Regulation of repetitive elements in cancer by P53 and epigenetic mechanisms

P53 和表观遗传机制对癌症中重复元件的调节

基本信息

批准号：
10609861
负责人：
Katherine B Chiappinelli
金额：
$ 36.38万
依托单位：
GEORGE WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-04-14 至 2026-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10609861
关键词：
Affect Antigen Presentation Antigens Apoptosis Basic Science Binding Binding Sites CD8-Positive T-Lymphocytes Cancer Patient Cancer cell line Cell Cycle Cell Cycle Regulation Cell Line Cells Chromatin Clinical Clinical Trials Clustered Regularly Interspaced Short Palindromic Repeats Combined Modality Therapy DNA Binding Domain DNA Methylation Data Disease Double-Stranded RNA Engineering Epigenetic Process Exhibits Future Genes Genetic Transcription Histone Deacetylase Inhibitor Human Human Genome Immune Immune Evasion Immune response Immune signaling Immune system Immunosuppression Immunotherapy Infiltration Interferons Libraries Lymphocyte Malignant Neoplasms Malignant neoplasm of ovary Methylation Missense Mutation Modification Mutate Mutation Oncogenic Outcome Patients Peptides Primary Neoplasm Production Proteins Proteomics Publishing Regulation Repetitive Sequence Research Role Sampling Serous Signal Transduction T cell response T cell therapy T-Lymphocyte TP53 gene Testing Time Tissues Transcript Transcriptional Regulation Transcriptional Silencer Elements Translating Tumor Antigens Tumor Burden Tumor-Infiltrating Lymphocytes Work anti-PD-1 antigen-specific T cells cancer cell cancer subtypes cell type chromatin immunoprecipitation demethylation epigenetic regulation epigenetic therapy gain of function immune checkpoint blockade immunotherapy clinical trials improved outcome inhibitor innovation mouse model mutant neoantigens novel novel therapeutics prevent recruit response targeted treatment transcriptome sequencing tumor tumor microenvironment

项目摘要

Despite focused research efforts, the five year survival for ovarian cancer (OC) has remained unchanged for decades and novel therapies are urgently needed for this deadly disease. Therapies that activate the immune system to kill cancer cells, including anti-PD-1 checkpoint blockade therapy, have shown vigorous and durable responses, but the majority of patients, including those with OC, fail to respond. The underlying mechanism remains unclear. Repetitive elements (REs) comprise the majority (45%) of the human genome. In most somatic tissues, REs are silenced by DNA methylation and other epigenetic modifications to prevent their transcription. We demonstrated that treating OC cells with DNA methylation inhibitors (DNMTis) and histone deacetylase inhibitors (HDACis) increases immune signaling from tumors through demethylation of REs and production of RE double-stranded RNA to activate the interferon response. This signaling recruits CD8+ T cells to sensitize tumors to anti-PD-1 immunotherapy. REs translate proteins that can be targeted as tumor-associated antigens. Thus RE activation both promotes interferon signaling to reverse the immune- suppressive tumor microenvironment and presents potential tumor-specific antigens as T cell targets. The premise of this proposal is that P53 and epigenetic mechanisms regulate REs in cancer and thus mutant TP53 will affect immune signaling and response to epigenetic and immune therapy. Approximately half of all cancers have mutations in TP53, the gene encoding the P53 protein, 90% of which are “hotspot” mutations located in the DNA binding domain. These missense mutations encode functional proteins with reduced transcriptional activity at canonical cell cycle target genes that may also exhibit oncogenic gain of function transcriptional activity at new targets. High grade serous OC makes up about 70% of all cases and is characterized by nearly 100% mutant TP53. While the critical role of P53 in cell cycle regulation and apoptosis is known, P53 regulation of REs in cancer remains poorly defined. Approximately 30% of P53 binding sites are found in REs and our preliminary data show that P53 binds directly to REs. Further, we show that P53 hotspot mutant cell lines treated with DNMTi/HDACi exhibit significantly increased chromatin accessibility at REs and transcription of REs compared to TP53 wild type cell lines. We hypothesize that mutant P53 aberrantly activates REs, amplifying the RE-induced immune response. We will test this hypothesis via the following aims: In Aim 1, we will determine how wild type and mutant TP53 regulate REs to affect the DNMTi/HDACi-induced interferon response. In Aim 2, we will determine how p53 status affects the DNMTi/HDACi-induced T cell response and sensitization to immune therapy in a mouse model of OC and a clinical trial of OC patients treated with immunotherapy. In Aim 3, we will evaluate REs as tumor antigens in different P53 backgrounds. Results of this innovative work will answer novel basic science questions about REs and P53 and open new directions for epigenetic and immune therapy in OC.

尽管进行了重点研究工作，但卵巢癌（OC）的五年生存仍然存在数十年来不变，这种致命疾病迫切需要新的疗法。疗法激活免疫系统以杀死癌细胞，包括抗PD-1检查点阻断疗法，已显示有力且耐用的反应，但是大多数患者，包括患有OC的患者，都无法反应。这基本机制尚不清楚。重复元素（RES）占人类的大多数（45％）基因组。在大多数体细胞组织中，RES被DNA甲基化和其他表观遗传学修饰沉默防止其转录。我们证明了用DNA甲基化抑制剂（DNMTIS）处理OC细胞组蛋白脱乙酰基酶抑制剂（HDACIS）通过脱甲基来增加肿瘤的免疫信号传导 RES和RE双链RNA的生产以激活干扰素反应。此信号报告 CD8+ T细胞将肿瘤感知到抗PD-1免疫疗法。重新翻译可以针对的蛋白质肿瘤相关的抗原。重新激活两者都促进了干扰素信号传导以逆转免疫抑制性肿瘤微环境并将潜在的肿瘤特异性抗原作为T细胞靶标。该提议的前提是p53和表观遗传机制在癌症中调节RES，因此突变TP53将影响免疫信号传导以及对表观遗传和免疫治疗的反应。大约一半在所有癌症中，在TP53中都有突变，编码p53蛋白的基因，其中90％是“热点” 位于DNA结合结构域中的突变。这些错义突变与在规范细胞周期靶基因上降低了转录活性，这也可能表现新目标的功能转录活动。高级浆液OC占所有情况的70％，IS 以接近100％突变体TP53为特征。而p53在细胞周期调节和凋亡中的关键作用众所周知，癌症中RES的p53调节仍然很差。大约30％的p53结合位点是在RES中发现，我们的初步数据表明p53直接与RES结合。此外，我们表明p53热点用DNMTI/HDACI处理的突变细胞系暴露于RES和与TP53野生型细胞系相比，RES的转录。我们假设突变体p53异常激活RES，扩大重新诱导的免疫反应。我们将通过以下目的检验该假设：在AIM 1中，我们将确定野生类型和突变体的方式 TP53调节RES以影响DNMTI/HDACI诱导的干扰素反应。在AIM 2中，我们将确定如何 p53状态影响DNMTI/HDACI诱导的T细胞反应和对小鼠免疫治疗的敏感性 OC模型和通过免疫疗法治疗的OC患者的临床试验。在AIM 3中，我们将评估RES 不同p53背景的肿瘤抗原。这项创新工作的结果将回答新颖的基础科学关于RES和P53以及OC中表观遗传和免疫治疗的新方向的问题。