EPHB2-Dependent Signaling: A New Molecular Paradigm in Barrett's Neoplasia

项目概要/摘要 Barrett食管（BE）是一种远端食管的分子复杂疾病，其病因仍然是 难以捉摸。BE患者发生食管腺癌（EAC）的风险增加， 越来越普遍，是美国最常见的食管恶性肿瘤。我们的长期目标是 确定BE发病和恶性进展的致病机制，并制定 循证生物标志物和化学预防/治疗策略，用于后续临床实施。 本项目的项目3是基于我们最近发现的EphB 2受体酪氨酸激酶作为一种新的 巴雷特瘤形成的促进者在初治患者中进行RNA测序和通路建模 活组织检查显示在绝大多数（>90%）BE和EAC中EphB 2信号传导显著超活化 病变体外和体内的表型评估证明EphB 2信号传导对于EphB 2的表达是必需的。 EAC和异型增生/BE细胞的活力。随后的机制研究将c-MYC确定为一种新的靶点， EphB 2信号传导，而食管祖细胞的单细胞RNA测序进一步证实了EphB 2信号传导的强表达。 EphB 2活化与柱状/BE样细胞谱系的关联。总的来说，我们的研究表明EphB 2 EphB 2和MYC在BE-EAC发病机制中的首次发现，并进一步揭示了EphB 2和MYC之间的新联系。 任何疾病背景。扩展这些挑衅性的发现，我们现在建议充分表征生物学 EphB 2在Barrett瘤形成中的作用如下：在目标1中，我们将确定EphB 2激活是否是一种免疫抑制剂。 柱状/BE化生发展的结果或先决条件。我们将测试是否激活 推定的BE祖细胞中的EphB 2信号传导促进柱状/BE样转化状态。在目标2中，我们 确定EphB 2在食管中体内激活的病理后果，使用组成型- 活性EphB 2激酶（Ephb 2F 613 D）小鼠模型。我们将专门测试EphB 2 激活诱导食管中的BE样化生和异型增生/癌症;自发地，或在 暴露于反流损伤和/或在食管炎症的情况下。我们将进一步描述这把钥匙 食管中EphB 2激活破坏的分子程序。在目标3中，我们将确定 和EphB 2信号传导的上游调节级联。总的来说，我们提出的研究将描绘出 EphB 2信号转导的研究，揭示了BE-EAC发病机制的新驱动机制。

PROJECT SUMMARY/ABSTRACT The etiology of Barrett's esophagus (BE), a molecularly complex disorder of the distal esophagus, remains elusive. Patients with BE are at an increased risk of developing esophageal adenocarcinoma (EAC), a lethal, increasingly prevalent, and the most common esophageal malignancy in the U.S. Our long-term objective is to identify the causative mechanisms underlying the onset and malignant progression of BE, and to develop evidence-based biomarkers and chemopreventive/therapeutic strategies for subsequent clinical implementation. Project 3 of this program is based on our recent discovery of EphB2 Receptor Tyrosine Kinase as a novel promoter of Barrett's neoplasia. RNA sequencing coupled with pathway modeling in treatment-naïve patient biopsies showed significant hyperactivation of EphB2 signaling in the vast majority (>90%) of BE and EAC lesions. Phenotypic assessments in vitro and in vivo demonstrated EphB2 signaling to be essential for the viability of EAC and dysplastic/BE cells. Subsequent mechanistic studies identified c-MYC as a novel target of EphB2 signaling, while single-cell RNA sequencing of esophageal progenitor cells further confirmed a strong association of EphB2 activation with columnar/BE-like cell lineage. Collectively, our study implicates EphB2 signaling for the first time in BE-EAC pathogenesis, and further reveals a novel link between EphB2 and MYC in any disease context. Expanding on these provocative findings, we now propose to fully characterize the biologic role of EphB2 in Barrett's neoplasia as follows: In Aim 1, we will determine whether EphB2 activation is a consequence of, or a pre-requisite for, columnar/BE metaplasia development. We will test whether activation of EphB2 signaling in putative BE-progenitor cells promote columnar/BE-like transformative state. In Aim 2, we will determine the pathologic consequences of EphB2 activation in vivo in the esophagus, using a constitutively- active EphB2 kinase (Ephb2F613D) mouse model that we recently developed. We will specifically test if EphB2 activation induces BE-like metaplasia and dysplasia/cancer in the esophagus; either spontaneously, or upon exposure to reflux injury, and/or in the setting of esophageal inflammation. We will further characterize the key molecular programs disrupted by EphB2 activation in the esophagus. In Aim 3, we will determine the downstream and upstream regulatory cascades of EphB2 signaling. Collectively, our proposed studies will delineate the role of EphB2 signaling for the first time, uncovering novel driver mechanisms of BE-EAC pathogenesis.