Circ_0006873 suppresses the osteogenic differentiation of human-derived mesenchymal stem cells through mediating miR-20a/SMURF2 axis in vitro.

The clinical application of human-derived mesenchymal stem cells (hMSCs) in osteoporosis (OP) treatment is promising. We aimed to uncover the role of circular RNA 0006873 (circ_0006873) in OP progression using hMSCs. The levels of circ_0006873, pantothenate kinase 2 (PANK2) messenger RNA (mRNA), microRNA-20a (miR-20a), SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) mRNA and the mRNA levels of osteogenesis-related markers were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of osteogenesis-related markers and SMURF2 was detected by Western blot assay. Alkaline phosphatase (ALP) staining and activity were determined using an ALP staining Kit and an ALP Colorimetric Assay Kit. Circ_0006873 was highly expressed in the serum samples and bone tissue samples of OP patients compared with control cases. Circ_0006873 overexpression down-regulated the expression of osteogenesis-related markers and reduced ALP staining and activity. Circ_0006873 down-regulated miR-20a level through its interaction with miR-20a in hMSCs. Circ_0006873 suppressed osteogenic differentiation through targeting miR-20a. SMURF2 was a molecular target of miR-20a, and miR-20a promoted osteogenic differentiation through targeting SMURF2. Circ_0006873 suppressed the osteogenic differentiation of hMSCs by upregulating SMURF2 level via sponging miR-20a in vitro.