Induction of interleukin-8 by Epstein-Barr virus latent membrane protein-1and its correlation to angiogenesis in nasopharyngeal carcinoma

Purpose: The EBV latent membrane protein-1 (LMP-1) is a multifunctional pro tein. Recently, the contribution of LMP-I to the metastasis of nasopharynge al carcinoma (NPC) has been suggested. Angiogenesis is a key step for metas tasis, Thus, the association of LMP-I to neovascularization of NPC was exam ined in this study. Experimental Design: The association of LMP-1 to angiogenesis in 39 patient s with NPC was evaluated by immunohistochemical study, and then induction o f angiogenic factors by LMP-1 was examined by ELISA and luciferase reporter assay. Results: In an immunohistochemical study, the expression of LMP-1 was signi ficantly correlated to microvessel counts (P = 0.0003), suggesting that LMP -1 may induce some angiogenic factors. Therefore, we studied the relationsh ip between LMP-1 expression and interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) expression by immunohistochemical analysis. IL-8, VEGF, and bFGF expression were corre lated to microvessel counts, but only IL-8 expression was significantly cor related to LMP-1 expression (P < 0.0001). Transfection with LMP-I expressio n plasmid induced IL-8 protein expression in C33A cells, The expression of LMP-1 transactivated IL-8 promoter, as demonstrated by IL-8 promoter lucife rase reporter assay. Mutation of the nuclear factor KB responsive element i n the IL-8 promoter region completely abolished transactivation by LMP-I, w hereas mutation of the activator protein responsive element did not affect promoter activity. Conclusion: These results suggested that LMP-1 induces expression of IL-8 t hrough the nuclear factor KB binding site, which may contribute in part to angiogenesis in NPC.