Transforming growth factor β regulates β-catenin expression in lung fibroblast through NF-κB dependent pathway

β-catenin contributes to the pathogenesis of lung fibrosis. However, the expression of β-catenin in fibroblasts under fibrotic conditions has not been studied. We investigated the expression of β-catenin in lung fibroblasts from bleomycin (BLM)-challenged mice and human lung fibroblasts treated with transforming growth factor β (TGF-β) or lysophosphatidic acid (LPA) by western blot analysis. The result showed that the expression of β-catenin was significantly increased in lung fibrotic foci and lung fibroblasts from bleomycin-challenged mice. TGF-β stimulated β-catenin expression and induced differentiation in human lung fibroblasts in vitro. Pretreatment of the NF-κB activation inhibitor attenuated the TGF-β-induced expression of β-catenin and differentiation in human lung fibroblasts. Similarly, LPA induced β-catenin expression in human lung fibroblasts, and pre-treatment of the neutralized anti-TGF-β antibody attenuated the LPA-induced expression of β-catenin and differentiation in human lung fibroblasts. The results suggested that β-catenin expression is upregulated in lung fibroblast during differentiation, and that TGF-β induced β-catenin expression in human lung fibroblasts through the activation of NF-κB.