VEGF-D is an X-linked/AP-1 regulated putative onco-angiogen in human glioblastoma multiforme.
BACKGROUND
Glioblastoma multiforme (GBM) is a hypervascularized and locally infiltrating brain tumor of astroglial origin with a very poor prognosis. An X-linked c-fos oncogene-inducible mitogenic, morphogenic, and angiogenic factor, endothelial growth factor-D (VEGF-D), is the newest mammalian member of VEGF family. We analyzed VEGF-D in GBM because of its high angiogenic potential and its linkage to the X chromosome.


METHODS
Nonmalignant brain and GBM tissue sections as well as GBM cell lines were analyzed by immunofluorescence for the expression of VEGF-D, factor VIII (endothelial cell marker), glial-fibrillary acidic protein (GFAP) (astrocytic cell lineage cytoplasmic marker), and several Fos family transcription factors, including c-Fos and Fra-1. The proteins were also detected by Western blots. The differences between genotypes of normal brain and GBM cells were examined by cDNA microarrays.


CONCLUSIONS
GBM expressed ubiquitously VEGF-D, which colocalized with GFAP. Contrary to our expectations, low levels of c-Fos were detected in GBM cells. However, we identified another Fos family member, Fra-1, together with its transcriptional activation partner, c-Jun, as being stably up-regulated in GBM cells. Furthermore, we demonstrated that a fra-1 transgene induced VEGF-D expression in cultured cells and GBM cell stimulation evoked a sustained increase in both Fra-1 and VEGF-D levels. This study reveals that an up-regulation of AP-1 factors may be a hallmark of GBM. Because VEGF-D activates VEGF receptor 2 and 3, receptors important for tumor angiogenesis, it may represent an X-linked/AP-1-regulated onco-angiogen in human GBM. The VEGF-D system and AP-1 activity appear to be very attractive targets for new molecular diagnostics and rational molecular anti-cancer therapies.
Debinski
W
W
Division of Neurosurgery, Pennsylvania State University College of Medicine, Hershey 17033-0850, USA. wdebinski@psu.edu
Slagle-Webb
B
B
Achen
M G
MG
Stacker
S A
SA
Tulchinsky
E
E
Gillespie
G Y
GY
Gibo
D M
DM
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism*; D008040:Genetic Linkage; D005909:Glioblastoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D009389:Neovascularization, Pathologic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014407:Tumor Cells, Cultured; D042643:Vascular Endothelial Growth Factor D; D014960:X Chromosome / Q000235:genetics*; D000099169:Fos-Related Antigen 1
D016228:Endothelial Growth Factors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D042643:Vascular Endothelial Growth Factor D; D000099169:Fos-Related Antigen 1