利用新型突变p53蛋白水平报告基因小鼠模型研究胸腺T细胞淋巴瘤恶性转化的早期事件

TP53是最重要的抑癌基因，在50%以上的肿瘤中突变。突变型p53（mut-p53）蛋白在终末期肿瘤中高度积累，作为特异标志物广泛应用于病理诊断。包括申请人所在课题组Cancer Cell论文的多项研究表明，mut-p53在癌前细胞中也大量积累。由于缺乏蛋白水平的mut-p53报告基因鼠，mut-p53高积累细胞在体内具有怎样的分子特征、如何恶性转化为肿瘤尚不清楚。我们前期通过基因编辑首次构建了荧光融合蛋白报告基因鼠p53ΔE5Cherry，在蛋白水平模拟了mut-p53，能特异标记终末期和早期肿瘤细胞。我们计划进一步确立p53ΔE5Cherry模拟mut-p53的准确性和通用性，并在已构建的p53ΔE5Cherry胸腺T细胞淋巴瘤模型中将其应用于分离分析高积累mut-p53的终末期和早期肿瘤细胞，为淋巴瘤早期诊断和干预提供潜在靶标，也为将此模型应用于其他mut-p53驱动的肿瘤提供基础。

TP53 is the most important tumor suppressor which is mutated in more than half of human cancers. Mutant p53 (mut-p53) protein is highly accumulated in end-stage tumors and its accumulation has been widely used as a diagnostic marker in many types of cancers. In addition, a number of studies including our previously published Cancer Cell paper have shown that mut-p53 is also highly accumulated in precancerous cells and early cancerous lesions. However, mainly due to the lack of a transgenic mouse model that can accurately report the protein levels of mut-p53, the molecular characteristics and malignant transformation process of these precancerous cells remain unclear. Using CRISPR/Cas9-based gene-editing technology, we for the first time have successfully constructed a fluorescent fusion protein reporter mouse model, p53ΔE5Cherry, which can faithfully report mut-p53 protein accumulation in both early and advanced tumors. In this proposal, we plan to further establish in which aspects p53ΔE5Cherry could accurately mimic the characteristics of known p53 mutants, and as a proof of concept use this reporter to isolate and analyze early and terminal stage tumor cells with high level of mut-p53 accumulation in an established p53ΔE5Cherry thymic T cell lymphoma mouse model. This study could reveal potential targets for early diagnosis and intervention of lymphoma, and provide the basis for applying this model to many other mut-p53-driven tumors.