Dysregulated circular RNAs and their pathological implications in knee osteoarthritis: potential novel therapeutic targets and diagnostic biomarkers

Osteoarthritis (OA) is the most common form of arthritis and a leading cause of chronic pain and disability in the elderly. However, the detailed molecular mechanisms of OA remain unclear. Therefore, uncovering the molecular mechanisms underlying OA progression is crucial for the development of OA therapy. Of note, for the last 6 years (especially in 2020 and 2021), increasing numbers of studies have suggested that aberrantly expressed circular RNAs (circRNAs) are involved in the pathogenesis of OA. Until now, circRNAs have been attracting high attention as microRNA (miRNA) sponges that sequester miRNAs from their endogenous targets, meanwhile alternative functions of circRNAs have been also suggested. Moreover, it has been reported that circulating or tissue-specific circRNAs can be used for diagnosing different types of human diseases, including cancers, neurological diseases, and inflammatory diseases. Given the putative involvement of circRNAs in the pathogenesis of OA, it looks promising that some of the dysregulated circRNAs may have the potential to serve as therapeutic targets and/or diagnostic biomarkers for OA. This review summarizes the current progress on dysregulated circRNAs and their pathological implications in knee OA, which may provide a direction for revealing their therapeutic potential in OA.