Chromatin Modifications in GBM-Propagating Cells

摘要/摘要 多形性胶质母细胞瘤(GBM)是最常见的脑癌，其中位生存期为~ 18个月。迫切需要新的治疗方法。GBM在细胞水平上是异质性的， 肿瘤增殖性干细胞(又名：GBM干细胞，GSCs) 与基底膜生长、治疗耐药和复发不成比例。确凿的证据表明 GBM细胞是高度增殖性的，并在干细胞样/肿瘤增殖表型之间动态转换 以及更多分化/非肿瘤传播表型，以响应上下文表观遗传事件。 阐明GSCs产生和维持的表观遗传学机制(即抑制 分化和激活去分化转录程序)对于理解 恶性胶质母细胞瘤的分子基础及将进一步发展更有效 治疗学。我们发现再编程转录因子Oct4和Sox2(Oct4/Sox2) 通过沉默miRNAs，表型将非GSCs重新编程为肿瘤传播的GSCs 协同抑制GSC表型。我们现在假设，对特定miRNA的抑制 靶向(I)非组蛋白DNA结合蛋白HMGA1，和(Ii)多梳抑制物的成分 催化组蛋白3K27三甲基化的复合体2(PRC2)(H3K27me3)在 通过Oct4/Sox2生成GSC。该提案重点讨论了HMGA1和PRC2如何协同调节 诱导人神经干细胞增殖过程中染色质的结构和功能及基因表达 Oct4/Sox2，以及测试抑制这些Oct4/Sox2调节的miRNA电路的治疗效果。 这些目标将通过三个具体目标来实现-(1)确定Oct4/Sox2抑制的miRNAs在 Oct4/Sox2上调HMGA1、PrC2、H3K27me3和GSC的诱导；(2)决定HMGA1如何 和H3K27me3共同调节染色质功能和转录网络以响应Oct4/Sox2；(3) 基于抑制GSC诱导的这些机制，开发新的GBM治疗策略 10月4日/Sox2。这项研究将填补我们对重编程转录是如何影响因素的理解的关键空白 诱导GSCs和GBM增殖。我们将特别确定“结构转录因子”是如何 HMGA1和依赖于PRC2的H3K27me3协同调节GSC诱导的转录组。我们会 还评估了使用创新纳米颗粒在治疗上靶向这些新型GSC驱动程序的可能性。 以药物为基础的疗法。

SUMMARY/ABSTRACT Glioblastoma multiforme (GBM), the most common brain cancer, is universally fatal with median survival of ~ 18 months. New therapies are desperately needed. GBM is heterogeneous at the cellular level with small populations of tumor propagating stem-like cells (aka, GBM stem cells, GSCs) that contribute disproportionately to GBM growth, therapeutic resistance and recurrence. Substantial evidence indicates that GBM cells are highly plastic and dynamically transition between the stem-like/tumor propagating phenotype and more differentiated/non-tumor propagating phenotype in response to contextual epigenetic events. Elucidating the epigenetic mechanisms involved in the generation and maintenance of GSCs (i.e. repression of differentiating and activation of dedifferentiation transcriptional programs) is critical to understanding the molecular underpinnings of glioblastoma malignancy and will further the development of more effective therapeutics. We have found that the reprogramming transcription factors Oct4 and Sox2 (Oct4/Sox2) phenotypically reprogram non-GSCs to tumor-propagating GSCs through the silencing of miRNAs that cooperatively inhibit the GSC phenotype. We now hypothesize that the repression of specific miRNAs that target (i) the non-histone DNA-binding protein HMGA1, and (ii) components of the polycomb repressor complex 2 (PRC2) that catalyzes histone3K27 trimethylation (H3K27me3) plays an essential role in the generation of GSCs by Oct4/Sox2. This proposal focuses on how HMGA1 and PRC2 cooperatively regulate chromatin structure and function and gene expression during the induction of tumor propagating GSCs by Oct4/Sox2 and on testing the therapeutic efficacy of inhibiting these Oct4/Sox2-regulated miRNA circuits. These goals will be achieved via three specific aims- (1) Determine the role of Oct4/Sox2-repressed miRNAs in the up-regulation of HMGA1, PRC2, H3K27me3 and GSC induction by Oct4/Sox2; (2) Determine how HMGA1 and H3K27me3 co-regulate chromatin function and transcriptional networks in response to Oct4/Sox2; (3) Develop novel GBM treatment strategies based on inhibiting these mechanism of GSC induction by Oct4/Sox2. This research will fill critical gaps in our understanding of how reprogramming transcriptions factors induce GSCs and GBM propagation. We will specifically identify how the “structural transcription factor” HMGA1 and the PRC2-dependent H3K27me3 cooperate to regulate the GSC-inducing transcriptome. We will also evaluate the potential to therapeutically target these novel GSC-drivers using innovative nanoparticle- based and pharmacologic therapeutics.