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

基本信息

批准号：
8245030
负责人：
FELIPE SAMANIEGO
金额：
$ 17.18万
依托单位：
UNIVERSITY OF TX MD ANDERSON CAN CTR
依托单位国家：
美国
项目类别：
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

项目摘要

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（由申请人提供）：临床细胞白血病（PML）/视黄酸受体（RAR）α融合蛋白（PMLRAR？）是受体信号传导，核转录和癌症发展的中心。 pmlrar？通过对核转录的显性阴性作用来调节死亡受体信号传导和凋亡。 PML是已知刺激凋亡的肿瘤抑制剂，是癌症中最常见的（> 60％）的肿瘤抑制剂。因此，癌症中PML功能的恢复将是一种有效的疗法。如果PMLRAR的直接影响？在FAS死亡受体介导的凋亡中的PML和PML将建立，这将是理解凋亡调节的突破，并可能为癌症治疗开辟新的可能性。我们筛选了造血癌细胞的潜在FAS结合抑制剂，并将PML鉴定为这种蛋白质。鉴于PML的促凋亡作用和PMLRAR的亲源作用？我们测试了PMLRAR是否？阻塞FAS介导的细胞凋亡。在初步研究中，PMLRAR？ FAS配体（FASL）诱导的凋亡阻塞。 pmlrar？与直接从患者中直接分离的急性前临床白血病细胞中与FAS相互作用。 pmlrar？ - 表达U937/PR9细胞在死亡诱导的信号传导复合物（DISC）中结合CFLIP并排除了procaspase 8；因此，caspase 8的激活被阻断。另外，击倒PMLRAR？在NB4细胞中，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。拟议研究的结果将对所有癌症都具有重大影响，因为PMLRAR？反调用PML在凋亡调节中的影响。通过证明PML和PMLAR的直接相互作用？使用FAS，我们将揭示一个新的细胞凋亡调节靶标，该目标可以用于预防和治疗许多具有缺陷PML功能的癌症。公共卫生相关性：FAS系统是一个重要的细胞消除系统，具有多种已建立的功能，包括消除自动反应性淋巴细胞，感染和缺陷的细胞以及通过化学疗法和辐照受损的细胞。我们已经确定了临时细胞性白血病蛋白 - 反毒酸受体是FAS结合蛋白和FAS信号传导的潜在关键调节剂。该项目将表征PML与FAS的结合，并证明在急性前临床白血病细胞和小鼠中如何调节FAS；因此，通过显示调节的关键部位，我们将能够鉴定出绝大多数具有有缺陷的临床前细胞性白血病蛋白和恢复凋亡信号传导的癌症的治疗方法。