Effects of Histone 3.3 K27M mutation on CBP- and BET-mediated epigenetic gene regulation in pediatric diffuse intrinsic pontine gliomas (DIPG). Towards a combined epigenetic therapy approach for DIPG

组蛋白 3.3 K27M 突变对 CBP 和 BET 介导的儿童弥漫性脑桥胶质瘤 (DIPG) 表观遗传基因调控的影响。

• 批准号: 396708675
• 负责人: Dr. Maria Wiese
• 金额: --
• 依托单位: Abteilung Pädiatrische Hämatologie und Onkologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/396708675?language=en
• 关键词: Effects; Histone; 3.3; K27M; mutation

Pediatric high-grade gliomas (pedHGG) represent the most aggressive pediatric brain tumor entity with very poor prognosis and overall-survival rates of less than 15 %. There are specific genetic alterations involving mutations in lysine 27 of histone 3 (H3K27M) in 30-40% of pedHGG resulting in even worse prognosis of affected patients. Although it is known that H3K27M-mutation leads to global loss of H3K27 trimethylation (H3K27me3) combined with hyperacetylation of H3K27, the underlying biological mechanism is still unknown. We hypothesize that the H3K27M-induced hyperacetylation (H3K27ac) by histone acetyltransferases (= epigenetic writer), such as CREB Binding Protein (CBP), might be accompanied by a greater impact of acetylation-dependent epigenetic readers. Indeed, the reader Bromodomain and Extra Terminal domain protein (BET) BRD4 was found to be strongly bound by H3K27M-mutated nucleosomes. Thus, targeting both, H3K27ac-specific epigenetic readers and writers, could represent an effective therapeutic combination to treat H3K27M mutated pedHGG. Our previous investigations already proved that tumor related characteristics of H3K27M pedHGG cells are stronger decreased by inhibition of BRD4 than characteristics of H3.3 wildtype pedHGG cells. Combinations of BET and CBP inhibition even enhanced anti-tumor effects. However, the underlying gene regulatory functions of BRD4 and CBP in H3K27M pedHGG cells are not yet really known. The present project aims at further elucidating the H3K27ac-associated gene regulatory processes by investigating the impact of CBP and BET as epigenetic H3K27ac-associated writers and readers in H3K27M and H3K27 wildtype pedHGG cells. To this end, we will determine the H3K27M/CBP/BET-dependent epigenome and transcriptome together with resulting tumor phenotype features, such as proliferation, invasion, and stemness. Finally, we aim to translate the gained knowledge about H3K27ac-associated epigenetic regulatory events in H3.3K27M-mutated pedHGG into an optimized targeted treatment approach in vitro by identifying further inhibitors for BET/CBP which will help to improve the clinical situation of children with H3K27M pedHGG.

儿童高级别胶质瘤 (pedHGG) 是最具侵袭性的儿童脑肿瘤实体，预后极差，总体存活率低于 15%。 30-40% 的 pedHGG 存在涉及组蛋白 3 赖氨酸 27 (H3K27M) 突变的特定基因改变，导致受影响患者的预后更差。尽管已知 H3K27M 突变会导致 H3K27 三甲基化 (H3K27me3) 的整体丧失以及 H3K27 的过度乙酰化，但其潜在的生物学机制仍不清楚。我们假设组蛋白乙酰转移酶（= 表观遗传书写器）（例如 CREB ​​结合蛋白 (CBP)）诱导的 H3K27M 诱导的超乙酰化 (H3K27ac) 可能伴随着乙酰化依赖性表观遗传阅读器的更大影响。事实上，阅读器布罗莫结构域和额外末端结构域蛋白 (BET) BRD4 被发现与 H3K27M 突变核小体强烈结合。因此，针对 H3K27ac 特异性表观遗传读取器和写入器，可能代表治疗 H3K27M 突变 pedHGG 的有效治疗组合。我们之前的研究已经证明，通过抑制BRD4，H3K27M pedHGG细胞的肿瘤相关特征比H3.3野生型pedHGG细胞的特征更强。 BET 和 CBP 抑制的组合甚至增强了抗肿瘤作用。然而，BRD4 和 CBP 在 H3K27M pedHGG 细胞中的潜在基因调控功能尚不清楚。本项目旨在通过研究 CBP 和 BET 作为表观遗传 H3K27ac 相关写入器和读取器在 H3K27M 和 H3K27 野生型 pedHGG 细胞中的影响，进一步阐明 H3K27ac 相关基因调控过程。为此，我们将确定 H3K27M/CBP/BET 依赖的表观基因组和转录组以及由此产生的肿瘤表型特征，例如增殖、侵袭和干细胞性。最后，我们的目标是通过鉴定更多的 BET/CBP 抑制剂，将 H3.3K27M 突变 pedHGG 中 H3K27ac 相关表观遗传调控事件的知识转化为优化的体外靶向治疗方法，这将有助于改善 H3K27M pedHGG 儿童的临床状况。