Integrative mouse pathobiology: GI epithelial biology and genetics

描述(申请人提供)：对Notch信号在食道鳞状上皮生物学和疾病中的作用知之甚少。特别是，在理解Notch信号如何促进正常的食道上皮鳞状细胞分化、癌变和瘤内细胞异质性方面存在着根本的空白，其特征是在最致命的癌症之一的食管鳞癌(ESCC)中发现的分化良好的细胞巢(即角蛋白珍珠)和弥漫的、侵袭性的低分化细胞具有间质特征。这一缺口的持续存在是一个重要的问题，因为在它被填补之前，Notch介导的食道上皮细胞命运调控机制仍将在很大程度上无法理解。其长期目标是更好地了解组织微环境影响食管鳞状上皮细胞恶变的分子机制。这项建议的目的是利用创新的基因工程小鼠模型，确定Notch信号在食道正常生物学和肿瘤生物学中的作用。中心假设是Notch以CSL依赖的方式诱导鳞状细胞分化和衰老。在肿瘤进展过程中，微环境线索激活CSL非依赖性途径，以丰富移行肿瘤干细胞(CSCs)。这一假设是根据申请者实验室提供的初步数据提出的。这项拟议研究的基本原理是，一旦知道Notch是如何控制细胞命运的，就可以通过药理学来操纵它们，从而在预防和治疗ESCC方面产生新颖和创新的方法。在强大的初步数据指导下，将通过追求三个相互关联的特定目标来检验这一假说：(1)阐明Notch活性如何在新的小鼠食道癌发生的早期阶段起作用；(2)在有条件的p120-catenin基因敲除小鼠模型中确定Notch在肿瘤进展中的作用；(3)在一种新型的肿瘤微环境重建的原位移植模型中描述Notch在小鼠CSCs中的作用。在新的小鼠模型中，将以可诱导的方式进行遗传功能获得和功能丧失实验。活体成像将被用来评估体内Notch调节的CSC活性。这项拟议的研究意义重大，因为它有望纵向推进和扩大对食道上皮稳态调节机制的理解，进而通过对小鼠病理生物学的评价，解除对食道疾病(包括良性和恶性的食道疾病，以及其他组织类型的潜在其他鳞状疾病)的调节。这些知识将导致创新的药理学策略的开发，这些策略将操纵Notch信号来改变食道细胞的命运，并有可能在ESCC的治疗和预防疾病进展方面取得进展。

DESCRIPTION (provided by applicant): Little is known about the role of Notch signaling in esophageal squamous epithelial biology and diseases. In particular, there is a fundamental gap in understanding how Notch signaling contribute to normal esophageal epithelial squamous differentiation, carcinogenesis, and intratumoral cell heterogeneity, characterized by co- existing well-differentiated cell nests (i.e. keratin pearl) and disseminated, invasive poorly differentiated cells with mesenchymal traits found in esophageal squamous cell carcinoma (ESCC), one of the most deadly cancers. Continued existence of this gap represents an important problem because, until it is filled, mechanisms for Notch-mediated esophageal epithelial cell fate regulation will remain largely incomprehensible. The long-term goal is to better understand the molecular mechanisms by which tissue microenvironment influences malignant transformation of esophageal squamous epithelial cells. The objective in this proposal is to define the roles of Notch signaling in normal biology and tumor biology of the esophagus using innovative genetically engineered mouse models. The central hypothesis is that Notch induces squamous differentiation and senescence in a CSL-dependent manner. During tumor progression, microenvironmental cues activate a CSL-independent pathway to enrich migratory cancer stem cells (CSCs). This hypothesis has been formulated on the basis of preliminary data produced in the applicants' laboratories. The rationale for the proposed research is that, once it is known how Notch control cell fates, they can be manipulated pharmacologically, resulting in novel and innovative approaches in the prevention and treatment of ESCC. Guided by strong preliminary data, this hypothesis will be tested by pursuing three interrelated Specific Aims: (1) To elucidate how Notch activities contribute to the early stages of esophageal carcinogenesis in new mouse models; (2) To determine the roles of Notch for tumor progression in a conditional p120-catenin knockout mouse model; and (3) To delineate the roles of Notch in mouse CSCs in a novel orthotopic transplantation model where the tumor microenvironment is recapitulated. Genetic gain-of-function and loss-of-function experiments will be done in an inducible fashion in new mouse models. In vivo live imaging will be performed to assess the Notch-regulated CSC activities in vivo. The proposed research is significant, because it is expected to vertically advance and expand understanding of mechanisms by which esophageal epithelial homeostasis is regulated and in turn, deregulated in esophageal diseases, both benign and malignant, and potentially other squamous diseases in other tissue types, all through an appreciation of mouse pathobiology. Such knowledge will lead to development of innovative pharmacological strategies that will manipulate Notch signaling to alter esophageal cell fates and have the potential to advance in the therapy of ESCC and prevention of disease progression.