MicroRNA expression profile and functional analysis reveal their roles in contact inhibition and its disruption switch of rat vascular smooth muscle cells

Ye-ying SUN1, Shan-shan QIN2, Yun-hui CHENG2, Chao-yun WANG1,2, Xiao-jun LIU2, Ying LIU2, Xiu-li ZHANG1,2, Wendy ZHANG2, Jia-xin ZHAN2, Shuai SHAO2, Wei-hua BIAN1, Bi-hui LUO2, Dong-feng LU2, Jian YANG2, Chun-hua WANG1, Chunxiang ZHANG1,2
1 Sino-US Translational Medicine Institute and College of Pharmacy, Binzhou Medical University, Yantai 264003, China
2 Department of Biomedical Engineering, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
Correspondence to: Chunxiang ZHANG:,
DOI: 10.1038/aps.2018.6
Received: 20 November 2017
Accepted: 7 January 2018
Advance online: 26 April 2018


Contact inhibition and its disruption of vascular smooth muscle cells (VSMCs) are important cellular events in vascular diseases. But the underlying molecular mechanisms are unclear. In this study we investigated the roles of microRNAs (miRNAs) in the contact inhibition and its disruption of VSMCs and the molecular mechanisms involved. Rat VSMCs were seeded at 30% or 90% confluence. MiRNA expression profiles in contact-inhibited confluent VSMCs (90% confluence) and non-contact-inhibited low-density VSMCs (30% confluence) were determined. We found that multiple miRNAs were differentially expressed between the two groups. Among them, miR-145 was significantly increased in contact-inhibited VSMCs. Serum could disrupt the contact inhibition as shown by the elicited proliferation of confluent VSMCs. The contact inhibition disruption accompanied with a down-regulation of miR-145. Seruminduced contact inhibition disruption of VSMCs was blocked by overexpression of miR-145. Moreover, downregulation of miR-145 was sufficient to disrupt the contact inhibition of VSMCs. The downregulation of miR-145 in serum-induced contact inhibition disruption was related to the activation PI3-kinase/Akt pathway, which was blocked by the PI3-kinase inhibitor LY294002. KLF5, a target gene of miR-145, was identified to be involved in miR-145-mediated effect on VSMC contact inhibition disruption, as it could be inhibited by knockdown of KLF5. In summary, our results show that multiple miRNAs are differentially expressed in contact-inhibited VSMCs and in non-contact-inhibited VSMCs. Among them, miR-145 is a critical gene in contact inhibition and its disruption of VSMCs. PI3-kinase/ Akt/miR-145/KLF5 is a critical signaling pathway in serum-induced contact inhibition disruption. Targeting of miRNAs related to the contact inhibition of VSMCs may represent a novel therapeutic approach for vascular diseases.
Keywords: smooth muscle cells; contact inhibition; microRNAs; miR-145; PI3-kinase/Akt; LY294002; KLF5; vascular diseases

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