MicroRNA‑34a‑3p inhibits proliferation of rheumatoid arthritis fibroblast‑like synoviocytes

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by synovial inflammation. Fibroblast-like synoviocytes (FLS) serve a vital role in the initiation and perpetuation of the immune response in patients with RA. The present study aimed to investigate the potential role of microRNA (miR)-34a-3p in the pathogenesis of RA. FLS were collected from patients with RA and osteoarthritis (OA). The miR-34a-3p mimics and inhibitor vectors were constructed and transfected into RAFLS using Lipofectamine ® 2000. Cell proliferation was determined by Cell Counting kit-8 assay and cell cycle progression was analyzed by flow cytometry. In addition, the expression levels of cell cycle control genes, matrix metalloproteinase (MMP)-1 and MMP-9, and pro-inflammatory cytokines were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis. The potential targets of miR-34a-3p were predicted by TargetScan and MiRWalk; the target genes were further verified using a luciferase reporter assay. The expression levels of miR-34a-3p were generally lower in RAFLS compared with in OAFLS. miR-34a-3p overexpression significantly inhibited the proliferation of FLS (P<0.01) by suppressing the expression levels of cyclin-dependent kinase 2, cell division cycle 25A and cyclin D1 (P<0.01), and arresting FLS cell cycle progression at the G 1 phase. Furthermore, the expression levels of MMP-1 and 9 were markedly decreased, as were the mRNA and protein expression levels of pro-inflammatory cytokines (tumor necrosis factor α and interleukin 6; P<0.01). Murine double minute 4 (MDM4) was predicted and verified as a potential target gene of miR-34a-3p; the 547–554 nt position of the MDM4 3′-untranslated region harbored one potential binding site for miR-204-3p. The results of the present study indicated that miR-34a-3p may be considered a promising therapeutic target for RA through inhibiting FLS proliferation and suppressing the production of pro-inflammatory cytokines and MMPs.

Roles of MicroRNAs in Bone Destruction of Rheumatoid Arthritis

“…MiRNAs have become an important regulator of osteoclastogenesis, osteoblasts growth and differentiation (Chen et al, 2015;Baum and Gravallese, 2016;Liu J. et al, 2019). In experimental arthritis models, miRNAs analogs and antagonists have shown encouraging results as experimental treatments (Hou et al, 2019).…”

The role of miRNAs in MDMX‐p53 interplay

“…12 Several miRNAs, including miR-34a-3p, let-7, miR-191-5p, and miR-887-3p, have been shown to interfere with the expression of MDMX by directly binding to the 3′-UTR of MDMX mRNA. [117][118][119] Intriguingly, these miRNAs reduced the levels of MDMX protein but not MDMX mRNA. These results are not surprising given that the miRNA machinery does not frequently affect the mRNA levels but only inhibits the translation of the target genes.…”

“…It has also been found that miR-34a overexpression inhibits the growth of colorectal cancer LOVO cells and suppresses the proliferation and cell cycle progression of fibroblast-like synoviocytes (RAFLS). 118,124 In two separate cohorts of lung adenocarcinomas, a strong inverse correlation exists between miR-34 and full-length MDMX, and a considerable positive correlation occurs between miR-34 and canonical p53 targets. 124 These results suggest that the disruption of the p53-miR-34-MDMX feedback could be regarded as an important mechanism to dampen the p53-dependent tumor suppression.…”

MicroRNAs in Synovial Pathology Associated With Osteoarthritis

“…Intriguingly, several miRNAs that negatively regulate inflammation or FLS proliferation are expressed at higher levels in OA synovium and FLS compared to RA, including miR-34a-3p, miR-124a, miR-30a, miR-10a, miR-140-3p, and miR-140-5p (49)(50)(51)(52)(53). MiR-34a-3p expression is decreased in RA FLS, leading to increased inflammation and proliferation (49). Downregulation of miR-34a passenger strand (miR-34a * ) in RA FLS, due to methylation of its promoter, promotes apoptosis resistance (54).…”

“…However, it is now appreciated that OA FLS exhibit an independent miRNA signature from RA FLS ( 22 ). Intriguingly, several miRNAs that negatively regulate inflammation or FLS proliferation are expressed at higher levels in OA synovium and FLS compared to RA, including miR-34a-3p, miR-124a, miR-30a, miR-10a, miR-140-3p, and miR-140-5p ( 49 – 53 ). MiR-34a-3p expression is decreased in RA FLS, leading to increased inflammation and proliferation ( 49 ).…”