Abstract: Background and purpose: miR-21 is ovexpressed in various types of human cancers. This study was designed to investigate the effect of miR-21 knockdown on cell proliferation, migration and invasion of nasopharyngeal carcinoma (NPC) cell line CNE2. Methods: CNE2 was transfected with miR-21 inhibitor by Lipofectamine^TM2000. Meanwhile CNE2 was transfected with NC inhibitor as negative control. qRT-PCR was used to detect the miR-21 expression in these cells. The effects of miR-21 downregulation on cell proliferation, migration and invasion were evaluated by MTS, wound-healing Transwell and invasion assays. Results: miR-21 expression was remarkably downregulated in miR-21 inhibitor-transfected cells in concentration-dependent manner, indicating transfection with miR-21 inhibitor can effectively reduce expression level of miR-21 in CNE2 cells. Transfection of miR-21 inhibitor into CNE2 cells led to a significant decrease in cell proliferation rate compared with control cells (P<0.05). miR-21 downregulation results in reduction of cell migration(P<0.05). Moreover, the cell invasion by Transwell invasion assay was reduced in miR-21-downregulated cells relative to control cells. Conclusion: miR-21 can promote cell proliferation, migration and invasion of NPC cells. And it maybe plays an important role in tumorigenesis and development of NPC.

Key words: Nasopharyngeal carcinoma, MiR-21, Cell proliferation, Cell invasion