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J Biol Chem. 2015 Jan 30;290(5):3057-68. doi: 10.1074/jbc.M114.621995. Epub 2014 Dec 9.

Apurinic/apyrimidinic endonuclease/redox factor-1 (APE1/Ref-1) redox function negatively regulates NRF2.

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From the Departments of Pediatrics, Wells Center for Pediatric Research, Pharmacology and Toxicology,
Microbiology and Immunology.
Pharmacology and Toxicology.
From the Departments of Pediatrics, Wells Center for Pediatric Research.
From the Departments of Pediatrics, Wells Center for Pediatric Research, Pharmacology and Toxicology.
Biostatistics, and.
Pathology, Indiana University School of Medicine, Indianapolis, Indiana 46202 and.
the Departments of Oncology and Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Microbiology and Immunology, Medicine,


Apurinic/apyrimidinic endonuclease/redox factor-1 (APE1/Ref-1) (henceforth referred to as Ref-1) is a multifunctional protein that in addition to its base excision DNA repair activity exerts redox control of multiple transcription factors, including nuclear factor κ-light chain enhancer of activated B cells (NF-κB), STAT3, activator protein-1 (AP-1), hypoxia-inducible factor-1 (HIF-1), and tumor protein 53 (p53). In recent years, Ref-1 has emerged as a promising therapeutic target in cancer, particularly in pancreatic ductal carcinoma. Although a significant amount of research has centered on Ref-1, no wide-ranging approach had been performed on the effects of Ref-1 inhibition and transcription factor activity perturbation. Starting with a broader approach, we identified a previously unsuspected effect on the nuclear factor erythroid-related factor 2 (NRF2), a critical regulator of cellular defenses against oxidative stress. Based on genetic and small molecule inhibitor-based methodologies, we demonstrated that repression of Ref-1 potently activates NRF2 and its downstream targets in a dose-dependent fashion, and that the redox, rather than the DNA repair function of Ref-1 is critical for this effect. Intriguingly, our results also indicate that this pathway does not involve reactive oxygen species. The link between Ref-1 and NRF2 appears to be present in all cells tested in vitro, noncancerous and cancerous, including patient-derived tumor samples. In particular, we focused on understanding the implications of the novel interaction between these two pathways in primary pancreatic ductal adenocarcinoma tumor cells and provide the first evidence that this mechanism has implications for overcoming the resistance against experimental drugs targeting Ref-1 activity, with clear translational implications.


APE1/Ref-1; HMOX1; Hypoxia; Nuclear Factor 2 (Erythroid-derived 2-like Factor) (NFE2L2) (Nrf2); Pancreatic Adenocarcinoma; Reactive Oxygen Species (ROS); Redox Signaling; Transcription Factor

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