Chemogenomic Identification of Ref-1/AP-1 as a Therapeutic Target for Asthma

Asthma is characterized by an oxidant/antioxidant imbalance in the lungs leading to activation of redox-sensitive transcription factors, nuclear factor $\kappa B\>(NF\!-\!\kappa B)$, and activator protein-1 (AP-1). To develop therapeutic strategies for asthma, we used a chemogenomics approach to screen for small molecule inhibitor(s) of AP-1 transcription. We developed a β-strand mimetic template that acts as a reversible inhibitor (pseudosubstrate) of redox proteins. This template incorporates an enedione moiety to trap reactive cysteine nucleophiles in the active sites of redox proteins. Specificity for individual redox factors was achieved through variations in X and Y functionality by using a combinatorial library approach. A limited array (2 x 6) was constructed where X was either NHCH3or NHCH2Ph and Y was methyl, phenyl, m-cyanophenyl, m-nitrophenyl, m-acetylaniline, or m-methylbenzoate. These analogs were evaluated for their ability to inhibit transcription in transiently transfected human lung epithelial A549 cells from either an AP-1 or NF-κ B reporter. A small-molecule inhibitor, PNRI-299, was identified that selectively inhibited AP-1 transcription $(IC_{50}\>of\>20\> \mu M)$ without affecting NF-κ B transcription (up to $200\> \mu M$) or thioredoxin (up to $200\> \mu M$). The molecular target of PNRI-299 was determined to be the oxidoreductase, redox effector factor-1 by an affinity chromatography approach. The selective redox effector factor-1 inhibitor, PNRI-299, significantly reduced airway eosinophil infiltration, mucus hypersecretion, edema, and IL-4 levels in a mouse asthma model. These data validate AP-1 as an important therapeutic target in allergic airway inflammation.