The Fox M1 in Human Glioma Development and Progression

描述(申请人提供)：恶性胶质瘤是最常见的脑肿瘤，与极高的发病率和死亡率有关。我们研究的长期目标是揭示胶质瘤发生和发展的分子机制，目前对此知之甚少。最近利用寡核苷酸芯片分析的研究表明，Forkhead box M1(FOXM1)转录因子的改变是恶性胶质瘤中最常见的分子改变之一。我们的初步结果表明FOXM1的表达水平与胶质瘤的级别直接相关。在永生化的正常人星形胶质细胞(NHAS)中增强FOXM1的表达足以将其转化为胶质瘤细胞。FOXM1在间变性星形细胞瘤细胞中的表达增强，促进其在裸鼠模型中发展为胶质母细胞瘤，抑制FOXM1的表达，抑制胶质母细胞瘤细胞的贴壁生长。此外，FOXM1转基因细胞产生的胶质瘤具有高增殖性、侵袭性和血管生成性。转染FOXM1的胶质瘤细胞表达活化的Akt、血管内皮生长因子和基质金属蛋白酶-2，而转染FOXM1-siRNA的胶质瘤细胞表达活化的Akt减少。在这里，我们建议确定FOXM1异常表达在胶质瘤发生和发展中的因果效应和机制。我们假设FOXM1的异常表达通过促进不受控制的细胞增殖、侵袭和血管生成而促进胶质瘤的发生和发展。我们的具体目标是：1)确定FOXM1表达改变对胶质瘤生物学的影响。我们将通过FOXM1-siRNA抑制系统、FOXM1过表达的细胞系和体内小鼠模型来确定FOXM1在胶质瘤细胞增殖、侵袭和血管生成中的关键作用。2)探讨FOXM1过表达与Rb缺失在脑胶质瘤发生发展中的作用。我们将研究FOXM1转基因表达是否加速了胶质瘤的形成，并在具有失活的pRB途径的遗传性小鼠胶质瘤模型中促进了胶质瘤的进展。3)探讨FOXM1过表达是否通过激活Akt通路参与脑胶质瘤的发生发展。4)明确FOXM1调控胶质瘤侵袭和血管生成的分子机制。FOXM1调节侵袭和血管生成的机制将被研究，特别是它如何调节基质金属蛋白酶-2和血管内皮生长因子基因的表达。我们提出的研究结果将有助于更好地了解胶质瘤发生和发展的分子机制，并将确定潜在的靶点，为治疗恶性胶质瘤的新策略。

DESCRIPTION (provided by applicant): Malignant gliomas are the most common brain tumors and are associated with extremely high rates of morbidity and mortality. The long-term goal of our research is to reveal the molecular mechanisms underlying glioma development and progression, of which very little is currently known. Recent studies using oligonucleotide microarray analysis have shown that alteration to the Forkhead box M1 (FoxM1) transcription factor is one of the most frequent molecular alterations in malignant gliomas. Our preliminary results indicate a direct correlation between FoxM1 expression level and the grade of gliomas. Enforced FoxM1 expression in immortalized normal human astrocytes (NHAs) was sufficient to transform the cells into glioma cells. Enforced FoxM1 expression in anaplastic astrocytoma cells promoted their progression into glioblastomas in nude mouse models, and suppressed FoxM1 expression inhibited the anchorage-independent growth of glioblastoma cells. Moreover, gliomas arisen from FoxM1-transfected cells were highly proliferative, invasive, and angiogenic. FoxM1-transfected glioma cells had increased expression of activated Akt, VEGF and MMP-2, whereas FoxM1-siRNA-transfected glioma cells had decreased expression of activated Akt. Here, we propose to determine the causal effects and mechanisms of aberrant FoxM1 expression on glioma development and progression. We hypothesize that aberrant expression of FoxM1 contributes to glioma development and progression by promoting uncontrolled cell proliferation, invasion, and angiogenesis. Our Specific Aims are 1) To determine the effect of altered FoxM1 expression on glioma biology. We will determine the critical contribution of FoxM1 to glioma cell proliferation, invasion, and angiogenesis in vitro and in vivo by using the FoxM1-siRNA inhibition system, FoxM1-overexpressing cell lines, and in vivo mouse models. 2) To determine the cooperation between FoxM1 overexpression and Rb loss in glioma development and progression. We will investigate whether FoxM1 transgene expression accelerates glioma formation and promotes glioma progression in a genetic mouse glioma model with an inactivated pRb pathway. 3) To determine whether FoxM1 overexpression contributes to glioma development and progression via activation of Akt pathway. 4) To identify the molecular mechanisms by which FoxM1 regulates glioma invasion and angiogenesis. The mechanisms of FoxM1 regulating invasion and angiogenesis will be investigated with a particular focusing on how it regulates the expression of the MMP-2, and VEGF genes. The findings from our proposed studies will contribute to a better understanding of the molecular mechanisms of glioma development and progression and will identify potential targets for novel therapeutic strategies against malignant glioma.