Oligomeric peroxiredoxin-I is an essential intermediate for p53 to activate MST1 kinase and apoptosis

Mammalian Ste20-like kinase-1 (MST1) kinase mediates H(2)O(2)-induced cell death by anticancer drugs such as cisplatin in a p53-dependent manner. However, the mechanism underlying MST1 activation by H(2)O(2) remains unknown. Here we show that peroxiredoxin-I (PRX-I) is an essential intermediate in H(2)O(2)-induced MST1 activation and cisplatin-induced cell death through p53. Cell stimulation with H(2)O(2) resulted in PRX-I oxidation to form homo-oligomers and interaction with MST1, leading to MST1 autophosphorylation and augmentation of kinase activity. In addition, RNA interference knockdown experiments indicated that endogenous PRX-I is required for H(2)O(2)-induced MST1 activation. Live-cell imaging showed H(2)O(2) generation by cisplatin treatment, which likewise caused PRX-I oligomer formation, MST1 activation and cell death. Cisplatin-induced PRX-I oligomer formation was not observed in embryonic fibroblasts obtained from p53-knockout mice, confirming the importance of p53. Indeed, ectopic expression of p53 induced PRX-I oligomer formation and cell death, both of which were cancelled by the antioxidant NAC. Moreover, we succeeded in reconstituting H(2)O(2)-induced MST1 activation in vitro, using purified PRX-I and MST1 proteins. Collectively, our results show a novel PRX-I function to cause cell death in response to high levels of oxidative stress by activating MST1, which underlies the p53-dependent cytotoxicity caused by anticancer agents. Oncogene (2011) 30, 4208-4218; doi:10.1038/onc.2011.139; published online 25 April 2011