Inducing transcriptional reprogramming of leukemic B-cells by facilitating transcription factors binding to nascent decondensed chromatin

通过促进转录因子与新生脱浓缩染色质结合来诱导白血病 B 细胞的转录重编程

• 批准号: 10408669
• 负责人: David Deming
• 金额: $ 4.68万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10408669
• 关键词: Acute Promyelocytic Leukemia; Apoptosis; Arsenic; B cell differentiation; B-Cell Acute Lymphoblastic Leukemia; B-Cell Development; B-Lymphocytes; B-cell precursor acute lymphoblastic leukemia cell; Binding; Biochemical; Biological Assay; Blast Cell; Cell Aging; Cell Cycle Arrest; Cell Death; Cell Line; Cell Maturation; Cell Survival; Cell physiology; Cells; Child; Chromatin; Chromatin Modeling; Clinical; Combined Modality Therapy; DNA Binding; DNA biosynthesis; Differentiation Therapy; Dose; EZH2 gene; Epigenetic Process; Euchromatin; Gene Targeting; Genes; Genetic Transcription; Genome; Genotype; Hematopoietic stem cells; Histone H3; In Vitro; Instruction; Knowledge; Lead; Ligands; Malignant Neoplasms; Metabolic syndrome; Methylation; Methyltransferase; Modeling; Molecular; Mus; Mutation; Nature; Nucleic Acid Regulatory Sequences; Nucleosomes; Outcome; Patients; Pharmaceutical Preparations; Pharmacology; Phenotype; Reporting; S phase; Sampling; Site; Specific qualifier value; Structure; Therapeutic; Time; Toxic effect; Tretinoin; Tumor Burden; Undifferentiated; Work; Xenograft Model; base; chromatin immunoprecipitation; cytokine; dosage; follow-up; hematopoietic differentiation; histone methyltransferase; improved; in vivo; in vivo Model; leukemia; novel; novel therapeutic intervention; older patient; patient derived xenograft model; pediatric patients; receptor; screening; self-renewal; senescence; small molecule; standard of care; steroid hormone; success; transcription factor; transcriptional reprogramming; transcriptome; transcriptome sequencing

Project Summary/Abstract B cell acute lymphoblastic leukemia (B-ALL) consist of Leukemic Blast Cells (LBCs) that become arrested at distinct stages of B cell development because of underlying alterations in transcriptional and epigenetic programming. The inability to differentiate confers a capacity for unlimited self-renewal and increased proliferative capability. Based on the successes in the treatment of the APL leukemia with ATRA and arsenic, leading to cell maturation and senescence, the differentiation-based therapies became a popular, but rarely successful, therapeutic strategy. We propose that this strategy has been unsuccessful due to a gap in the knowledge of the underlying mechanism through which transcriptional reprogramming occurs. My new strategy is based on our group’s recent observations that differentiation of normal hematopoietic progenitor cells (HPCs) is dependent on their ability to transiently decondense their post-replicative chromatin upon induction with lineage specifying cytokines. At the early stages of DNA replication, this decondensed state of nascent chromatin offers a window of opportunity for lineage-specific transcription factors (TFs) to overcome the barrier of the condensed structure of nucleosomes at repressed genes and to bind and activate their target sites. Preliminary results indicate that B-ALL LBCs have lost the inherent ability to open nascent chromatin, thus creating a barrier in their transcriptional reprogramming that differentiation-based therapies cannot overcome. In this proposal, to overcome this barrier of condensed nascent chromatin and to reprogram LBCs, I will utilize the following approach. First, I will pharmacologically ablate H3K27me3 to decondense nascent chromatin by inhibiting H3K27me3 histone methyltransferases EZH1/2. Second, I will use small molecules to activate inducible transcription factors, which can then readily bind to their target genes due to the decondensed structure of nascent chromatin. Cancers are commonly known to accumulate mutations in inducible TFs and receptors; thus, screens of small molecule inducers for a variety of TFs/receptors will be performed to determine the best possible inducer for distinct subtypes of B-ALL. Preliminary results provide strong indications that induction by novel small molecule ligands/inducers may lead to transcriptional reprogramming in B-ALL LBCs, which results in an almost complete loss of viability of these cells. This strategy has also shown significant promise in increasing the efficacy of and in decreasing the effective dosages of clinical standard of care drugs, such as steroid hormones. Furthermore, my results indicate that synchronization of B-ALL cells into the entry of the S-phase greatly increase the efficiency of our reprogramming strategy. Overall, our conceptual advance is in that we are not attempting to induce hematopoietic differentiation of LBCs, but rather through decondensing nascent chromatin induce transcriptional reprogramming to aberrant lineages, which may lead to terminal maturation, and thus to senescence, reduced proliferation, and cell death.

项目总结/摘要 B细胞急性淋巴细胞白血病（B-ALL）由白血病母细胞（LBC）组成， B细胞发育的不同阶段，因为转录和表观遗传的潜在改变 编程.无法区分赋予了无限自我更新的能力， 增殖能力。在全反式维甲酸联合砷剂治疗急性早幼粒细胞白血病取得成功的基础上， 导致细胞成熟和衰老，基于分化的疗法成为流行的，但很少 成功的治疗策略我们认为，这一战略一直是不成功的，由于差距， 了解转录重编程发生的潜在机制。我的新策略 是基于我们小组最近的观察，正常造血祖细胞（HPC）的分化 依赖于它们在诱导时瞬时解密集其复制后染色质的能力， 谱系特异性细胞因子。在DNA复制的早期阶段，新生染色质的这种去致密状态 为谱系特异性转录因子（TF）克服转录障碍提供了一个机会窗口。 抑制基因的核小体的浓缩结构，并结合和激活其靶位点。初步 结果表明，B-ALL LBC已经失去了打开新生染色质的固有能力，从而形成了一个屏障， 这是基于分化的疗法无法克服的。在这项建议中， 为了克服新生染色质浓缩的障碍并对LBC进行重编程，我将利用以下方法 approach.首先，我将通过抑制H3 K27 me 3来使新生染色质去致密化， H3 K27 me 3组蛋白甲基转移酶EZH 1/2。第二，我会用小分子来激活 转录因子，然后可以很容易地结合到它们的靶基因，由于解密集的结构， 新生染色质癌症通常已知在诱导型TF和受体中积累突变;因此， 将对各种TF/受体的小分子诱导剂进行筛选，以确定最佳可能的 B-ALL不同亚型的诱导剂。初步结果提供了强有力的迹象表明，诱导新的小 分子配体/诱导剂可能会导致B-ALL LBC的转录重编程，从而导致几乎 这些细胞的活力完全丧失。这一策略在提高疗效方面也显示出了巨大的希望。 减少临床标准护理药物如类固醇激素的有效剂量。 此外，我的结果表明B-ALL细胞进入S期的同步化大大增加 我们重编程策略的效率总的来说，我们在概念上的进步在于， 诱导LBC造血分化，而是通过解致密新生染色质诱导 转录重编程为异常谱系，这可能导致终末成熟，从而 衰老、增殖减少和细胞死亡。