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  • 1
    ISSN: 1432-0533
    Keywords: Key words Vascular endothelial growth factor ; Brain ; tumor ; Pituitary adenoma ; Germ cell tumor ; Neurocytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Compared to normal brain an increased expression of vascular endothelial growth factor (VEGF) has been reported in many types of brain tumors. However, the numbers of samples analyzed and information about the cellular distribution of VEGF have been limited. Here we used novel monochlonal antibodies against VEGF to analyze, using immunohistochemistry, Western blotting and enzyme-linked immunosorbent assay, its expression in 108 human brain tumors that included astrocytic tumors, meningiomas, pituitary adenomas, primary intracranial germ cell tumors and neuronal tumors. The results showed that 37 of 48 astrocytic tumors (77%) and 15 of 19 meningiomas (79%) were immunoreactive for VEGF, consistent with previous reports. However, in contrast to a previous report that analyzed only VEGF mRNA; all of our 15 pituitary adenomas showed specific immunoreactivity for VEGF. We also extended the studies to previously unanalyzed neoplasms: 13 of 15 primary intracranial germ cell tumors (82%), and 7 of 10 neuronal tumors (70%) were immunoreactive for VEGF. Direct protein analysis by Western blotting confirmed the expression of VEGF in those tumors, and showed differential expression of the isoforms of VEGF protein; a pituitary adenoma expressed both VEGF165 and VEGF189 proteins, a central neurocytoma expressed only VEGF165, while an immature teratoma expressed only VEGF189. The data herein show that VEGF is expressed in a wide spectrum of brain tumors and suggest differences among tumor entities in the mechanisms of VEGF up-regulation as well as their employment of distinct VEGF isoforms for neovascularization.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Key words Vascular endothelial growth factor ; Brain tumor ; Astrocytoma ; Angiogenesis ; Vascularization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Marked neovascularization is a hallmark of many neoplasms in the nervous system. Recent reports indicate that the endothelial mitogen vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation in malignant gliomas. Using novel monoclonal antibodies to the VEGF polypeptide we have determined the expression and cellular distribution of VEGF protein in a representative series of 171 human central nervous system (CNS) tumors by immunohistochemistry and immunoblotting. In agreement with previous in situ hybridization data, 19 out of 20 glioblastomas (95%) showed immunoreactivity for VEGF, whereas both the percentage of immunoreactive tumors and the extent of immunoreactivity for VEGF were significantly lower in astrocytomas. Of the pilocytic astrocytomas (WHO grade I) 44% were immunoreactive for VEGF, but we observed several cases with pronounced vascular proliferates in the absence of VEGF. In ependymomas, meningiomas, hemangioblastomas, and primitive neuroectodermal tumors, there was no correlation between VEGF expression, vascular endothelial proliferation and the grade of malignancy. Oligodendrogliomas and the oligodendroglial component of mixed gliomas lacked immunoreactive VEGF, indicating that endothelial growth factors other than VEGF may regulate tumor angiogenesis in these neoplasms. Western blot analysis showed a predominant VEGF protein species of 23 kDa and confirmed the immunohistochemical data in all cases. Our findings demonstrate that VEGF is expressed in a wide spectrum of brain tumors in which it may induce neovascularization. However, other angiogenic factors also appear to contribute to the vascularization of CNS neoplasms.
    Type of Medium: Electronic Resource
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