Novel Role of ThPOK in Mammary Carcinoma

项目总结/摘要 概述：鉴于HER 2+乳腺癌的发病机制， 大多数患者最终变得对包括抗HER 2疗法在内的治疗难治。在此我们 提供了将人类HER 2+乳腺癌的不良临床结局与存在以下因素联系起来的初步数据： 高细胞质水平的转录因子ThPOK（cytoThPOK）。此外，使用新的小鼠模型， 细胞质限制性ThPOK（ThPOKΔNLS小鼠），我们建立了细胞ThPOK之间的因果关系， 和高渗透性Her 2+乳腺癌的发展。小鼠乳腺癌细胞的蛋白质组学分析 表明cytoThPOK与Her 2信号传导中涉及的多种胞质蛋白相互作用，包括 几种可能与ThPOK中保守的富含脯氨酸基序结合的SH 3蛋白。由于核心作用， 在HER 2+乳腺癌生物学中，我们假设cytoThPOK与这些因子的相互作用 以某种方式增强HER 2介导的信号传导，这是乳腺癌的重要驱动因素 发展/进步，这是迄今为止被忽视的。 研究重点：POK转录因子与多种人类癌症有关， 被认为反映了对转录的直接影响。相反，我们现在暗示ThPOK的胞浆定位 在人类和小鼠的乳腺癌中，证明了POK介导的肿瘤发生的新模式， 核功能。这些发现为拟议的研究提供了一个创新和令人信服的前提。 具体目的：我们将根据3个目的阐明cytoThPOK在乳腺癌中的作用：SA-1： 阐明ThPOKΔ NLS介导的肿瘤发生的分子基础-以测试cytoThPOK对 细胞系中HER 2/EGFR表达和信号传导，并测试ThPOK SH 3相互作用的要求 cytoThPOK介导的小鼠乳腺癌。SA-2：解剖预后价值和分子 人BC中ThPOK细胞质定位的基础-评估高水平ThPOK与细胞质定位之间的相关性 cytoThPOK和生存在不同的人类HER 2+乳腺癌亚型，并确定分子基础 用于ThPOK在人乳腺癌细胞中的细胞质定位。SA-3：阐明cytoThPOK的作用 BC肿瘤维持-阐明肿瘤维持/进展是否需要cytoThPOK 从ThPOKΔNLS小鼠建立的癌症，并表征一种新的人源化ThPOK小鼠模型， H22 pTfs *6等位基因的变体。 影响：鉴于在具有强化细胞质ThPOK定位的小鼠中观察到的癌症发病率高， 和人HER 2+乳腺癌患者中细胞质ThPOK定位的高频率，阐明了 cytoThPOK促进乳腺癌的分子基础可能对人类具有高度影响， 健康在这里，我们联合收割机新的动物模型和分子方法来阐明这些机制。 这些研究有能力改变POK因素的基本概念框架 促进肿瘤发生。阐明这些机制可能会导致新的治疗方法 靶向HER 2+乳腺癌和其他可能涉及cytoThPOK的人类恶性肿瘤。

PROJECT SUMMARY/ABSTRACT Overview: There is an urgent need to understand the molecular basis of HER2+ breast cancer, given that the majority of patients eventually become refractory to treatment including with anti-HER2 therapy. Herein, we provide preliminary data linking poor clinical outcome of human HER2+ breast cancers with the presence of high cytoplasmic levels of the transcription factor ThPOK (cytoThPOK). Further, using a novel mouse model of cytoplasmically restricted ThPOK (ThPOKΔNLS mice), we establish a causal relationship between cytoThPOK and development of highly penetrant Her2+ breast cancer. Proteomic analysis of mouse breast cancer cells indicates that cytoThPOK interacts with multiple cytosolic proteins implicated in Her2 signaling, including several SH3 proteins that probably bind to a conserved proline-rich motif in ThPOK. Given the central role of HER2 signaling in HER2+ breast cancer biology, we hypothesize that cytoThPOK interaction with these factors enhances HER2-mediated signaling in some way, and that this represents an important driver of breast cancer development/progression, that has so far been overlooked. Research Focus: POK transcription factors have been implicated in diverse human cancers, which was presumed to reflect direct effects on transcription. In contrast, we now implicate cytosolic localization of ThPOK in breast cancer in humans and mice, demonstrating a novel mode of POK-mediated oncogenesis not based on nuclear function. These findings provide an innovative and compelling premise for the proposed studies. Specific Aims: We will elucidate the role of cytoThPOK in breast cancer according to 3 aims: SA-1: Elucidating molecular basis of ThPOKΔNLS–mediated oncogenesis - to test effect of cytoThPOK on HER2/EGFR expression and signaling in cell lines, and test the requirement for the ThPOK SH3-interaction domain for cytoThPOK-mediated breast cancer in mice. SA-2: Dissecting prognostic value and molecular basis for cytoplasmic localization of ThPOK in human BC - to evaluate correlation between high cytoThPOK and survival in different human HER2+ breast cancer subtypes, and determine the molecular basis for cytoplasmic localization of ThPOK in human breast cancer cells. SA-3: Elucidating effect of cytoThPOK on BC tumor maintenance - to elucidate whether cytoThPOK is required for tumor maintenance/progression of established cancers from ThPOKΔNLS mice, and characterize a new humanized ThPOK mouse model that expresses a variant hThPOKp.H22pTfs*6 allele found in some human breast cancer patients. Impact: Given the high incidence of cancer observed in mice with enforced cytoplasmic ThPOK localization and the high frequency of cytoplasmic ThPOK localization in human HER2+ breast cancer patients, elucidating the molecular basis by which cytoThPOK promotes breast cancer is likely to have high impact on human health. Here we combine novel animal models and molecular approaches to elucidate these mechanisms. These studies have the capacity to shift the basic conceptual framework by which POK factors are presumed to promote oncogenesis. Potentially, elucidating these mechanisms may lead to novel therapeutic approaches to target HER2+ breast cancer and other human malignancies in which cytoThPOK may be implicated.