Thioredoxin Peroxidase-1 (peroxiredoxin-1) Is Increased in Thioredoxin-1 Transfected Cells and Results in Enhanced Protection against Apoptosis Caused by Hydrogen Peroxide but Not by Other Agents Including Dexamethasone, Etoposide, and Doxorubicin

Thioredoxin-1 (Trx-1) is a small redox oncoprotein whose expression is increased in a number of human primary cancers where it is associated with aggressive tumor growth, inhibition of apoptosis and decreased patient survival. We report that Trx-1-transfected MCF-7 human breast cancer cells have increased expression of thioredoxin peroxidase-1 (TrxP-1) a peroxiredoxin family member that scavenges H2O2 using Trx-1 as a source of reducing equivalents. Our work shows that TrxP-1 is more effective than selenium-dependent glutathione peroxidase in protecting cells against H2O2 damage. Transfection of mouse WEHI7.2 lymphoma cells with human TrxP-1 or TrxP-2, but not TrxP-4, protects the cells against H2O2 induced apoptosis but does not protect against apoptosis induced by dexamethasone, etoposide, or doxorubicin. The results show that an increase in TrxP-1 expression contributes to the protection against H2O2 induced apoptosis caused by Trx-1, but does not protect against apoptosis induced by other agents.