title: Vascular endothelial growth factor tyrosine kinase inhibitor AZD2171 and fractionated radiotherapy in mouse models of lung cancer.
abstract: The vascular endothelial growth factor receptor (VEGFR) tyrosine kinases are being explored as targets for antiangiogenic cancer therapy. Radiotherapy also inhibits tumor growth and affects vasculature. We investigated the combination of the potent VEGFR tyrosine kinase inhibitor AZD2171 and ionizing radiation in cell culture and mouse models of lung cancer. We show that ionizing radiation induces expression of phosphorylated VEGFR-2 (Flk-1) in endothelial cells and that this phosphorylation is inhibited by AZD2171. Human umbilical vascular endothelial cells become more sensitive to radiation after treatment with AZD2171 as determined by clonogenic assay. Matrigel assay showed a decrease in in vitro endothelial tubule formation with AZD2171/radiation combination treatment. When similar combination was applied to the H460 lung cancer xenograft model in nude mice, loss of radiation-induced phosphorylated Flk-1 was observed in the combination treatment group, which also showed a large decrease in tumor vascular density by staining of the von Willebrand factor. H460 tumor growth delay was enhanced in the combination treatment group compared with the groups treated with AZD2171 or radiation alone. Additionally, after therapy, Ki67 index showed >4-fold reduction of tumor proliferation in the combination therapy group, which also showed increased intratumoral apoptotic index by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. In conclusion, AZD2171 sensitizes lung tumor xenografts to radiation and inhibits angiogenesis both in vitro and in vivo. When used as a radiation enhancer, AZD2171 has the potential to improve tumor growth delay by inhibiting tumor proliferation and promoting apoptosis. Clinical trials are needed to determine the potential of this combination therapy in patients with locally advanced lung cancer.
authors.affiliation: Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-5671, USA.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Cao
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Albert
authors.forename: Ling
authors.initials: L
authors.lastname: Geng
authors.forename: Percy S
authors.initials: PS
authors.lastname: Ivy
authors.forename: Alan
authors.initials: A
authors.lastname: Sandler
authors.forename: David H
authors.initials: DH
authors.lastname: Johnson
authors.forename: Bo
authors.initials: B
authors.lastname: Lu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D004307:Dose-Response Relationship, Radiation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D011799:Quinazolines / Q000494:pharmacology / Q000627:therapeutic use*; D011839:Radiation, Ionizing; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors*; D013997:Time Factors; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D007211:Indoles
chemical_list: D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D040262:Receptors, Vascular Endothelial Growth Factor; D040301:Vascular Endothelial Growth Factor Receptor-2; C500926:cediranib; D007211:Indoles