Mechanisms of p53 Engagement and Action at the Benign-to-Malignant Transition in Sporadic Tumorigenesis

项目摘要 转录因子p53是肿瘤发生的最关键障碍之一。p53在超过一半的 所有人类肿瘤和p53突变型肿瘤通常具有更差的预后。作为一种肿瘤抑制因子，p53 似乎在良性疾病向恶性疾病的转变中起作用，阻止具有 已经获得了一些促肿瘤特征，如癌基因激活或DNA损伤。几十年的研究 已经试图确定是什么使p53成为一种有效的肿瘤抑制因子，因为这些知识可以有效地指导治疗。 癌症预防和治疗的策略。这项研究表明，p53可以被多种激活， 信号，反过来激活的p53可以调节各种各样的细胞过程，包括细胞存活， 衰老、基因组稳定性和可塑性。然而，p53的诱导物和作用随环境而变化， 在早期肿瘤形成过程中p53参与何种信号以及p53参与何种生物学程序方面， 对肿瘤抑制功能最为重要。此外，我们仍然不知道关键事件 p53丢失后，可转变为恶性肿瘤。试图获得这些知识的努力受到了阻碍 由于缺乏直接研究p53在特定细胞中进行内源性转化的工具， contexts.为了填补这些知识空白，我们将研究围绕p53激活和丢失的事件。 在胰腺导管癌（PDAC）的起始阶段，PDAC是一种p53丢失的侵袭性癌症， 发生在70%的PDAC中，使良性前驱病变进展为全面的癌症。我们 最近开发了新的PDAC小鼠模型，使我们能够“看到”p53在细胞生长过程中的作用， 从良性到恶性的转变在癌前胰腺细胞中，我们发现了一个亚群 与已建立的肿瘤细胞有许多转录特征，因此这些细胞似乎是 从癌前病变转变为恶性病变这些过渡细胞也是具有最强p53的细胞 因此，它们为研究p53参与和肿瘤抑制功能提供了独特的机会。 从良性到恶性的转变使用单细胞转录和空间分析，新的计算 推断细胞状态转换的方法，以及我们建立的用于快速遗传扰动的平台， 在体内，我们将定义导致这种p53活性转变细胞状态的细胞内在和细胞外在事件。 此外，我们将研究激活的p53抑制肿瘤转化的机制。 在转化细胞中，以及在p53丢失后立即影响癌症起始的事件。 该项目将提供新的洞察机制，驱动PDAC启动，并提供一个直接的， p53在内源性环境中的作用的详细表征。鉴于TP53的高流行率 通过研究人类癌症中的突变，我们希望对肿瘤发生的见解适用于许多癌症类型。

PROJECT SUMMARY The transcription factor p53 is one of the most critical barriers to tumorigenesis. p53 is mutated in over half of all human tumors, and p53-mutant tumors typically carry a worse prognosis. As a tumor suppressor, p53 appears to act at the transition from benign to malignant disease, preventing transformation of cells that have already acquired some pro-tumor features, such as oncogene activation or DNA damage. Decades of research have sought to identify what makes p53 a potent tumor suppressor, as such knowledge could inform effective strategies for cancer prevention and treatment. This research has shown that p53 can be activated by a variety of signals, and in turn activated p53 can regulate a wide variety of cellular processes, including cell survival, senescence, genomic stability, and plasticity. However, the inducers and actions of p53 vary with context, and there is still no consensus on what signals engage p53 during early neoplasia and what biological programs are most important for its tumor-suppressive functions. Furthermore, we still do not know the key events following p53 loss that enable transition to malignancy. Attempts to gain this knowledge have been hampered by a lack of tools to directly study p53 in the specific cells undergoing transformation within endogenous contexts. To address these gaps in knowledge, we will study the events surrounding p53 activation and loss during the initiation of pancreatic ductal carcinoma (PDAC), an aggressive cancer in which p53 loss—which occurs in 70% of PDACs—enables progression from benign precursor lesions to full-blown cancer. We recently developed new mouse models of PDAC that allow us to “see” p53 in action as cells progress through the benign-to-malignant transition. Among the premalignant pancreas cells, we discovered a subpopulation that shares many transcriptional features with established tumor cells, and thus these cells appear to be transitioning from premalignant to malignant. These transitioning cells are also the cells with the strongest p53 activation, and so they provide a unique opportunity to study p53 engagement and tumor-suppressive function at the benign-to-malignant transition. Using single-cell transcriptional and spatial analyses, new computational approaches to infer cell state transitions, and our well-established platform for rapid genetic perturbations in vivo, we will define the cell-intrinsic and cell-extrinsic events that lead to this p53-active transitioning cell state. Furthermore, we will investigate the mechanisms by which activated p53 suppresses neoplastic transformation in the transitioning cells, as well as the events that influence cancer initiation immediately following p53 loss. This project will provide novel insight into the mechanisms that drive PDAC initiation and provide a direct and detailed characterization of p53 in action in endogenous contexts. Given the high prevalence of TP53 mutations in human cancers, we expect the insights into tumorigenesis to be applicable to many cancer types.