Characterizing age-associated epigenetic alterations and their roles in tumor development

表征与年龄相关的表观遗传改变及其在肿瘤发展中的作用

• 批准号: 9926803
• 负责人: STEPHEN B. BAYLIN
• 金额: $ 12.28万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-15 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9926803
• 关键词: ATAC-seq; Affect; Age; Aging; Appearance; BRAF gene; Biological Assay; Cancer Biology; Cancer Burden; Case Study; Cells; Characteristics; Chromatin; Chromatin Structure; Clustered Regularly Interspaced Short Palindromic Repeats; Colon; Colorectal Cancer; CpG Islands; DNA; DNA Methylation; Data; Defect; Development; Disease; Enhancers; Epigenetic Process; Epithelial; Epithelial Cells; Epithelium; Event; Evolution; Gene Expression Regulation; Gene Silencing; Genes; Genomics; Gerontology; Goals; Histones; Human; Hypermethylation; KRAS2 gene; Large Intestine; Link; Malignant Neoplasms; Maps; Mediating; Methylation; Minor; Modeling; Modification; Mus; Mutation; Nature; Neoplasms; Oncogenic; Oncology; Organ Model; Organoids; Outcome; Participant; Pathway interactions; Phenotype; Play; Population; Predisposition; Prevention strategy; Probability; Property; Publishing; Regulatory Element; Research; Role; System; Testing; Tissues; Tumorigenicity; Variant; Work; age group; age related; aged; anticancer research; base; cancer initiation; cancer prevention; cancer risk; cell age; colorectal cancer risk; data modeling; driver mutation; epigenetic variation; epigenomics; epithelial stem cell; genome-wide; histone modification; in vivo; insight; mouse model; non-histone protein; normal aging; novel; novel strategies; prevent; promoter; protein structure; role model; senescence; stem cell population; stem cells; stemness; theories; transcriptome; tumor; tumor initiation; tumorigenesis; tumorigenic

The goal of this proposal is to characterize in detail the age-associated epigenetic alterations and their functional roles in the age-related risk for cancer, so that we can devise approaches to either prevent or treat early neoplasms. This proposal builds on our current ongoing and recently published work indicating that cancers derive from ageing, dividing cells due to accumulation of epigenetic changes. Multiple studies have shown that normal ageing involves accumulation of epigenetic alterations involving DNA methylation, modifications to histone and non-histone proteins, and chromatin structure. However, most studies have focused on DNA methylation, and the functional roles of these various age-related epigenetic modifications in promoting tumorigenesis has been lacking. Our work uses novel approaches employing ex vivo colon-derived stem cell organoid and in vivo mouse models. In preliminary data, we show that “ex vivo ageing” of mouse colon organoids involves evolution of promoter DNA hypermethylation, akin to in vivo ageing, which facilitates activation of the Wnt-pathway and predisposes to transformation by oncogenic-Braf. To obtain in-depth insights into alterations in the transcriptome due to age-associated epigenetic changes, and its impact on tumor initiation, we will map key histone modifications (H3K4me3, H3K27me3, H3K27ac), DNA methylation and chromatin structure (open/closed chromatin configuration) in colon epithelial cells from mice of different age groups. Changes to gene regulation mediated by epigenetic alterations in promoters and other genomic regulatory elements, such as enhancers, will be identified. The genomic analyses will be followed by functionally testing the roles of important age-altered genes and pathways in promoting tumor initiation using the novel organoid-based ex vivo tumorigenesis assays. Importantly, our work focuses on understanding the epigenetic changes in long-lived colon epithelial stem cells, from which tumors most likely derive. Our current data invokes the concept that epigenetic events in stem cells, arising in the context of ageing, may initially allow escape from senescence, retention of stem cell characteristics, and cause differentiation defects. We hypothesize that minor stem cell subpopulations with such characteristics exist in aged tissues and are predisposed to tumorigenesis in the context of cancer driver mutations. We will test this hypothesis using ex vivo organoids generated form mice of different age groups, and enriching for cells with increased stem cell properties/differentiation defects. Finally, we will directly test if epithelial stem cells from aged organoids are predisposed to tumorigenesis in the context of oncogenic mutations. In ongoing work we have teamed up with Dr. Rafael de Cabo (NIA); the complementary expertise of our groups in age-related disorders (de Cabo) and cancer epigenetics (Baylin, Easwaran) will help achieve the stated goals. Ultimately, our findings using the colon model will be applicable to other tumor types and to the human ageing scenario in general, which will have high impact on strategies to reduce age-related cancer risk.

这项建议的目标是详细描述与年龄相关的表观遗传改变及其功能。 在与年龄相关的癌症风险中的作用，因此我们可以设计出预防或早期治疗的方法， 肿瘤。这项建议建立在我们目前正在进行的和最近发表的工作基础上，表明癌症 源自衰老，由于表观遗传变化的积累而导致的细胞分裂。多项研究表明， 正常的衰老涉及表观遗传改变的积累，包括DNA甲基化， 组蛋白和非组蛋白蛋白，以及染色质结构。然而，大多数研究都集中在DNA上， 甲基化，以及这些各种年龄相关的表观遗传修饰在促进 缺乏肿瘤发生。我们的工作采用了新的方法， 类器官和体内小鼠模型。在初步数据中，我们表明小鼠结肠类器官的“离体老化” 涉及启动子DNA超甲基化的进化，类似于体内老化，这有助于激活 Wnt途径并易于被致癌Braf转化。为了深入了解 在转录组中由于年龄相关的表观遗传变化，以及其对肿瘤发生的影响，我们将绘制 关键组蛋白修饰（H3 K4 me 3、H3 K27 me 3、H3 K27 ac）、DNA甲基化和染色质结构 (open/闭合的染色质构型）。更改 由启动子和其他基因组调控元件中的表观遗传改变介导的基因调控， 作为增强子。基因组分析之后将进行功能测试， 使用新型基于类器官的离体方法在促进肿瘤起始中的重要年龄改变的基因和途径 肿瘤发生测定。重要的是，我们的工作重点是了解长寿的表观遗传变化， 结肠上皮干细胞，肿瘤最有可能来源于此。我们目前的数据表明， 衰老背景下发生的干细胞表观遗传事件最初可能会使衰老得以逃脱， 保留干细胞特性，并导致分化缺陷。我们假设微小干细胞 具有这种特征的亚群存在于衰老组织中，并且在衰老组织中易于发生肿瘤。 癌症驱动突变的背景。我们将使用从以下小鼠产生的离体类器官来测试这一假设： 不同年龄组，并富集具有增加的干细胞特性/分化缺陷的细胞。最后， 我们将直接测试来自衰老类器官的上皮干细胞是否在这种情况下易发生肿瘤。 致癌基因突变。在正在进行的工作中，我们与Rafael de卡波博士（NIA）合作; 我们的团队在年龄相关疾病（de卡波）和癌症表观遗传学（Baylin，Easwaran）方面的专业知识将有所帮助 实现既定目标。最终，我们使用结肠模型的发现将适用于其他肿瘤类型 以及人类老龄化的总体情况，这将对减少与年龄有关的 癌症风险。