title: Hepatitis B virus X protein accelerates hepatocarcinogenesis with partner survivin through modulating miR-520b and HBXIP.
abstract: BACKGROUND
  Hepatitis B virus X protein (HBx) plays crucial roles in hepatocarcinogenesis. However, the underlying mechanism remains elusive. We have reported that HBx is able to up-regulate survivin in hepatocellular carcinoma tissues. The oncopreotein hepatitis B X-interacting protein (HBXIP), a target of miR-520b, is involved in the development of cancer. In this study, we focus on the investigation of hepatocarcinogenesis mediated by HBx.
  
  
  METHODS
  The expression of HBx and survivin was examined in the liver tissues of HBx-Tg mice. The effect of HBx/survivin on the growth of LO2-X-S cells was determined by colony formation and transplantation in nude mice. The effect of HBx/survivin on promoter of miR-520b was determined by Western blot analysis, luciferase reporter gene assay, co-immunoprecipitation (co-IP) and chromatin immunoprecipitation (ChIP), respectively. The expression of HBx, survivin and HBXIP was detected by immunohistochemistry and real-time PCR in clinical HCC tissues, respectively. The DNA demethylation of HBXIP promoter was examined. The functional influence of miR-520b and HBXIP on proliferation of hepatoma cells was analyzed by MTT, colony formation, EdU and transplantation in nude mice in vitro and in vivo.
  
  
  RESULTS
  In this study, we provided evidence that HBx up-regulated survivin in the liver cancer tissues of HBx-Tg mice aged 18 M. The engineered LO2 cell lines with survivin and/or HBx were successfully established, termed LO2-X-S. MiR-520b was down-regulated in LO2-X-S cells and clinical HCC tissues. Our data revealed that HBx survivin-dependently down-regulated miR-520b through interacting with Sp1 in the cells. HBXIP was highly expressed in LO2-X-S cells, liver cancer tissues of HBx-Tg mice aged 18 M and clinical HCC tissues (75.17%, 112/149). The expression level of HBXIP was positively associated with those of HBx or survivin in clinical HCC tissues. In addition, we showed that HBx survivin-dependently up-regulated HBXIP through inducing demethylation of HBXIP promoter in LO2-X-S cells and clinical HCC tissues. In function, low level miR-520b and high level HBXIP mediated by HBx with partner survivin contributed to the growth of LO2-X-S cells in vitro and in vivo.
  
  
  CONCLUSIONS
  HBx accelerates hepatocarcinogenesis with partner survivin through modulating tumor suppressor miR-520b and oncoprotein HBXIP.
authors.forename: Weiying
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhanping
authors.initials: Z
authors.lastname: Lu
authors.forename: Guangyao
authors.initials: G
authors.lastname: Kong
authors.forename: Yuen
authors.initials: Y
authors.lastname: Gao
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Na
authors.initials: N
authors.lastname: Cai
authors.forename: Honghui
authors.initials: H
authors.lastname: Wang
authors.forename: Fabao
authors.initials: F
authors.lastname: Liu
authors.forename: Lihong
authors.initials: L
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, Institute for Molecular Biology, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, P,R, China. zhangxd@nankai.edu.cn.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D063646:Carcinogenesis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000209:etiology / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D019175:DNA Methylation; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000235:genetics* / Q000378:metabolism; D006509:Hepatitis B / Q000150:complications / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D054884:Host-Pathogen Interactions; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000209:etiology / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D000077022:Survivin; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; C110719:LAMTOR5 protein, human; C575048:MIRN520 microRNA, human; D035683:MicroRNAs; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D000077022:Survivin; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein