Role of DDX3 in DR5-Mediated Apoptosis

DDX3 在 DR5 介导的细胞凋亡中的作用

• 批准号: 7667182
• 负责人: TONG ZHOU
• 金额: $ 20.06万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7667182
• 关键词: Adaptor Signaling Protein; Address; Animal Model; Antibodies; Apoptosis; Binding; Biological Markers; Biological Models; Boxing; Cancer Patient; Cancer cell line; Caspase; Caspase Inhibitor; Cells; Cessation of life; Clinical; Clinical Trials; Complex; Death Domain; Development; Dominant-Negative Mutation; Exhibits; Failure; Family; Feedback; Goals; Hepatocyte; Human; Human Genome; Interruption; Malignant Neoplasms; Mediating; Modeling; Monoclonal Antibodies; N-terminal; Phase I Clinical Trials; Play; Post-Translational Protein Processing; Predisposition; Protein Binding; Protein Family; RNA Helicase; RNA Interference; Recruitment Activity; Regulation; Research Personnel; Resistance; Resistance development; Role; Safety; Science; Signal Transduction; TNF-related apoptosis-inducing ligand; TNFRSF10A gene; TNFRSF10B gene; Testing; Therapeutic; Therapeutic Agents; Toxic effect; Treatment Efficacy; adapter protein; cancer cell; cancer therapy; caspase-3; caspase-8; chemotherapeutic agent; cytotoxicity; improved; insight; member; mimicry; neoplastic cell; nonhuman primate; novel; preclinical study; prevent; programs; receptor; receptor expression; resistance mechanism; response; small molecule; therapy development; tumor

DESCRIPTION (provided by applicant): The death receptor-induced apoptosis of tumor cells by TRAIL or agonistic antibodies is thought to be an important emerging strategy for cancer therapy. We have developed an agonistic anti-human DR5 monoclonal antibody, TRA-8. Our pre-clinical studies have demonstrated its strong anti-tumor efficacy and safety in animal models, and Phase I clinical trials are planned. However, both pre-existing and induced resistance of tumor cells to DR5-mediated apoptosis is a concern. We have identified a RNA helicase of the DEAD box protein family, DDX3, which serves as a critical adaptor protein in regulation of DR5 signaling transduction, and plays a causative role in induction of DR5 apoptosis resistance. The overall goal of this proposal is to examine the role of DDX3 in the development of resistance to DR5-mediated apoptosis. The central hypothesis is that DDX3, functioning as an adaptor protein, is constitutively associated with DR5 via a specific binding motif in each molecule. Near its N-terminus, DDX3 recruits clAP1 via a CARD/CARD interaction between the two molecules. Thus, a default function of the DR5/DDX3/clAP1 is to negatively regulate DR5-mediated apoptosis. In DR5 apoptosis sensitive cells, activation of the initiator caspase 8 leads to cleavage of DDX3 at aa135, which releases the N-terminal CARD of DDX3 and clAP1 from DR5/DDX3/clAP complex, thereby enabling a positive feedback loop to amplify apoptosis signal. In contrast, in DR5 apoptosis resistant cells, increased recruitment of clAP1 leads to inhibition of caspase 8 activity and failure of DDX3 cleavage, thereby forming a negative feedback loop to prevent amplification of the initial apoptosis signal. The Aims to test four hypotheses are: 1) that the association of DDX3 with DR5 is essential; 2) that the clAP1 recruited by a CARD of DDX3 is a key inhibitory molecule in the initiation of DR5-mediated apoptosis; 3) that the caspase-mediated cleavage of DDX3 releases the N-terminal CARD from DR5 thereby reversing the resistance; and 4) that the interruption of the DR5/DDX3/clAP1 complex may improve the therapeutic efficacy of TRA-8 and other DR5-directed agents. The proposed studies will provide novel insights into the role of DDX3 in DR-5 mediated apoptosis, and also will have implications for the further development of interventions to enhance the therapeutic efficacy of TRA-8 and other agonistic DR5 antibodies and TRAIL.

描述（由申请人提供）：通过TRAIL或激动抗体对死亡受体诱导的肿瘤细胞凋亡被认为是癌症治疗的重要新兴策略。我们已经开发了一种激动的抗人DR5单克隆抗体Tra-8。我们的临床前研究表明，其在动物模型中的强烈抗肿瘤功效和安全性，并计划进行I期临床试验。然而，肿瘤细胞对DR5介导的细胞凋亡的耐药性和诱导的耐药性是一个问题。我们已经鉴定出DDX3的Dead Box蛋白家族的RNA解旋酶，它是调节DR5信号转导调节的关键衔接蛋白，并在诱导DR5凋亡耐药性中起致病作用。该提案的总体目标是检查DDX3在对DR5介导的细胞凋亡抗性发展中的作用。中心假设是DDX3充当衔接蛋白，通过每个分子中的特定结合基序与DR5组成相关。 DDX3在其N末端附近，通过两个分子之间的卡/卡相互作用募集CLAP1。因此，DR5/DDX3/CLAP1的默认函数是负调节DR5介导的细胞凋亡。在DR5凋亡敏感细胞中，引发剂caspase 8的激活导致AA135处的DDX3裂解，从而释放了DDX3和Clap1的N末端卡中，从DR5/DDX3/CLAP CLAP复合物中释放了CLAP1，从而启用了阳性反馈回路以放大凋亡信号。相反，在DR5抗凋亡细胞中，增加CLAP1的募集会导致抑制caspase 8活性和DDX3裂解的失败，从而形成负反馈回路，以防止放大初始凋亡信号。检验四个假设的目的是：1）DDX3与DR5的关联至关重要； 2）DDX3卡募集的CLAP1是启动DR5介导的凋亡的关键抑制分子； 3）caspase介导的DDX3的切割可从DR5释放N末端卡，从而逆转电阻； 4）DR5/DDX3/CLAP1复合物的中断可以提高Tra-8和其他DR5定向剂的治疗功效。拟议的研究将为DDX3在DR-5介导的凋亡中的作用提供新的见解，并将对进一步发展干预措施产生影响，以增强Tra-8和其他激动的DR5抗体和TRAIL的治疗功效。