Exploiting Oncogenic Chromatin Regulators in Cancer Initiation and Progression

项目总结 癌细胞中的基因改变可导致结合染色质靶点的调节因子的激活 基因位点启动转录程序，驱动肿瘤的启动和进展。然而，尽管 在多种肿瘤类型中鉴定这些致癌调控因子，这个快速发展的领域的一个空白是 分子机制的描绘为针对这些调节者打开了机会。因此，我的长期 目标是定义染色质结合的调节子内的相互作用表面，这对它们的致癌功能至关重要。 在这项提案的F99阶段，我将重点介绍转录调节因子KAP1及其以前的 在结直肠癌(CRC)中激活致癌WNT信号的前所未有的作用。尽管井很好- 公认的知识，即WNT信号驱动CRC转化并促进肿瘤进展，a 在结直肠癌中成功灭活WNT的治疗臂尚未使用。潜在地解决了这个问题 知识缺口，我的研究发现KAP1是WNT靶基因表达所必需的 对致癌的WNT刺激的反应。重要是，令人信服的初步数据支持两个非相互的 解释KAP1如何调节WNT信号的排他性机制。首先，KAP1可以直接激活 通过使用染色质阅读器将关键转录机制支架到WNT靶基因启动子上 模块。第二，KAP1可以与β-连环蛋白的稳定性(WnT转录效应)相互作用并调节其稳定性。这就做 测试这两个模型，然后评估是否干扰KAP1-染色质和/或KAP1-β-连环蛋白 相互作用将阻断WNT诱导的CRC表型。 在K00阶段，我将把重点转移到另一个与生物医学相关的染色质调节复合体(SWI/SNF)。 SWI/SNF正常重塑染色质上的核小体以激活靶基因的表达，但其失调 会导致致癌程序的异常激活。同样，在软组织恶性肿瘤滑膜中 肉瘤(S)，转化性基因改变是SWI/SNF成员SS18易位到SSX 转录因子。因为SSX，而不是SSX18，通常与修饰的核小体结合，SSX异常 将SS18重定向到一组癌症特异的基因组位置，导致促进 肿瘤发生学。尽管有这种机制上的理解，SS18-SSX的分子和结构基础- 核小体相互作用尚不清楚，靶向SS18-SSX的策略目前尚不确定。要实现 这些未得到满足的需求，我将从生物物理上表征SS18-SSX-核小体相互作用，然后确定 破坏SS18-SSX-核小体相互作用的小分子抑制剂。最后，我会测试铅的缓蚀剂 癌症检测特征(增殖和侵袭)的候选人。 在这两个阶段获得的培训将实现我经营自己的实验室的长期目标，重点是 关于基因调控的分子机制，让我对癌症患者有积极的影响。

PROJECT SUMMARY Genetic alterations in cancer cells can cause activation of regulatory factors that bind chromatin at target gene loci to turn on transcription programs that drive tumor initiation and progression. However, despite identification of these oncogenic regulatory factors in multiple tumor types, a gap in this rapidly evolving field is the delineation of molecular mechanisms that open opportunities to target those regulators. Thus, my long-term goal is to define interaction surfaces within chromatin-bound regulators critical for their oncogenic functions. In the F99 phase of this proposal I will focus on the transcription regulator KAP1 and its previously unprecedented role in activating oncogenic WNT signaling in colorectal cancer (CRC). Despite the well- established knowledge that WNT signaling drives CRC transformation and promotes tumor progression, a therapeutic arm that successfully inactivates WNT in CRC has yet to be employed. Potentially addressing this gap in knowledge, my studies have discovered that KAP1 is required for expression of WNT target genes in response to oncogenic WNT stimulation. Importantly, compelling preliminary data support two non-mutually exclusive mechanisms explaining how KAP1 may regulate WNT signaling. First, KAP1 could directly activate WNT by scaffolding key transcriptional machinery to WNT target gene promoters using its chromatin reader module. Second, KAP1 could interact with and regulate β-Catenin stability (the WNT transcription effector). I will test these two models and then evaluate whether perturbing the KAP1–chromatin and/or KAP1–β-Catenin interactions will block WNT-induced CRC phenotypes. In the K00 phase, I will shift focus to another biomedically relevant chromatin regulatory complex (SWI/SNF). SWI/SNF normally remodels nucleosomes on chromatin to activate target gene expression, but its dysregulation in cancer can cause aberrant activation of oncogenic programs. Likewise, in the soft-tissue malignancy Synovial Sarcoma (SS), the transforming genetic alteration is translocation of SS18, a member of SWI/SNF, to the SSX transcription factor. Because SSX, but not SSX18, normally binds modified nucleosomes, SSX abnormally redirects SS18 to a cancer-specific set of genomic sites, causing upregulation of genes that promote tumorigenesis. Despite this mechanistic understanding, the molecular and structural basis of the SS18-SSX– nucleosome interaction remains unclear, and a strategy to target SS18-SSX is currently undefined. To achieve these unmet needs, I will biophysically characterize the SS18-SSX-nucleosome interaction and then identify small-molecule inhibitors that disrupt the SS18-SSX-nucleosome interaction. Finally, I will test lead inhibitor candidates in hallmarks of cancer assays (proliferation and invasion). The training obtained under both phases will fulfill my long-term goal of running my own lab with an emphasis on molecular mechanisms of gene regulation, allowing me to have a positive impact on cancer patients.