Circular RNA circCTNNA1 is downregulated in osteoarthritis and sponges miR-29a to suppress LPS-induced apoptosis of synoviocytes.

Objective: CircRNA circCTNNA1 has been characterized as a critical player in cancer biology, while its role in other human diseases is unknown. This study was carried out to study the role of circCTNNA1 in osteoarthritis (OA).
Materials and Methods: RNA was extracted from synovial fluid samples donated by OA patients ( n  = 62). RT-qPCRs were then performed to determine the expression of circCTNNA1 and miR-29a in these synovial fluid samples. The interaction between circCTNNA1 and miR-29a was predicted using an online program IntaRNA 2.0 and confirmed by RNA pull-down assay. Overexpression of circCTNNA1 and miR-29a was achieved in synoviocytes to analyze their effects on each other's expression. The role of circCTNNA1 and miR-29a in regulating synoviocyte apoptosis was explored by cell apoptosis assay.
Results: CircCTNNA1 was downregulated in OA, while miR-29a was overexpressed in OA. CircCTNNA1 and miR-29a were not significantly correlated. RNA pull-down assay illustrated the direct interaction between circCTNNA1 and miR-29a. In synoviocytes, overexpression of circCTNNA1 and miR-29a failed to regulate the expression of each other. CircCTNNA1 overexpression suppressed the enhancing effects of miR-29a overexpression on cell apoptosis induced by LPS.
Conclusions: CircCTNNA1 is downregulated in OA, and its overexpression suppresses synoviocyte apoptosis via sponging miR-29a.