Biomolecules & Therapeutics  
A Novel Urotensin II Receptor Antagonist KR-36996 Inhibits Smooth Muscle Proliferation through ERK/ROS Pathway
Tae-Ho Kim1,†, Dong Gil Lee1,†, Young-Ae Kim1, Byung Ho Lee2, Kyu Yang Yi2 and Yi-Sook Jung1,3,*
1College of Pharmacy, Ajou University, Suwon 16499, 2Korea Research Institute of Chemical Technology, Daejeon 34114, 3Research Institute of Pharmaceutical Sciences and Technology, Ajou University, Suwon 16499, Republic of Korea
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The first two authors contributed equally to this work.
Received: September 27, 2016; Revised: October 7, 2016; Accepted: October 27, 2016; Published online: February 6, 2017.
© The Korean Society of Applied Pharmacology. All rights reserved.

Urotensin II (UII) is a mitogenic and hypertrophic agent that can induce the proliferation of vascular cells. UII inhibition has been considered as beneficial strategy for atherosclerosis and restenosis. However, currently there is no therapeutics clinically available for atherosclerosis or restenosis. In this study, we evaluated the effects of a newly synthesized UII receptor (UT) antagonist, KR-36996, on the proliferation of SMCs in vitro and neointima formation in vivo in comparison with GSK-1440115, a known potent UT antagonist. In primary human aortic SMCs (HASMCs), UII (50 nM) induced proliferation was significantly inhibited by KR-36996 at 1, 10, and 100 nM which showed greater potency (IC50: 3.5 nM) than GSK-1440115 (IC50: 82.3 nM). UII-induced proliferation of HASMC cells was inhibited by U0126, an ERK1/2 inhibitor, but not by SP600125 (inhibitor of JNK) or SB202190 (inhibitor of p38 MAPK). UII increased the phosphorylation level of ERK1/2. Such increase was significantly inhibited by KR-36996. UII-induced proliferation was also inhibited by trolox, a scavenger for reactive oxygen species (ROS). UII-induced ROS generation was also decreased by KR-36996 treatment. In a carotid artery ligation mouse model, intimal thickening was dramatically suppressed by oral treatment with KR-36996 (30 mg/kg) which showed better efficacy than GSK-1440115. These results suggest that KR-36996 is a better candidate than GSK-1440115 in preventing vascular proliferation in the pathogenesis of atherosclerosis and restenosis.
Keywords: Urotensin II, Antagonist, KR-36996, GSK-1440115, Vascular smooth muscle, Proliferation

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