Gene X Environment Interactions in the Pathogenesis of Uterine Fibroids

摘要 子宫肌瘤(UF)是一种起源于子宫肌层的单克隆性肿瘤，是子宫肌瘤中最常见的 育龄妇女常见肿瘤。越来越多的证据支持 假设UF起源于子宫肌层中的异常干细胞。我们现在已经确定了 一种可自我更新和再生的Stro-1/CD44子宫肌层干细胞 子宫肌层组织，这会在动物模型中引起UF。我们有能力识别和识别 分离这些MSCs，我们处于独特的地位，可以解决风险因素如何影响UF 以启动和促进这些肿瘤的发展。 像许多疾病一样，有充分的证据表明，环境暴露和基因 改变在UF的发病机制中起重要作用。我们和其他人已经证明了早期生命 环境暴露于内分泌干扰物(EDCs)可通过以下方式增加UF风险 诱导表观基因组的发育重编程。这种表观基因组重编程 涉及组蛋白和DNA甲基化模式的变化，从而改变染色质结构和 基因转录，当在生命早期被诱导时，会持续到成年。中国的基因改变 介质12(MED12)和结节性硬化症复合体2(TSC2)肿瘤抑制因子，DRIVE 分别在人类和啮齿动物模型中发展UF肿瘤。有趣的是，MED12 和TSC2缺陷共有一个共同的下游效应器：激活β-连环蛋白信号和 Tcf/Lef反式激活基因表达。 我们以前无法询问UF的来源细胞，这限制了我们对 基因：环境交互作用(GxE)如何影响UF风险。现在我们可以分离和分析 MSCS，我们第一次能够克服这一理解的关键障碍 这种重要疾病的风险决定因素。在此应用程序中，我们将使用我们的新发现 能够隔离和审问MSCs，并应用有关环境如何的最新见解 暴露重新编程表观基因组，以探索促进GxE相互作用 尿路结石原发细胞中的肿瘤发生。 具体目标1：测试激活β-连环蛋白信号是一种常见的假设 驱动尿路衰竭的基因改变的效应途径。在这个机械性的目标下，我们将测试 假设在MSCs中，MED12突变(人)或TSC2丢失(大鼠)会导致改变 转录图谱的特征是TCF/LEF基因表达的反式激活增加。 具体目标2：检验发育中的EDC暴露会导致表观遗传的假设 与MSC/TIC中的遗传缺陷相配合的重新编程。在这个机械化的目标中， 我们将描述EDC诱导的表观基因组的重新编程，并检验以下假设 当β-连环蛋白被激活时，Tcf/LEF靶基因的重新编程加剧了它们的表达 在rMSCs和肿瘤起始细胞(TICs)中被激活。 具体目标3：验证与高风险与低风险UF相关的MSCs表现出的假设 表观遗传组蛋白修饰的差异。在这个翻译目标中，我们将探索 骨髓间充质干细胞表观遗传模式与UF风险的关系 无UF妇女的子宫肌层(Myon)和有UF的高危妇女的子宫肌层 (MyoF)。由于表观基因组的改变可能是可逆的，我们还将测试 假设降低UF风险的干预是通过减少MSC数量和/或 将MSC表观基因组“重置”回低风险状态。 影响：我们的工作解决了NIH定义的几个知识差距和优先研究领域 包括：干细胞/祖细胞在妇科健康和疾病中的跨学科研究 以及妇科疾病中的“OMICS”。重要的是，这也将是GxE的首次探索 在UF的起源细胞中驱动疾病的相互作用。

Abstract Uterine Fibroids (UFs) are monoclonal tumors arising in the myometrium, and are the most common tumor of reproductive age women. An increasing body of evidence supports the hypothesis that UFs originate from aberrant stem cells in the myometrium. We have now identified a Stro-1+/CD44+ myometrial stem cell (MSC) capable of self-renewal and regeneration of myometrial tissues, which gives rise to UFs in animal models. With our ability to identify and isolate these MSCs, we are in a unique position to address how risk factors impact the UF cell-of-origin to initiate and promote the development of these tumors. Like many diseases, there is ample evidence that both environmental exposures and genetic alterations contribute to UF pathogenesis. We, and others have shown that early life environmental exposures to endocrine disrupting compounds (EDCs) increase UF risk by inducing developmental reprogramming of the epigenome. Such epigenomic reprogramming involves changes in histone and DNA methylation patterns that alter chromatin architecture and gene transcription, and when induced in early life, persist into adulthood. Genetic alterations in mediator 12 (MED12) and the tuberous sclerosis complex 2 (TSC2) tumor suppressor, drive development of UF tumors in both humans and rodent models, respectively. Interestingly, MED12 and TSC2 defects share a common downstream effector: activation of β-catenin signaling and TCF/LEF transactivation of gene expression. Our previous inability to interrogate the cells-of-origin for UFs has limited our understanding of how gene:environment interactions (GxE) influence UF risk. Now that we can isolate and profile MSCs, we are for the first time in a position to overcome this critical barrier to understanding determinants of risk for this important disease. In this application we will utilize our new-found ability to isolate and interrogate MSCs, and apply recent insights on how environmental exposures reprogram the epigenome, to explore GxE interactions that promote tumorigenesis in the cell-of-origin for UFs. Specific Aim 1: Test the hypothesis that activation of β-catenin signaling is a common effector pathway for genetic alterations that drive UFs. In this mechanistic Aim, we will test the hypothesis that in MSCs, MED12 mutation (human) or loss of Tsc2 (rat) results in an altered transcriptional profile characterized by increased TCF/LEF transactivation of gene expression. Specific Aim 2: Test the hypothesis that developmental EDC exposure results in epigenetic reprogramming that cooperates with genetic defects in MSC/TICs. In this mechanistic Aim, we will characterize EDC-induced reprogramming of the epigenome, and test the hypothesis that reprogramming of TCF/LEF target genes exacerbates their expression when β-catenin is activated in rMSCs and in tumor initiating cells (TICs). Specific Aim 3: Test the hypothesis that MSCs associated with high vs low UF risk exhibit differences in epigenetic histone modifications. In this translational Aim, we will explore the relationship between MSC epigenetic patterns and UF risk using MSCs isolated from normal myometrium of women without UFs (MyoN) and at-risk myometrium from women with UFs (MyoF). Because epigenomic alterations are potentially reversable, we will also test the hypothesis that an intervention that reduces UF risk does so by decreasing MSC number and/or “resetting” the MSC epigenome back to a low risk profile. Impact: Our work address several knowledge gaps and priority research areas as defined by NIH including; Stem/Progenitor Cells in Gynecologic Health and Disease, Transdisciplinary Research and '–Omics' in Gynecologic Disorders. Importantly, it will also be the first exploration of GxE interactions that drive disease in the cells of origin for UFs.