PMLRARalpha and PML directly regulate Fas-mediated apoptosis in vivo

PMLRARα 和 PML 直接调节体内 Fas 介导的细胞凋亡

• 批准号: 8100046
• 负责人: FELIPE SAMANIEGO
• 金额: $ 20.62万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8100046
• 关键词: Acute Promyelocytic Leukemia; Apoptosis; Apoptotic; Arsenic Trioxide; Attention; Binding; Binding Proteins; Boxing; Cell Line; Cells; Cessation of life; Chimeric Proteins; Complex; Development; Dominant-Negative Mutation; Genetic Transcription; Hematologic Neoplasms; Lymphocyte; Malignant Neoplasms; Maps; Mediating; Mus; Nuclear; Patients; Prevention; Proteins; Receptor Signaling; Regulation; Retinoic Acid Receptor; Role; Signal Transduction; Site; System; Testing; Therapeutic; Tretinoin; Tumor Necrosis Factor Ligand Superfamily Member 6; Tumor Suppressor Proteins; Xenograft procedure; cancer cell; cancer therapy; caspase-8; cell injury; chemotherapy; effective therapy; in vivo; inhibitor/antagonist; irradiation; prevent; pro-caspase-8; receptor; restoration; retinoic acid receptor alpha; transcription factor PML

DESCRIPTION (provided by applicant): The promyelocytic leukemia (PML)/retinoic acid receptor (RAR) alpha fusion protein (PMLRAR?) is at the center of regulation of receptor signaling, nuclear transcription, and cancer development. PMLRAR? has been implicated in regulating death receptor signaling and apoptosis through dominant-negative effects on nuclear transcription. PML is a tumor suppressor known to stimulate apoptosis and is one of the most commonly defective (>60%) in cancers. Thus, restoration of PML function in cancer would be an effective therapy. If direct effects of PMLRAR? and PML on Fas death receptor-mediated apoptosis were to be established, this would represent a breakthrough in understanding apoptosis regulation and may open new possibilities for cancer therapy. We screened hematopoietic cancer cells for potential Fas binding inhibitors and identified PML as such a protein. Given the pro-apoptotic role of PML and pro-survival role of PMLRAR?, we tested whether PMLRAR? blocked Fas-mediated apoptosis. In preliminary studies, PMLRAR? blocked apoptosis induced by Fas ligand (FasL). PMLRAR? interacted with Fas in acute promyelocytic leukemia cells isolated directly from patients. PMLRAR? -expressing U937/PR9 cells bound cFLIP and excluded procaspase 8 in the death-induced signaling complex (DISC); thus, activation of caspase 8 was blocked. Also, knockdown of PMLRAR? in NB4 cells sensitized these cells to Fas-mediated apoptosis. Our hypothesis is that PMLRAR? diverts Fas signaling to a non-apoptosis endpoint. The results of the proposed studies will have significant implications for all cancers because PMLRAR? counters the effects of PML in apoptosis regulation. By demonstrating a direct interaction of PML and PMLRAR? with Fas, we will reveal a new target for apoptosis regulation that can be exploited for preventing and treating the many cancers that have defective PML function. PUBLIC HEALTH RELEVANCE: The Fas system is an important cell elimination system that has several established functions, including the elimination of autoreactive lymphocytes, infected and defective cells, and cells damaged by chemotherapy and irradiation. We have identified promyelocytic leukemia protein-retinoic acid receptor as a Fas-binding protein and potential key regulator of Fas signaling. This project will characterize the binding of PML with Fas and demonstrate how Fas is regulated in acute promyelocytic leukemia cells and in mice; thus, by showing the pivotal site of regulation, we will be able to identify a therapeutic approach for the vast majority of cancers that have defective promyelocytic leukemia protein and restore apoptosis signaling.

描述(申请人提供)：早幼粒细胞白血病(PML)/维甲酸受体(RAR)α融合蛋白(PMLRAR？)处于受体信号、核转录和癌症发展的调节中心。PMLRAR？通过对核转录的显性-负性作用，参与调节死亡受体信号和细胞凋亡。PML是一种已知的能刺激细胞凋亡的肿瘤抑制因子，是癌症中最常见的缺陷之一(&gt；60%)。因此，恢复肿瘤的PML功能将是一种有效的治疗方法。如果PMLRAR的直接影响？而PML在Fas死亡受体介导的细胞凋亡中的建立，将代表着对细胞凋亡调控的认识上的突破，并可能为肿瘤的治疗开辟新的可能性。我们对造血癌细胞进行了潜在的Fas结合抑制物筛选，并确定PML就是这样一种蛋白质。鉴于PML的促凋亡作用和PMLRAR？的促生存作用，我们测试了PMLRAR？阻断Fas介导的细胞凋亡。在初步研究中，PMLRAR？阻断Fas配体(FasL)诱导的细胞凋亡。PMLRAR？直接从患者体内分离的急性早幼粒细胞白血病细胞与Fas相互作用。表达pMLRAR？的U937/PR9细胞结合cFlIP并排除死亡诱导信号复合体(DISC)中的原天冬氨酸蛋白酶8，从而阻断caspase8的激活。还有，PMLRAR的击倒？NB4细胞使这些细胞对Fas介导的细胞凋亡敏感。我们的假设是PMLRAR？将Fas信号转移到非凋亡终点。拟议的研究结果将对所有癌症产生重大影响，因为PMLRAR？对抗PML在细胞凋亡调控中的作用。通过演示PML和PMLRAR的直接相互作用？通过Fas，我们将揭示一个新的细胞凋亡调控靶点，可用于预防和治疗许多具有PML功能缺陷的癌症。 公共卫生相关性：Fas系统是一种重要的细胞清除系统，具有多种既定功能，包括清除自身反应性淋巴细胞、感染和缺陷细胞以及化疗和放射损伤的细胞。我们已经确定早幼粒细胞白血病蛋白-维甲酸受体是一种Fas结合蛋白，也是Fas信号的潜在关键调节因子。这个项目将描述PML与Fas的结合，并展示Fas在急性早幼粒细胞白血病细胞和小鼠中是如何调控的；因此，通过展示调控的关键部位，我们将能够确定一种治疗绝大多数具有缺陷的早幼粒细胞白血病蛋白的癌症的方法，并恢复凋亡信号。