title: Epstein-Barr virus-encoded latent membrane protein 1 activates beta-catenin signaling in B lymphocytes.
abstract: The Epstein-Barr virus-encoded latent membrane protein 1 is considered the Epstein-Barr virus oncogene based on its importance in Epstein-Barr virus-induced B-lymphocyte transformation. Beta-catenin is a potential oncogene, and its accumulation has been implicated in a variety of human cancers. Here, we found that beta-catenin protein was highly expressed in Epstein-Barr virus-immortalized B-cell lines compared with peripheral blood mononuclear cells from healthy donors. Beta-catenin expression in Epstein-Barr virus-immortalized B-cell line decreased following treatment with LY294002, an inhibitor of phosphatidylinositol 3-kinase. Treatment with LY294002 or knockdown of beta-catenin by small interfering RNA reduced the growth of Epstein-Barr virus-immortalized B-cell line. Transient transfection of latent membrane protein 1 expression plasmid increased beta-catenin protein expression and beta-catenin-dependent transcription. Latent membrane protein 1 deletions mutants lacking the carboxyl-terminal activating region 1 domain failed to enhance beta-catenin protein expression and beta-catenin-dependent transcriptional activity. They also failed to increase phosphorylated AKT expression. Dominant-negative AKT suppressed latent membrane protein 1-induced beta-catenin-dependent transcriptional activity. These results suggest that latent membrane protein 1 activates beta-catenin through the phosphatidylinositol 3-kinase/AKT signaling pathway. Activation of the beta-catenin pathway by Epstein-Barr virus may contribute to the lymphoproliferation characteristic of Epstein-Barr virus-infected B-cells.
authors.affiliation: Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Tomita
authors.forename: Md Zahidunnabi
authors.initials: MZ
authors.lastname: Dewan
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Kikuchi
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D051820:TCF Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; D051820:TCF Transcription Factors; D014763:Viral Matrix Proteins; D051176:beta Catenin; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt