltd
• Subjects: 2-AAPA; Acetylcysteine - analogs & derivatives; Acetylcysteine - pharmacology; Antineoplastic Agents - pharmacology; Cell Line, Tumor; Cell Survival - drug effects; Cells; Cumene; Cumene hydroperoxide; Dimers; Electron transport; Glioblastoma; Glioblastoma - drug therapy; Glioblastoma - metabolism; Glioblastoma cells; Glutathione; Glutathione reductase; Glutathione Reductase - antagonists & inhibitors; Glutathione Reductase - metabolism; Homeostasis; Humans; Hydrogen Peroxide - pharmacology; Inhibition; Lipid peroxidation; Membrane potential; Metabolism; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Oxidation; Peroxide; Peroxides; Peroxiredoxin; Peroxiredoxins; Peroxiredoxins - metabolism; Propionic acid; Redox properties; Reductases; Reserve capacity; Thiocarbamates - pharmacology; Thiol metabolism; Thioredoxin; Thioredoxin reductase; Thioredoxin-Disulfide Reductase - antagonists & inhibitors; Thioredoxin-Disulfide Reductase - metabolism; Toxicity; Thiol metabolism; Glutathione reductase; Thioredoxin reductase; 2-AAPA; Peroxiredoxins
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2017.04.028

Thiol homeostasis has a critical role in the maintenance of proper cellular functions and survival, being coordinated by the action of several reductive enzymes, including glutathione (GSH)/glutathione reductase (GR) and thioredoxin (Trx)/thioredoxin reductase (TrxR) systems. Here, we investigated the effects of the GR inhibitor 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylthiocarbonylamino)phenylthiocarbamoylsulfanyl]propionic acid (2-AAPA) on the activity of thiol reductases (GR and TrxR), redox balance and mitochondrial function of A172 glioblastoma cells. 2-AAPA inhibited cell GR (IC50=6.7μM) and TrxR (IC50=8.7μM). A significant decrease in the cellular ability to decompose cumene hydroperoxide was observed and associated to a greater susceptibility to this peroxide. The redox state of peroxiredoxins (Prx1, Prx2 and Prx3) was markedly shifted to dimer 30min after treatment with 100μM 2-AAPA, an event preceding 2-AAPA-induced decrease in cell viability. Furthermore, mitochondrial function was also severely impaired, leading to a decrease in the respiratory control ratio, reserve capacity, and ATP synthesis-coupled respiration, as well as an increase in mitochondrial membrane potential. Our results indicate that inhibition of GR and TrxR activities, disruption of the ability to detoxify peroxides, increased oxidation of Prxs, as well as compromised mitochondrial function represent early events mediating 2-AAPA toxicity to A172 glioblastoma cells. •2-AAPA is toxic to A172 cells by inhibiting glutathione and thioredoxin reductases.•2-AAPA decreased organic peroxide detoxification, potentiating oxidative cell death.•Increased oxidation of peroxiredoxins by 2-AAPA would decrease antioxidant defenses.•Mitochondrial dysfunction and peroxiredoxin oxidation precede A172 cell death.•Dual inhibition of thioredoxin and glutathione reductases may improve cancer therapy.