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 incr eased in a number of human primary cancers where it is associated with aggr essive tumor growth, inhibition of apoptosis and decreased patient survival . We report that Trx-1-transfected MCF-7 human breast cancer cells have inc reased expression of thioredoxin peroxidase-1 (TrxP-1) a peroxiredoxin fami ly member that scavenges H2O2 using Trx-1 as a source of reducing equivalen ts. Our work shows that TrxP-1 is more effective than selenium-dependent gl utathione 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 ag ainst apoptosis induced by dexamethasone, etoposide, or doxorubicin. The re sults show that an increase in TrxP-1 expression contributes to the protect ion against H2O2 induced apoptosis caused by Trx-1, but does not protect ag ainst apoptosis induced by other agents. (C) 2001 Academic Press.