Mechanisms of c-CBL Regulation in Cutaneous T-Cell Lymphoma (CTCL)

c-CBL 在皮肤 T 细胞淋巴瘤 (CTCL) 中的调节机制

• 批准号: 9242573
• 负责人: GARY S WOOD
• 金额: $ 16.64万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9242573
• 关键词: Address; Aneuploidy; Apoptosis; Apoptotic; Attention; B-Cell Lymphomas; Binding; Cell Death; Cells; Cessation of life; Chromosome abnormality; Chromosomes, Human, Pair 11; Chronic; Cutaneous; Cutaneous Involvement; DNA; DNA Methylation; Data; Data Aggregation; Defect; Dermatologic; Dermatology; Development; Epigenetic Process; Exhibits; Exons; Family; Gatekeeping; Gene Abnormality; Gene Expression; Genes; Genetic; Genetic Transcription; Goals; Histone Acetylation; Human; In Vitro; Investigation; Journals; Lead; Ligands; Lymphoma; Malignant - descriptor; Maps; Messenger RNA; Methotrexate; Methylation; Mutation; Nodal; Oncogenic; Pathogenesis; Patients; Play; Prevention; Process; Protein Overexpression; Proteins; Published Comment; Publishing; Receptor Activation; Receptor Signaling; Regulation; Research; Resistance; Role; Sampling; Small Interfering RNA; Somatic Mutation; Structural defect; T-Cell Lymphoma; T-Cell Receptor; T-Lymphocyte; Testing; TimeLine; Tumor Necrosis Factor Ligand Superfamily Member 6; Tumor Suppressor Genes; Up-Regulation; Ursidae Family; Work; base; demethylation; design; diagnostic assay; experimental study; follow-up; histone methylation; improved; insertion/deletion mutation; insight; knock-down; leukemia; novel; novel diagnostics; novel strategies; novel therapeutics; outcome prediction; overexpression; preclinical study; promoter; public health relevance; receptor; response; restoration; screening; skin disorder; transcription factor; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Casitas B-lineage lymphoma (CBL) proteins belong to a family of E3 ubiquitin ligases with oncogenic potential. In human T cells, they work as important gatekeeper components for T-cell receptor (TCR) activation and subsequent activation-induced cell death (AICD). AICD is a process of apoptosis that is triggered by the death receptor/ligand pair: FAS/FAS-ligand (FASL). Lack of FASL expression blocks the AICD apoptosis cascade even in FAS-high cells. Previously, we and others documented low FAS expression in the majority of cases of cutaneous T-cell lymphoma (CTCL). In keeping with its role as a tumor suppressor gene, we found that FAS was silenced by methylation of its promoter and that it can be upregulated by DNA demethylation. We also showed that FASL is generally not expressed by CTCL cells. In contrast to normal T cells, CTCL cells do not upregulate FASL in response to TCR engagement. While investigating this abnormality, we found that over- expressed c-CBL protein plays a key role in inhibiting FASL expression and contributing to resistance to AICD. We showed that c-CBL is over-expressed in most cases of CTCL compared to normal T cells. When c-CBL is reduced by siRNA treatment, TCR signaling cascades are restored, FASL expression is upregulated and CTCL cells undergo massive apoptosis as long as FAS expression is adequate. When FAS expression is inadequate, demethylating agents such as methotrexate can increase FAS and render cells sensitive to apoptosis. This groundbreaking work provided important insights into the correction of apoptotic defects in CTCL and was published in the Journal of Investigative Dermatology (135: 861-8, 2015) [1] and highlighted by an accompanying editorial comment. Our findings suggest that over-expressed c-CBL plays a key role in the pathogenesis of CTCL by blocking AICD. Therefore, it is critical to extend our research to elucidate the mechanisms underlying c-CBL over-expression. Our preliminary data suggest that c-CBL is transcriptionally regulated. CTCL lines and malignant T cells from CTCL patients have shown karyotypic abnormalities involving chromosome 11 which contains the c-CBL gene. Based on our preliminary findings, we hypothesize that c-CBL over-expression in CTCL is caused by structural abnormalities and/or epigenetic dysregulation of the c-CBL gene. To test this hypothesis, we will conduct experiments incorporated into two specific aims: 1) To determine whether structural abnormalities of the c-CBL gene result in c-CBL protein over-expression in CTCL; and 2) To determine whether epigenetic dysregualtion of the c-CBL gene results in c-CBL protein over- expression in CTCL. This project is a novel investigation of c-CBL regulatory mechanisms in the context of deficient FASL expression and associated apoptotic blockade in CTCL. These studies have strong translational significance. In addition to their potential for novel diagnostic assays, they will allow new prevention and treatment approaches targeting c-CBL for restoration of apoptosis in CTCL.

 描述(申请人提供)：酪蛋白B系淋巴瘤(CBL)蛋白属于具有致癌潜力的E3泛素连接酶家族。在人类T细胞中，它们是T细胞受体(TCR)激活和随后的激活诱导细胞死亡(AICD)的重要把关组件。AICD是一个由死亡受体/配体对：Fas/Fas配体(FASL)触发的细胞凋亡过程。缺乏FASL的表达阻碍了AICD的凋亡级联反应，即使在Fas高表达的细胞中也是如此。以前，我们和其他人记录了大多数皮肤T细胞淋巴瘤(CTCL)病例中Fas的低表达。与其作为肿瘤抑制基因的作用一致，我们发现Fas通过其启动子的甲基化而沉默，而它可以通过DNA去甲基化而上调。我们还发现，FASL在CTCL细胞中一般不表达。与正常T细胞不同，CTCL细胞不会因TCR的参与而上调FASL。在研究这种异常时，我们发现过表达的c-CBL蛋白在抑制FASL表达和对AICD的抵抗中起着关键作用。我们发现，与正常T细胞相比，c-CBL在大多数CTCL病例中过度表达。当c-CBL被siRNA处理后，TCR信号级联被恢复，FASL表达上调，只要Fas表达充足，CTCL细胞就会经历大量的凋亡。当Fas表达不足时，甲氨蝶呤等去甲基化药物可以增加Fas，使细胞对凋亡敏感。这项开创性的工作为纠正CTCL的凋亡缺陷提供了重要的见解，并发表在《调查皮肤病学杂志》(135：861-8,2015)[1]上，并由随附的编辑评论重点介绍。我们的研究结果表明，c-CBL的过度表达通过阻断AICD在CTCL的发病机制中起关键作用。因此，我们的研究对于阐明c-CBL过表达的机制是至关重要的。我们的初步数据表明，c-CBL是转录调控的。来自CTCL患者的CTCL株和恶性T细胞显示出核型异常，涉及含有c-CBL基因的11号染色体。根据我们的初步发现，我们假设c-CBL在CTCL中的过度表达是由c-CBL基因的结构异常和/或表观遗传失调引起的。为了验证这一假设，我们将进行两个特定目的的实验：1)确定c-CBL基因的结构异常是否导致CTCL中c-CBL蛋白的过度表达；2)确定c-CBL基因的表观遗传异常是否导致CTCL中c-CBL蛋白的过度表达。这个项目是在CTCL中FASL表达不足和相关的凋亡阻断的背景下对c-CBL调控机制的新的研究。这些研究具有很强的翻译意义。除了它们在新诊断方面的潜力之外 通过检测，他们将允许针对c-CBL的新的预防和治疗方法，以恢复CTCL的凋亡。