title: Entecavir combined with furin inhibitor simultaneously reduces hepatitis B virus replication and e antigen secretion.
abstract: BACKGROUND
  The antiviral therapy of chronic hepatitis B virus (HBV) infection pursues the dual goals, virological response (undetectable serum HBV DNA) and hepatitis B e antigen (HBeAg) serological response (serum HBeAg loss/seroconversion). It is relatively difficult, however, to realize the serological response, especially for nucleotide/nucleoside analogs. Furin, a proprotein convertase, is involved in HBeAg maturation. The suppression of furin using inhibitors accordingly reduces HBeAg secretion, but possibly enhances HBV replication. For these reasons, the strategy based on the combination of nucleoside analog entecavir (ETV) and furin inhibitors to inhibit HBV replication and HBeAg secretion simultaneously were studied here.
  
  
  METHODS
  The suppression of furin was performed using inhibitors decanoyl-RVKR-chloromethylketone (CMK) and hexa-D-arginine (D6R) or the expression of furin inhibitory prosegment. The influence of furin suppression on HBV replication and the effect of CMK combined with nucleoside analog entecavir (ETV) on HBV replication and HBeAg secretion was investigated in HepG2.2.15 cells. HBeAg level in media was detected using enzyme-linked immunosorbent assay. Intracellular viral antigens and HBV DNA were detected using Western and Southern blotting analyses, respectively.
  
  
  RESULTS
  CMK, D6R and the expression of inhibitory prosegment all significantly reduced HBeAg secretion, but only CMK enhance HBV replication. Concordantly, only CMK post-transcriptionally accumulated cytosolic HBV replication-essential hepatitis B core antigen (HBcAg). The HBcAg-accumulating effect of CMK was further found to be resulted from its redundant inhibitory effect on the trypsin-like activity of cellular proteasomes that are responsible for HBcAg degradation. Moreover, the viral replication-enhancing effect of CMK was abrogated by ETV and ETV combined with CMK reduced HBV replication and HBeAg secretion simultaneously.
  
  
  CONCLUSIONS
  The suppression of furin itself does not enhance HBV replication. Nucleotide/nucleoside analogs combined with furin inhibitors may be a potential easy way to realize the dual goals of the antiviral therapy for chronic hepatitis B in the future.
authors.forename: Hui Y
authors.initials: HY
authors.lastname: Yang
authors.forename: Nai Q
authors.initials: NQ
authors.lastname: Zheng
authors.forename: Dong M
authors.initials: DM
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Gu
authors.affiliation: Hepatology Laboratory, the Hospital for Liver Disease, Sun Yat-Sen University, 600 Tianhe Road, Guangzhou 510630, China. xiaomoupeng@hotmail.com.
authors.forename: Xiao M
authors.initials: XM
authors.lastname: Peng
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000008:administration & dosage / Q000494:pharmacology*; D000956:Antigens, Viral / Q000302:isolation & purification / Q000378:metabolism; D000998:Antiviral Agents / Q000008:administration & dosage / Q000494:pharmacology; D045683:Furin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D006147:Guanine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D056945:Hep G2 Cells; D006513:Hepatitis B e Antigens / Q000235:genetics / Q000378:metabolism*; D006515:Hepatitis B virus / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000956:Antigens, Viral; D000998:Antiviral Agents; D006513:Hepatitis B e Antigens; D009842:Oligopeptides; C460143:decanoylRVKRchloromethylketone; C000597783:hexa-D-arginine; C413685:entecavir; D006147:Guanine; D045683:Furin