Role of DDX3 in DR5-Mediated Apoptosis

DDX3 在 DR5 介导的细胞凋亡中的作用

• 批准号: 7908430
• 负责人: TONG ZHOU
• 金额: $ 20.49万
• 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/7908430
• 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或激动性抗体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。我们开发了一种激动性抗人 DR5 单克隆抗体 TRA-8。我们的临床前研究已在动物模型中证明了其强大的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 介导的细胞凋亡的预先存在的抵抗力和诱导的抵抗力都令人担忧。我们已经鉴定出 DEAD box 蛋白家族的 RNA 解旋酶 DDX3，它是调节 DR5 信号转导的关键接头蛋白，并在诱导 DR5 细胞凋亡抵抗中发挥致病作用。该提案的总体目标是检查 DDX3 在 DR5 介导的细胞凋亡抗性发展中的作用。核心假设是，DDX3 作为衔接蛋白，通过每个分子中的特定结合基序与 DR5 组成型相关。在其 N 末端附近，DDX3 通过两个分子之间的 CARD/CARD 相互作用招募 clAP1。因此，DR5/DDX3/clAP1 的默认功能是负向调节 DR5 介导的细胞凋亡。在 DR5 凋亡敏感细胞中，启动子 caspase 8 的激活导致 DDX3 在 aa135 处裂解，从而从 DR5/DDX3/clAP 复合物中释放 DDX3 的 N 端 CARD 和 clAP1，从而实现正反馈环路以放大凋亡信号。相反，在 DR5 抗凋亡细胞中，clAP1 募集的增加会导致 caspase 8 活性的抑制和 DDX3 裂解的失败，从而形成负反馈环以防止初始凋亡信号的放大。测试四个假设的目的是：1）DDX3 与 DR5 的关联是必不可少的； 2) DDX3的CARD募集的clAP1是启动DR5介导的细胞凋亡的关键抑制分子； 3) caspase 介导的 DDX3 裂解从 DR5 中释放 N 端 CARD，从而逆转耐药性； 4) DR5/DDX3/clAP1 复合物的中断可能会提高 TRA-8 和其他 DR5 靶向药物的治疗效果。拟议的研究将为 DDX3 在 DR-5 介导的细胞凋亡中的作用提供新的见解，并且还将对进一步开发增强 TRA-8 和其他激动性 DR5 抗体和 TRAIL 治疗功效的干预措施产生影响。