Triptolide inhibits angiogenesis in microvascular endothelial cells through regulation of miR-92a

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ORIGINAL ARTICLE

Triptolide inhibits angiogenesis in microvascular endothelial cells through regulation of miR-92a Xiaomeng Xu 1,2 & Li Tian 3 & Zhimian Zhang 1 Received: 17 April 2019 / Accepted: 13 September 2019 # University of Navarra 2019

Abstract Atherosclerosis is one common chronic inflammatory disease in which angiogenesis is involved. Here we established an in vitro cell model of angiogenesis made by human dermal microvascular endothelial cells (HMEC-1) and work to investigate the role of triptolide (TPL) in this model. To induce angiogenesis, HMEC-1 cells were cultured in Matrigel-conditioned medium. The ratio of tubes to nucleus was detected. To evaluate angiogenesis, Western blot assay was carried out to detect endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor receptor-2 (VEGFR2) and VEGF. Cell counting kit-8 was utilized to estimate the viability of HMEC-1 cells. microRNA (miR)-92a was analyzed by qRT-PCR. The targeting relationship between integrin subunit alpha 5 (ITGA5) and miR-92a was verified through luciferase activity assay. The effects of ITGA5 on signaling transducers (ERK, PI3K, and AKT) in a phosphorylated form were valued using Western blot method. After stimulated by TPL, LY294002 and PD98059, the alteration in phosphorylation of the signaling transducers was evaluated by Western blot assay. The ratio of tubes to nucleus and angiogenesis related factors were increased with the delaying of culture time. TPL decreased the expression of angiogenesis factors. Furthermore, miR-92a was upregulated by TPL and miR-92a silence upregulated angiogenesis factors. In addition, TPL decreased ITGA5 which was proved as a target of miR-92a. ITGA5 overexpression resulted in the abundance of angiogenesis factors while ITGA5 silence led to the opposite results. Meanwhile, ITGA5 overexpression increased phosphorylation of ERK, PI3K and AKT while ITGA5 silence reversed the trend. TPL (as an anti-angiogenesis agent) suppressed angiogenesis by upregulating miR-92a, and miR-92a-mediated down-regulation of ITGA5 blocked the signaling transduction of ERK and PI3K/AKT pathways. Keywords Atherosclerosis . Angiogenesis . Triptolide . miR-92a . ERK . PI3K/AKT

Introduction Xiaomeng Xu and Li Tian contributed equally to this research. Highlights 1. TPL inhibits HMEC-1 cell angiogenesis; 2. TPL upregulates the expression of miR-92a; 3. TPL inhibits cell angiogenesis via upregulating miR-92a expression; 4 ITGA5 is a target of miR-92a; 5. Overexpression of ITGA5 promotes angiogenesis while ITGA5 silence inhibits angiogenesis. * Zhimian Zhang [email protected] 1

Medical Examination Center of Qilu Hospital of Shandong University, No.107 Culture West Road, Jinan 250012, Shandong, China

2

Department of Health Management, Jining NO.1 People’s Hospital, Jining 272011, Shandong, China

3

Department of Critical Care Medicine, Jining NO.1 People’s Hospital, Jining 272011, Shandong, China

According to the World Health Organization global status report, cardiovascular diseases are responsible