Background: Previously, we found that c-jun  was highly expressed in radiation-resistant human nasopharyngeal carcinoma cells (CNE-2R) compared with human nasopharyngeal carcinoma cells (CNE-2). 
Materials and methods: In this study, we first used the scratch assays and transwell assays to detect the migration and invasion of CNE-2R and CNE-2 cells and tested the epithelial mesenchymal transformation (EMT)-related proteins E-cadherin and N-cadherin by Western blot analysis. Subsequently, c-jun  was knocked down to establish the effect of c-jun  on EMT, migration, and invasion of CNE-2R cells both in vitro and in vivo. 
Results: A high EMT level, CNE-2R cells were more capable of migration and invasion than CNE-2 cells. Moreover, silencing of c-jun  has upregulated the expression of E-cadherin and downregulated N-cadherin in CNE-2R cells, and subsequently the migration and invasion capacity of the cells was decreased. Consistent with in vitro results, in vivo studies indicated that the c-jun  silencing reduced pulmonary migration of CNE-2R cells. Immunohistochemistry of lung metastatic tumor tissue showed that E-cadherin was upregulated, and N-cadherin was downregulated. 
Conclusion: These findings suggest that silencing of c-jun  in CNE-2R cells reduces cells migration, invasion, and EMT both in vitro and in vivo.
Keywords: nasopharyngeal carcinoma, c-jun , migration, invasion, EMT