Knockdown of lncRNA XIST suppresses osteosarcoma progression by inactivating AKT/mTOR signaling pathway by sponging miR-375-3p.

BACKGROUND:Osteosarcoma (OS) is one of the most common bone tumors in adolescents and young adults. Emerging evidence suggested ncRNA (lncRNA and miRNA) are closely associated with cell progression, apoptosis and autophagy. However, the role of regulatory network between ncRNA and mRNA in OS has not been fully verified. METHODS:lncRNA XIST, miRNA expression were detected by qRT-PCR. The protein expression of LC3, p62, AKT, p-AKT, mTOR and p-mTOR was measured by western blot. MTT assay and flow cytometry were applied to measure cell proliferation and apoptosis. Luciferase assay was used to ensure the relationship between lncRNA, miRNA and mRNA. GFP-LC3 cells were observed using fluorescence microscope. RESULTS:XIST expression was up-regulated but miR-375-3p was down-regulated in OS tissues and cells. Luciferase assay results demonstrated that miR-375-3p was a target of XIST and mTOR was a target mRNA of miR-375-3p. In addition, knockdown of XIST and mTOR inhibited OS cell proliferation and autophagy, but induced apoptosis. Knockdown of XIST could reverse the effect of miR-375-3p inhibitor on OS cells. The effects of si-mTOR of OS cells could be reversed by silencing miR-375-3p. Moreover, knockdown of XIST inhibited AKT/mTOR signaling pathway via sponging miR-375-3p. CONCLUSION:Knockdown of XIST inhibited cell growth and autophagy but induced cell apoptosis by suppressing the AKT/mTOR signaling pathway by sponging miR-375-3p.