Delineating the Role of KAP1 in WNT-induced Colorectal Cancer

项目总结 细胞信号-转录程序在正常发育中发挥着不同的作用，包括调节 新陈代谢、细胞存活/死亡和分化，所有这些都可能在肿瘤发生中失灵。WNT 程序保持细胞干性并高度增殖，这些特性是癌细胞劫持启动和 维持肿瘤的形成。大量工作表明，WNT计划对两个CRC都很重要 开始和进展。然而，尽管先前对小分子进行了表征和鉴定 在多个水平上针对WNT计划的分子，一种成功灭活WNT的治疗臂 还没有被雇佣。我们的研究已经确定，转录辅助调节KAP1/TRIM28是必需的 对于致癌WNT激活时WNT靶基因的表达，提示KAP1是一种替代 WNT诱导的结直肠癌的药物靶点。因此，在CRC中以KAP1为目标将需要全面的表征 如果受到干扰，将阻止KAP1依赖的致癌WNT激活，并 下游是癌症的特征。我们发表的研究已经确定了KAP1使用一种 以前未鉴定的染色质读取盒直接结合低乙酰化组蛋白4个尾巴周围 非WNT基因的启动子(以促进其激活)。我们未发表的研究提供了证据 KAP1与途径和序列特异性因子β-连环蛋白的相互作用。然而，目前仍不清楚 染色质和β-连环蛋白结合活性对于KAP1WNT靶标的募集和激活是至关重要的 支持依赖WNT的癌症特征的基因。 鉴于这些发现和知识中的关键差距，这一提议的中心假设是KAP1 使用其染色质和β-连环蛋白结合功能激活致癌的WNT程序以促进结直肠癌 转化和扩散。因此，这项研究提案的主要目标是探索KAP1是否利用 这些功能激活WNT靶基因，以及它们的干扰是否会阻断WNT靶基因 活化和WNT诱导的CRC表型(CRC转化和细胞增殖)。要做到这一点 目标，我们将利用基因组学(整合的rna-seq/芯片-seq方法)和表型分析的力量。 在已建立的结直肠癌发生模型中(正常和致癌的结肠上皮细胞)。具体来说，我们将 探讨KAP1在正常结肠上皮细胞中致癌WNT激活时是否与WNT靶基因结合 激活WNT靶基因(AIM)是否需要KAP1染色质和β-连环蛋白结合能力 1)和保持癌症的特征(目标2)。本《自成一体》中提出的基础科学研究 提案“不仅揭示了染色质阅读器如何在癌症背景下工作的基本原理 但也为确定KAP1目标方法铺平了道路，这符合NCI确定新技术的使命 治疗目标，将发现从替补席上转移到诊所。

PROJECT SUMMARY Cell signaling - transcriptional programs play diverse roles in normal development including the regulation of metabolism, cell survival/death, and differentiation, all of which can malfunction in tumorigenesis. The WNT program maintains cell stemness and is highly proliferative, properties that cancer cells hijack to initiate and sustain tumorigenesis. A large body of work has defined that the WNT program is important for both CRC initiation and progression. However, despite previous molecular characterization and identification of small molecules that target the WNT program at multiple levels, a therapeutic arm that successfully inactivates WNT has yet to be employed. Our studies have defined that the transcriptional coregulator KAP1/TRIM28 is required for expression of WNT target genes upon oncogenic WNT activation, suggesting that KAP1 is an alternative drug target in WNT-induced CRC. As such, targeting KAP1 in CRC will require comprehensive characterization of druggable pockets, that if perturbed, would prevent KAP1-dependent oncogenic WNT activation and downstream hallmarks of cancer. Our published studies have identified a mechanism whereby KAP1 uses a previously uncharacterized chromatin reader cassette to directly bind hypoacetylated Histone 4 tails surrounding promoters of non-WNT genes (to facilitate their activation). Our unpublished studies have provided evidence of KAP1 interaction with the pathway- and sequence-specific factor β-Catenin. However, it remains unknown if the chromatin- and β-Catenin–binding activities are critical for KAP1 recruitment to, and for activation of, WNT target genes to support WNT-dependent hallmarks of cancer. Given these findings and critical gaps in knowledge, the central hypothesis of this proposal is that KAP1 uses its chromatin- and β-Catenin–binding functions to activate the oncogenic WNT program to promote CRC transformation and proliferation. As such, the major goal of this research proposal is to explore if KAP1 utilizes these functions to activate WNT target genes, and whether their perturbation would block WNT target gene activation and WNT-induced CRC phenotypes (CRC transformation and cell proliferation). To accomplish this goal, we will leverage the power of genomics (integrated RNA-seq/ChIP-seq approach) and phenotypic assays in established models of CRC tumorigenesis (normal and oncogenic colon epithelial cells). Specifically, we will explore if KAP1 binds WNT target loci upon oncogenic WNT activation in normal colon epithelial cells and whether KAP1 chromatin- and β-Catenin–binding capabilities are required to activate WNT target genes (Aim 1) and to sustain hallmarks of cancer (Aim 2). The basic science research proposed in this “self-contained proposal” will not only reveal fundamental principles of how chromatin readers operate in the context of cancer but also pave the way to identify KAP1 targeting approaches, which is in-line with NCI’s mission to identify novel therapeutic targets to move the discoveries from the bench to the clinics.