Activin Receptor-Like Kinase 5 Inhibitor Attenuates Fibrosis in Fibroblasts Derived from Peyronie's Plaque.
OBJECTIVE
Transforming growth factor-β1 (TGF-β1) is the key fibrogenic cytokine associated with Peyronie's disease (PD). The aim of this study was to determine the antifibrotic effect of 3-((5-(6-Methylpyridin-2-yl)-4-(quinoxalin-6-yl)-1H-imidazol-2-yl) methyl)benzamide (IN-1130), a small-molecule inhibitor of the TGF-β type I receptor activin receptor-like kinase 5 (ALK5), in fibroblasts isolated from human PD plaque.


METHODS
Plaque tissue from a patient with PD was used for primary fibroblast culture, and we then characterized primary cultured cells. Fibroblasts were pretreated with IN-1130 (10 µM) and then stimulated with TGF-β1 protein (10 ng/ml). We determined the inhibitory effect of IN-1130 on TGF-β1-induced phosphorylation of Smad2 and Smad3 or the nuclear translocation of Smad proteins in fibroblasts. Western blot analyses for plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV were performed to evaluate effect of IN-1130 on the production of extracellular matrix proteins.


RESULTS
The treatment of fibroblasts with TGF-β1 significantly increased phosphorylation of Smad2 and Smad3 and induced translocation of Smad proteins from the cytoplasm to the nucleus. Pretreatment with IN-1130 substantially inhibited TGF-β1-induced phosphorylation of Smad2 and Smad3 and nuclear accumulation of Smad proteins. The TGF-β1-induced production of extracellular matrix proteins was also significantly inhibited by treatment with IN-1130 and returned to basal levels.


CONCLUSIONS
Overexpression of TGF-β and activation of Smad transcriptional factors are known to play a crucial role in the pathogenesis of PD. Thus, inhibition of the TGF-β signaling pathway by ALK5 inhibitor may represent a promising therapeutic strategy for treating PD.
National Research Laboratory of Regenerative Sexual Medicine, Department of Urology, Inha University School of Medicine, Incheon, Korea.
Jin Hyuk
JH
Jang
Ji Kan
JK
Ryu
Jun Kyu
JK
Suh