LncRNA HOTAIR regulates the PI3K/AKT pathway via the miR-126-3p/PIK3R2 axis to participate in synovial angiogenesis in rheumatoid arthritis.

Abstract: Background: The abnormal expression of lncRNA HOTAIR has been associated with synovial angiogenesis in rheumatoid arthritis (RA). The aim of this study is to investigate whether lncRNA HOTAIR can participate in synovial angiogenesis in RA by regulating the PI3K/AKT pathway through the miR-126/PIK3R2 axis. Methods: In this study, we conducted in vitro experiments by designing overexpression plasmids and small interfering RNAs targeting lncRNA HOTAIR and then transfected them into fibroblast-like synoviocytes (FLS) obtained from RA patients. We then co-cultured the modified FLS with human umbilical vein endothelial cells (HUVEC) to establish an RA-FLS-induced HUVEC model. We investigated the effects of lncRNA HOTAIR on the proliferation, migration, and tube formation abilities of HUVECs, as well as the expression of synovial endothelial cell markers, angiogenic factors, and the PI3K/AKT pathway. To validate the interactions between lncRNA HOTAIR, miR-126-3p, and PIK3R2, we used bioinformatics and luciferase reporter experiments. We also used a combination of real-time fluorescence quantitative (RT-qPCR), Western blotting (WB), and immunofluorescence (IF) methods to identify target genes and proteins. Results: LncRNA HOTAIR was highly expressed in HUVEC cells induced by RA-FLS. Overexpression of lncRNA HOTAIR significantly increased the expression of VEGF, bFGF, CD34 and CD105 in HUVEC cells, promoted their proliferation, invasion, and tube formation, while the silencing of lncRNA HOTAIR reversed these effects, and the PI3K/AKT activator also reversed them. Overexpression of lncRNA HOTAIR activated the PI3K/AKT pathway, promoting the expression of PI3K, AKT, and P-AKT proteins. Bioinformatics and dual-luciferase assays verified the targeting relationship between LncRNA HOTAIR, miR-126-3p, and PIK3R2. Conclusion: LncRNA HOTAIR can activate the PI3K/AKT pathway, possibly through the regulatory axis of miR-126-3p/PIK3R2, and thus participate in synovial angiogenesis in rheumatoid arthritis.