title: Hepatitis B virus X protein promotes hepatoma cell proliferation via upregulation of MEKK2.
abstract: OBJECTIVE
  To investigate the mechanism underlying the increase of hepatoma cell proliferation by hepatitis B virus X protein (HBx).
  
  
  METHODS
  HepG2, H7402 and HepG2.2.15 cells, which constitutively replicated hepatitis B virus were used. The effects of HBx on hepatoma cell proliferation were examined using 5-ethynyl-2-deoxyuridine (EdU) incorporation assay and MTT assay. The expression level of MEKK2 was measured using RT-PCR, Western blot and luciferase reporter gene assay. The activity of activator protein 1 (AP-1) was detected using luciferase reporter gene assay. The phosphorylation levels of JNK and c-Jun were measured using Western blot. The expression levels of HBx and MEKK2 in 11 clinical hepatocellular carcinoma (HCC) tissues were measured using real time PCR and Western blot. In addition, the expression of MEKK2 in 95 clinical HCC tissues was examined using immunohistochemistry.
  
  
  RESULTS
  HBx significantly enhanced HepG2-X cell proliferation. In HepG2-X, H7402-X and HepG2.2.15 cells, the expression level of MEKK2 was remarkably increased. In HepG2.2.15 cells, HBx was found to activate JNK and AP-1, which were the downstream effectors of MEKK2 in HepG2-X and HepG2.2.15 cells. In 11 clinical HCC tissues, both HBx and MEKK2 expression levels were remarkably increased, as compared to those in the corresponding peritumor tissues. In 95 clinical HCC tissues, the rate of detection of MEKK2 was 85.3%.
  
  
  CONCLUSIONS
  HBx promotes hepatoma cell proliferation via upregulating MEKK2, which may be involved in hepatocarcinogenesis.
authors.affiliation: Department of Cancer Research, Key Laboratory of Molecular Microbiology and Technology of Ministry of Education, Institute for Molecular Biology, Nankai University, Tianjin 300071, China.
authors.forename: Guang-yao
authors.initials: GY
authors.lastname: Kong
authors.forename: Jun-ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Chang-liang
authors.initials: CL
authors.lastname: Shan
authors.forename: Li-hong
authors.initials: LH
authors.lastname: Ye
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Zhang
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology / Q000821:virology; D048730:MAP Kinase Kinase Kinase 2 / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D048730:MAP Kinase Kinase Kinase 2