Novel Rho/MRTF/SRF inhibitors block matrix-stiffness and TGF-β-induced fibrogenesis in human colonic myofibroblasts

• Published in: Inflammatory bowel diseases Vol. 20; no. 1; pp. 154 - 165
• Main Authors: Johnson, Laura A, Rodansky, Eva S, Haak, Andrew J, Larsen, Scott D, Neubig, Richard R, Higgins, Peter D R
• Format: Journal Article
• Language: English
• Published: England 01.01.2014
• Subjects: Anilides - pharmacology; Benzamides - pharmacology; Blotting, Western; Cell Adhesion - drug effects; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cells, Cultured; Colon - drug effects; Colon - metabolism; Colon - pathology; DNA-Binding Proteins - antagonists & inhibitors; DNA-Binding Proteins - metabolism; Extracellular Matrix - drug effects; Extracellular Matrix - metabolism; Fibrosis - metabolism; Fibrosis - pathology; Fibrosis - prevention & control; Humans; Myofibroblasts - drug effects; Myofibroblasts - metabolism; Myofibroblasts - pathology; Oncogene Proteins, Fusion - antagonists & inhibitors; Oncogene Proteins, Fusion - metabolism; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; rho GTP-Binding Proteins - antagonists & inhibitors; rho GTP-Binding Proteins - metabolism; RNA, Messenger - genetics; Serum Response Factor - antagonists & inhibitors; Serum Response Factor - metabolism; Signal Transduction - drug effects; Trans-Activators; Transforming Growth Factor beta - genetics; Transforming Growth Factor beta - metabolism
• ISSN: 1078-0998; 1536-4844
• DOI: 10.1097/01.MIB.0000437615.98881.31

Ras homolog gene family, member A (RhoA)/Rho-associated coiled-coil forming protein kinase signaling is a key pathway in multiple types of solid organ fibrosis, including intestinal fibrosis. However, the pleiotropic effects of RhoA/Rho-associated coiled-coil forming protein kinase signaling have frustrated targeted drug discovery efforts. Recent recognition of the role of Rho-regulated gene transcription by serum response factor (SRF) and its transcriptional cofactor myocardin-related transcription factor A (MRTF-A) suggest a novel locus for pharmacological intervention. Because RhoA signaling is mediated by both physical and biochemical stimuli, we examined whether pharmacological inhibition of RhoA or the downstream transcription pathway of MRTF-A/SRF could block intestinal fibrogenesis in 2 in vitro models. In this study, we demonstrate that inhibition of RhoA signaling blocks both matrix-stiffness and transforming growth factor beta-induced fibrogenesis in human colonic myofibroblasts. Repression of alpha-smooth muscle actin and collagen expression was associated with the inhibition of MRTF-A nuclear localization. CCG-1423, a first-generation Rho/MRTF/SRF pathway inhibitor, repressed fibrogenesis in both models, yet has unacceptable cytotoxicity. Novel second-generation inhibitors (CCG-100602 and CCG-203971) repressed both matrix-stiffness and transforming growth factor beta-mediated fibrogenesis as determined by protein and gene expression in a dose-dependent manner. Targeting the Rho/MRTF/SRF mechanism with second-generation Rho/MRTF/SRF inhibitors may represent a novel approach to antifibrotic therapeutics.