ObjectivesIn this study, we aim to determine the effect of metformin on osteoarthritis (OA) development and progression.MethodsDestabilisation of the medial meniscus (DMM) surgery was performed in 10-week-old wild type and AMP-activated protein kinase (AMPK)α1 knockout (KO) mice. Metformin (4 mg/day in drinking water) was given, commencing either 2 weeks before or 2 weeks after DMM surgery. Mice were sacrificed 6 and 12 weeks after DMM surgery. OA phenotype was analysed by micro-computerised tomography (μCT), histology and pain-related behaviour tests. AMPKα1 (catalytic alpha subunit of AMPK) expression was examined by immunohistochemistry and immunofluorescence analyses. The OA phenotype was also determined by μCT and MRI in non-human primates.ResultsMetformin upregulated phosphorylated and total AMPK expression in articular cartilage tissue. Mild and more severe cartilage degeneration was observed at 6 and 12 weeks after DMM surgery, evidenced by markedly increased Osteoarthritis Research Society International scores, as well as reduced cartilage areas. The administration of metformin, commencing either before or after DMM surgery, caused significant reduction in cartilage degradation. Prominent synovial hyperplasia and osteophyte formation were observed at both 6 and 12 weeks after DMM surgery; these were significantly inhibited by treatment with metformin either before or after DMM surgery. The protective effects of metformin on OA development were not observed in AMPKα1 KO mice, suggesting that the chondroprotective effect of metformin is mediated by AMPK signalling. In addition, we demonstrated that treatment with metformin could also protect from OA progression in a partial medial meniscectomy animal model in non-human primates.ConclusionsThe present study suggests that metformin, administered shortly after joint injury, can limit OA development and progression in injury-induced OA animal models.

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Intervertebral disc degeneration (IDD) is an important factor leading to low back pain, but the underlying mechanisms remain poorly understood. Compared with normal nucleus pulposus (NP) tissues, the expression of circ-GRB10 was downregulated in IDD. Furthermore, overexpression of circ-GRB10 inhibited NP cell apoptosis. circ-GRB10 could sequester miR-328-5p, which could potentially lead to the upregulation of target genes related to cell proliferation via the ErbB pathway. In conclusion, the present study revealed that circ-GRB10/miR-328-5p/ERBB2 signaling pathway is involved in IDD development, suggesting that circ-GRB10 might be a novel therapeutic target for IDD.

The long non-coding RNA (lncRNA) small nucleolar RNA host gene 12 (SNHG12) has a role in cell proliferation and migration. Angiomotin, encoded by the AMOT gene, is a protein that regulates the migration and organization of endothelial cells. SNHG12 and AMOT have been shown to play a role in a variety of human cancers but have yet to be studied in detail in human osteosarcoma. Tissue samples from primary osteosarcoma (n = 20) and adjacent normal tissues (n = 20), the osteosarcoma cell lines, SAOS-2, MG-63, U-2 OS, and the human osteoblast cell line hFOB (OB3) were studied using Western blot for angiomotin, and quantitative real-time polymerase chain reaction for the expression of SNHG12 and AMOT. The expression of SNHG12 was knocked down using RNA interference. Cell migration assays were performed. Cell apoptosis was studied using flow cytometry. SNHG12 and AMOT messenger RNA (mRNA) expression was upregulated in osteosarcoma tissues and cell lines when compared with normal tissues and cells. Upregulation of AMOT mRNA was associated with upregulation of SNHG12. Knockdown of SNHG12 reduced the expression of angiomotin in osteosarcoma cells and suppressed cell proliferation and migration but did not affect cell apoptosis. This preliminary study has shown that the lncRNA SNHG12 promotes cell proliferation and migration by upregulating AMOT gene expression in osteosarcoma cells in vivo and in vitro. Further studies are recommended to investigate the role of SNHG12 and AMOT expression in tumor cell proliferation and migration and angiogenesis in osteosarcoma and a range of malignant mesenchymal tumors.