title: VEGF-subtype specific protection of SCC and HUVECs from radiation induced cell death.
abstract: The contribution of VEGF (vascular endothelial growth factor) to angiogenesis and tumor aggressiveness has been shown in several tumor types, but no comparative data regarding the impact of the VEGF-subtypes on endothelial and tumor cell protection are available. Therefore, we analysed the cytoprotective effects of the two major soluble VEGF-subtypes, VEGF-121 and -165, on HUVEC cell cultures (human umbilical vein endothelial cells) and squamous cell carcinoma (SCC) cell lines after ionizing radiation. We performed clonogenic analyses and proliferation assays for evaluation of cell survival and proliferative activity. Experiments were performed employing different intensities up to 8 Gy with or without added recombinant VEGF-121 or -165 and compared to non-irradiated cultures. To evaluate a possible contribution of the VEGF-receptors, we performed immunohistochemical stainings of VEGF-R1 (flt), -R2 (KDR,flk), and Neuropilin-1. In the SCC cell lines and HUVEC cultures, cell survival and proliferative activity were reduced in a dosage-dependent manner. The addition of VEGF-121 yielded a significant increase of resistance from 1.2 to 2.7 Gy (+125%) for killing 50% of subjected cells, while VEGF-165 was less effective in this regard (+83%). Conversely, in HUVEC cultures, 50%-survival was increased more strongly by VEGF-165 compared to VEGF-121 (+100% vs. +43%). Accordingly, proliferation was more intensely stimulated in HUVECs by VEGF-165 than by VEGF-121. VEGF-receptors were expressed in all cell cultures analysed at comparable levels. We conclude that the two VEGF-subtypes differentially increase the survival of tumor and endothelial cells after irradiation in vitro. We hypothesise, that the release of VEGF by the tumor protects tumor cells and endothelium resulting in increased radiation resistance.
authors.affiliation: Department of Otorhinolaryngology, Laboratory of Molecular Tumour Biology, University Hospital of Mainz, 55101 Mainz, Germany. brieger@mail.uni-mainz.de
authors.forename: Jürgen
authors.initials: J
authors.lastname: Brieger
authors.forename: Petra
authors.initials: P
authors.lastname: Schroeder
authors.forename: Jan
authors.initials: J
authors.lastname: Gosepath
authors.forename: Wolf J
authors.initials: WJ
authors.lastname: Mann
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D006801:Humans; D007150:Immunohistochemistry; D040262:Receptors, Vascular Endothelial Growth Factor / Q000378:metabolism; D012995:Solubility; D014470:Umbilical Cord / Q000166:cytology*; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D042461:Vascular Endothelial Growth Factor A; D040262:Receptors, Vascular Endothelial Growth Factor