Circular RNA-CDR1as acts as the sponge of microRNA-641 to promote osteoarthritis progression

Background The antisense cerebellar degenerative-related protein-1 (CDR1as) has been identified as a sponge for several microRNAs. MiR-641 has been shown to be downregulated in osteoarthritic human chondrocytes, but its regulation and function in osteoarthritis (OA) has not been reported. Methods OA cartilage samples were obtained from the knee joints of 12 patients (8 males and 4 females at age of 57-73 years old) who underwent total knee arthroplasty. Normal articular cartilage samples were obtained from the knee joints of 10 trauma patients at age of 29-65 years old (6 males and 4 females). The levels of circRNA-CDR1as mRNA and miR-641 were examined by qRT-PCR and the contents of type II collagen (Col II), IL-6, MMP13 and GAPDH in chondrocytes were examined by Western blot. Results In this study, we found that circRNA-CDR1as level was significantly upregulated in OA chondrocytes, and negatively related with that of miR-641. RNA pull down assay confirmed that circRNA-CDR1as directly targets to miR-641. Furthermore, downregulation of circRNA-CDR1as increased type II collagen level but reduced MMP13 and IL-6 contents, while these effects were partly reversed by down-regulation of miR-641. Conclusion Overall, our results indicate that circRNA-CDR1as plays a crucial role in regulating OA progression via modulating extracellular matrix metabolism and inflammation via sponging miR-641 and provide a novel regulatory role of circRNA-CDR1as in OA.