Microenvironmental regulation of glioblastoma radiosensitivity

描述（由申请人提供）： 尽管放射治疗显著提高了胶质母细胞瘤（GB）患者的生存率，但绝大多数患者在诊断后1-2年内死于疾病。 本提案的总体目标是描述有助于GB的辐射抗性的分子和过程。 传统上，人GB放射反应的实验室研究主要集中在单层培养和/或腿部肿瘤异种移植物中生长的肿瘤细胞系上，实质上忽略了正常脑环境的影响。 然而，我们的初步数据表明，脑内生长的GB细胞系改变其基础和辐射诱导的基因表达谱。 这一建议的首要前提是，大脑微环境具有决定性的影响GB的辐射反应，因此要了解介导GB辐射抗性的机制，将有必要考虑其独特的原位情况。 为此，拟议的研究将集中于从CD 133 + GB肿瘤起始细胞（TIC）生长的脑内异种移植物。 与已建立的细胞系相反，从TIC生长的脑内异种移植物复制原代GB的基因型/表型和体内生长模式;然后，这种异种移植物也可能最好地模拟脑微环境对GB放射反应的后果。 拟议的研究将涉及3个目标。 第一个目标是确定原位生长对GB TIC的基础和辐射诱导的基因表达谱的影响。 这些研究将涉及基于微阵列的转录组和基因翻译分析的GB TIC生长在体外和体内的腿部肿瘤和脑内异种移植。 这些全基因组的询问将测试的假设，即原位环境独特地影响GB TIC基因的表达。 沿着这些思路，待检验的另一个假设是GB TIC的放射反应包括在脑内条件下独特表达或诱导的蛋白质。 第二个目的是确定TIC脑内异种移植物内细胞的放射反应是否根据拓扑学和/或表型而不同。 这些研究将检验原位生长产生的肿瘤内异质性导致亚群具有不同程度的放射敏感性的假设。 最后，第三个目的是测试的假设，有独特的原位环境GB放射增敏的目标。 研究将首先确定单次和分次放射方案控制TIC脑内异种移植物生长的能力。 然后将测试目标1和2中提出的有针对性的战略是否能够加强辐射诱导的生长控制。 预计这些研究将产生新的见解GB辐射抗性的分子和细胞的决定因素，从而为开发新的战略，其放射增敏的基础。 公共卫生相关性： 提高放射治疗胶质母细胞瘤（GB）的疗效需要彻底了解有助于其放射抗性的分子和过程，这需要考虑微环境的影响。 为此，拟议的研究将使用原位异种移植模型描绘GB放射反应的基本决定因素。 预计这些研究将提供新的见解GB的辐射抗性，从而为开发新的战略，其放射增敏提供了基础。

DESCRIPTION (provided by applicant): Whereas radiotherapy significantly prolongs the survival of patients with glioblastoma (GB), the vast majority succumb to disease within 1-2 years of diagnosis. The overall goal of this proposal is to delineate the molecules and processes that contribute to the radioresistance of GB. Traditionally, laboratory investigations of human GB radioresponse have primarily focused on tumor cell lines grown in monolayer culture and/or as leg tumor xenografts, in essence neglecting the impact of the normal brain milieu. However, our initial data indicate that intracerebral growth of established GB cell lines alters their basal and radiation-induced gene expression profiles. The overriding premise of this proposal is that the brain microenvironment has a determining impact on GB radioresponse; thus to understand the mechanisms mediating GB radioresistance it will be necessary to account for its unique in situ circumstances. Towards this end, the proposed studies will focus on intracerebral xenografts grown from CD133+ GB tumor initiating cells (TICs). In contrast to established cell lines, intracerebral xenografts grown from TICs replicate the genotype/phenotype and in vivo growth pattern of primary GBs; such xenografts are then also likely to best simulate the consequences of the brain microenvironment on GB radioresponse. The proposed studies will involve 3 Aims. The first aim will define the influence of orthotopic growth on the basal and radiation-induced gene expression profiles of GB TICs. These studies will involve microarray-based transcriptome and gene translation analyses of GB TICs grown in vitro and in vivo as leg tumor and intracerebral xenografts. These genome-wide interrogations will test the hypothesis that the orthotopic environment uniquely influences GB TIC gene expression. Along these lines, an additional hypothesis to be tested is that the radioresponse of GB TICs includes proteins uniquely expressed or induced under intracerebral conditions. The second aim will determine whether the radioresponse of cells within a TIC intracerebral xenograft differ according to topology and/or phenotype. These studies will test the hypothesis that the intra-tumor heterogeneity generated by orthotopic growth results in subpopulations with varying degrees of radiosensitivity. Finally, the third aim is to test the hypothesis that there are targets for GB radiosensitization unique to the orthotopic environment. Studies will initially define the ability of single and fractionated radiation protocols to control the growth of TIC intracerebral xenograft. Targeted strategies suggested from Aims 1 and 2 will then be tested for their ability to enhance radiation-induced growth control. It is anticipated that these studies will generate novel insights into the molecular and cellular determinants of GB radioresistance and thus provide the basis for developing novel strategies for their radiosensitization. PUBLIC HEALTH RELEVANCE: Improving the efficacy of radiation as a treatment for glioblastoma (GB) will require a thorough understanding of the molecules and processes that contribute to their radioresistance, which necessitates taking into account the impact of the microenvironment. Towards this end, the proposed studies will delineate the fundamental determinants of GB radioresponse using orthotopic xenograft models. It is anticipated that these studies will provide novel insight into GB radioresistance and thus provide the basis for developing novel strategies for their radiosensitization.