EZH2 as a Transcriptional Activator of NF-kappaB in Triple Negative Breast Cancer

项目摘要 人类基因组中的异常转录可以极大地干扰发育，并诱导和 使癌症等疾病恶化。在三阴性乳腺癌(TNBC)中，转录异常表现为 慢性途径激活，如核因子-kappaB(NF-κB)介导的炎症信号 转录因子家族，以及通过表观遗传学在基因激活或抑制方面的全球变化 复杂的功能障碍。EZH2是多梳抑制物2(PRC2)的催化成分， 负责组蛋白H3(H3K27me3)赖氨酸27三甲基化的表观遗传复合体，它促进 染色质浓缩和基因沉默。EZH2过度表达和高甲基化与多发性硬化有关 包括TNBC在内的癌症，但EZH2自相矛盾的非规范功能越来越多地被报道。我们的 实验室已证明EZH2型是编码核因子-κB转录的基因的转录激活因子 RelB因子，支持肿瘤起始细胞在TNBC细胞中的生长。初步发现进一步表明EZH2 与核因子-κB转录因子RelA共定位，转录激活核因子-κB靶基因。我们预测 一个新的EZH2-NF-κB信号轴参与肿瘤的发生和发展，我们建议 利用TNBC细胞系和患者--阐明该信号转导的机制和与癌症相关的意义 衍生的有机化合物。我们假设EZH2作为一种非依赖于PRC2的转录激活子在 TNBC与NF-κB因子RelA协同发挥作用。在目标1中，我们将定义非规范的EZH2 通过确定EZH2全局定位和EZH2依赖基因在TNBC细胞中的基因激活特征 包括NF-κB靶基因的表达，并进一步确定哪些激活基因是不依赖于PrC2的。 在目标2中，我们将通过确定哪些基因是 EZH2和RelA共同占据和共同调控，以及EZH2和RelA是否直接或功能上相互作用。 在目标3中，我们将通过确定EZH2在TNBC细胞中的非规范功能的机制 EZH2过度表达和/或翻译后修饰是充分和必要的，以推动非规范 EZH2活性与核因子-κB的关系 拟议的研究将在合作和富有成效的研究环境中进行， 北卡罗来纳大学教堂山分校阿尔伯特·鲍德温博士的实验室里，鲍德温博士是这方面的长期专家 核因子-κB信号转导及其在癌症中的作用 表观遗传学和染色质生物学专家。这些研究的完成将界定和确定 非典范EZH2-NF-κB信号在肿瘤细胞中的作用这将从根本上提升乳房 癌症和表观遗传学，并说明了当前EZH2靶向策略和新的 在开发和推进TNBC的治疗方法时要考虑的目标。

PROJECT ABSTRACT Aberrant transcription in the human genome can dramatically disrupt development and both induce and worsen diseases like cancer. In Triple Negative Breast Cancer (TNBC), dysregulated transcription manifests in chronic pathway activation, such as inflammatory signaling mediated by the Nuclear Factor-kappaB (NF-κB) family of transcription factors, as well as global alterations in gene activation or suppression through epigenetic complex dysfunction. EZH2 is the catalytic component of Polycomb Repressive Complex 2 (PRC2), an epigenetic complex responsible for trimethylation of lysine 27 of histone H3 (H3K27me3), which promotes chromatin condensation and gene silencing. EZH2 overexpression and hypermethylation is implicated in multiple cancers including TNBC, but paradoxical non-canonical functions of EZH2 are increasingly reported. Our laboratory has demonstrated that EZH2 is a transcriptional activator of the gene encoding NF-κB transcription factor RelB, and supports tumor initiating cell growth in TNBC cells. Preliminary findings further suggest EZH2 colocalizes with NF-κB transcription factor RelA and transcriptionally activates NF-κB target genes. We predict a novel EZH2-NF-κB signaling axis contributes to TNBC development and progression, and we propose to elucidate the mechanism and cancer-related implications of this signaling using TNBC cell lines and patient- derived organoids. We hypothesize that EZH2 functions as a PRC2-independent transcriptional activator in TNBC functioning cooperatively with the NF-κB factor RelA. In Aim 1, we will define the non-canonical EZH2 gene activation signature in TNBC cells by determining global EZH2 localization and EZH2-dependent gene expression including NF-κB target genes, and further determining which activated genes are PRC2-independent. In Aim 2, we will characterize the EZH2 and NF-κB relationship in TNBC cells by determining which genes are co-occupied and co-regulated by EZH2 and RelA, and whether EZH2 and RelA interact directly or functionally. In Aim 3, we will elucidate mechanisms of EZH2 non-canonical function in TNBC cells by determining whether EZH2 overexpression and/or post-translational modification are sufficient and necessary to drive non-canonical EZH2 activity in relation to NF-κB. The proposed research will take place in the collaborative and productive research environment at the University of North Carolina at Chapel Hill in the laboratory of Dr. Albert Baldwin, a longstanding expert in the field of NF-κB signaling and its role in cancer, with the support of co-sponsor Dr. Brian Strahl, a recognized expert in epigenetics and chromatin biology. Completion of these studies will define and determine the contributions of non-canonical EZH2-NF-κB signaling in TNBC cells. This will fundamentally advance breast cancer and epigenetics biology, and illuminate both pitfalls in the current EZH2-targeting strategy and novel targets to consider in developing and advancing therapeutics for TNBC.