New Molecular Approaches to Inhibit Glioma Angiogenesis

描述：(申请者摘要)胶质母细胞瘤(GBM)是 已知的化疗耐药和血管生成类型的肿瘤。有几种治疗方法 未能改变诊断超过12个月的存活率。广泛的目标 这项提案的重点将是研究抑制血管生成的新方法 采用不同的动物模型。缺氧诱导因子Lα(HIF-1a) 在低氧条件下上调，并通过以下途径导致血管生成 血管内皮生长因子(VEGF)的表达。正常野生型p53 促进MDM2介导的HIF-1a泛素化和蛋白酶体降解 蛋白质，从而限制血管内皮生长因子诱导的血管生成。野生型p53功能丧失 与裸体移植瘤的新生血管和生长有关 老鼠。我们假设MDM2的过度表达(超过50%) GbM)，一个受P53直接调控的基因，也与抗药性有关 在人GBM细胞系中的化疗可能导致P53在 P53-MDM2复合体阻止正常P53-MDM2介导的细胞降解 HIF-1a。在这里，我们展示了一种新的蛋白激酶抑制剂黄烷醇， 已报道的抗血管生成活性，下调胶质瘤中HIF-1a的表达 体外培养细胞系，从而为其抗血管生成提供了一种机制 活动。拟议的研究将评估MDM2反义治疗与 不加黄烷醇促进脑胶质瘤MDM2基因表达下调 细胞系和异种移植，上调和下调P53介导的反应 调节HIF-1a/VEGF的表达以减少血管生成信号。这 将通过1)使用体外研究优化MDM2反义来实现 以及促进P53功能和/或降低的药物治疗条件 缺氧生长条件下HIF-1a/VEGF的表达。2)使用 小鼠脑胶质瘤GL261脑内血管生成模型的建立 黄烷醇抑制HIF-1a/VEGF表达及抗血管生成作用的研究 在低氧条件下的活动。3、4)使用裸鼠异种移植 皮下和脑内测定MDM2的体内活性 反义治疗加或不加黄烷醇抑制血管生成和 肿瘤在低氧条件下生长。

DESCRIPTION: (Applicant's Abstract) Glioblastoma (GBM) is one of the most chemoresistant and angiogenic types of tumors known. Several treatments have failed in altering survivals beyond 12 months of diagnosis. The broad objective of this proposal will be to investigate new approaches to inhibit angiogenesis in GBM using different animal models. Hypoxia-inducible factor l alpha (HIF-1a) becomes up regulated in hypoxic conditions and leads to angiogenesis via vascular endothelial growth factor (VEGF) expression. Normally wildtype p53 promotes MDM2-mediated ubiquitination and proteosomal degradation of the HIF-la protein, thus limiting VEGF-induced angiogenesis. Loss of wildtype p53 function has been associated with neovascularization and growth of xenografts in nude mice. We hypothesize that overexpression of MDM2 (seen in more than 50 percent of GBM), a gene directly regulated by p53 and also linked with resistance to chemotherapy in human GBM cell lines, could lead to the sequestration of p53 in p53-MDM2 complexes preventing the normal p53 MDM2-mediated degradation of HIF-1a. Here we show flavopiridol, a novel protein kinase inhibitor with reported antiangiogenic activity, down regulates HIF-1a expression in glioma cell lines in vitro, thus providing one mechanism for its antiangiogenic activity. The proposed studies will evaluate MDM2 antisense treatment with and without flavopiridol to promote down regulation of MDM2 expression in glioma cell lines and xenografts, up regulation of p53-mediated responses and down regulation of HIF-1a/VEGF expression to decrease angiogenic-signaling. This will be accomplished by 1) Use of in vitro studies to optimize MDM2 antisense and drug treatment conditions that promote p53 function and/or decrease HIF-la/VEGF expression, respectively, under hypoxic growth conditions. 2) Use of the murine glioma GL261 intracranial model of angiogenesis to determine the capacity of flavopiridol to decrease HIF-1a/VEGF expression and antiangiogenic activity in hypoxic conditions. 3,4) Use of nude mice xenografts both subcutaneously and intracranially to determine the in vivo activity of MDM2 antisense treatment with and without flavopiridol to inhibit angiogenesis and tumor growth in hypoxic conditions.