Identifying/Targeting Mechanisms of Lymphomagenesis Driven by CREBBP Inactivation

CREBBP 失活驱动的淋巴瘤发生的识别/靶向机制

基本信息

批准号：
9326262
负责人：
Michael Richard Green
金额：
$ 35.66万
依托单位：
UNIVERSITY OF TX MD ANDERSON CAN CTR
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-08-04 至 2021-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9326262
关键词：
Acetylation Antigen Presentation Antigens Automobile Driving B cell differentiation B lymphoid malignancy B-Cell Development B-Lymphocytes BCL2 gene Biological Assay CD4 Positive T Lymphocytes CREBBP gene Cell Line Cell Proliferation Cell physiology Cells Chromosomal translocation Clustered Regularly Interspaced Short Palindromic Repeats Coculture Techniques Complex Cytotoxic T-Lymphocytes Development Disease Down-Regulation EZH2 gene Epigenetic Process Event Evolution Follicular Lymphoma Frequencies Gene Expression Gene Expression Profile Gene Targeting Genes Genetic Genetic Transcription Genome Helper-Inducer T-Lymphocyte Histone Acetylation Histone Deacetylase Inhibitor Human Immune Evasion Immunocompetent In Vitro Induced Mutation Isogenic transplantation Lead Lymphoma Lymphomagenesis MHC Class II Genes MHC class II transactivator protein Malignant Neoplasms Measures Mediating Memory Modeling Modification Mus Mutation Non-Hodgkin&apos s Lymphoma Oncogenes Oncogenic Patient Care Pattern Phenotype Play Process Production Proteins Public Health Recruitment Activity Recurrent disease Relapse Role Stem cells Structure of germinal center of lymph node T cell response T-Cell Activation T-Lymphocyte Testing Time Transactivation Transgenic Mice Transgenic Organisms Validation Work YY1 Transcription Factor cytokine differentiated B cell effective therapy epigenetic drug epigenetic regulation experimental study genetic signature histone acetyltransferase in vivo in vivo Model inhibitor/antagonist insight mouse model mutant neoplastic cell novel overexpression programs promoter therapeutic target transcription factor tumor tumor microenvironment

项目摘要

Project Summary / Abstract Follicular lymphoma (FL) is an incurable malignancy of germinal center B-cells, in which sequential relapses originate from a tumor cell progenitor with a small number of genetic alterations. We recently defined inactivating mutations of a histone acetyltransferase gene, CREBBP, as an early event in disease genesis following translocation of the BCL2 oncogene. CREBBP inactivation in primary FL tumors silenced a germinal center B- cell transcriptional program that was significantly enriched for genes involved in antigen presentation on MHC class II and targets of the YY1 transcription factor. Reduced antigen presentation was associated with a decreased ability of tumor cells to activate CD4 T-cell proliferation and a reduced number of T-cells within the tumor microenvironment. CREBBP epigenetically regulates gene expression via histone acetylation that is directed via interactions with transcription factors such as CIITA, a central regulator of MHC class II gene expression, and YY1, a key regulator of germinal center B-cell development. We therefore hypothesize that inactivating mutations of CREBBP plays dual roles in promoting lymphomagenesis by driving immune evasion via decreased antigen presentation, and by deregulating B-cell development to allow stalling at the germinal center B-cell stage. To investigate this, we have developed in vitro and in vivo models of CREBBP inactivation using CRISPR-modification of lymphoma cell lines and transgenic mouse models, respectively. Importantly, CRISPR-modified cell lines recapitulate the phenotype of reduced MHC class II expression observed in primary FL tumors, and transgenic mouse models develop FL-like tumors when Crebbp is deleted and Bcl2 is over- expressed specifically within B-cells. We will use these models, in parallel with primary human tumors, to explore the hypothesized mechanistic roles of CREBBP inactivation in lymphomagenesis. Specifically, we will evaluate the capacity for CREBBP inactivation to reduce antigen presentation on MHC class II, and measure the effect that this has on T-cell responses in vitro and in vivo. In addition, we will investigate the role of CREBBP inactivation in reducing the expression of germinal center B-cell genes that are regulated by the YY1 transcription factor, and determine whether this leads to stalled differentiation at the germinal center B-cell stage in vivo using transgenic mouse models. We further hypothesize that these phenotypes are driven by epigenetic alterations, and may therefore potentially be corrected using epigenetic modifying drugs. We will therefore investigate the potential for HDAC inhibitors and EZH2 inhibitors to restore antigen presentation and associated T-cell responses, and to reestablish normal epigenetic and transcriptional programs of B-cell development. Together this work will provide validation for CREBBP inactivation as a key event in the development of FL, define the mechanism by which these genetic events contribute to immune evasion and deregulated B-cell development, and evaluate the use of epigenetic modifying compounds for counteracting these features of CREBBP inactivation. This will contribute important advances in the understanding and treatment of FL.

