Selective targeting of CBP/β-catenin inhibits growth of and extracellular matrix remodelling by airway smooth muscle

Background and Purpose Asthma is a heterogeneous chronic inflammatory disease, characterized by the development of structural changes (airway remodelling). β-catenin, a transcriptional co-activator is fundamentally involved in airway smooth muscle growth, and may be a potential target in the treatment of airway smooth muscle remodelling. Experimental Approach Using small-molecule compounds that selectively target β-catenin breakdown or its interactions with transcriptional co-activators, we assessed their ability to inhibit airway smooth muscle remodelling in vitro and in vivo. Key Results ICG-001, a small-molecule compound that inhibits the β-catenin/CBP interaction, strongly and dose-dependently inhibited serum-induced smooth muscle growth and TGF-β1-induced production of extracellular matrix components in vitro. Inhibition of β-catenin/p300 interactions using IQ-1 or inhibition of tankyrase 1/2 using XAV-939 had considerably less effect. In a mouse model of allergic asthma, β-catenin expression in the smooth muscle layer was found unaltered in control versus ovalbumin-treated animals, a pattern that was found to be similar in smooth muscle within biopsies taken from asthmatic and non-asthmatic donors. However, β-catenin target gene expression was highly increased in response to ovalbumin, which was prevented by topical treatment with ICG-001. Interestingly, ICG-001 dose dependently reduced airway smooth thickness after repeated ovalbumin challenge, but had no effect on the deposition of collagen around the airways, mucus secretion or eosinophil infiltration. Conclusions and Implications Together, our findings highlight the importance of β-catenin/CBP signalling in the airways and suggest ICG-001 may be a new therapeutic approach to treat airway smooth muscle remodelling in asthma.