Circ_0088194 Promotes the Invasion and Migration of Rheumatoid Arthritis Fibroblast-Like Synoviocytes via the miR-766-3p/MMP2 Axis.

Dysregulation of circular RNAs (circRNAs) is involved in various human diseases. Fibroblast-like synoviocytes (FLSs), which form the lining of the joint, are epigenetically imprinted with an aggressive phenotype and contribute to joint destruction in rheumatoid arthritis (RA). In the present study, we identified a novel circRNA, Circ_0088194, which was upregulated in RA fibroblast-like synoviocytes (RA-FLSs) and correlated with the disease activity score in 28 joints. Overexpression of Circ_0088194 promoted RA-FLS migration and invasion, while inhibition of Circ_0088194 had the opposite effect. Mechanistically, Circ_0088194 acted as a miR-766-3p sponge to relieve the repressive effect of miR-766-3p on its target, MMP2 (encoding matrix metalloproteinase 2), thereby promoting migration and invasion. The expression level of Circ_0088194 was inversely correlated with that of miR-766-3p in RA-FLSs. Importantly, overexpression of miR-766-3p partially blocked the migration and invasion induced by Circ_0088194 overexpression. Collectively, this study identified a novel circRNA Circ_0088194 that promotes RA-FLS invasion and migration via the miR-766-3p/MMP2 axis. Circ_0088194 might represent a novel therapeutic target to prevent and treat RA.

Cai Y ，Liang R ，Xiao S ，Huang Q ，Zhu D ，Shi GP ，Ouyang Q ，Yang M ... -  《Frontiers in Immunology》

Circular RNA circ_0130438 suppresses TNF-α-induced proliferation, migration, invasion and inflammation in human fibroblast-like MH7A synoviocytes by regulating miR-130a-3p/KLF9 axis.

Circular RNAs (circRNAs) can play a critical role in rheumatoid arthritis (RA) pathogenesis by involving gene regulation by competing for shared microRNAs (miRNAs), a family of small noncoding RNAs. MiR-130a-3p is a disease-related miRNA and Kruppel-like factor 9 (KLF9) is a zinc finger transcription factor, which are involved in RA pathogenesis. Here, we identified the action of circRNA circ_0130438 in regulating fibroblast-like synoviocytes (FLSs) stimulated by tumor necrosis factor α (TNF-α). The direct relationship between miR-130a-3p and circRNA circ_0130438 or KLF9 was predicted by bioinformatics analysis and examined by a dual-luciferase reporter or RNA immunoprecipitation (RIP) assay. CircRNA circ_0130438, miR-130a-3p and KLF9 factor expression levels were gauged by a quantitative real-time PCR (qRT-PCR) or a western blot method. Cell proliferation ability was analyzed by a 5-Ethynyl-2'-Deoxyuridine (EdU) staining assay. The transwell assay was used to evaluate cell migration and invasion capacities. The production levels of interleukin-1β (IL)-1β, IL-6 and IL-8 were assessed by enzyme-linked immunosorbent assay (ELISA). The level of circRNA circ_0130438 was reduced in RA tissues (P = 0.0001) and FLSs isolated from RA tissues (P = 0.0001) compared with corresponding normal controls. Exposure of human fibroblast-like MH7A synoviocytes to TNF-α suppressed circRNA circ_0130438 expression (P < 0.0001). In contrast, the elevated expression of circRNA circ_0130438 suppressed the TNF-α-induced proliferation (P = 0.0047) and migration (P = 0.0023) of MH7A cells, as well as their pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production (P < 0.0001, P < 0.0001 and P < 0.0001). The circRNA circ_0130438 contained a miR-130a-3p binding site. Furthermore, the increase of miR-130-3p in TNF-α-stimulated MH7A cells reversed the effects of circRNA circ_0130438 elevation on cell proliferation (P = 0.0006), migration (P = 0.0406) and pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production (P = 0.0036, P < 0.0001 and P = 0.0004), indicating that miR-130a-3p was a functional mediator of circRNA circ_0130438 regulation. We also documented that KLF9 was a direct target and downstream effector of miR-130a-3p. Importantly, circRNA circ_0130438 enhanced KLF9 expression (P < 0.0001) in TNF-α-stimulated MH7A cells by functioning as a competing endogenous RNA (ceRNA) for miR-130a-3p (P = 0.0004). Our findings demonstrate that the elevated expression of circRNA circ_0130438 suppresses TNF-α-induced migration, proliferation and pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production of human MH7A cells by enhancing KLF9 expression by operating as a ceRNA for miR-130a-3p.

