De novo expression of vascular endothelial growth factor in human pancreatic cancer: evidence for an autocrine mitogenic loop.
OBJECTIVE
The role of vascular endothelial growth factor (VEGF) and its receptors in tumor angiogenesis has been well established. We analyzed the expression pattern and biologic significance of VEGF and its receptors in human pancreatic cancer.


METHODS
VEGF, KDR/flk-1, and flt-1 expression were examined by immunohistochemistry, in situ hybridization, reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and receptor phosphorylation. VEGF-stimulated mitogenesis was investigated by mitogen-activated protein kinase (MAPK) phosphorylation, transactivation of a c-fos promoter reporter construct, DNA synthesis assays, and stable transfection of a dominant-negative flk-1 complementary DNA (cDNA) construct.


RESULTS
Compared with normal pancreas and chronic pancreatitis, VEGF and its receptors were overexpressed in pancreatic cancer. KDR and flt-1 were detected not only in endothelial cells but also in tumor cells. VEGF expression was observed in all human pancreatic tumor cell lines examined, and the KDR/flk-1 and flt-1 receptor was detected in 2 cell lines. VEGF treatment results in phosphorylation of MAPKs, transactivation of a c-fos promoter construct, and growth stimulation in KDR/flk-1-expressing cell lines, which could be blocked by VEGF antagonists. Furthermore, stable transfection of a dominant-negative flk-1 cDNA significantly inhibited tumor cell growth.


CONCLUSIONS
These results not only support the important role of the VEGF/VEGF receptor system in pancreatic tumor biology but also suggest the existence of an autocrine/paracrine mitogenic loop for pancreatic cancer cells.
von Marschall
Z
Z
Department of Hepatology and Gastroenterology, Charité, Humboldt-University, Berlin, Germany.
Cramer
T
T
Höcker
M
M
Burde
R
R
Plath
T
T
Schirner
M
M
Heidenreich
R
R
Breier
G
G
Riecken
E O
EO
Wiedenmann
B
B
Rosewicz
S
S
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D019898:Autocrine Communication; D002455:Cell Division / Q000187:drug effects; D016228:Endothelial Growth Factors / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008222:Lymphokines / Q000378:metabolism* / Q000494:pharmacology; D008938:Mitosis; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D017978:Receptors, Growth Factor / Q000378:metabolism / Q000627:therapeutic use; D040262:Receptors, Vascular Endothelial Growth Factor; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D040281:Vascular Endothelial Growth Factor Receptor-1