Combinational targeting the feed forward epigenetic circuitry in mixed lineage leukemia

项目摘要/摘要 MLL重排(MLL-r)白血病占人类急性白血病的5%-10%，与 预后不良。临床需求未得到满足，缺乏有效的靶向治疗 白血病强调了新疗法的必要性。最近的癌症表观遗传学研究发现， 组蛋白H3赖氨酸79(H3K79)甲基转移酶DOT1L在MLL-r白血病发生中的作用重要 已经注意到DOT1L抑制剂作为单一药物治疗的临床反应，然而，它是可望的 这种联合治疗将是必要的。 我们基于DOT1L抑制剂敏化筛选的初步研究已经确定了一个重要的作用 PHF20/KAT8组蛋白乙酰转移酶复合体对DOT1L驱动表达的支持 致癌基因。这项应用的目标是确定关键的表观遗传机制， 与DOT1L合作维持MLL-r白血病的癌基因表达。我们的中心假设是 PHF20介导KAT8募集以维持位点特异性的组蛋白乙酰化和转录 DOT1L驱动的白血病计划。我们将研究DOT1L和PHF20/KAT8的疗效 联合疗法(目标1)，剖析PHF20/KAT8染色质靶向机制(目标2)，以及 验证一种新的高密度CRISPR蛋白扫描技术从头发现功能 DOT1L/PHF20/KAT8中的要素(目标3)。 本研究的创新之处在于：(1)引入了同时瞄准多个目标的新概念 表观遗传前馈循环的组成部分，以有效地抑制癌症计划，以及(2)它 建立了一种全新的基因筛选方法，用于亚蛋白质水平的功能域发现。这个 这项研究的影响将具有重要意义，因为(1)它立即提供了新的治疗方法 针对难治性MLL-r白血病的机会，以及(2)它将有助于识别新的功能性 表观遗传调节器中的元素用于未来的药物靶向。

PROJECT SUMMARY/ABSTRACT MLL-rearranged (MLL-r) leukemias account for 5-10% of human acute leukemia and is associated with poor prognosis. The unmet clinical needs and the lack of an effective targeted therapy to the MLL-r leukemias emphasize the need for novel regimens. Recent cancer epigenetics studies discovered a central role for the histone H3 lysine 79 (H3K79) methyltransferase DOT1L in MLL-r leukemogenesis. Important clinical responses have been noted with DOT1L inhibitor treatment as a single agent, however, it is expected that combination treatments will be necessary. Our preliminary studies based on a DOT1L-inhibitor sensitization screen have identified an essential role of the PHF20/KAT8 histone acetyltransferase complex, in supporting the expression of DOT1L-driven oncogenes. The objective of this application is to determine the critical epigenetic mechanisms that collaborate with DOT1L to maintain oncogene expression in MLL-r leukemia. Our central hypothesis is that PHF20 mediates KAT8 recruitment to maintain the locus-specific histone acetylation and transcription of the DOT1L-driven leukemic program. We will investigate the efficacy of DOT1L and PHF20/KAT8 combination therapies (Aim 1), dissect the PHF20/KAT8 chromatin targeting mechanisms (Aim 2), and validate a novel high-density CRISPR protein scan technology for de novo discovery of the functional elements in DOT1L/PHF20/KAT8 (Aim 3). This study is innovative because (1) it introduces a novel concept of simultaneously targeting multiple components of an epigenetic feed-forward loop to efficiently suppress the cancer programs, and (2) it establishes a brand new genetic screen approach for a sub-protein level functional domain discovery. The impact of this research will be of significance because (1) it immediately provides novel therapeutic opportunities against the difficult-to-treat MLL-r leukemias, and (2) it will help identify novel functional elements in epigenetic regulators for future pharmaceutical targeting.