MOLECULAR REGULATION OF ANGIOGENIC PHENOTYPE

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The long-term objective of my research team is to understand the molecular mechanism of growth regulation and tumor progression in human gliomas. We have focused on the role of several growth factors and their receptors that may have direct relationships to the two main pathologic features that characterize the progression of low grade astrocytoma to high grade astrocytoma: cellular proliferation and vascular proliferation. Recent studies have demonstrated increased expression of transforming growth factor-alpha (TGF-alpha), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) in high grade malignant gliomas, suggesting that these factors play a predominant role in angiogenesis. In the next five years, we plan to focus on the molecular modulation of these three angiogenic factors as a basis for future molecular therapy for malignant gliomas in the clinic. The hypotheses to be tested are 1) that expression of angiogenic growth factors correlates with malignant phenotype, and 2) that regulation of angiogenic growth factor expression leads to modulation of malignant phenotype. The specific aims are l) to determine the expression and alteration of bFGF, TGF-alpha and VEGF in glioma and brain adjacent to tumor by PCR, in situ hybridization and immunohistochemical methods; 2) to modulate the expression of bFGF and VEGF using triple helix-forming oligonucleotides (TFOs), using an in vitro cell culture system to test for growth inhibition, inhibition of transcription by PCR, RNA protection assay and expression of the mRNA and protein and an in vivo with nude mice xenograft system; 3) to modulate the activity of VEGF and TGF-alpha by antisense approaches including ribozymes, antisense oligonucleotides, and antisense vectors; and 4) to determine the anti-angiogenic effects of wtp53 protein expression and two other newly discovered anti-angiogenic agents. We believe the molecular approaches proposed here to modulate the expression of critical angiogenic growth factors bFGF, TGF-alpha and VEGF will provide insight into molecular therapy and therapeutic development of these TFOs and antisense agents in the future.