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Functional and phenotypic differences between
glioblastoma multiforme-derived and normal human brain endothelial cells
Charalambous C, Hofman FM, Chen TC
Department of Molecular Microbiology, University of Southern California Keck
School of Medicine, Los Angeles, California, USA.
Object. Glioblastomas multiforme (GBMs) are hypervascular tumors
characterized by endothelial cell (EC) proliferation.
There is increasing
evidence that ECs that infiltrate systemic tumors are different from normal
blood vessel cells; whether this difference is seen in the central nervous
system between GBM and normal brain tissue is not known.
The goal of this
investigation was to characterize and compare the functional and phenotypic
properties of GBM-associated ECs and normal brain ECs.
Methods. Human ECs
were isolated from fresh tissue specimens, purified using flow cytometry,
and characterized by immunostaining.
Proliferation was measured by
determining bromodeoxyuridine incorporation and Ki-67 staining, and by
performing the monotetrazolium assay.
The migration rate of the cells was
determined using the modified Boyden chamber technique.
Apoptosis was
evaluated by performing the TUNEL assay, cell death enzyme-linked
immunosorbent assay (ELISA), and annexin V staining.
Growth factor
production was analyzed using the ELISA technique.
The brain tumor ECs
differed from normal brain ECs morphologically and by their expression and
distribution of specific markers (that is, vascular endothelial cadherin
[VE-cadherin] and CD31).
Functional differences between the two cell
populations were also evident.
The brain tumor ECs proliferated more slowly
and underwent less apoptosis than normal brain ECs; however, the tumor ECs
migrated faster than the normal ECs.
The normal ECs were sensitive to growth
factors such as vascular endothelial growth factor (VEGF) and endothelin-1
(ET-1), whereas the tumor ECs were not.
In addition, the brain tumor ECs
constitutively produced higher levels of ET-1 and VEGF, compared with the
normal ECs.
Conclusions. The data demonstrated that ECs derived from normal
brain and from GBMs have significant phenotypic and functional distinctions.
Further characterization of brain tumor ECs is essential for efficient
antiangiogenic treatment of gliomas.
PMID: 15871513 [PubMed - in process]
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