Childhood Cancer Gene Program Project Grant

摘要：本项目的长期目标是提高我们对儿童癌症发病机制和病理生理的认识，并利用这些基础研究获得的见解来设计评估预后和改进治疗的新方法。这一广泛的目标正在通过四个相互作用的项目来实现，这些项目的目标是确定嵌合转录因子和改变的肿瘤抑制因子对儿童癌症发病机制的影响。具体来说，该项目将研究易位编码的融合癌蛋白AML1-ETO和Pax3-FKHR以及ARF/Mdm2/p53肿瘤抑制途径。总之，这些基因异常代表了多种常见儿科恶性肿瘤的潜在病变，包括白血病、软组织肉瘤和上皮性肿瘤。Project 1 （M. Roussel）的重点是通过研究p16INK4a和ARF的调控、下游靶点和基因修饰因子，了解p16INK4a和ARF在不同生理环境下如何介导肿瘤抑制功能。Project 2 （J. Downing）试图通过定义与t（8;21）编码的AML1- eto癌蛋白协同诱导白血病的突变谱，来定义AML1改变导致白血病的分子途径，并确定AML1的点突变如何使造血干细胞易发生白血病转化。Project 3 （G. Grosveld）将使用生化、细胞生物学和小鼠实验来确定Pax3-FKHR如何在肺泡横纹肌肉瘤中作为激活的癌基因，并确定与Pax3-FKHR合作诱导完整肿瘤表型所需的继发性遗传改变。在Project 4中，G. Zambetti将直接研究一种新的生殖系p53突变（p53R337H）的生化和生物物理特性，他在巴西南部的一群患有肾上腺皮质癌（ACC）的儿科患者中发现了这种突变。这些患者缺乏Li-Fraumeni综合征的特征，表明p53R337H仅在肾上腺皮质细胞的细胞内状态下功能失活，从而特异性地使患者易患ACC。为了验证这一假设，Zambetti博士将直接检测突变的p53蛋白的生化和生物物理特性，并将在种系中培育含有这种突变的小鼠。拟议的研究由一个行政核心和三个科学核心提供支持，这些核心为转基因小鼠的产生提供帮助，并通过病理学核心和微阵列基因表达实验室对这些动物进行后续分析。通过这个协调的研究项目，我们期待朝着改善儿童癌症治疗的最终目标取得实质性进展。

Revised Abstract: The long-range goal of this program project is to improve our understanding of the pathogenesis and pathophysiology of childhood cancers, and to capitalize on the insights gained from these basic studies to devise new means of assessing prognosis and improving therapy. This broad objective is being pursued through four interactive projects whose goal is to define the mechanisms by which chimeric transcription factors and altered tumor suppressors contribute to the pathogenesis of childhood cancer. Specifically, this program will examine the translocation-encoded fusion oncoproteins AML1-ETO and Pax3-FKHR and the ARF/Mdm2/p53 tumor suppressor pathway. Together, these genetic abnormalities represent the underlying lesions in a variety of common pediatric malignancies, including leukemias, soft tissue sarcomas, and epithelial tumors. The focus of Project 1 (M. Roussel) is to understand how p16INK4a and ARF mediate tumor suppressive functions in different physiologic contexts, by studying their regulation, downstream targets and genetic modifiers. Project 2 (J. Downing) seeks to define the molecular pathway by which alterations of AML1 lead to leukemia, by defining the spectrum of mutations that cooperate with the t(8;21)-encoded AML1-ETO oncoprotein to induce leukemia, and determine how point mutations in AML1 predispose hematopoietic stem cells to leukemic transformation. Project 3 (G. Grosveld) will use biochemical, cell biological and mouse experiments to determine how Pax3-FKHR acts as an activated oncogene in alveolar rhabdomyosarcoma, and to identify the secondary genetic alterations that are required to cooperate with Pax3-FKHR to induce a full tumor phenotype. In Project 4 (G. Zambetti) will directly examine the biochemical and biophysical properties of a novel germline p53 mutation (p53R337H) that he has identified in a cluster of pediatric patients in Southern Brazil with adrenal cortical carcinoma (ACC). These patients lack features of Li-Fraumeni syndrome, suggesting that p53R337H is functionally inactive only under the intracellular conditions found in the adrenal cortical cells, thus specifically predisposing patients to ACC. To test this hypothesis, Dr Zambetti will directly examine the biochemical and biophysical properties of this mutant p53 protein, and will develop mice that contain this mutation in the germline. The proposed research is supported by an Administrative Core and three scientific Core's that provide assistance in the generation of genetically modified mice and the subsequent analysis of these animals through a Pathology Core and a Microarray Gene Expression Laboratory. Through this coordinated program of research, we anticipate substantial progress toward the ultimate goal of improving the treatment of children with cancer.