Potentials of reactivated mutant p53

描述(由申请人提供)：在近50%的癌症病例中，p53基因内的突变会导致无功能缺陷蛋白的积累。P53功能的丧失会导致产生遗传稳定性和内在抗癌防御的自杀程序的废除，为癌细胞的不受控制的增殖和恶性进展打开道路。与此同时，在p53基因内部存在结构缺陷的细胞中，P53途径的其他组成部分通常保持不变，使肿瘤细胞对重新引入野生型P53高度敏感。从理论上讲，突变型P53蛋白的活性受损可以被小分子药物纠正，从而产生治疗作用。在一项初步研究中，通过在基于细胞的读出中高通量筛选化学文库，获得了一组恢复His273 p53突变体转录活性的小分子。其中一些化合物显示His273 P53突变依赖的生长抑制和促凋亡活性，并降低了裸鼠A431细胞移植瘤的生长。 在拟议计划的目标1中，我们将通过分析其他正在进行的筛选的结果，在人类肿瘤细胞的背景下识别重新激活几类p53突变的转录活性的小分子。这些化合物将根据化学相似性、对不同类别的p53突变体的活性光谱以及作用机制的差异进行分类。在该计划的目标2中，将挑战由P53再激活化合物引起的P53途径内变化的详细特征及其作用机制。目的3旨在评估修复的p53通路在携带突变型p53的人肿瘤细胞中的治疗潜力。P53通路的重新激活将通过有条件地表达野生型P53和通过在项目过程中获得的突变型P53的化学再激活剂来实现。恢复的P53活性与其他治疗方法的最佳组合将被发现，以确保细胞毒性高于细胞抑制效应的流行。这些研究将在体外和在肿瘤异种移植中进行。将开发和实验测试调节人类肿瘤细胞中P53依赖的反应的方法。该项目完成后，将提出新的潜在的抗癌药物类别，将突变的p53转化为治疗，并将评估恢复的突变的p53的治疗潜力。

DESCRIPTION (provided by applicant): Mutations within the p53 gene leading to accumulation of non-functional faulty protein occur in nearly 50% of cancer cases. Loss of p53 function results in abrogation of suicidal programs that produce genetic stability and intrinsic anticancer defense, opening the way for uncontrolled proliferation and malignant progression of cancer cells. Meanwhile, in the cells harboring structural defects within the p53 gene, the other components of the p53 pathway usually remain intact, leaving tumor cells highly sensitive to reintroduced wild-type p53. Theoretically, the impaired activity of mutant p53 protein could be pharmacologically corrected by small molecules, which induce a therapeutic effect. In a preliminary study, a set of small molecules that restore transcriptional activity of the His273 p53 mutant was obtained by high throughput screening of a chemical library in a cell-based readout. Some of the compounds show His273 p53 mutant-dependent growth suppressing and pro-apoptotic activity, and reduced growth of xenografts of A431 cell in nude mice. In Aim 1 of the proposed program, we shall identify small molecules that reactivate transcriptional activity of several classes of p53 mutants in the context of human tumor cells by analyzing results of additional ongoing screenings. These compounds will be classified according to chemical similarity, spectrum of activity toward different classes of p53 mutants, and differences in the mechanisms of action. Detailed characterization of changes within the p53 pathway, caused by the p53-reactivating compounds, and their mechanisms of action will be challenged in Aim 2 of the program. Aim 3 is designed to evaluate therapeutic potentials of restored p53 pathways in human tumor cells bearing mutant p53. Reactivation of p53 pathways will be achieved both by conditional expression of the wild-type p53, and by chemical reactivators of mutant p53 obtained in the course of the project. Optimal combinations of restored p53 activity with other therapeutic treatments will be found to ensure prevalence of cytotoxicity over cytostatic effects. These studies will be conducted both in vitro and in tumor xenografts. Approaches for modulation of the p53-dependnet response in human tumor cells will be developed and experimentally tested. Upon the completion of the project, novel potential classes of anticancer drugs that convert mutant p53 into a therapeutic will be suggested, and therapeutic potentials of restored mutant p53 will be evaluated.