The Antibiotic Cefotaxime Works as Both an Activator of Nrf2 and an Inducer of HSP70 in Mammalian Cells

Both NF-E2-related factor 2 (Nrf2) and heat shock protein 70 (HSP70) contribute to cellular defense to various stresses, and have emerged as candidates of therapeutic targets to improve or prevent tissue damage. Cefotaxime (CTX), a third-generation cephalosporin antibiotic, is conceived as a safe drug largely free from side effects. CTX exhibits broad-spectrum antimicrobial activity, and thereby, is most commonly prescribed for the treatment of infectious diseases induced by Gram-positive or Gram-negative bacteria. In this study, we unexpectedly found the beneficial properties of CTX that upregulate both Nrf2 and HSP70 to the extent that stress-induced damage is ameliorated. Non-toxic levels of reactive oxygen species (ROS) induced by CTX activated the Nrf2 pathway without cytotoxicity, which in turn upregulated HSP70. Interestingly, the cytotoxicity of Fas/CD95 ligand (FasL), a cytotoxic cytokine that strongly induces apoptosis, was significantly ameliorated by pre-treatment with CTX, most likely because of the upregulation of Nrf2 and HSP70. Our results therefore show novel properties of CTX, which raise the possibility that CTX works as a non-toxic therapeutic agent for preventing and repairing tissue damage.