KMUP-1 inhibits pulmonary artery proliferation by targeting serotonin receptors/transporter and NO synthase, inactivating RhoA and suppressing AKT/ERK phosphorylation

KMUP-1 inhibits monocrotaline (MCT)-induced pulmonary artery (PA) proliferation by targeting serotonin (5-HT) receptors, inactivating RhoA and reducing phosphorylation of AKT/ERK. In MCT-treated rats, KMUP-1 f (5 mg/kg p.o.; 1 mg/kg i.p. x 21 days) decreased proliferation (PCNA-positive) cells and 5-HTT-expression in lung and 5-HT levels in plasma. In isolated PA, KMUP-1 and simvastatin (0.1-100 mu M) inhibited 5-HT (10 mu M)-induced PA constriction. L-NAME-pretreatment reduced KMUP-1-induced relaxation. In pulmonary arterial smooth muscle cells (PASMCs), KMUP-1 (1-100 mu M) and simvastatin (10 mu M) inhibited 5-HT-induced cell migration and proliferation and KMUP-1 (1-100 mu M) inhibited 5-HT-induced Ca2+ influx. Similar to Y27632, KMUP-1 (1-100 mu M) inhibited 5-HT-induced RhoA/ROCK expression, while KMUP-1, Y27632 and simvastatin at 10 mu M inhibited 5-HT-induced 5-HTT expression and KMUP-1 inhibited 5-HT-induced phosphorylation of AKT and ERK1/2 in PASMCs. In human pulmonary arterial endothelial cell (HPAEC), KMUP-1 (1-100 mu M) increased the expression of eNOS and 5-HT2B and also at 10 mu M augmented eNOS expression and production of nitric oxide (NO) in 5-HT-treated HPAEC. In radioligand binding, the IC50/K-i values of KMUP-1 for 5-HT2A, 5-HT2B and 5-HT2C receptors were 0.34/0.0971, 0.04/0.0254, and 0.408/0.214 mu M respectively. In conclusion, KMUP-1 inhibits MCT-induced PA proliferation by binding to 5-HT2A, 5-HT2B and 5-HT2C receptors, increasing endothelial eNOS/5-HT2B receptor expression and NO release and inhibiting 5-HTT/RhoA/ROCK expression and AKT/ERK phosphorylation. KMUP-1 is suggested to be useful in the treatment of 5-HT-induced pulmonary artery proliferation. (C) 2010 Elsevier Inc. All rights reserved.