Deciphering Critical Changes in the Methylome of Hematopoietic Stem Cells in Age-related Clonal Hematopoiesis and Myeloid Leukemogenesis

高龄是急性髓系白血病(AML)发病的危险因素之一。考虑到在西方世界，65岁及以上的人预计还能再活20年，急性髓细胞白血病对这个年龄段的人的生存有毁灭性的影响。关键问题之一一直是，现在仍然是，是什么确切的机制导致老年人急性髓细胞白血病的急剧增加。一些独立的报告表明，衰老与克隆性造血的发展有关，所谓的年龄相关克隆性造血(ARCH)显著增加了受影响的个体发展成血液肿瘤的可能性。这些临床意义导致了一种新的疾病的提出，称为“克隆性造血不确定潜能”(CHIP)，描述的是健康个体携带已知在血液系统恶性肿瘤中反复突变的基因突变。重要的是，CHIP与表观遗传修饰物的突变有关。在我们的建议中，我们假设来自非克隆性造血的年轻和老年HSCs、来自克隆性造血的老年HSCs和来自携带已知驱动克隆性造血的突变的老年AML患者的LSCs之间存在DNA甲基组的关键变化。首先，数据表明，从年轻到年老，全球DNA甲基化模式与年龄有关。在即将到来的资助期间，我们将通过RNA-Seq将全球DNA甲基化图谱与个体样本中的转录本联系起来。我们将进一步通过单细胞测序鉴定克隆性和非克隆性HSCs的转录组和甲基组，并将这种分析扩展到原始AML样本，其特征是具有和不具有年龄相关突变的白血病干细胞和残留HSCs的嵌合体。这些数据将得到功能分析的补充，测试候选基因，如同源盒基因在体内芯片开发中的作用。

One of the risk factors for developing acute myeloid leukemia (AML) is higher age. Considering that in the Western world, individuals aged 65 and older, are expected to survive approximately another 20 years, AML has a devastating impact on the survival of this age group. One of the key questions has been, and still is, which precise mechanisms lead to the steep increase in AML in the elderly. Several independent reports have demonstrated that aging is associated with the development of clonal hematopoiesis and that so called “age-related clonal hematopoiesis” (ARCH) significantly increases the probability of affected individuals to develop hematological neoplasias. These clinical implications have led to the proposal of a new disorder called “clonal hematopoiesis of indeterminate potential” (CHIP), which describes healthy individuals carrying mutations in genes known to be recurrently mutated in hematological malignancies. Importantly, CHIP is associated with mutations in epigenetic modifiers. In our proposal we hypothesize that there are critical changes in the DNA methylome between young versus aged HSCs derived from non-clonal hematopoiesis, aged HSCs from clonal hematopoiesis and LSCs from elderly patients with AML carrying mutations known to drive clonal hematopoiesis. First data indicate age-dependent global DNA methylation patterns from young to old. In the upcoming funding period, we will link global DNA methylation profiling with transcriptomes in the individual samples by RNA-Seq. We will furthermore characterize the transcriptome and methylome of clonal versus non-clonal HSCs by single cell sequencing and extend this analysis to primary AML samples characterized by a mosaique of leukemic stem cells and residual HSCs with and without age-related mutations. These data will be complemented by functional analyses, testing the role of candidate genes such as homeobox genes on development of CHIP in vivo.