title: Vascular endothelial growth factor accelerates establishment of a model of hepatic metastasis in Walker-256 tumor-bearing rats.
abstract: BACKGROUND
  Animal models of secondary liver cancer are limited by the time required for the development of hepatic metastases. The authors administered vascular endothelial growth factor (VEGF) to stimulate tumor growth in a model of hepatic metastasis.
  
  
  METHODS
  A 0.5 to 1.0 mm³ Walker-256 carcinosarcoma tumor tissue was implanted into the livers of 45 Sprague-Dawley rats, randomly assigned to 3 equal groups to receive daily injections (0.1 mL), for 1 week, of either normal saline (control group), 20 mg/L VEGF (VEGF-20 group) or 40 mg/L VEGF (VEGF-40 group). Tumor growth was assessed by magnetic resonance imaging after 3, 7 and 14 days, and overall survival was recorded.
  
  
  RESULTS
  Three days after implantation, no tumors were detected by magnetic resonance imaging in the control group. In contrast, tumors were observed in 50% of rats in the VEGF-20 group and 66.7% of rats in the VEGF-40 group (P < 0.05). By day 7, tumors were detected in 92.8% of rats in the VEGF-20 group, 86.7% of rats in the VEGF-40 group, but only 21.4% of rats in the control group (P < 0.05). Tumor size increased progressively, reaching 1.81 ± 0.08, 2.51 ± 0.12 and 2.67 ± 0.10 cm³ in the control, VEGF-20 and VEGF-40 groups, respectively, 14 days after implantation of tumor tissue. Median survival times were significantly shorter in the VEGF-40 group (15 days) than in the control and VEGF-20 groups (27 and 25, respectively) (both P < 0.05).
  
  
  CONCLUSIONS
  Daily VEGF injection (20 mg/L, 1 week) accelerates tumorigenesis without compromising survival, potentially extending the period in which experiments can be conducted in this model.
authors.affiliation: Department of Interventional Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Ni
authors.initials: N
authors.lastname: Liu
authors.forename: Jianyong
authors.initials: J
authors.lastname: Yang
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Huang
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Jiaping
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D008099:Liver / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D008297:Male; D017208:Rats, Wistar; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat