*Department of Internal Medicine, †Department of Pharmacology, and ‡Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
Inflamm Bowel Dis. 2014 Jan;20(1):154-65. 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.
Ras 同源基因家族成员 A（RhoA）/Rho 相关卷曲螺旋形成蛋白激酶信号转导是多种实体器官纤维化的关键途径，包括肠道纤维化。然而，RhoA/Rho 相关卷曲螺旋形成蛋白激酶信号转导的多效性影响挫败了靶向药物发现的努力。最近认识到 Rho 调节的基因转录由血清反应因子（SRF）及其转录共因子心肌营养素相关转录因子 A（MRTF-A）介导，这表明了药理学干预的一个新的位点。
因为 RhoA 信号转导是由物理和生化刺激介导的，我们检查了 RhoA 的药理学抑制或 MRTF-A/SRF 的下游转录途径是否可以阻断 2 种体外模型中的肠道纤维化。
在这项研究中，我们证明抑制 RhoA 信号转导可阻断人结肠肌成纤维细胞基质硬度和转化生长因子β诱导的纤维化。MRTF-A 核定位的抑制与α-平滑肌肌动蛋白和胶原蛋白表达的抑制相关。第一代 Rho/MRTF/SRF 通路抑制剂 CCG-1423 抑制了两种模型中的纤维化，但具有不可接受的细胞毒性。新型第二代抑制剂（CCG-100602 和 CCG-203971）以剂量依赖的方式抑制基质硬度和转化生长因子β介导的纤维化，通过蛋白和基因表达来确定。
用第二代 Rho/MRTF/SRF 抑制剂靶向 Rho/MRTF/SRF 机制可能代表一种新的抗纤维化治疗方法。
