Association of latent membrane protein 1 and matrix metalloproteinase 9 with metastasis in nasopharyngeal carcinoma

BACKGROUND, Nasopharyngeal carcinoma (NPC) is a highly metastatic carcinoma whose consistent association with Epstein-Barr virus (EBV) has been establ ished. Latent membrane protein 1 (LMP1), an EBV membrane protein expressed in latent infection, is considered to be the EBV oncoprotein. Matrix metall oproteinase 9 (MMPS), one of the MMP families, degrades Type TV collagen, a major component of extracellular matrix and is believed to be crucial for cancer invasion and metastasis. Although MMPS is reported to be expressed i n a variety of cancers, no reports concerning NPC have been published to da te to the authors' knowledge. Recently, the authors have shown that LMP1 in duces MMPS in vitro cell line, which suggests the possibility of a mechanis m in which LMP1 of EBV contributes to the metastasis and tumorigenesis of N PC by the induction of MMPS. METHODS. The expressions of LMP1 and MMPS were immunohistochemically examin ed in 38 NPC sections, and the relation of these proteins were statisticall y analyzed. The authors also analyzed the associations of these proteins wi th clinical features. RESULTS. Both LMP1 and MMP9 proteins were predominantly immunolocalized in cancer nests. The expression of MMP9 showed a significant positive correlat ion with the expression of LMP1 (r = 0.75; P < 0.0001). Also, the expressio n of MMPS correlated with lymph node metastasis (P = 0.0004). CONCLUSIONS. The results suggest that the induction of MMPS by LMP1 contrib utes to the metastatic potential of NPC. (C) 2000 American Cancer Society.