Overcoming apoptotic resistance in glioblastoma by CP-d/n-ATF5, a novel tumor spe

描述（由申请人提供）：多形性胶质母细胞瘤 WHO IV (GBM) 是最常见的原发性脑肿瘤，目前尚无治愈性治疗，进展和复发迅速，导致在 12-18 个月内死亡。转录因子 ATF5 是激活转录因子 (ATF)/cAMP 反应元件结合蛋白 (CREB) 家族的成员，与非肿瘤性星形胶质细胞和神经元相比，在 GBM 中过度表达。在该提案中，ATF5 是一种新型设计的肽药物的靶标，称为 CP-d/n-ATF5（细胞穿透显性失活 ATF5）。初步数据表明，CP-d/n-ATF5 在体外和体内均能有效杀死 GBM 细胞。我们将确定 CP-d/n-ATF5 引发抗神经胶质瘤作用的机制，并测试其体外和体内药物联合治疗的适用性。在我们的初步数据中，我们表明 CP-d/n-ATF5 介导 p73、DR5（死亡配体 TRAIL 的促凋亡受体）和 PUMA（促凋亡 Bcl-2 家族蛋白）蛋白质水平的显着增加。 P73 是肿瘤抑制因子 p53 的同源物，与 TP53 相比，p53 在 GBM 中并不常见突变，但具有相似的下游靶标，例如DR5 和 PUMA，可增强细胞凋亡（程序性细胞死亡）并促进细胞周期停滞。因此，诱导p73的试剂是非常有价值的肿瘤治疗剂。我们将检验以下假设：CP-d/n-ATF5 通过上调 p73 杀死 GBM 细胞，而 p73 反过来又通过 PUMA 依赖性细胞凋亡诱导死亡。我们还将评估以下假设：CP-d/n-ATF5 诱导 DR5 依赖于 p73，并且升高的 DR5 将允许 CP-d/n-ATF5 与 DR5 配体 TRAIL 的 GBM 联合治疗。我们使用 TRAIL/CP-d/n-ATF5 组合的初步数据表明，与单一治疗相比，对 GBM 细胞具有协同杀伤作用。这些效应是由 CP-d/n-ATF5 诱导的 DR5 上调介导的，并且与 p73 蛋白水平的增加同时发生。 siRNA 对 DR5 的特异性抑制可减轻 CP-d/n-ATF5/TRAIL 介导的细胞死亡。该研究计划将在劳埃德·格林博士（哥伦比亚大学病理学和细胞生物学系）的指导下进行，他在培训医师科学家方面拥有丰富的记录，并为许多成功且有成就的生物医学研究人员开启了职业生涯。作为共同导师将为博士服务。 Peter Canoll（哥伦比亚大学病理学和细胞生物学系）和 Jeffrey Bruce（神经外科系）。卡诺尔博士和布鲁斯博士领导着哥伦比亚大学脑肿瘤中心，他们的成就很高。两者都积极开展由美国国立卫生研究院 (NIH) 资助的研究项目，这些项目涉及具有复杂药物输送系统的胶质母细胞瘤动物模型。该拟议项目及其著名且卓有成就的导师、课程作业、培训机会和职业发展计划将为申请人提供胶质母细胞瘤相关研究方面的培训，重点是临床前药物开发，并帮助他成为一名独立研究者。

DESCRIPTION (provided by applicant): Glioblastoma multiform WHO IV (GBM) is the most common primary brain tumor with no current curative treatment, rapid progression and recurrence, leading to death within 12-18 month. The transcription factor ATF5, a member of the activating transcription factor (ATF)/cAMP response-element binding protein (CREB) family, is over-expressed in GBMs compared to non-neoplastic astrocytes and neurons. In this proposal ATF5 is targeted by a novel designed peptide drug, called CP-d/n-ATF5 (cell penetrating dominant-negative ATF5). Preliminary data show that CP-d/n-ATF5 effectively kills GBM cells in vitro and in vivo. We will determine the mechanism by which CP-d/n-ATF5 elicits its anti-glioma effects and test its suitability for drug combination therapy in vitro and in vivo. In our preliminry data, we have shown that CP-d/n-ATF5 mediates striking increases in p73, DR5 (a pro-apoptotic receptor for death ligand TRAIL) and PUMA (a pro-apoptotic Bcl-2 family protein) protein levels. P73 is a homolog of the tumor suppressor p53, which, in contrast to TP53 is not commonly mutated in GBM, but which shares similar downstream targets, e.g. DR5 and PUMA, that enhance apoptosis (programmed cell death) and promote cell cycle arrest. Therefore, reagents that induce p73 are highly valuable tumor therapeutics. We will test the hypothesis that CP-d/n-ATF5 kills GBM cells by up- regulating p73 that in turn induces death via PUMA-dependent apoptosis. We will also evaluate the hypotheses that induction of DR5 by CP-d/n-ATF5 is dependent on p73 and that elevated DR5 will permit a combination GBM therapy of CP-d/n-ATF5 with the DR5 ligand TRAIL. Our preliminary data with the TRAIL/CP-d/n-ATF5 combination demonstrate synergistic killing of GBM cells as compared to single treatments. These effects were mediated by CP-d/n-ATF5-induced up-regulation of DR5, and coincided with an increase of p73 protein levels. Specific suppression of DR5 by siRNA mitigates CP-d/n-ATF5/TRAIL mediated cell death. The research program will be conducted under the guidance of Dr. Lloyd Greene (Department of Pathology and Cell Biology at Columbia University) who has a significant track record of training physician-scientists and who has launched many careers of successful and accomplished biomedical researchers. As Co-Mentors will serve Drs. Peter Canoll (Department of Pathology and Cell Biology at Columbia University) and Jeffrey Bruce (Department of Neurosurgery). Dr. Canoll and Dr. Bruce are leading the Brain Tumor Center at Columbia and are highly accomplished. Both have active NIH-funded research projects related to glioblastoma animal models with sophisticated drug delivery systems. This proposed project along with its renowned and accomplished mentors, course work, training opportunities and career development plan will train the applicant in glioblastoma-related research with an emphasis on preclinical drug development and assist him to become an independent investigator.