Mithramycin selectively attenuates DNA-damage-induced neuronal cell death

Cell Death Dis. 2020 Jul 27;11(7):587. doi: 10.1038/s41419-020-02774-6.


DNA damage triggers cell death mechanisms contributing to neuronal loss and cognitive decline in neurological disorders, including traumatic brain injury (TBI), and as a side effect of chemotherapy. Mithramycin, which competitively targets chromatin-binding sites of specificity protein 1 (Sp1), was used to examine previously unexplored neuronal cell death regulatory mechanisms via rat primary neurons in vitro and after TBI in mice (males). In primary neurons exposed to DNA-damage-inducing chemotherapy drugs in vitro we showed that DNA breaks sequentially initiate DNA-damage responses, including phosphorylation of ATM, H2AX and tumor protein 53 (p53), transcriptional activation of pro-apoptotic BH3-only proteins, and mitochondrial outer membrane permeabilization (MOMP), activating caspase-dependent and caspase-independent intrinsic apoptosis. Mithramycin was highly neuroprotective in DNA-damage-dependent neuronal cell death, inhibiting chemotherapeutic-induced cell death cascades downstream of ATM and p53 phosphorylation/activation but upstream of p53-induced expression of pro-apoptotic molecules. Mithramycin reduced neuronal upregulation of BH3-only proteins and mitochondrial dysfunction, attenuated caspase-3/7 activation and caspase substrates' cleavage, and limited c-Jun activation. Chromatin immunoprecipitation indicated that mithramycin attenuates Sp1 binding to pro-apoptotic gene promoters without altering p53 binding suggesting it acts by removing cofactors required for p53 transactivation. In contrast, the DNA-damage-independent neuronal death models displayed caspase initiation in the absence of p53/BH3 activation and were not protected even when mithramycin reduced caspase activation. Interestingly, experimental TBI triggers a multiplicity of neuronal death mechanisms. Although markers of DNA-damage/p53-dependent intrinsic apoptosis are detected acutely in the injured cortex and are attenuated by mithramycin, these processes may play a reduced role in early neuronal death after TBI, as caspase-dependent mechanisms are repressed in mature neurons while other, mithramycin-resistant mechanisms are active. Our data suggest that Sp1 is required for p53-mediated transactivation of neuronal pro-apoptotic molecules and that mithramycin may attenuate neuronal cell death in conditions predominantly involving DNA-damage-induced p53-dependent intrinsic apoptosis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Biomarkers / metabolism
  • Brain Injuries, Traumatic / drug therapy
  • Brain Injuries, Traumatic / pathology
  • Cell Death / drug effects
  • DNA Damage*
  • Etoposide / pharmacology
  • Male
  • Mice, Inbred C57BL
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Models, Biological
  • Neurons / drug effects
  • Neurons / pathology*
  • Neuroprotective Agents / pharmacology
  • Plicamycin / pharmacology*
  • Plicamycin / therapeutic use
  • Proto-Oncogene Proteins c-jun / metabolism
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Transcription, Genetic / drug effects
  • Tumor Suppressor Protein p53 / metabolism


  • Biomarkers
  • Neuroprotective Agents
  • Proto-Oncogene Proteins c-jun
  • Tumor Suppressor Protein p53
  • Etoposide
  • Plicamycin