Bartholdy Boris A, Wang Xiahoua, Yan Xiao-Jie, Pascual Marién, Fan Manxia, Barrientos Jacqueline, Allen Steven L, Martinez-Climent Jose Angel, Rai Kanti R, Chiorazzi Nicholas, Scharff Matthew D, Roa Sergio
Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY.
The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY.
Blood Adv. 2020 Mar 10;4(5):893-905. doi: 10.1182/bloodadvances.2019000817.
Intraclonal subpopulations of circulating chronic lymphocytic leukemia (CLL) cells with different proliferative histories and reciprocal surface expression of CXCR4 and CD5 have been observed in the peripheral blood of CLL patients and named proliferative (PF), intermediate (IF), and resting (RF) cellular fractions. Here, we found that these intraclonal circulating fractions share persistent DNA methylation signatures largely associated with the mutation status of the immunoglobulin heavy chain locus (IGHV) and their origins from distinct stages of differentiation of antigen-experienced B cells. Increased leukemic birth rate, however, showed a very limited impact on DNA methylation of circulating CLL fractions independent of IGHV mutation status. Additionally, DNA methylation heterogeneity increased as leukemic cells advanced from PF to RF in the peripheral blood. This frequently co-occurred with heterochromatin hypomethylation and hypermethylation of Polycomb-repressed regions in the PF, suggesting accumulation of longevity-associated epigenetic features in recently born cells. On the other hand, transcriptional differences between paired intraclonal fractions confirmed their proliferative experience and further supported a linear advancement from PF to RF in the peripheral blood. Several of these differentially expressed genes showed unique associations with clinical outcome not evident in the bulk clone, supporting the pathological and therapeutic relevance of studying intraclonal CLL fractions. We conclude that independent methylation and transcriptional landscapes reflect both preexisting cell-of-origin fingerprints and more recently acquired hallmarks associated with the life cycle of circulating CLL cells.
在慢性淋巴细胞白血病（CLL）患者的外周血中，已观察到具有不同增殖历史以及CXCR4和CD5相互表面表达的循环CLL细胞的克隆内亚群，并将其命名为增殖性（PF）、中间性（IF）和静止性（RF）细胞组分。在此，我们发现这些克隆内循环组分共享持续的DNA甲基化特征，这些特征在很大程度上与免疫球蛋白重链基因座（IGHV）的突变状态及其源自抗原接触过的B细胞不同分化阶段有关。然而，白血病出生率的增加对循环CLL组分的DNA甲基化影响非常有限，且与IGHV突变状态无关。此外，随着白血病细胞在外周血中从PF向RF进展，DNA甲基化异质性增加。这经常与PF中异染色质低甲基化和多梳抑制区域的高甲基化同时发生，表明在新生细胞中积累了与寿命相关的表观遗传特征。另一方面，配对的克隆内组分之间的转录差异证实了它们的增殖经历，并进一步支持了外周血中从PF到RF的线性进展。这些差异表达基因中的几个与临床结局表现出独特的关联，而在整体克隆中并不明显，这支持了研究克隆内CLL组分的病理和治疗相关性。我们得出结论，独立的甲基化和转录图谱既反映了预先存在的起源细胞指纹，也反映了最近获得的与循环CLL细胞生命周期相关的特征。
