title: Downregulation of FGL2/prothrombinase delays HCCLM6 xenograft tumour growth and decreases tumour angiogenesis.
abstract: BACKGROUND
  Fibrinogen-like protein 2 (FGL2), which directly generates thrombin from prothrombin without activation of the conventional coagulation cascade, was shown to be overexpressed in various human malignant tumours.
  
  
  OBJECTIVE
  Herein, we aimed to investigate its expression pattern, biological function and mechanism of action in hepatocellular carcinoma (HCC).
  
  
  METHODS
  FGL2 expression and colocalization with fibrin was examined in 15 HCC tissues. FGL2 downregulation was performed by targeting microRNA in a HCCLM6 cell line in which FGL2 was highly expressed in xenografts of nude mice. The effects of FGL2 knockdown on tumour growth and angiogenesis were evaluated in vitro and in vivo. Cytometric bead arrays were employed to identify FGL2-regulated signalling pathways.
  
  
  RESULTS
  FGL2 was overexpressed in HCC tissues and colocalized with fibrin deposition. Knockdown of FGL2 expression in HCCLM6 cells (hFGL2(low) HCCLM6) resulted in delayed xenografts tumour growth within an observation period of 42 days and decreased vascularization, which was accompanied by decreased phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). In vitro hFGL2(low) HCCLM6 cells exhibited decreased proliferation without significant induction of apoptosis. Overexpression of FGL2 in HCCLM6 cells or addition of recombinant hFGL2 protein induced phosphorylation of p38-MAPK and ERK1/2 involving protease-activated receptors (PARs).activation.
  
  
  CONCLUSIONS
  FGL2 contributes to HCC tumour growth and angiogenesis in a thrombin-dependent manner, and downregulation of its expression might be of therapeutic significance in HCC.
authors.affiliation: Department and Institute of Infectious Disease, Tongji hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Qili
authors.initials: Q
authors.lastname: Zeng
authors.forename: Jingli
authors.initials: J
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Xi
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Wang
authors.forename: Daofeng
authors.initials: D
authors.lastname: Yang
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Luo
authors.forename: Qin
authors.initials: Q
authors.lastname: Ning
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005337:Fibrin / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism*; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000503:physiopathology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013925:Thromboplastin
chemical_list: C095202:FGL2 protein, human; D035683:MicroRNAs; D005337:Fibrin; D005340:Fibrinogen; D013925:Thromboplastin; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases