MiR-613 inhibits proliferation and invasion and induces apoptosis of rheumatoid arthritis synovial fibroblasts by direct down-regulation of DKK1

Liang Liu,Ying Li,Zongfang Zhang,Yanhua Zuo,Yan Xu,Jie Pang

doi:10.1186/s11658-018-0130-0

Abstract

BackgroundThis study aimed to investigate the effects of miR-613 on the proliferation, invasion and apoptosis of rheumatoid arthritis synovial fibroblasts (RASFs).MethodsSynovial tissue samples were collected from 20 rheumatoid arthritis (RA) patients and 10 patients with joint trauma undergoing joint replacement surgery. The RASFs were isolated and cultured. MiR-613 and DKK1 expression in both synovial tissues and cells was detected using quantitative real-time PCR (qRT-PCR). Dual luciferase reporter gene assay was employed to evaluate the effect of miR-613 on the luciferase activity of DKK1. Then RASFs were transfected with miR-613 mimics, si-DKK1 and pcDNA-DKK1. Changes in cellular proliferation, invasion and apoptosis were detected through BrdU assay, Transwell invasion assay and flow cytometry analysis, respectively.ResultsMiR-613 was significantly down-regulated in RA tissues and RASFs compared to normal tissues and cells, whereas DKK1 was up-regulated in RA tissues and RASFs. Dual luciferase reporter gene assay showed that miR-613 could specifically bind to the 3′UTR of DKK1 and significantly inhibit the luciferase activity. Moreover, miR-613 significantly reduced the expression of DKK1. Overexpression of miR-613 or knockdown of DKK1 suppressed proliferation and invasion of RASFs, and induced RASF apoptosis. The reverse results were observed when DKK1 was up-regulated in miR-613-overexpressing RASFs.ConclusionsMiR-613 can inhibit proliferation and invasion and induce apoptosis of RASFs by directly targeting DKK1 expression.

Highlights

Introduction of miR613 inhibited invasion and expression of related molecules in rheumatoid arthritis synovial fibroblasts (RASFs) To determine the function of miR-613 in invasion of RASFs, we evaluated the invasive capacities of RASFs transfected with the miR-613 mimic by Transwell invasion assays
The level of DKK1 miR-613 is down-regulated in synovial tissues and RASFs It has been reported that the level of DKK1 was significantly up-regulated in synovial fibroblasts from PATIENTS [13]
We found that the expression of DKK1 in synovial tissues from Rheumatoid arthritis (RA) patients was significantly increased in comparison to the adjacent normal tissues (Fig. 1a)

Summary

Introduction

Introduction of miR613 inhibited invasion and expression of related molecules in RASFs To determine the function of miR-613 in invasion of RASFs, we evaluated the invasive capacities of RASFs transfected with the miR-613 mimic by Transwell invasion assays. The data from Transwell assays showed that the invasion capability of RASFs was significantly inhibited in the miR-613 mimic group compared to miR-NC group (Fig. 5a). These results showed that miR-613 might play a critical role in suppression of invasion in RASFs. MMPs may be responsible for the impaired invasion of anti-miR-613-transfected cells. Rheumatoid arthritis (RA), as one of the most common inflammatory diseases, affects more than 1% of the general population worldwide It is characterized by inflammation, synovitis and damage of articular cartilage as well as bone, and if not treated effectively 40–70% of patients will eventually progress to disability [1, 2]. Knockdown of DKK1 significantly suppressed proliferation and invasion of RASFs, and induced RASF apoptosis

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