Hsa_circ_0020378 targets miR-556-5p/MAPK1 to regulate osteosarcoma cell proliferation and migration.

Osteosarcoma (OS) is still a disorder threatening children life. A growing number of evidences highlights the role of circular RNAs (circRNAs) during OS malignancy. Herein, we aimed to address the pathological contribution of the unrecognized circ_0020378 to OS progression. Analysis of the expression of circ_0020378, miR-556-5p, and MAPK1 in OS tissues and cells was performed using RT-qPCR or western blotting. CCK8, colony formation assays, and Tranwell migration assays were adopted to assess the OS cell viability, clone formation ability and migration. Tumor xenograft mouse model was used to assess the in vivo function of circ_0020378. The relationship between miR-556-5p and circ_0020378 or MAPK1 was discovered using luciferase reporter assays and RNA binding protein immunoprecipitation tests. In OS tissues and cells, circ_0020378 and MAPK1 were significantly elevated, although miR-556-5p expression exhibited a different pattern. Circ_0020378 silence attenuated OS cell proliferation, colony formation ability and migration in vitro, and retarded tumor growth in vivo. MiR-556-5p was targeted by circ_0020378. Furthermore, miR-556-5p inhibitor promoted the OS cell proliferation and migration, while this promoted malignant actions of OS cells were abrogated by circ_0020378 silence. Additionally, miR-556-5p directly bound to MAPK1, and MAPK1 silence exerted its inhibitory effect on OS cell proliferation and migration, and yet the inhibition was offset by miR-556-5p inhibitor. Circ_0020378 acts as a novel tumor promoter that controls OS growth by miR-556-5p/MAPK1 axis, suggesting circ_0020378/miR-556-5p/MAPK1 might be a novel target for OS intervention.

Long non-coding RNA XIST promotes osteoporosis by inhibiting the differentiation of bone marrow mesenchymal stem cell by sponging miR-29b-3p that suppresses nicotinamide N-methyltransferase.

Bone formation is important in the development of osteoporosis (OP). X-inactive specific transcript (XIST), a lncRNA, is involved in this process; however, mode of its action is not known. We compared the serum levels of XIST and miR-29b-3p among the patients with and without OP. In rat bone marrow mesenchymal stem cells (BMSCs), during osteogenic differentiation, XIST expression was detected first, followed by overexpression or suppression of miR-29b-3p and NNMT. Expression of osteogenic genes, ALP (electrochemical alkaline phosphatase) and RUNX2 (Runt-related transcription factor 2) were detected by RT-qPCR and western blots, and the calcium nodules in BMSCs were detected by staining. The relationships of XIST, miR-29b-3p, and NNMT were characterized by dual-luciferase reporter assay. Serum XIST was significantly upregulated in patients of OP. XIST downregulated the ALP and Runx2 levels and inhibited calcium nodules, whereas low expression of XIST reversed these events. MiR-29b-3p was inhibited by XIST sponge and lowered the levels of ALP, Runx2, and calcium nodules. NNMT was negatively regulated by miR-29b-3p, promoting the osteogenic differentiation of BMSCs. In conclusion, XIST is highly expressed in OP, and regulates NNMT by sponging miR-29b-3p to suppress the osteogenic differentiation of BMSCs.

MicroRNA­338­3p regulates age­associated osteoporosis via targeting PCSK5.

Bone loss is a disease that is highly associated with aging. This deleterious health condition has become a public concern worldwide, and there is an urgent need to discover more novel therapeutic strategies for the development of age­associated osteoporosis. The present study aimed to explore the association between proprotein convertase subtilisin/kexin type 5 (PCSK5) and microRNA(miR)­338­3p in bone­formation and bone­loss processes. Western blotting assay and reverse transcription­quantitative PCR were employed to analyze PCSK5 and miR­338­3p expression levels in bone mesenchymal stem cells (BMSCs). Dual­luciferase reporter and RNA pull­down assays were used to determine the target. For osteoblastic differentiation verification, alkaline phosphatase activity, osteocalcin secretion detection, bone formation­related indicators (osterix, runt­related gene 2, osteopontin and bone sialoprotein), hematoxylin and eosin staining and Alizarin Red S staining were performed. The findings of the present study indicated that the expression level of PCSK5 was higher in BMSCs from young rat samples, whereas the expression level of miR­338­3p was higher in BMSCs from samples of old rats. Experimental results also revealed that unlike miR­338­3p, downregulation of PCSK5 inhibited osteoblastic differentiation and osteogenesis by inhibiting alkaline phosphatase, osteocalcin, osterix, runt­related transcription factor 2, osteopontin, bone sialoprotein and mineralized nodule formation. Overall, the results suggested that miR­338­3p could suppress age­associated osteoporosis by regulating PCSK5.