Effect of microRNA-21 on Proliferation and Apoptosis of Osteosarcoma Cells via Phosphatase and Tensin Homologue (PTEN)-Phosphoinositide 3-Kinase (PI3K)/AKT Pathway

Objective: PTEN can inhibit the activity of PI3K/AKT signaling and regulate cell proliferation and apoptosis. Increased expression of microRNA-21 is associated with osteosarcoma. Bioinformatics analysis showed a targeted binding site between microRNA-21 and PTEN 3'-UTR. Our study assessed whether microRNA-21 regulates PTEN-PI3K/AKT signaling and affects the proliferation, cloning and apoptosis of osteosarcoma cells. Methods: Dual luciferase reporter gene assay was used to assess the targeted interaction between microRNA-21 and PTEN. Expression of microRNA21 and PTEN was measured in human normal osteoblasts hFOB1.19, osteosarcoma Saos-2 and MG-63. Saos-2 cells were cultured and divided into microRNA-NC group and microRNA-21 inhibitor group followed by measuring the expression of microRNA-21, PTEN and p-AKT, cell apoptosis by flow cytometry, cell proliferation by EdU staining and cloning ability by plate cloning. Results: There was a targeted relationship between microRNA-21 and PTEN. Compared with hFOB1.19 cells, microRNA-21 level in Saos-2 and MG-63 cells was increased and PTEN was decreased. Transfection of microRNA-21 inhibitor significantly reduced microRNA-21 level in Saos-2 cells, increased PTEN, decreased p-AKT, cell proliferation and cloning ability, as well as promoted cell apoptosis. Conclusion: The increased microRNA-21 expression may play a role in reducing PTEN level and promoting osteosarcoma pathogenesis. Inhibiting microRNA-21 can inhibit the activity of PTEN-PI3K/AKT signaling, reduce the proliferation and cloning ability of osteosarcoma cells, and promote cell apoptosis.