title: Using Sensors and Generators of H2O2 to Elucidate the Toxicity Mechanism of Piperlongumine and Phenethyl Isothiocyanate.
abstract: Chemotherapeutics target vital functions that ensure survival of cancer cells, including their increased reliance on defense mechanisms against oxidative stress compared to normal cells. Many chemotherapeutics exploit this vulnerability to oxidative stress by elevating the levels of intracellular reactive oxygen species (ROS). A quantitative understanding of the oxidants generated and how they induce toxicity will be important for effective implementation and design of future chemotherapeutics. Molecular tools that facilitate measurement and manipulation of individual chemical species within the context of the larger intracellular redox network present a means to develop this understanding. In this work, we demonstrate the use of such tools to elucidate the roles of H2O2 and glutathione (GSH) in the toxicity mechanism of two ROS-based chemotherapeutics, piperlongumine and phenethyl isothiocyanate.
  
  
  
  Depletion of GSH as a result of treatment with these compounds is not an important part of the toxicity mechanisms of these drugs and does not lead to an increase in the intracellular H2O2 level. Measuring peroxiredoxin-2 (Prx-2) oxidation as evidence of increased H2O2, only piperlongumine treatment shows elevation and it is GSH independent. Using a combination of a sensor (HyPer) along with a generator (D-amino acid oxidase) to monitor and mimic the drug-induced H2O2 production, it is determined that H2O2 produced during piperlongumine treatment acts synergistically with the compound to cause enhanced cysteine oxidation and subsequent toxicity. The importance of H2O2 elevation in the mechanism of piperlongumine promotes a hypothesis of why certain cells, such as A549, are more resistant to the drug than others.
  
  
  
  The approach described herein sheds new light on the previously proposed mechanism of these two ROS-based chemotherapeutics and advocates for the use of both sensors and generators of specific oxidants to isolate their effects. Antioxid. Redox Signal. 24, 924-938.
authors.affiliation: 1 Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts.
authors.forename: Beijing K
authors.initials: BK
authors.lastname: Huang
authors.affiliation: 2 Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts.
authors.forename: Troy F
authors.initials: TF
authors.lastname: Langford
authors.affiliation: 2 Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts.
authors.forename: Hadley D
authors.initials: HD
authors.lastname: Sikes
mesh_terms: D000072283:A549 Cells; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D015374:Biosensing Techniques; D002470:Cell Survival / Q000187:drug effects; D004148:Dioxolanes / Q000633:toxicity*; D004354:Drug Screening Assays, Antitumor; D005978:Glutathione / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D017879:Isothiocyanates / Q000633:toxicity*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010881:Piperidones
chemical_list: D000970:Antineoplastic Agents; D004148:Dioxolanes; D005978:Glutathione; D006861:Hydrogen Peroxide; D017879:Isothiocyanates; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C058305:phenethyl isothiocyanate; C498077:piperlongumine; D010881:Piperidones