title: Functional advantage of NPC-related V-val subtype of Epstein-Barr virus nuclear antigen 1 compared with prototype in epithelial cell line.
abstract: Epstein-Barr virus (EBV) is closely associated with nasopharyngeal carcinoma (NPC) and the viral nuclear antigen 1 (EBNA1) plays a crucial role in viral latency. Three EBNA1 subtypes, P-ala, V-thr and V-val have been detected from healthy carriers in Guangzhou area. A close relation of V-val EBNA1 with NPC was suggested by its preference to infect NPC cells. We therefore investigated the functional difference among these three EBNA1 subtypes in human epithelial cell line. The three coding sequences of the EBNA1 subtypes were cloned into the pGFP-C2 vector, and transfected into 293 cells, respectively. Effect of EBNA1 expression on cell proliferation was examined. The maintenance activity and expression level of EBNA1-plasmid in 293 cells were evaluated by using GFP as a reporter. The expression of P-ala, V-thr or V-val EBNA1 had no effect on 293 cell growth, while the relative average intensity of fluorescence after 14-day selection in V-val-EBNA1/293 cells was statistically higher than P-ala-EBNA1/293 (P<0.05, t test). We suggest that V-val EBNA1 with the functional advantage compared with prototype shown in this study might contribute to the tumorigenesis of NPC by increasing the expression of itself or other viral or cellular genes.
authors.affiliation: Department of Experimental Research, State Key Laboratory of Oncology in Southern China, Cancer Center, Sun Yat-sen University, 651 Dong-Feng Road East, GuangZhou 510060, P.R. China.
authors.forename: Shi-Juan
authors.initials: SJ
authors.lastname: Mai
authors.forename: Tadamasa
authors.initials: T
authors.lastname: Ooka
authors.forename: Da-Jiang
authors.initials: DJ
authors.lastname: Li
authors.forename: Mu-Sheng
authors.initials: MS
authors.lastname: Zeng
authors.forename: Ri-Cheng
authors.initials: RC
authors.lastname: Jiang
authors.forename: Xing-Juan
authors.initials: XJ
authors.lastname: Yu
authors.forename: Ru-Hua
authors.initials: RH
authors.lastname: Zhang
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Chen
authors.forename: Yi-Xin
authors.initials: YX
authors.lastname: Zeng
mesh_terms: D048708:Cell Growth Processes / Q000502:physiology; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology / Q000821:virology; D019309:Epstein-Barr Virus Nuclear Antigens / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014644:Genetic Variation; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000821:virology*; D010957:Plasmids / Q000235:genetics; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D014162:Transfection
chemical_list: D019309:Epstein-Barr Virus Nuclear Antigens; D020033:Protein Isoforms; D049452:Green Fluorescent Proteins; C417029:EBV-encoded nuclear antigen 1