Li L ，Zhan M ，Li M 《-》

Circ-AFF2/miR-650/CNP axis promotes proliferation, inflammatory response, migration, and invasion of rheumatoid arthritis synovial fibroblasts.

Qu W ，Jiang L ，Hou G 《Journal of Orthopaedic Surgery and Research》

Circular RNA circ_0008360 Inhibits the Proliferation, Migration, and Inflammation and Promotes Apoptosis of Fibroblast-Like Synoviocytes by Regulating miR-135b-5p/HDAC4 Axis in Rheumatoid Arthritis.

Circular RNAs (circRNAs) have been demonstrated to play crucial roles in the development and progression of many diseases, including rheumatoid arthritis (RA). However, the functions and molecular mechanism of circ_0008360 in RA remain unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to determine the expression of circ_0008360, microRNA-135b-5p (miR-135b-5p), and histone deacetylase 4 (HDAC4). Cell Counting Kit-8 (CCK-8) assay, wound healing assay, and flow cytometry analysis were performed to assess cell proliferation, migration, and apoptosis, respectively. Inflammatory response was evaluated by enzyme-linked immunosorbent assay (ELISA). The interaction between miR-135b-5p and circ_0008360 or HDAC4 was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) and RNA pull-down assays. Western blot assay was used to detect the protein expression of HDAC4 and proliferating cell nuclear antigen (PCNA). The expression of circ_0008360 was downregulated in RA synovial tissues and RA fibroblast-like synoviocytes (RA-FLSs). Circ_0008360 suppressed the proliferation, migration, and inflammation and promoted apoptosis of RA-FLSs, and circ_0008360 knockdown showed opposite effects. Moreover, miR-135b-5p was a direct target of circ_0008360, and miR-135b-5p could reverse the effects of circ_0008360 on proliferation, migration, inflammation, and apoptosis in RA-FLSs. Furthermore, HDAC4 was a downstream target of miR-135b-5p, and miR-135b-5p accelerated the proliferation, migration, and inflammation and suppressed apoptosis of RA-FLSs by targeting HDAC4. In addition, circ_0008360 positively regulated HDAC4 expression by sponging miR-135b-5p. Circ_0008360 inhibited the proliferation, migration, and inflammation and facilitated apoptosis of RA-FLSs by sponging miR-135b-5p and upregulating HDAC4, providing a potential target for prevention and treatment of RA.

Hao J ，Chen Y ，Yu Y 《-》

Circ_AFF2 facilitates proliferation and inflammatory response of fibroblast-like synoviocytes in rheumatoid arthritis via the miR-375/TAB2 axis.

Circular RNAs (circRNAs) have been implicated in the pathological regulation of human diseases by acting as microRNA (miRNA) sponges to affect gene expression. CircRNA Fragile Mental Retardation 2 (circ_AFF2) was dysregulated in rheumatoid arthritis (RA), but little is known about its specific function and hidden molecular mechanism in RA. Circ_AFF2, miR-375 and TAK1-binding 2 (TAB2) expression levels were determined through the quantitative real-time polymerase chain reaction (qRT-PCR). Flow cytometry was performed to analyze cell cycle and apoptosis. Cell proliferation detection was conducted by 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The protein levels were measured using western blot. Inflammatory response was evaluated by enzyme-linked immunosorbent assay (ELISA). RNA pull-down assay was used to select the miRNA target of circ_AFF2. The interaction between miR-375 and circ_AFF2 or TAB2 was analyzed using the dual-luciferase reporter assay. Contrasted to normal samples and fibroblast-like synoviocytes (FLS), circ_AFF2 expression was upregulated in RA blood samples and FLS-RA cells. Cell cycle, proliferation and inflammatory response were blocked while apoptosis was promoted in FLS-RA after the downregulation of circ_AFF2. In addition, circ_AFF2 could interact with miR-375 and the function of circ_AFF2 was achieved by sponging miR-375 in FLS-RA cells. Moreover, TAB2 was a target of miR-375 and miR-375 repressed RA progression by decreasing TAB2 expression in FLS-RA cells. More importantly, circ_AFF2 promoted the expression of TAB2 by targeting miR-375. These findings clarified that circ_AFF2 induced cell progression, inflammatory response in FLS-RA cells via the miR-375/TAB2 axis. Circ_AFF2 could be used as a biomarker in the diagnosis and treatment of RA.

Zhi L ，Liang J ，Huang W ，Ma J ，Qing Z ，Wang X ... -  《-》