Epigenomic Mapping in Human Tumor Stem Cells

描述（由申请人提供）：肿瘤干细胞（一种能够再生肿瘤的自我更新细胞）的概念揭示了人类癌症的持久性，并为转化研究提供了新的焦点。我们的目标是了解将肿瘤干细胞与其他肿瘤细胞以及其他正常的自我更新细胞区分开来的表观遗传机制。表观遗传机制，如染色质修饰，DNA甲基化和小的非编码RNA是细胞转录潜力的稳定，长期（通常是可遗传的）变化，不依赖于基础基因组序列的变化。细胞的表观遗传状态用于定义细胞身份和该细胞潜在命运的限制。因此，细胞的表观遗传状态的知识可以识别肿瘤干细胞身份和潜力的特征。组蛋白修饰、DNA甲基化和小的非编码RNA的表观遗传状态将使用染色质免疫沉淀、亚硫酸氢盐转化和结合全基因组测序的RNA文库的产生来绘制。为了深入了解肿瘤干细胞，我们将利用先前开发的模型系统，该系统提供了具有肿瘤干细胞能力的细胞的一致来源。拟议的实验将检查一组细胞之间的差异，每个细胞都被分选以富集具有肿瘤干细胞能力的亚群。为了进行比较，将从相同来源分离非肿瘤干细胞，并检查肿瘤干细胞与多能和多能干细胞之间的差异。将设计额外的实验来干扰细胞的表观基因组，并直接测试原始细胞的表观遗传状态如何影响随后的肿瘤表型。所产生的知识可能会导致大量的新见解，包括识别用于早期诊断，预后或肿瘤治疗监测的推定标志物。了解肿瘤干细胞和其他自我更新细胞之间的差异可能会导致对正常细胞毒性较小的更特异性的治疗。操纵表观基因组状态和检查致瘤性的结果将提供关于这些特征如何转化为临床相关表型的直接见解。

DESCRIPTION (provided by applicant): The concept of a tumor stem cell, a self-renewing cell capable of regenerating the tumor, has shed light on the persistence of human cancers and offers a new focus for translational research. Our goal is to understand the epigenetic mechanisms that distinguish the tumor stem cell from other cells of the tumor and from other normal, self-renewing cells. Epigenetic mechanisms, such as chromatin modifications, DNA methylation and small noncoding RNAs are stable, long-term (typically heritable) changes in the transcriptional potential of a cell that are independent of changes in the underlying genomic sequence. The epigenetic state of a cell serves to define cell identity and the limits of that cell's potential fates. Thus, knowledge of the epigenetic state of cells may identify signature for both tumor stem cell identity and potential. The epigenetic states of histone modifications, DNA methylation and small noncoding RNAs will be mapped using chromatin immunoprecipitation, bisulfite conversion and generation of RNA libraries coupled with genome-wide sequencing. For insight on tumor stem cells, we will take advantage of a previously developed model system that provides a consistent source of cells with tumor stem cell ability. Proposed experiments will examine the differences between a panel of cells, each sorted to enrich for the subpopulation with tumor stem cell ability. For comparisons, non-tumor stem cells will be isolated from the same source and the differences between tumor stem cells and pluripotent and multipotent stem cells will be examined. Additional experiments will be designed to perturb the epigenome of cells and directly test how the epigenetic state of the cell-of-origin affects subsequent tumor phenotype. The knowledge generated could lead to substantial new insights, including the identification of putative markers for early diagnosis, prognosis or monitoring of tumor therapies. Understanding the differences between tumor stem cells and other self-renewing cells could lead to more specific therapies that were also less toxic to normal cells. Manipulating the epigenomic state and examining the results on tumorigenicity would provide direct insight on how these signatures translate into clinically relevant phenotypes.