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显著地破坏发育，并诱导和 使癌症等疾病恶化。在三阴性乳腺癌（TNBC）中，转录失调表现为： 慢性途径激活，如核因子-κ B（NF-κB）介导的炎症信号传导 转录因子家族，以及通过表观遗传的基因激活或抑制的全局改变 复杂功能障碍EZH 2是多梳抑制复合物2（PRC 2）的催化组分， 表观遗传复合物，负责组蛋白H3（H3 K27 me 3）赖氨酸27的三甲基化，促进 染色质浓缩和基因沉默。EZH 2过表达和高甲基化与多种 癌症，包括TNBC，但越来越多地报道EZH 2的矛盾的非典型功能。我们 实验室已经证明EZH 2是编码NF-κB转录的基因的转录激活因子 因子RelB，并支持TNBC细胞中的肿瘤起始细胞生长。初步研究结果进一步表明EZH 2 与NF-κB转录因子RelA共定位并转录激活NF-κB靶基因。我们预测 一种新的EZH 2-NF-κB信号传导轴有助于TNBC的发生和进展，我们建议 使用TNBC细胞系和患者阐明这种信号传导的机制和癌症相关意义， 衍生类器官。我们假设EZH 2作为PRC 2非依赖性转录激活因子在细胞内发挥作用。 TNBC与NF-κB因子RelA协同作用。在目标1中，我们将定义非规范EZH 2 通过确定整体EZH 2定位和EZH 2依赖性基因在TNBC细胞中的基因激活特征 表达，包括NF-κB靶基因，并进一步确定哪些活化的基因是PRC 2非依赖性的。 在目的2中，我们将通过确定哪些基因与EZH 2和NF-κB相关来表征TNBC细胞中EZH 2和NF-κB的关系。 EZH 2和RelA共同占据和共同调节，以及EZH 2和RelA是否直接或功能性相互作用。 在目的3中，我们将通过确定EZH 2是否在TNBC细胞中具有非典型功能来阐明EZH 2在TNBC细胞中的机制。 EZH 2过表达和/或翻译后修饰对于驱动非典型的细胞凋亡是足够和必要的。 EZH 2活性与NF-κB相关。 拟议的研究将在合作和富有成效的研究环境中进行， 位于查佩尔山的北卡罗来纳州大学的阿尔伯特·鲍德温博士的实验室， NF-κB信号领域及其在癌症中的作用，在共同赞助者Brian Strahl博士的支持下， 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 在TNBC细胞中非典型EZH 2-NF-κB信号传导的贡献。这将从根本上推进乳房 癌症和表观遗传学生物学，并阐明当前EZH 2靶向策略和新策略中的两个陷阱 在开发和推进TNBC疗法时考虑的目标。

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.