title: Novel Rho/MRTF/SRF inhibitors block matrix-stiffness and TGF-β-induced fibrogenesis in human colonic myofibroblasts.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  Targeting the Rho/MRTF/SRF mechanism with second-generation Rho/MRTF/SRF inhibitors may represent a novel approach to antifibrotic therapeutics.
authors.affiliation: *Department of Internal Medicine, †Department of Pharmacology, and ‡Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Johnson
authors.forename: Eva S
authors.initials: ES
authors.lastname: Rodansky
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Haak
authors.forename: Scott D
authors.initials: SD
authors.lastname: Larsen
authors.forename: Richard R
authors.initials: RR
authors.lastname: Neubig
authors.forename: Peter D R
authors.initials: PD
authors.lastname: Higgins
mesh_terms: D000813:Anilides / Q000494:pharmacology*; D001549:Benzamides / Q000494:pharmacology*; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005355:Fibrosis / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D006801:Humans; D058628:Myofibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015514:Oncogene Proteins, Fusion / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D026362:Serum Response Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000813:Anilides; D001549:Benzamides; C523455:CCG 1423; D004268:DNA-Binding Proteins; C431575:MRTFA protein, human; D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger; D026362:Serum Response Factor; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D020741:rho GTP-Binding Proteins