The Role of ING4 in Modulating the Tumorigenic Contribution of NF-kB in Gliomas

描述(申请人提供)：恶性胶质瘤是一种侵袭性、高度侵袭性、神经破坏性和致命性的脑肿瘤。胶质瘤的弥漫性浸润性是患者死亡的主要原因之一。最近，炎症反应的失调被认为与胶质瘤的病理生物学有关。核因子-kB家族转录因子负责介导免疫/炎症反应，而核因子-kB的结构性激活与神经胶质瘤的发生有关。核因子-KB的激活通常是短暂的，并受到多种机制的调节，包括与其他蛋白质的相互作用。ING4就是一种这样的蛋白质，最近被证明可以抑制神经胶质瘤细胞中由核因子-KB介导的IL-8、IL-6和COX-2的表达。这种抑制作用可能通过ING4和p65核因子-KB亚型之间的相互作用而发生。因此，NF-KB通路和ING4蛋白是治疗胶质瘤的潜在靶点。我们发现ING4在抑制IL-8表达的同时促进了基质金属蛋白酶-9(MMP9)的表达，从而不同程度地影响了NF-KB介导的人脑胶质瘤细胞的基因诱导。这些结果表明，ING4对NF-KB介导的基因表达的影响是复杂的，即ING4对基因表达的影响可能是积极的，也可能是消极的，这取决于启动子环境、辅因子组成、染色质的可及性和基因表达的动力学。我们认为，有必要研究ING4对胶质瘤中NF-KB活性调控的分子机制，重点是ING4对IL-8、IL-6、MMP-9和CXCR4表达的调控，这些基因都依赖于NF-KB的激活，并参与胶质瘤的生长、侵袭和血管生成。我们将检测ING4基因在人脑胶质瘤组织中的状态和完整性以及核因子-KB的激活状态，并确定是否存在相关关系。在诱导表达ING4的人脑胶质瘤细胞中，ING4对核因子-kB转位到核内、体内外结合DNA以及调节IL-8、IL-6、MMP-9和CXCR4表达的作用将被分析(Aim 1)。在目标2中，翻译研究将验证ING4对体内核因子-KB介导的基因表达的影响。将可诱导表达ING4的人脑胶质瘤细胞移植到SCID小鼠脑内，在体内评价ING4表达变化对核因子-KB活性、基因表达、胶质瘤生长、侵袭和血管生成的影响。这种基础科学实验和翻译研究的结合代表了第一次系统地研究了NF-KB和ING4在胶质瘤形成中的功能参与，并将使人们更好地理解在恶性胶质瘤中治疗干预NF-KB途径和/或ING4的可能性。

DESCRIPTION (provided by applicant): Malignant gliomas are an aggressive, highly invasive, neurologically destructive and deadly tumors of the brain. The diffusively infiltrative nature of gliomas is one of the major causes of mortality in patients afflicted with this cancer. Recently, dysregulation of the inflammatory response has been implicated in the pathobiology of gliomas. The NF-KB family of transcription factors are responsible for mediating immune/inflammatory responses, and constitutive activation of NF-KB has been correlated with gliomagenesis. NF-KB activation is normally transient and regulated by a variety of mechanisms, including interactions with other proteins. One such protein, ING4, has recently been shown to inhibit NF-KB-mediated expression of IL-8, IL-6 and COX-2 in glioma cells. This inhibition may occur through interactions between ING4 and the p65 NF-KB isoform. Thus, the NF-KB pathway and ING4 protein represent potential therapeutic targets for the treatment of gliomas. We have made the novel observation that ING4 differentially affects NF-KB-mediated gene induction in human glioma cells, inhibiting IL-8 expression, yet enhancing expression of matrix metalloproteinase-9 (MMP-9). These results suggest that the influence of ING4 on NF-KB-mediated genes is complex, i.e., ING4 may have either a positive or negative effect on gene expression that is dependent on promoter context, co- factor composition, chromatin accessibility, and kinetics of gene expression. We believe that studies to investigate the molecular mechanisms of ING4-mediated regulation of NF-KB activity in gliomas are warranted, focusing on ING4 regulation of expression of IL-8, IL-6, MMP-9 and CXCR4, all genes dependent on NF-KB for activation, and involved in glioma growth, invasion and angiogenesis. We will examine the status and integrity of the ING4 gene and the activation status of NF-KB in human glioma tissues, and determine if correlates exist. The effect of ING4 on NF-KB's ability to translocate into the nucleus, bind DNA in vitro and in vivo, and regulate expression of IL-8, IL-6, MMP-9 and CXCR4 will be analyzed in human glioma cells that inducibly express ING4 (Aim 1). In Aim 2, translational studies will validate the influence of ING4 on NF-KB-mediated gene expression in vivo. Human glioma cells inducibly expressing ING4 will be transplanted into the brains of scid mice, and the effects of changes in ING4 expression on NF-KB activity, gene expression, glioma growth, invasion and angiogenesis assessed in vivo. This combination of basic science experimentation and translational studies represent the first systematic study of the functional involvement of NF-KB and ING4 in gliomagenesis, and will lead to a greater understanding of the potential for therapeutic intervention of the NF-KB pathway and/or ING4 in malignant gliomas.