title: Response of endothelial cells to a dual tyrosine kinase receptor inhibition combined with irradiation.
abstract: Recent studies suggest the possibility of a direct antiangiogenic effect of anti-epidermal growth factor receptor (EGFR) drugs due to the presence of EGFR on endothelial cells. The aim of this study was to analyze the direct effect on endothelial cells of associating EGFR targeting, vascular endothelial growth factor receptor (VEGFR)-2 targeting, and irradiation. We examined both the cytotoxic effects and the effect on molecular markers resulting from the combined action of gefitinib (Iressa; anti-EGFR), ZM317450 [VEGFR tyrosine kinase inhibitor (VTKI); anti-VEGFR-2], and irradiation (radiation therapy) on HMME7 cells, an immortalized microvascular endothelial cell of human origin. The presence of a functional EGFR pathway sensitive to gefitinib was shown in HMME7 cells (gefitinib-induced decrease in phospho-EGFR, phospho-p42/p44, and phospho-Akt). The stimulation of VEGFR-2 pathway led to an increase in Akt phosphorylation that was inhibited by VTKI. Of note, a post-radiation therapy induction of phospho-p42/p44 was observed on HMME7 cells, and this effect was inhibited by a pretreatment with gefitinib. Based on combination indexes (Chou and Talalay analyses), the associations gefitinib-radiation therapy, VTKI-radiation therapy, VTKI-gefitinib, and gefitinib-VTKI-radiation therapy were found to be additive, slightly synergistic, and markedly synergistic, respectively, for the cytotoxicity on HMME7 cells. Among molecular explanatory factors that were examined, the combination gefitinib-radiation therapy totally abolishes DNA-dependent protein kinase expression, and gefitinib attenuates the radiation therapy-induced enhancement of ERCC1 and augments the VTKI-induced CD95 enhancement. The existence of a radiation therapy-dependent neoangiogenesis may be related to the induction of EGFR pathway in endothelial cells, a phenomenon that can be attenuated by anti-EGFR drugs like gefitinib. In complement to the direct antitumor effects of radiation therapy and anti-EGFR drugs, a strong antiangiogenic effect may be obtained with therapeutic strategies combining radiation therapy with EGFR and VEGFR-2 targeting agents.
authors.affiliation: Oncopharmacology Unit, Centre Antoine-Lacassagne, 33, Avenue de Valombrose, 06189 Nice Cedex 2, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bozec
authors.forename: Patricia
authors.initials: P
authors.lastname: Formento
authors.forename: Joseph
authors.initials: J
authors.lastname: Ciccolini
authors.forename: Raphaëlle
authors.initials: R
authors.lastname: Fanciullino
authors.forename: Laetitia
authors.initials: L
authors.lastname: Padovani
authors.forename: Xavier
authors.initials: X
authors.lastname: Murraciole
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Fischel
authors.forename: Gerard
authors.initials: G
authors.lastname: Milano
mesh_terms: D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000502:physiology; D000077156:Gefitinib; D006801:Humans; D011799:Quinazolines / Q000494:pharmacology; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D015398:Signal Transduction / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D011799:Quinazolines; D042461:Vascular Endothelial Growth Factor A; D004815:Epidermal Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D000077156:Gefitinib