Circular RNA CCDC66 Regulates Osteoarthritis Progression by Targeting miR-3622b-5p

Objective: CircCCDC66 is involved in cancer progression, but its role in osteoarthritis (OA) remains unknown. This study was carried out to explore the biological role of circCCDC66 in OA and its underlying mechanism. Methods: The expression levels of miR-3622b-5p and circCCDC66 in OA cartilage tissues were detected by qRT-PCR. Cell Counting Kit-8 (CCK8) and flow cytometry were used to detect the chondrocyte viability and apoptosis. The expression of chondrocyte inflammatory factors (IL-6 and TNF-alpha) was measured by ELISA. The target genes of circCCDC66 and miR-3622b-5p were analyzed by bioinformatics analysis and luciferase reporter gene assay. The relationship between circCCDC66 and miR-3622b-5p was analyzed by bioinformatics analysis and luciferase reporter gene assay. Results: It was found that circCCDC66 expression in OA cartilage tissues was upregulated. CircCCDC66 overexpression inhibited proliferation and promoted apoptosis of chondrocytes and increased IL-6 and TNF-alpha levels in chondrocytes. miR-3622b-5p was predicted to be a downstream target gene of circCCDC66, and circCCDC66 overexpression inhibited miR-3622b-5p expression in chondrocytes. Moreover, miR-3622b-5p expression was downregulated in OA cartilage tissues. miR-3622b-5p overexpression increased chondrocyte proliferation, inhibited chondrocyte apoptosis, and enhanced the expression of IL-6 and TNF-alpha in chondrocytes. In addition, circCCDC66 overexpression enhanced SIRT3 expression in chondrocytes, while miR-3622b-5p overexpression inhibited SIRT3 expression in chondrocytes. Conclusion: CircCCDC66 promoted OA chondrocyte apoptosis by regulating the miR-3622b-5p/SIRT3 axis. CircCCDC66 may be a new therapeutic target of OA.