项目概要/摘要滤泡性淋巴瘤 (FL) 是一种无法治愈的生发中心 B 细胞恶性肿瘤，会连续复发起源于具有少量遗传改变的肿瘤细胞祖细胞。我们最近定义了失活组蛋白乙酰转移酶基因 CREBBP 的突变是疾病发生的早期事件 BCL2 癌基因易位。原发性 FL 肿瘤中 CREBBP 失活沉默了生发中心 B- 参与 MHC 抗原呈递的基因显着富集的细胞转录程序 YY1 转录因子的 II 类和靶标。抗原呈递减少与肿瘤细胞激活 CD4 T 细胞增殖的能力下降，并且肿瘤细胞内 T 细胞数量减少肿瘤微环境。 CREBBP 通过组蛋白乙酰化来表观遗传调节基因表达，即通过与 CIITA（MHC II 类基因的中央调节因子）等转录因子的相互作用进行调控表达，以及 YY1，生发中心 B 细胞发育的关键调节因子。因此我们假设 CREBBP 失活突变通过驱动免疫逃避在促进淋巴瘤发生中发挥双重作用通过减少抗原呈递，并解除 B 细胞发育的管制，使生发细胞停滞中心B细胞阶段。为了研究这一点，我们开发了 CREBBP 失活的体外和体内模型分别使用淋巴瘤细胞系和转基因小鼠模型的 CRISPR 修饰。重要的是， CRISPR 修饰的细胞系重现了原代细胞中观察到的 MHC II 类表达减少的表型当 Crebbp 被删除且 Bcl2 过度表达时，FL 肿瘤和转基因小鼠模型会形成 FL 样肿瘤。在 B 细胞内特异性表达。我们将使用这些模型，与原发性人类肿瘤并行，来探索 CREBBP 失活在淋巴瘤发生中的假设机制作用。具体来说，我们将评估 CREBBP 失活减少 MHC II 类抗原呈递的能力，并测量效果这对体外和体内 T 细胞反应都有影响。此外，我们将研究CREBBP的作用失活可减少受 YY1 转录调节的生发中心 B 细胞基因的表达因子，并使用以下方法确定这是否会导致体内生发中心 B 细胞阶段的分化停滞转基因小鼠模型。我们进一步假设这些表型是由表观遗传改变驱动的，因此可能会使用表观遗传修饰药物来纠正。因此，我们将调查 HDAC 抑制剂和 EZH2 抑制剂恢复抗原呈递和相关 T 细胞的潜力反应，并重建 B 细胞发育的正常表观遗传和转录程序。一起这项工作将为 CREBBP 失活作为 FL 发展中的关键事件提供验证，定义这些遗传事件导致免疫逃避和 B 细胞发育失调的机制，并评估使用表观遗传修饰化合物来抵消 CREBBP 的这些特征失活。这将有助于对 FL 的理解和治疗取得重要进展。