Molecular basis of MED12 in the pathogenesis of uterine fibroids

MED12在子宫肌瘤发病机制中的分子基础

基本信息

批准号：
9927654
负责人：
THOMAS G BOYER
金额：
$ 31.03万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-08-01 至 2022-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9927654
关键词：
Accounting Address Agonist Autologous Benign Binding Biochemical Cell division Cells ChIP-seq Chemicals Common Neoplasm DNA Polymerase II DNA-Directed RNA Polymerase Development Disease Enhancers Enzyme Kinetics Etiology Fibroid Tumor Functional disorder Gene Expression Genes Genetic Genetic Transcription Genetic Transformation Glucocorticoid Receptor Growth Gynecologic Habitual Abortion Hemorrhage In Vitro Infertility Link Mediator of activation protein Medical Molecular Mutate Mutation Neoplasms Operative Surgical Procedures Pathogenesis Pathogenicity Pathologic Pathway interactions Pelvic Pain Peptides Pharmacology Phenotype Phosphorylation Phosphotransferases Premature Labor Process RNA Receptor Signaling Recurrence Role Seeds Signal Pathway Signal Transduction Site Somatic Mutation Testing Therapeutic Therapeutic Intervention Tumor Suppressor Proteins Uterine Fibroids Woman beta catenin cell transformation clinically significant cyclin C epigenomics genome-wide in vivo insight loss of function mutation mutant myometrium new therapeutic target novel paralogous gene personalized medicine programs reproductive restoration stem cells transcription factor transcriptome sequencing transcriptomics tumor tumorigenesis tumorigenic

项目摘要

PROJECT SUMMARY/ABSTRACT Uterine leiomyomas (LM; fibroids) are monoclonal neoplasms of the myometrium (MM) and represent the most frequent tumors in women worldwide. Although benign, they nonetheless account for significant gynecologic and reproductive dysfunction. As no long-term non-invasive treatment option exists for LM, deeper insight regarding tumor etiology is key to the development of newer targeted therapies. Accordingly, this proposal is impactful as it suggests an etiologic basis for the predominant LM subtype and further offers proof of concept for therapeutic intervention involving new druggable targets in this specific genetic setting. LM arise from the genetic transformation of a single MM stem cell (SC) into a tumor initiating cell (LM SC) that seeds and sustains fibroid growth through asymmetric cell divisions. Heretofore, the dominant drivers of cell transformation have been largely identified. The most prevalent among these, accounting for ~70% of LM, are recurrent somatic mutations in the gene encoding the MED12 subunit of Mediator, a multiprotein signal processor through which regulatory information conveyed by gene- specific transcription factors is transduced to RNA polymerase II (Pol II). However, the impact of these mutations on MED12 function and the molecular basis for their tumorigenic potential remain unknown. Herein, we show that LM-linked mutations in MED12 disrupt its ability to activate Cyclin C (CycC)-dependent kinase 8 (CDK8) in Mediator, leading to reduced site-specific RNA Pol II phosphorylation and global gene dysregulation. We also identify genetic programs uniquely dysregulated in MED12-mutant fibroids, leading us to hypothesize that Mediator kinase disruption as a consequence of MED12 mutations elicits transcriptional reprogramming and altered signaling sufficient to drive MM SC transformation. We further hypothesize that MED12-mutant LM are therapeutically susceptible to reactivation of CDK8 or pharmacologic modulation of uniquely dysregulated signaling pathways. To test these hypotheses we will: (1) Establish the pathogenic role of Mediator kinase disruption in MED12-mutant LM. We will ask if genetic or chemical disruption of CDK8 (or its paralog CDK19) in Mediator can induce fibrotic transformation of MM SCs and, conversely, if WT MED12 can restore CDK8/19 kinase activity and suppress the fibrotic phenotype of MED12-mutant LM SCs; (2) Elucidate the pathogenic mechanism of Mediator kinase disruption in MED12- mutant LM. We will define the biochemical basis by which MED12 mutations disrupt CycC-CDK8/19 kinase activity and employ an integrated genome-scale approach to acquire the unique transcriptomic and epigenomic profiles of MED12 WT and mutant LM SCs; (3) Examine the therapeutic implications of Mediator kinase disruption in MED12-mutant LM. We will ask if reactivation of CDK8/19 or pharmacologic manipulation of signaling pathways uniquely dysregulated in MED12-mutant LM SCs can reverse their fibrotic phenotype. We expect these studies to significantly impact personalized treatment of women with LM.

项目概要/摘要子宫肌瘤（LM；肌瘤）是子宫肌层（MM）的单克隆肿瘤，代表全球女性中最常见的肿瘤。尽管它们是良性的，但它们仍然具有重要意义妇科和生殖功能障碍。由于 LM 不存在长期非侵入性治疗选择，对肿瘤病因学的更深入了解是开发更新的靶向疗法的关键。因此，该提议具有影响力，因为它提出了主要 LM 亚型的病因学基础并进一步提供了涉及该特定药物靶点的治疗干预的概念证明遗传设置。 LM 源自单个 MM 干细胞 (SC) 基因转化为肿瘤起始细胞（LM SC）通过不对称细胞分裂播种并维持肌瘤生长。迄今为止，细胞转化的主要驱动因素已基本被确定。最普遍的其中约 70% 的 LM 是编码 MED12 的基因中的反复体细胞突变 Mediator 的亚基，一种多蛋白信号处理器，通过基因传递调节信息特定转录因子被转导为 RNA 聚合酶 II (Pol II)。然而，这些影响 MED12 功能的突变及其致瘤潜力的分子基础仍然未知。在此处，我们发现 MED12 中的 LM 相关突变破坏了其激活细胞周期蛋白 C (CycC) 依赖性的能力介体中的激酶 8 (CDK8)，导致位点特异性 RNA Pol II 磷酸化和全局基因减少失调。我们还确定了 MED12 突变肌瘤中独特的失调基因程序，导致我们假设 MED12 突变导致介导激酶破坏转录重编程和信号改变足以驱动 MM SC 转化。我们进一步假设 MED12 突变 LM 在治疗上对 CDK8 重新激活敏感，或对独特失调的信号通路进行药理调节。为了检验这些假设，我们将： (1) 确定介质激酶破坏在 MED12 突变 LM 中的致病作用。我们会询问是否遗传或 Mediator 中 CDK8（或其旁系同源物 CDK19）的化学破坏可诱导 MM SC 的纤维化转化相反，如果 WT MED12 可以恢复 CDK8/19 激酶活性并抑制纤维化表型 MED12 突变 LM SC； (2) 阐明MED12-介导激酶破坏的致病机制突变型LM。我们将定义 MED12 突变破坏 CycC-CDK8/19 激酶的生化基础活性并采用集成的基因组规模方法来获得独特的转录组和表观基因组 MED12 WT 和突变 LM SC 的概况； (3) 检查介体激酶的治疗意义 MED12 突变 LM 的破坏。我们会询问是否重新激活 CDK8/19 或药物操作 MED12 突变 LM SC 中独特的失调信号通路可以逆转其纤维化表型。我们预计这些研究将对患有 LM 的女性的个性化治疗产生重大影响。