Rapamycin inhibits epithelial‐to‐mesenchymal transition of peritoneal mesothelium cells through regulation of Rho GTPases

• Published in: The FEBS journal 2016-06, Vol.283 (12), p.2309-2325
• Main Authors: Xiang, Shilong, Li, Meng, Xie, Xishao, Xie, Zhoutao, Zhou, Qin, Tian, Yuanshi, Lin, Weiqiang, Zhang, Xiaohui, Jiang, Hong, Shou, Zhangfei, Chen, Jianghua
• Format: Article
• Language: English
• Subjects: Animals; Antibiotics; cdc42 GTP-Binding Protein - biosynthesis; cdc42 GTP-Binding Protein - genetics; Cells; Disease Models, Animal; Enzymes; Epithelial-Mesenchymal Transition - drug effects; epithelial–mesenchymal transition; Epithelium - drug effects; Epithelium - pathology; Fibronectins; Gene Expression Regulation - drug effects; Glucose - toxicity; high glucose; Humans; mesothelial cells; Peritoneal Fibrosis - chemically induced; Peritoneal Fibrosis - drug therapy; Peritoneal Fibrosis - genetics; Peritoneum - drug effects; Peritoneum - metabolism; Peritoneum - pathology; Phosphorylation; rac1 GTP-Binding Protein - biosynthesis; rac1 GTP-Binding Protein - genetics; rapamycin; Rats; Rho GTPases; rhoA GTP-Binding Protein - biosynthesis; rhoA GTP-Binding Protein - genetics; Rodents; Sirolimus - administration & dosage
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.13740

Epithelial–mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) is a key process of peritoneal fibrosis. Rapamycin has been previously shown to inhibit EMT of PMCs and prevent peritoneal fibrosis. In this study, we investigated the undefined molecular mechanisms by which rapamycin inhibits EMT of PMCs. To define the protective effect of rapamycin, we initially used a rat PD model which was daily infused with 20 mL of 4.25% high glucose (HG) dialysis solution for 6 weeks to induce fibrosis. The HG rats showed decreased ultrafiltration volume and obvious fibroproliferative response, with markedly increased peritoneal thickness and higher expression of α‐smooth muscle actin (α‐SMA) and transforming growth factor‐β1. Rapamycin significantly ameliorated those pathological changes. Next, we treated rat PMCs with HG to induce EMT and/or rapamycin for indicated time. Rapamycin significantly inhibited HG‐induced EMT, which manifests as increased expression of α‐SMA, fibronectin, and collagen I, decreased expression of E‐cadherin, and increased mobility. HG increased the phosphorylation of PI3K, Akt, and mTOR. Importantly, rapamycin inhibits the RhoA, Rac1, and Cdc42 activated by HG. Moreover, rapamycin repaired the pattern of F‐actin distribution induced by HG, reducing the formation of stress fiber, focal adhesion, lamellipodia, and filopodia. Thus, rapamycin shows an obvious protective effect on HG‐induced EMT, by inhibiting the activation of Rho GTPases (RhoA, Rac1, and Cdc42). We demonstrated that high glucose activated the PI3K–Akt–mTOR pathway, inducing EMT of peritoneal mesothelial cells and peritoneal fibrosis. Rapamycin suppressed this process by inhibiting the activation of Rho GTPases (RhoA, Rac1, and Cdc42). The role of Rho GTPases in EMT may provide a possible direction for treatment of peritoneal fibrosis.