Screening for H ₂O ₂-Mediated Cancer Therapeutics Using a Genetically Encoded Probe

Small-molecule compounds that modulate H2O2 reaction networks have potential applications as targeted cancer therapeutics. Previous studies to identify cancer therapeutics that induce oxidants have relied upon probes that respond to many different oxidants in cells. In this study, we used a genetically encoded fluorescent probe for human peroxiredoxin-2 (Prx2) oxidation to develop a high-throughput screen to identify small-molecule compounds that modulate H2O2 pathways. We further characterized cellular responses to several compounds selected from the screen. Our results revealed that some of the compounds enact H2O2-mediated toxicity. Among them, SMER3, an anti-fungal, has not been reported as an oxidant-inducing drug. Several drugs, including cisplatin, that previously have been shown to induce ROS did not appear to oxidize Prx2, suggesting H2O2 was not among the ROS induced by those drugs. Understanding which ROS-elevating therapeutics specifically induce H2O2 may allow more targeted therapy of tumors characterized by certain mutations and metabolic alterations.