Journal Article

Early Induction of Angiogenetic Signals in Gliomas of GFAP-v- src Transgenic Mice

Aguzzi, Adriano, Hainfellner, Johannes, Weissenberger, Jakob, Maddalena, Alessia, Theurillat, Jean-Philippe

1999

Overview

Angiogenesis is a prerequisite for solid tumor growth. Glioblastoma multiforme, the most common malignant brain tumor, is characterized by extensive vascular proliferation. We previously showed that transgenic mice expressing a GFAP-v- src fusion gene in astrocytes develop low-grade astrocytomas that progressively evolve into hypervascularized glioblastomas. Here, we examined whether tumor progression triggers angiogenetic signals. We found abundant transcription of vascular endothelial growth factor (VEGF) in neoplastic astrocytes at surprisingly early stages of tumorigenesis. VEGF and v- src expression patterns were not identical, suggesting that VEGF activation was not only dependent on v- src. Late-stage gliomas showed perinecrotic VEGF up-regulation similarly to human glioblastoma. Expression patterns of the endothelial angiogenic receptors flt-1, flk-1, tie-1, and tie-2 were similar to those described in human gliomas, but flt-1 was expressed also in neoplastic astrocytes, suggesting an autocrine role in tumor growth. In crossbreeding experiments, hemizygous ablation of the tumor suppressor genes Rb and p53 had no significant effect on the expression of VEGF, flt-1, flk-1, tie-1, and tie-2. Therefore, expression of angiogenic signals is an early event during progression of GFAP-v- src tumors and precedes hypervascularization. Given the close similarities in the progression pattern between GFAP-v- src and human gliomas, the present results suggest that these mice may provide a useful tool for antiangiogenic therapy research.

• Publisher: Elsevier Inc,ASIP,American Society for Investigative Pathology
• Subject: Animals / Artificial Gene Fusion / Astrocytes - metabolism / Astrocytes - pathology / Astrocytoma - genetics / Astrocytoma - metabolism / Astrocytoma - pathology / Biological and medical sciences / Brain Neoplasms - genetics / Brain Neoplasms - metabolism / Brain Neoplasms - pathology / Breeding / Endothelial Growth Factors - genetics / Endothelial Growth Factors - metabolism / Female / Genes, p53 - genetics / Genes, Retinoblastoma - genetics / Genes, src - genetics / Glial Fibrillary Acidic Protein - genetics / Lymphokines - genetics / Lymphokines - metabolism / Male / Medical sciences / Mice / Mice, Transgenic / Neovascularization, Pathologic - genetics / Neovascularization, Pathologic - metabolism / Neovascularization, Pathologic - pathology / Neurology / Proto-Oncogene Proteins - genetics / Proto-Oncogene Proteins - metabolism / Receptor Protein-Tyrosine Kinases - genetics / Receptor Protein-Tyrosine Kinases - metabolism / Receptor, TIE-1 / Receptor, TIE-2 / Receptors, Cell Surface - genetics / Receptors, Cell Surface - metabolism / Receptors, Growth Factor - genetics / Receptors, Growth Factor - metabolism / Receptors, TIE / Receptors, Vascular Endothelial Growth Factor / Regular / RNA, Messenger - biosynthesis / Signal Transduction / Tumors of the nervous system. Phacomatoses / Vascular Endothelial Growth Factor A / Vascular Endothelial Growth Factor Receptor-1 / Vascular Endothelial Growth Factors