Mouse Models for Li Fraumeni Syndrome

Li Fraumeni 综合征小鼠模型

• 批准号: 7118386
• 负责人: GUILLERMINA LOZANO
• 金额: $ 20.08万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7118386
• 关键词: Li Fraumeni syndrome; biotechnology; brca gene; cancer risk; carcinoma; comparative genomic hybridization; disease /disorder model; family genetics; gene expression; gene mutation; genetically modified animals; laboratory mouse; microarray technology; molecular genetics; molecular oncology; neoplasm /cancer genetics; p53 gene /protein; pediatric neoplasm /cancer; phenotype; sarcoma

Mutation of p53, inherited in some individuals with Li-Fraumeni syndrome (LFS), is a critical event in the elaboration of many tumors of diverse origin. Most mutations of p53 are single nucleotide changes that alter critical amino acids in the DNA-binding domain rather than alterations that delete the p53 gene. The prevalence of p53 missense mutations coupled with in vitro data has led to the hypothesis that mutant p53 has additional properties that make it more detrimental for proper cell cycle regulation and more advantageous to the dividing cell. To test this hypothesis in vivo and model human LFS more accurately, we have generated mouse models inheriting the p53R172H mutation (corresponding to the p53R175H hotspot in human cancers). This mutation disrupts the conformation of p53 resulting in a protein that is tumorigenic in cooperation with ras, and readily immortalizes cells. Mice with the p53R172H mutation have gained additional tumorigenic properties and also exhibit a dominant-negative phenotype. Metastasis is rampant in p53R172H/+ mice as opposed to mice lacking one p53 allele. Additional experiments are needed to ascertain the events leading to tumorigenesis, metastasis, stability of the mutant p53, and the dominantnegative nature of the mutation. To examine the ability of p53R172H to cooperate with Brcal deletion, another common alteration that leads to breast cancer, crosses with Brca1+/- mice in a background sensitive to beast cancer will be performed. An important question that will be addressed in these studies is what other molecular changes, examined by CGH and Affymetric arrays, cooperate with mutant p53 in the genesis of different kinds of cancers. Lastly, since the type of p53 missense mutation may also contribute to different phenotypes, another p53 missense mutation will be generated in mice. The p53R245W mutation represents a DMA contact mutant that alters an arginine amino acid involved in direct contact to DNA. p53R245W is also transcriptionally inactive, but cannot immortalize cells. The p53R245W mutation in another hot spot mutation inherited in LFS patients. Comparison of the two classes of p53 mutants (conformation versus contact) should yield insights into the role of these mutants in tumorigenesis. Our studies suggest that treatment of a patient will have to be tailored not only to the kind of tumor that develops, but to the specific p53 missense mutation identified in the tumor as well. The research outlined in this application is directly relevant to public health in that it proposes to study a gene, p53, that is often altered in different kinds of cancers. The study aims to understand the nature of p53 mutations and of other changes that cooperate with this defect. These studies may identify novel therapeutic targets.

p53 突变在一些 Li-Fraumeni 综合征 (LFS) 患者中遗传，是疾病发生过程中的一个关键事件。 许多不同来源的肿瘤的详细阐述。 p53 的大多数突变是单核苷酸变化，这些变化改变了 DNA 结合域中的关键氨基酸，而不是删除 p53 基因的改变。这 p53 错义突变的普遍性加上体外数据导致了这样的假设：突变型 p53 具有其他特性，使其对适当的细胞周期调节更加不利等等 有利于细胞分裂。为了在体内验证这一假设并更准确地模拟人类 LFS，我们 已经生成了继承 p53R172H 突变的小鼠模型（对应于 p53R175H 热点 在人类癌症中）。这种突变破坏了 p53 的构象，产生了一种具有致瘤性的蛋白质。 与ras合作，容易使细胞永生化。携带 p53R172H 突变的小鼠获得了 额外的致瘤特性，并且还表现出显性失活表型。转移猖獗 p53R172H/+ 小鼠与缺乏一个 p53 等位基因的小鼠相反。需要额外的实验 确定导致肿瘤发生、转移、突变体 p53 稳定性和显性失活的事件 突变的性质。为了检查 p53R172H 与 Brcal 缺失配合的能力， 导致乳腺癌的另一种常见改变，与背景中的 Brca1+/- 小鼠杂交 对兽癌敏感者将进行。这些研究将解决的一个重要问题是 通过 CGH 和 Affymetric 阵列检查，还有哪些其他分子变化与突变体 p53 协同作用 不同种类癌症的起源。最后，由于 p53 错义突变的类型也可能有助于 不同的表型，小鼠体内会产生另一种p53错义突变。 p53R245W 突变 代表 DMA 接触突变体，它改变了与 DNA 直接接触所涉及的精氨酸。 p53R245W 也是转录失活的，但不能使细胞永生化。 p53R245W 突变 LFS 患者遗传的另一个热点突变。两类 p53 突变体的比较 （构象与接触）应该可以深入了解这些突变体在肿瘤发生中的作用。我们的 研究表明，对患者的治疗不仅要针对所发生的肿瘤类型， 但也针对肿瘤中发现的特定 p53 错义突变。 本申请中概述的研究与公共卫生直接相关，因为它建议研究一项 p53 基因在不同类型的癌症中经常发生改变。该研究旨在了解p53的本质 突变以及与此缺陷配合的其他变化。这些研究可能会确定新的治疗方法 目标。