Clinical Interventions in Aging (Mar 2020)
Downregulation of miR-34a Promotes Proliferation and Inhibits Apoptosis of Rat Osteoarthritic Cartilage Cells by Activating PI3K/Akt Pathway
Abstract
Haitao Tao, Lei Cheng, Ruixiang Yang Orthopedic Surgery, The 3rd People’s Hospital of Qingdao, Qingdao 266041, People’s Republic of ChinaCorrespondence: Ruixiang YangOrthopedic Surgery, The 3rd People’s Hospital of Qingdao, No. 29 Yongping Road, Licang District, Qingdao, People’s Republic of ChinaTel +86 138 6421 2816Email [email protected]: To elucidate the expression and function of miR-34a in rat osteoarthritic cartilage cells, and further to explore its mechanism.Material and Methods: Rat model of osteoarthritis was constructed and knee joint cartilage cells were isolated in vitro. Immunocytochemical staining was used for identification. qRT-PCR was used to detect the expression of miR-34a in cartilaginous tissues and cartilage cells. Cartilage cells were divided into blank control (BC), negative control (NC), miR-34a inhibitor (34aI), osteoarthritis model (OA), osteoarthritis model + negative control (OA + NC) and osteoarthritis model + miR-34a inhibitor (OA + 34aI) groups. Cell proliferation was detected by CCK-8 and colony formation assays. Cell apoptosis was studied by flow cytometry and Western blot. PI3K/AKT-pathway-related proteins were also analyzed by Western blot. To further validate the effect of miR-34a on the PI3K/Akt pathway, the cartilage cells were divided into blank control (BC), osteoarthritis model (OA), osteoarthritis model + miR-34a inhibitor (OA + 34aI), osteoarthritis model + PI3K activator (OA + IGF-1) and osteoarthritis model + miR-34a inhibitor + PI3K inhibitor (OA + 34aI + LY) groups, the experiments above were repeated.Results: The expression of miR-34a in cartilaginous tissues and cells of osteoarthritis model was significantly higher than that in normal (p < 0.05). After silencing miR-34a gene, the cell proliferation and proteins expression of PI3K/Akt pathway were increased, while the apoptosis rate and expression of apoptosis-related proteins were decreased. Addition of PI3K activator also evidently promoted proliferation and inhibited apoptosis. The protein expression of Bax, Cleaved caspase-3 and Cleaved caspase-9 were dramatically decreased, while the ratios of p-PI3K/PI3K and p-Akt/Akt were increased in OA + IGF-1 group.Conclusion: Downregulation of miR-34a regulated proliferation and apoptosis of cartilage cells by activating PI3K/Akt pathway, providing a potential therapeutic approach for the treatment of osteoarthritis.Keywords: miR-34a, proliferation, apoptosis, osteoarthritis, PI3K/Akt pathway
