Integrated approach to study early and late events in colonic neoplasia: mouse to man

EGFR参与许多人类癌症的发病机制，包括结肠直肠癌（CRC），其 是美国第三大最常见的癌症和第三大癌症死亡原因， 男人和女人EGFR已成为许多癌症的主要治疗靶点。EGFR中和 单克隆抗体西妥昔单抗被批准用于治疗晚期CRC， 然而，只有15%的野生型KRAS CRC患者对西妥昔单抗有反应， 突变型KRAS CRC对西妥昔单抗无应答。我建议解决的癌症研究挑战是： 为什么EGFR阻断剂在CRC（和其他实体瘤）中具有如此温和的临床益处。我建议 不能更有效地阻断CRC中的EGFR至少部分地是由于三个问题：1）不完全的免疫抑制， 对EGFR信号传导的复杂性的理解由其七种哺乳动物配体触发; 2）不充分 预测性临床前模型和3）耐药性的出现。通过解决这三个问题 问题，这一修订后的应用程序的总体目标是显着推进诊断，治疗和 监测CRC患者。我们的重点是CRC，从膜近端的角度来看， EGFR相关事件。我们预计，我们所取得的进展将适用于其他实体瘤， EGFR信号传导起着重要作用。根据我们最近的发现，Egfr抑制剂Lrig 1标志着一种新的免疫抑制剂， 结肠干细胞的独特群体，并作为肿瘤抑制因子，沿着使用独特的报告基因 小鼠（Lrig 1-Apple，Egfr-EmGFP），我们建议将结肠肿瘤形成中的关键事件与干细胞和Egfr- 相关事件。我们的实验室已经开发了一个强大的结肠肿瘤模型：在诱导损失的50天内， 在表达Lrig 1的结肠干细胞中有一个Apc等位基因，则出现多发性高度发育异常的结肠腺瘤， 可以通过结肠镜检查和新型PET成像探头进行监测。这些小鼠将接受第一次 可用的小鼠Egfr中和抗体。小鼠腺瘤中的发现将与人类腺瘤相关。 使用MulltiOmyx和DISSECT，我们将在单细胞分辨率下检查肿瘤景观，并解构肿瘤细胞。 肿瘤异质性使用新开发的3D培养系统，我们发现了一种新的模式， 西妥昔单抗耐药通过增加WNT信号传导，由于长的共编码RNA的显著上调， 此前与CRC有关联。我们将进一步阐明这种抗性的机制，并提出这些 临床发现。我们将进一步研究EGFR及其配体通过外泌体的信号传导的新模式， 测试含有EGFR的外泌体是否作为诱饵以减少递送至 肿瘤的我们将利用范德比尔特大学、范德比尔特-英格拉姆癌症中心和 范德比尔特的GI专业研究卓越计划（SPORE），以推进这项工作。

The EGFR contributes to the pathogenesis of many human cancers, including colorectal cancer (CRC), which is the third most commonly diagnosed cancer and the third leading cause of cancer deaths in the US for both men and women. The EGFR has become a major therapeutic target in many cancers. The EGFR neutralizing monoclonal antibody, cetuximab, is approved for the treatment of advanced CRCs that contain wild-type KRAS; however, only 15% of individuals with wild-type KRAS CRC respond to cetuximab, and individuals with mutant KRAS CRC do not respond to cetuximab. The challenge in cancer research I propose to address is: why has EGFR blockade in CRC (and other solid tumors) had such modest clinical benefit. I propose that the inability to more effectively block the EGFR in CRC is due, at least in part, to three issues: 1) an incomplete understanding of the complexity of EGFR signaling triggered by its seven mammalian ligands; 2) inadequate predictive preclinical models and 3) the emergence of drug resistance. By addressing each of these three issues, the overall goal of this revised application is to significantly advance the diagnosis, treatment and monitoring of individuals with CRC. Our focus is CRC, viewed from the perspective of membrane-proximal EGFR-related events. We anticipate that advances we make will be applicable to other solid tumors in which EGFR signaling plays a prominent role. Based on our recent finding that the Egfr inhibitor, Lrig1, marks a distinct population of colonic stem cells and acts as a tumor suppressor, along with the use of unique reporter mice (Lrig1-Apple, Egfr-EmGFP), we propose to link key events in colonic neoplasia to stem cells and Egfr- related events. Our lab has developed a robust model of colonic neoplasia: within 50 days of inducing loss of one Apc allele in Lrig1-expressing colonic stem cells, multiple, highly dysplastic colonic adenomas arise that can be monitored by colonoscopy and novel PET imaging probes. These mice will be treated with the first available mouse Egfr neutralizing antibody. Findings in mouse adenomas will be related to human adenomas. Using MulltiOmyx and DISSECT, we will examine the tumor landscape at single cell resolution and deconstruct tumor heterogeneity. Using a newly developed 3D culture system, we have discovered a novel mode of cetuximab resistance via increased WNT signaling due to marked upregulation of a long con-coding RNA not previously linked to CRC. We will further elucidate the mechanism of this resistance and advance these findings clinically. We will further examine a new mode of signaling by EGFR and its ligands via exosomes and test whether EGFR-containing exosomes act as a decoy to reduce the amount of EGFR antibody delivered to tumors. We will harness the tools and resources at Vanderbilt University, Vanderbilt-Ingram Cancer Center and Vanderbilt's GI Specialized Programs of Research Excellence (SPORE) to advance this work.