Functional analysis of novel analogues of E3330 that block the redox signaling activity of the multifunctional AP endonuclease/redox signaling enzyme APE1/Ref-1

Antioxid Redox Signal. 2011 Apr 15;14(8):1387-401. doi: 10.1089/ars.2010.3410. Epub 2011 Jan 4.


APE1 is a multifunctional protein possessing DNA repair and redox activation of transcription factors. Blocking these functions leads to apoptosis, antiangiogenesis, cell-growth inhibition, and other effects, depending on which function is blocked. Because a selective inhibitor of the APE redox function has potential as a novel anticancer therapeutic, new analogues of E3330 were synthesized. Mass spectrometry was used to characterize the interactions of the analogues (RN8-51, 10-52, and 7-60) with APE1. RN10-52 and RN7-60 were found to react rapidly with APE1, forming covalent adducts, whereas RN8-51 reacted reversibly. Median inhibitory concentration (IC(50) values of all three compounds were significantly lower than that of E3330. EMSA, transactivation assays, and endothelial tube growth-inhibition analysis demonstrated the specificity of E3330 and its analogues in blocking the APE1 redox function and demonstrated that the analogues had up to a sixfold greater effect than did E3330. Studies using cancer cell lines demonstrated that E3330 and one analogue, RN8-51, decreased the cell line growth with little apoptosis, whereas the third, RN7-60, caused a dramatic effect. RN8-51 shows particular promise for further anticancer therapeutic development. This progress in synthesizing and isolating biologically active novel E3330 analogues that effectively inhibit the APE1 redox function validates the utility of further translational anticancer therapeutic development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology*
  • Benzoquinones / chemical synthesis
  • Benzoquinones / chemistry
  • Benzoquinones / pharmacology*
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cloning, Molecular
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / antagonists & inhibitors*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / isolation & purification
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / metabolism
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Organization and Administration
  • Oxidation-Reduction / drug effects
  • Propionates / chemical synthesis
  • Propionates / chemistry
  • Propionates / pharmacology*
  • Signal Transduction / drug effects*
  • Structure-Activity Relationship


  • Antineoplastic Agents
  • Benzoquinones
  • Enzyme Inhibitors
  • Propionates
  • E 3330
  • APEX1 protein, human
  • DNA-(Apurinic or Apyrimidinic Site) Lyase