Abstract:Objective To explore whether microRNA (miR)-126 participates in the proliferation, invasion and apoptosis of rheumatoid arthritis (RA) synovial fibroblasts (RASFs) by targeting the expression of Dickkopf-1 (DKK1).Methods The synovial tissues of 25 RA patients (RA group) who were treated in Wuhan First Hospital from June 2018 to September 2019 were collected, while the synovial tissues of another 21 patients with non-rheumatoid arthritis undergoing the cruciate ligament reconstruction surgery in the hospital during the same period were collected as the healthy group. The expressions of miR-126 and DKK1 protein in the synovial tissues were detected. RASFs were isolated from the RA synovial tissues, and the relationship between miR-126 and DKK1 was determined via dual luciferase reporter assay. The RASFs were divided into the control group, miR-126 group, DKK1 group, and miR-126 + DKK1 group. The effects of overexpression of miR-126 and/or DKK1 on the proliferation, invasion and apoptosis of RASFs were tested via CCK-8, transwell assay and flow cytometry, respectively.Results The expression level of miR-126 in the synovial tissues of RA patients was lower than that of the healthy individuals (P < 0.05), while the expression level of DKK1 protein was higher in the synovial tissues of RA patients than that of the healthy individuals (P < 0.05). When co-transfected with Wt-DKK1 and miR-126 mimic, the relative luciferase activity in the cells was reduced compared to that in the cells co-transfected with Wt-DKK1 and miR-126 NC (P < 0.05), suggesting the targeted binding of miR-126 to DKK1. The proliferation and invasion abilities of RASFs in the miR-126 group were lower than those in the control group, while the apoptosis rate in the miR-126 group was significantly higher than that in the control group (P < 0.05). The proliferation and invasion abilities of RASFs in the DKK1 group were higher than those in the control group, whereas the apoptosis rate in the DKK1 group was lower than that in the control group (P < 0.05). The proliferation and invasion abilities of RASFs in the miR-126 + DKK1 group were higher than those in the miR-126 group and lower than those in the DKK1 group, while the apoptosis rate in the miR-126 + DKK1 group was lower than that in the miR-126 group and higher than that in the DKK1 group (P < 0.05).Conclusions The miR-126 is lowly expressed in RA synovial tissues, and can inhibit the proliferation, invasion and apoptosis of RASFs by targeting DKK1.