Delineating the Role of KAP1 in WNT-induced Colorectal Cancer

项目摘要 细胞信号传导-转录程序在正常发育中起着不同的作用，包括调节 代谢、细胞存活/死亡和分化，所有这些都可能在肿瘤发生中发生故障。所述WNT 程序保持细胞干细胞性，是高度增殖性的，癌细胞劫持启动的特性， 维持肿瘤发生。大量的工作已经确定，WNT程序是重要的CRC 启动和进展。然而，尽管以前的分子表征和鉴定的小， 在多个水平上靶向WNT程序的分子，成功灭活WNT的治疗臂 还没有被使用。我们的研究已经确定转录辅调节因子KAP 1/TRIM 28是必需的， 在致癌WNT激活后表达WNT靶基因，这表明KAP 1是一种替代物， WNT诱导的CRC中的药物靶点。因此，在CRC中靶向KAP 1将需要全面表征 如果受到干扰，将阻止KAP 1依赖性致癌WNT激活， 癌症的下游特征我们已发表的研究已经确定了KAP 1使用 先前未表征的染色质读取器盒直接结合低乙酰化组蛋白4尾周围 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 KAP 1与途径和序列特异性因子β-连环蛋白的相互作用。然而，目前尚不清楚， 染色质和β-连环蛋白结合活性对于KAP 1募集到WNT靶点和激活WNT靶点至关重要 支持WNT依赖性癌症标志的基因。 考虑到这些发现和知识上的关键差距，本提案的中心假设是KAP 1 利用其染色质和β-连环蛋白结合功能激活致癌WNT程序以促进CRC 转化和增殖。因此，本研究提案的主要目标是探索KAP 1是否利用 这些分子的作用是激活WNT靶基因，它们的干扰是否会阻断WNT靶基因的表达 活化和WNT诱导的CRC表型（CRC转化和细胞增殖）。为了实现这一 为了实现这一目标，我们将利用基因组学（整合RNA-seq/ChIP-seq方法）和表型分析的力量 在建立的CRC肿瘤发生模型（正常和致癌结肠上皮细胞）中。具体来说，我们将 探索在正常结肠上皮细胞中致癌WNT活化后KAP 1是否结合WNT靶位点， 是否需要KAP 1染色质和β-连环蛋白结合能力来激活WNT靶基因（Aim 1)并维持癌症的特征（目标2）。这部《自成体系》提出的基础科学研究 这项提案”不仅将揭示染色质阅读器在癌症背景下如何运作的基本原则， 同时也为确定KAP 1的目标定位方法铺平了道路，这与国家癌症研究所的使命是确定新的 将这些发现从实验室转移到临床。

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 Our unpublished studies have provided evidence of KAP1 interaction with the pathway- and sequence-specific factor β-Catenin.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.