Expression of vascular endothelial growth factor and its receptors in canine lymphoma.
Vascular endothelial growth factor (VEGF) stimulates endothelial cell proliferation and has a pivotal role in tumour angiogenesis. The expression of VEGF and its receptors VEGFR-1 and VEGFR-2 was examined immunohistochemically in 43 specimens of canine lymphoma and in six normal lymph nodes. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were performed to detect VEGF protein and mRNA, respectively. VEGF protein was expressed by 60% of the tumours with diffuse cytoplasmic labelling of the neoplastic cells. Endothelial cells, macrophages and plasma cells were also immunolabelled. VEGFR-1 was expressed by variable numbers of neoplastic cells in 54% of lymphoma specimens. VEGFR-1 was also expressed by macrophages, plasma cells, reticulum cells, and vascular endothelial cells. Macrophages and lymphocytes in germinal centres of normal lymph nodes were also immunoreactive with anti-VEGF and VEGFR-1. Most tumours did not express VEGFR-2 but in 7% of sections there was focal labelling of neoplastic and endothelial cells, with a cytoplasmic and perinuclear pattern. The observed variability in expression of VEGF and its receptors probably relates to the fact that lymphoma is a heterogeneous lymphoproliferative tumour. Individual differences in VEGF and VEGFR expression must be taken into account when VEGF and VEGFR-targeted approaches for anti-angiogenic therapy are considered in dogs.
Wolfesberger
B
B
Clinic of Internal Medicine and Infectious Diseases. Electronic address: birgitt.wolfesberger@vu-wien.ac.at.
Guija de Arespacohaga
A
A
Central Laboratory.
Willmann
M
M
Clinic of Internal Medicine and Infectious Diseases.
Gerner
W
W
Institute of Clinical Immunology.
Miller
I
I
Institute of Medical Chemistry.
Schwendenwein
I
I
Central Laboratory.
Kleiter
M
M
Clinic of Internal Medicine and Infectious Diseases.
Egerbacher
M
M
Institute of Histology and Embryology.
Thalhammer
J G
JG
Clinic of Internal Medicine and Infectious Diseases.
Muellauer
L
L
Clinical Pathology, Medical University of Vienna, Vienna, Austria.
Skalicky
M
M
Institute of Pathophysiology, University of Veterinary Medicine, Vienna.
Walter
I
I
Institute of Histology and Embryology.
D000818:Animals; D004283:Dog Diseases / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D015972:Gene Expression Regulation, Neoplastic; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000378:metabolism / Q000662:veterinary*; D016399:Lymphoma, T-Cell / Q000378:metabolism / Q000662:veterinary*; D012333:RNA, Messenger / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2