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

The present study aimed to investigate the mechanism by which cyclooxygenase‑2 (COX‑2) promotes the metastasis of MG‑63 osteosarcoma cells through the PI3K/AKT/NF‑κB pathway. To achieve this, a recombinant lentivirus containing the COX‑2 gene was constructed in order to overexpress COX‑2; a recombinant lentivirus containing a control sequence was also constructed. A Transwell chamber migration assay was performed to quantify the migration of the COX‑2‑transduced cells, and of cells treated with a COX‑2 inhibitor (NS398) or a PI3K inhibitor (LY294002). Immunofluorescence assays were performed to determine changes in E‑cadherin, vimentin and NF‑κB expression levels. ELISAs 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‑AKT, inhibitor of NF‑κΒ 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‑AKT and p‑IKK 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, COX‑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.