title: Enhanced susceptibility of irradiated tumor vessels to vascular endothelial growth factor receptor tyrosine kinase inhibition.
abstract: Previous experiments with PTK787/ZK222584, a specific inhibitor of vascular endothelial growth factor receptor (VEGFR) tyrosine kinases, using irradiated human FaDu squamous cell carcinoma in nude mice, suggested that radiation-damaged tumor vessels are more sensitive to VEGFR inhibition. To test this hypothesis, the tumor transplantation site (i.e., the right hind leg of nude mice) was irradiated 10 days before transplantation of FaDu to induce radiation damage in the host tissue. FaDu tumors vascularized by radiation-damaged blood vessels appeared later, grew at a slower rate, and showed more necrosis and a smaller vessel area per central tumor section than controls. PTK787/ZK222584 at a daily dose of 50 mg/kg body weight had no impact on growth of control tumors. In contrast, tumors vascularized by radiation-damaged vessels responded to PTK787/ZK222584 with longer latency and slower growth rate than controls, and a trend toward further increase in necrosis, indicating that irradiated tumor vessels are more susceptible to VEGFR inhibition than unirradiated vessels. Although not proving causality, expression analysis of VEGF and VEGFR2 shows that enhanced sensitivity of irradiated vessels to a specific inhibitor of VEGFR tyrosine kinases correlates with increased expression of the molecular target.
authors.affiliation: Department of Radiation Oncology and Experimental Center, Medical Faculty Carl Gustav Carus, University of Technology, Dresden, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zips
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eicheler
authors.forename: Peter
authors.initials: P
authors.lastname: Geyer
authors.forename: Franziska
authors.initials: F
authors.lastname: Hessel
authors.forename: Annegret
authors.initials: A
authors.lastname: Dörfler
authors.forename: Howard D
authors.initials: HD
authors.lastname: Thames
authors.forename: Martin
authors.initials: M
authors.lastname: Haberey
authors.forename: Michael
authors.initials: M
authors.lastname: Baumann
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000528:radiation effects; D002294:Carcinoma, Squamous Cell / Q000098:blood supply* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D048708:Cell Growth Processes / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000098:blood supply* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000201:enzymology / Q000532:radiotherapy; D010793:Phthalazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors*; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D010793:Phthalazines; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D042461:Vascular Endothelial Growth Factor A; C404768:vatalanib; D040262:Receptors, Vascular Endothelial Growth Factor; D040301:Vascular Endothelial Growth Factor Receptor-2