Signaling Modulators in Epidermal Carcinogenesis

描述(申请人提供)：RAS MAP激酶信号级联的激活是大多数人类恶性肿瘤的共同中心特征，使该途径成为癌症治疗的潜在高价值靶点。然而，作为一种治疗方法，直接靶向该途径的规范元件会因Ras MAPK信号在几乎所有人类组织中普遍活跃而引起的全身毒性而复杂化，这是组织生存所必需的。然而，完整的MAPK信号需要一系列MAPK相互作用的支架蛋白来调节和协调途径输出的功能。最近的数据表明，其中一个元件IQGAP1调节ERK MAPK活性、β-连环蛋白信号、细胞骨架重塑和细胞运动，对于正常的组织发育和动态平衡是必不可少的，但对于RAS的致癌作用的表现是必需的。这项建议的目的是在与医学相关的人体组织背景下为这一肿瘤特异性要求定义机制基础。为了实现这一点，我们将利用我们最近开发的侵袭性表皮肿瘤基因定义的三维人体组织模型，该模型由表达肿瘤相关活性RAS的原代表皮角质形成细胞、完整的基底膜和结构上忠实的天然基质产生。这些模型概括了活体内表皮恶性肿瘤的特征，包括分层和分化中断，以及通过基底膜侵袭支持基质。工程组织将结合具有RNAi介导的内源性IQGAP1拮抗作用的角质形成细胞，以及无法结合特定相互作用蛋白的IQGAP1突变体的表达。这些努力旨在确定哪些IQGAP1功能是支持肿瘤侵袭进展的最关键因素。这些功能性人体组织研究对于靶向治疗的设计将是重要的，其结构允许识别肿瘤组织唯一需要的其他下游效应。其次，我们将采用我们实验室开发的其他新的基因定义的人类肿瘤模型，该模型基于12种不同组织类型的原代细胞中不同肿瘤相关致癌驱动基因突变的表达。这些工程肿瘤将被用于实验，以确定IQGAP1支架在一系列人类肿瘤类型中的作用。在拟议的资助期结束时，我们的目标是A)了解IQGAP1在表皮来源肿瘤中的拮抗机制，以指导未来的肿瘤选择性治疗的发展，以及B)在人类肿瘤的光谱中建立IQGAP1必要性的范围，以确定最容易受到IQGAP1介导的过程抑制的肿瘤类型。

DESCRIPTION (provided by applicant): Activation of the Ras MAP kinase signaling cascade is a central feature common to the majority of human malignancies, making the pathway a potentially high-value target for cancer therapeutics. However, directly targeting canonical elements of this pathway as a therapeutic approach is complicated by systemic toxicities resulting from the fact that Ras MAPK signaling is ubiquitously active in nearly all human tissues, and is required for tissue viability. However, full MAP kinase signaling requires the function of a family of MAPK interacting scaffolding proteins that modulate and orchestrate pathway outputs. Recent data indicates that one of these elements, IQGAP1, which regulates Erk MAPK activity, ?-catenin signaling, cytoskeletal remodeling, and cell motility, is dispensable for normal tissue development and homeostasis, but is required for manifestation of the oncogenic effects of Ras. This proposal aims to define the mechanistic basis for this tumor-specific requirement in a medically-relevant human tissue context. To accomplish this, we will utilize our recently developed three-dimensional human tissue model of genetically-defined invasive epidermal neoplasia generated from primary epidermal keratinocytes expressing tumor-associated active Ras, intact basement membrane, and architecturally faithful native stroma. These models recapitulate hallmark features of epidermal malignancy in vivo including disrupted stratification and differentiation, and invasion through basement membrane into supporting stroma. Engineered tissues will incorporate keratinocytes with RNAi-mediated endogenous IQGAP1 antagonism, combined with expression of IQGAP1 mutants unable to bind specific interacting proteins. These efforts are designed to determine which IQGAP1 functions are most critical for supporting progression to neoplastic invasion. These functional human tissue studies will be important for the design of targeted therapeutics, and are structured to allow for identification of other downstream effectors uniquely required by neoplastic tissue. Second, we will employ additional new genetically-defined human tumor models developed in our laboratory based on expression of different tumor-associated oncogenic driver mutations in primary cells from 12 different tissue types. These engineered neoplasias will be deployed in experiments to define the role of the IQGAP1 scaffold in an array of human tumor types. At the end of the proposed funding period we aim to A) understand the mechanism of IQGAP1 antagonism in epidermal-derived neoplasias as a guide to development of future tumor-selective therapeutics, and B) establish the scope of IQGAP1 necessity in a spectrum of human neoplasias to identify tumor types most likely to be susceptible to inhibition of IQGAP1-mediated processes.