Inhibition of the Redox Function of APE1/Ref-1 in Myeloid Leukemia Cell Lines Results in a Hypersensitive Response to Retinoic Acid-Induced Differentiation and Apoptosis

Exp Hematol. 2010 Dec;38(12):1178-88. doi: 10.1016/j.exphem.2010.08.011. Epub 2010 Sep 6.

Abstract

Objective: The standard of care for promyelocytic leukemia includes use of the differentiating agent all-trans retinoic acid (RA) and chemotherapy. RA induces cell differentiation through retinoic acid receptor (RAR) transcription factors. Because redox mechanisms influence how readily transcription factors bind to DNA response elements (RARE), the impact of small molecule (E3330) inhibition of the redox regulatory protein, apurinic-apyrimidinic endonuclease/redox effector factor (APE1/Ref-1) on RAR DNA binding and function in RA-induced myeloid leukemia cell differentiation and apoptosis was investigated.

Materials and methods: The redox function of APE1 was studied using the small molecule inhibitor E3330 in HL-60 and PLB acute myeloid leukemia cells. Electrophoretic mobility shift assays were employed to determine effect of inhibitor on APE1/Ref-1 redox signaling function. Trypan blue assays, Annexin-V/propidium iodide and CD11b staining, and real-time polymerase chain reaction analyses were employed to determine survival, apoptosis, and differentiation status of cells in culture.

Results: RARα binds to its RARE in a redox-dependent manner mediated by APE1/Ref-1 redox regulation. Redox-dependent RAR-RARE binding is blocked by E3330, a small molecule redox inhibitor of APE1/Ref-1. Combination treatment of RA + E3330 results in a profound hypersensitivity of myeloid leukemia cells to RA-induced differentiation and apoptosis. Additionally, redox inhibition by E3330 results in enhanced RAR target gene, BLR-1, expression in myeloid leukemia cells.

Conclusions: The redox function of APE1/Ref-1 regulates RAR binding to its DNA RAREs influencing the response of myeloid leukemia cells to RA-induced differentiation. Targeting of APE1/Ref-1 redox function may allow manipulation of the retinoid response with therapeutic implications.

Publication types

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

MeSH terms

  • Apoptosis / drug effects*
  • Benzoquinones / pharmacology
  • Cell Differentiation / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / antagonists & inhibitors*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / physiology
  • Humans
  • Leukemia, Myeloid / drug therapy*
  • Leukemia, Myeloid / pathology
  • Oxidation-Reduction
  • Propionates / pharmacology
  • Receptors, CXCR5 / analysis
  • Receptors, Retinoic Acid / metabolism
  • Response Elements
  • Retinoic Acid Receptor alpha
  • Tretinoin / pharmacology*

Substances

  • Benzoquinones
  • CXCR5 protein, human
  • Propionates
  • RARA protein, human
  • Receptors, CXCR5
  • Receptors, Retinoic Acid
  • Retinoic Acid Receptor alpha
  • E 3330
  • Tretinoin
  • APEX1 protein, human
  • DNA-(Apurinic or Apyrimidinic Site) Lyase