title: After insufficient radiofrequency ablation, tumor-associated endothelial cells exhibit enhanced angiogenesis and promote invasiveness of residual hepatocellular carcinoma.
abstract: BACKGROUND
  The mechanism regarding rapid progression of residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA) has been preliminarily discussed. However, most studies have mainly focused on RFA-induced changes in the tumor cells. The present study was designed to determine whether tumor-associated endothelial cells (TAECs) could contribute to the invasiveness of HCC after insufficient RFA.
  
  
  METHODS
  TAECs were isolated from fresh HCC tissue and characterized. Morphological changes were observed in TAECs after heat treatment for 10 min. TAEC proliferation, migration and tube formation after heat treatment for 10 min at 37°C (control group), and 42 and 47°C (insufficient RFA groups) were examined. The differences in TAECs interactions with HepG2-GFP or HCCLM3-GFP cells among the two insufficient RFA groups and control group were evaluated. The expression of E-selectin, ICAM-1 and VCAM-1 in TAECs was measured. The effects of TAECs on the invasiveness of HepG2-GFP or HCCLM3-GFP cells after insufficient RFA were analyzed. The IL-6, IL-8, MCP-1 and GRO-α concentrations in conditioned medium from TAECs were measured after insufficient RFA. The associated signaling pathways of Akt, ERK1/2, STAT3 and NF-κB were analyzed in TAECs after insufficient RFA.
  
  
  RESULTS
  TAECs expressed the EC-specific markers and took up complexes of Dil-Ac-LDL. Relative to the control group, the proliferation of TAECs was significantly inhibited and their migration and tube formation were significantly enhanced in the insufficient RFA groups. Significantly more HepG2-GFP or HCCLM3-GFP cells adhered to TACEs in these groups than in the control group (all P<0.001), via up-regulated expression of E-selectin, ICAM-1 and VCAM-1. TAECs promoted the invasiveness of HepG2-GFP or HCCLM3-GFP cells after insufficient RFA via the up-regulation of IL-6, IL-8, MCP-1 and GRO-α in conditioned medium (all P<0.05). Insufficient RFA enhanced the activities of Akt, ERK1/2 and NF-κB signaling pathways and inhibited STAT3 signaling pathways.
  
  
  CONCLUSIONS
  Insufficient RFA enhanced TAEC migration and tube formation, and this may play a key role in the rapid growth of residual HCC. Increased expression of metastasis-related molecules in TAECs after insufficient RFA may be a potential mechanism for the metastasis of residual HCC.
authors.affiliation: Department of Hepatobiliary Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Kong
authors.forename: Lingqun
authors.initials: L
authors.lastname: Kong
authors.forename: Jinge
authors.initials: J
authors.lastname: Kong
authors.forename: Shan
authors.initials: S
authors.lastname: Ke
authors.forename: Jun
authors.initials: J
authors.lastname: Gao
authors.forename: Xuemei
authors.initials: X
authors.lastname: Ding
authors.forename: Lemin
authors.initials: L
authors.lastname: Zheng
authors.forename: Huichuan
authors.initials: H
authors.lastname: Sun
authors.forename: Wenbing
authors.initials: W
authors.lastname: Sun
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000098:blood supply* / Q000201:enzymology / Q000473:pathology* / Q000601:surgery; D017115:Catheter Ablation; D002448:Cell Adhesion; D002450:Cell Communication; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002469:Cell Separation; D048430:Cell Shape; D042783:Endothelial Cells / Q000201:enzymology / Q000473:pathology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D006979:Hyperthermia, Induced; D008113:Liver Neoplasms / Q000098:blood supply* / Q000201:enzymology / Q000473:pathology / Q000601:surgery; D016328:NF-kappa B / Q000378:metabolism; D009361:Neoplasm Invasiveness; D018365:Neoplasm, Residual / Q000201:enzymology / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000473:pathology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015203:Reproducibility of Results; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D016328:NF-kappa B; D050796:STAT3 Transcription Factor; D049452:Green Fluorescent Proteins; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases