COX-2 promotes epithelial-mesenchymal transition and migration in osteosarcoma MG-63 cells via PI3K/AKT/NF-κB signaling

Abstract

The present study aimed to investigate the mechanism by which cyclooxygenase-2 (CO X-2) promotes the metastasis of MG-63 osteosarcoma cells through the PI3K/AKT/NF-κB pathway. To achieve this, a recombinant lentivirus containing the CO X-2 gene was constructed in order to overexpress CO X-2; a recombinant lentivirus containing a control sequence was also constructed. A Transwell chamber migration assay was performed to quantify the migration of the CO X-2-transduced cells, and of cells treated with a CO X-2 inhibitor (NS398) or a PI3K inhibitor (LY294002). Immunofluorescence assays were performed to determine changes in E- cadherin, vimentin and NF-κB expression levels. ELI SAs were performed to quantify the levels of matrix metallopeptidase (MMP)-2, MMP-9 and vascular endothelial growth factor (VEGF) in the culture medium. Western blot analysis was conducted to measure the protein expression levels of MMP-2, MMP-9, PI3K, phosphorylated (p-) PI3K, AKT, p-A KT, inhibitor of NF-κB kinase (IKK) and p-IKK. The results demonstrated that the migration ability of the COX-2-overexpressing MG-63 cells was significantly increased compared with the control cells. The migration ability of cells treated with NS398 or LY294002 was significantly decreased. Compared with the control cells, E- cadherin expression was significantly decreased in COX-2-overexpressing cells, while the expression levels of vimentin, MMP-2, MMP-9, VEGF, p-PI3K, p-A KT and p-I KK were significantly increased. Compared with the control cells, E- cadherin expression was significantly increased in cells treated with NS398 or LY294002, while the expression levels of vimentin, MMP-2, MMP-9, VEGF, p-PI3K, p-AKT, and p-IKK were significantly decreased. The total protein levels of PI3K, AKT and IKK were not changed among the treatment groups. In summary, CO X-2 overexpression decreased the expression levels of the epithelial protein E- cadherin and increased the expression levels of the mesenchymal proteins vimentin, MMP-2 and MMP-9, as well as promoted cell migration, by activating the PI3K/AKT/NF-κB signaling pathway.