title: Herpes simplex virus amplicon delivery of a hypoxia-inducible soluble vascular endothelial growth factor receptor (sFlk-1) inhibits angiogenesis and tumor growth in pancreatic adenocarcinoma.
abstract: BACKGROUND
  Tumor hypoxia induces vascular endothelial growth factor (VEGF) expression, which stimulates angiogenesis and tumor proliferation. The VEGF signaling pathway is inhibited by soluble VEGF receptors (soluble fetal liver kinase 1; sFlk-1), which bind VEGF and block its interaction with endothelial cells. Herpes simplex virus (HSV) amplicons are replication-incompetent viruses used for gene delivery. We attempted to attenuate angiogenesis and inhibit pancreatic tumor growth through HSV amplicon-mediated expression of sFlk-1 under hypoxic control.
  
  
  METHODS
  A multimerized hypoxia-responsive enhancer (10 x HRE) was cloned upstream of the sFlk-1 gene (10 x HRE/sFlk-1). A novel HSV amplicon expressing 10 x HRE/sFlk-1 was genetically engineered (HSV10 x HRE/sFlk-1).Human pancreatic adenocarcinoma cells (AsPC1) were transduced with HSV10 x HRE/sFlk-1 and incubated in normoxia (21% oxygen) or hypoxia (1% oxygen). Capillary inhibition was evaluated by human umbilical vein endothelial cell assay. Western blot assessed sFlk-1 expression. AsPC1 flank tumor xenografts (n = 24) were transduced with HSV10 x HRE/sFlk-1.
  
  
  RESULTS
  Media from normoxic AsPC1 transduced with HSV10 x HRE/sFlk-1 yielded a 36% reduction in capillary formation versus controls (P < .05), whereas hypoxic AsPC1 yielded a 76% reduction (P < .005). Western blot of AsPC1 transduced with HSV10 x HRE/sFlk-1 demonstrated greater sFlk-1 expression in hypoxia versus normoxia. AsPC1 flank tumors treated with HSV10 x HRE/sFlk-1 exhibited a 59% reduction in volume versus controls (P < .000001).
  
  
  CONCLUSIONS
  HSV amplicon delivery of a hypoxia-inducible soluble VEGF receptor significantly reduces new vessel formation and tumor growth. Tumor hypoxia can thus be used to direct antiangiogenic therapy to pancreatic adenocarcinoma.
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
authors.forename: Maura
authors.initials: M
authors.lastname: Reinblatt
authors.forename: Richard H
authors.initials: RH
authors.lastname: Pin
authors.forename: William J
authors.initials: WJ
authors.lastname: Bowers
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Federoff
authors.forename: Yuman
authors.initials: Y
authors.lastname: Fong
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000628:therapy*; D020533:Angiogenesis Inhibitors / Q000008:administration & dosage*; D015153:Blotting, Western; D015687:Cell Hypoxia; D004742:Enhancer Elements, Genetic; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000628:therapy*; D018139:Simplexvirus / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000008:administration & dosage*
chemical_list: D020533:Angiogenesis Inhibitors; D051793:Hypoxia-Inducible Factor 1; D040301:Vascular Endothelial Growth Factor Receptor-2