Effect of radiation on vascular endothelial growth factor expression in the C2 canine mastocytoma cell line.
OBJECTIVE
To establish the radiosensitivity and effect of irradiation on vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) expression in the canine mastocytoma cell line C2.


METHODS
Canine mastocytoma cell line C2.


METHODS
C2 cells were irradiated with single doses of 2, 4, 6, and 8 Gy. The 3-(4, 5-di-methyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide assay and proliferation assays with (methyl-hydrogen 3) thymidine were used for radiosensitivity experiments. Expression of VEGFR was determined via flow cytometry and apoptotic rate via annexin assay. Human and canine VEGF ELISA kits were evaluated in crossover assay experiments, and the canine kit was used thereafter.


RESULTS
C2 cells secreted VEGF constitutively. Radiation did not induce a significant increase in VEGF secretion, regardless of radiation dose. Consistently, radiation did not up-regulate VEGFR. Cell survival rates decreased in a dose-dependent manner. The apoptotic cell fraction had a dose-dependent increase that reached its maximum 24 to 48 hours after radiation.


CONCLUSIONS
The C2 cell line was radiosensitive, and a fraction (up to 40%) of cells died via apoptosis in a dose-dependent manner. In response to radiation, C2 cells did not upregulate VEGF production or VEGFR. Further studies are needed to determine whether tumor control could be improved by combining radiotherapy with VEGFR inhibitors or apoptosis-modulating agents.
Sekis
Ivana
I
Division of Small Animal Internal Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna 1210, Austria.
Gerner
Wilhelm
W
Willmann
Michael
M
Rebuzzi
Laura
L
Tichy
Alexander
A
Patzl
Martina
M
Thalhammer
Johann G
JG
Saalmüller
Armin
A
Kleiter
Miriam M
MM
D000818:Animals; D017304:Annexin A5 / Q000235:genetics; D017209:Apoptosis / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D045744:Cell Line, Tumor; D004283:Dog Diseases / Q000473:pathology / Q000532:radiotherapy*; D004285:Dogs; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D012515:Mast-Cell Sarcoma / Q000473:pathology / Q000532:radiotherapy / Q000662:veterinary*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics
D017304:Annexin A5; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1