Refolding Mutant p53: A Strategy for Cancer Prevention in Li-Fraumeni Syndrome

项目摘要-项目1 Li-Fraumeni综合征（LFS），一种发生于生殖系突变杂合子携带者的遗传性疾病 在TP 53中，与许多不同来源组织中的早发性癌症相关。因为TP 53已经 研究如此广泛，存在一个独特的机会，早期干预-在肿瘤形成之前-在LFS 个体 无论是生殖系还是体细胞，大多数癌症相关的TP 53突变都是错义突变， 破坏p53结合DNA的能力。虽然这些突变中的一些映射到与DNA直接接触的残基， 许多人不这样做。相反，这些突变降低了p53的热力学稳定性，因此，不足量的p53蛋白质会导致p53蛋白质的失活。 （突变体）p53正确折叠：这导致功能丧失（LOF）。这些突变中的许多也赋予了 致癌功能获得（GOF）活性。在Li-Fraumeni人中，有证据表明， 癌前病变出现的阶段以及这些病变向癌症的进展，源自突变体 p53的GOF活性。 Karanicolas实验室正在进行的工作重点是开发结合和稳定折叠的药物。 突变体p53的构象，以直接纠正LOF和GOF活性的错义缺陷。 这些“重折叠药物”被设计为结合蛋白质表面上的一个区域，该区域与所有的p53都是分开的。 最常见的突变，因此可以应用相同的药物，而不管特定的突变。我们有 在TP 53中含有许多不同突变的不同癌细胞系中测试了这些药物。通过这些 研究中，我们已经证实这些重折叠药物：1）从突变型p53恢复LOF，2）从突变型p53恢复LOF。 p53的GOF活性。 我们拟议项目的目标有三个方面。首先，我们将定义突变集 LFS个体的特征可以通过这类新的代理来解决。其次，我们将优化我们的 目前“最好的”代理，以提高其预期的安全性和有效性，在动物研究。第三，我们将测试安全性 在LFS个体中常见的TP 53突变杂合子小鼠中， 在p53介导的鳞状细胞癌的小鼠模型中，提供了从 癌前病变到癌症成功完成这些研究将作为重要的概念验证， p53重折叠剂有可能成为预防和早期拦截癌症的新药， LFS个人。

PROJECT SUMMARY - PROJECT 1 Li-Fraumeni syndrome (LFS), an inherited disorder arising in heterozygous carriers of germline mutations in TP53, is associated with early-onset cancers in many different tissues of origin. Because TP53 has been studied so extensively, a unique opportunity exists to intervene early – prior to tumor formation – in LFS individuals. Whether germline or somatic, most cancer-associated TP53 mutations are missense mutations that disrupt p53’s ability to bind DNA. While some of these mutations map to residues in direct contact with DNA, many do not. Rather, these mutations reduce p53’s thermodynamic stability, so that an insufficient amount of (mutant) p53 is correctly folded: this leads to loss of function (LOF). Many of these mutations also confer oncogenic gain of function (GOF) activities. Among Li-Fraumeni individuals, evidence suggests that the earliest stages in the emergence of precancerous lesions, and progression of these lesions to cancer, derive from mutant p53’s GOF activities. Ongoing work in the Karanicolas lab focuses on developing drugs that bind and stabilize the folded conformation of mutant p53, to directly correct the missense defects that underlie the LOF and GOF activities. These “refolder drugs” are designed to bind a region on the protein surface that is separate from all of p53’s most common mutations, so that the same drug can be applied irrespective of the specific mutation. We have tested these drugs in diverse cancer cell lines harboring many different mutations in TP53. Through these studies, we have confirmed that these refolder drugs both: 1) restore LOF from mutant p53, and 2) revert mutant p53’s GOF activities. The objectives of our proposed project are three-fold. First, we will define the set of mutations characteristic of LFS individuals that can be addressed by this new class of agents. Second, we will optimize our current “best” agent to enhance its expected safety and efficacy in animal studies. Third, we will test the safety of the resulting agents’ in mice heterozygous for a TP53 mutation seen frequently in LFS individuals, and efficacy in a mouse model of p53-mediated squamous carcinoma that provides clear milestones of the progression from precancer to cancer. Successful completion of these studies will serve as important proof-of-concept that these p53 refolding agents hold the potential to become new drugs for prevention and early interception of cancer in LFS individuals.