Effects of EB virus latent membrane protein 1 (LMP1) on related factors of metastasis of nasopharyngeal carcinoma cell line CNE1

BACKGROUND & OBJECTIVE: It has been proved that Epstein- Barr virus (EBV) latent membrane protein 1 (EBV-LMP1) can induce the expression of matrix metalloproteinase-9 (MMP-9). This study was designed to investigate the effect of EBV-LMP1 on related factors of metastasis of nasopharyngeal carcinoma cell line CNE1. METHODS: Expression of MMP-9 was studied in human NPC cell lines cultured in vitro: CNE1 (well differentiated cell line of NPC) and CNE1-GL (CNE1 cell line transfected with an eukaryotic LMP1-expression plasmid) by SP immunohistochemistry and Western blot analysis. Cell-matrix adhesion assay was used to study the adhesive ability of CNE1-GL cells. The effects of LMP1 on the invasion and migration of CNE1 cells were investigated by transwell methods. RESULTS: MMP-9 was expressed in both cell lines but the intensity of the staining was different. The positive rates of expression of MMP-9 in CNE1 and CNE1-GL cells were 30.2% and 98.2%, respectively (P<0.05). The increased expression of MMP-9 was also shown in CNE1-GL cells by Western blot analysis. Cell-matrix adhesion assay showed that the adhesive ability of CNE1-GL with the matrix (mean A value: 1.2508+/-0.0711) was higher than that of CNE1 cell (mean A value: 0.9519+/-0.068) (P<0.001). Invasion assay and migration assay showed that the invasion and migration of CNE1-GL cell were higher than those of CNE1 cells (P<0.01). CONCLUSION: The transfection of LMP1 can increase the expression of MMP-9 in CNE1 cells. Abilities of adhesion, migration, and invasion of CNE1 cell were induced by LMP1. It is suggested that MMP-9 may have a role in the LMP1-induced acceleration of invasion and metastasis of NPC cells.