The Function of EGFL6 in Ovarian Cancer Cell Biology, Tumor Initiation, and Therapy

摘要：卵巢癌是一种致死性疾病，死亡率：发病率在所有癌症中排名第3。 高级别浆液性癌（HGSC）是最具侵袭性的卵巢癌亚型， 患者生存率几乎没有改善。因此，在确定和开发新的 HGSC中的治疗靶点。我们最近发现，干细胞调节因子EGFL6是一个关键的， ALDH + HGSC癌症干细胞样细胞（CSC）的调节因子，与治疗抗性相关的细胞。egfl6 促进ALDH + HGSC CSC的迁移和不对称分裂，而EGFL6敲低HGSC 癌细胞导致小鼠的干性丧失并显著降低肿瘤生长。因此我们 假设EGFL6是HGSC有希望治疗靶点。了解治疗潜力 EGFL6导向剂需要更深入地了解EGFL6在卵巢癌细胞生物学中的作用。的 癌细胞上的EGFL6受体是未知的。由于配体/受体信号传导的中断已被证明是一个非常 在其他途径的有效治疗机制，我们提出SA 1：确定EGFL6受体， 表征EGFL6信号传导复合物。除了调节HGSC CSC，EGFL6是一个重要的调节因子。 正常干细胞的调节器。突变的正常干细胞被认为是癌症起始细胞的来源。我们 假设EGFL6作为正常干细胞和HGSC CSC调节剂可能是卵巢癌所必需的， 癌症的发生和发展。因此，我们提出SA2：评估EGFL6在癌症发生中的作用。 我们将使用一种新的HGSC遗传小鼠模型来评估（i）EGFL6敲除的影响或（ii）EGFL6基因敲除对HGSC的影响。 EGFL6中和抗体对HGSC启动和生长的影响。我们已经证明，小鼠EGFL6 我们开发的中和抗体在小鼠中对人癌细胞系具有优异的治疗活性。 为了将这些研究转化为临床试验，我们开发了一组人源化EGFL6阻断抗体， （hEGFL6-Ab）。我们建议SA3：验证hEGFL6-Ab，并确定患者的EGFL6表达是否与患者的免疫反应有关。 肿瘤预测对抗EGFL6治疗的反应。使用体外试验和一种新的人源化基质- 在患者来源的异种移植模型中，我们将鉴定最有效的hEGFL6-Ab。我们假设病人 其肿瘤细胞表达EGFL6和/或表现出EGFL6途径活化的人将对这种治疗最有反应。 疗法通过对hEGFL6-Ab应答和非应答肿瘤的表达分析，我们提出， 生成一个算法来预测患者对抗EGFL6治疗的反应。 影响：这些研究将1）定义卵巢癌细胞中的EGFL6信号级联，2）定义 HGSC起始和生长中癌细胞EGFL6表达的要求，以及3）创建并验证 一种新的人源化抗EGFL6-Ab和伴随的识别/分层患者的算法， 最容易对这种疗法产生反应。最终，该项目将产生一种有前途的治疗剂 用于卵巢癌的首次人体临床试验。

ABSTRACT: Ovarian cancer is a deadly disease with the 3rd-highest mortality:incidence ratio of all cancers. High-grade serous cancer (HGSC) is the most aggressive ovarian cancer subtype for which we have seen only little or no improvement in patient survival. Thus there is a clear unmet need to identify and develop new therapeutic targets in HGSC. We recently showed that the stem cell regulatory factor EGFL6 is a critical regulator of ALDH+ HGSC cancer stem-like cells (CSC), cells associated with therapeutic resistance. EGFL6 promotes the migration and asymmetric division of ALDH+HGSC CSC, while EGFL6 knockdown in HGSC cancer cells leads to loss of stemness and dramatically reduced tumor growth in mice. We therefore hypothesize that EGFL6 is a promising therapeutic target for HGSC. Understanding the therapeutic potential EGFL6-directed agents will require greater understanding of EGFL6's roles in ovarian cancer cell biology. The EGFL6 receptor on cancer cells is unknown. As disruption of ligand/receptor signaling has proven a very effective therapeutic mechanism in other pathways, we propose SA1: To Identify the EGFL6 receptor and characterize the EGFL6 signaling complex. In addition to regulating HGSC CSC, EGFL6 is an important regulator of normal stem cells. Mutated normal stem cells are a proposed source of cancer initiating cells. We hypothesize EGFL6 as a regulator of both normal stem cells and HGSC CSC may be essential for ovarian cancer initiation and growth. We therefore propose SA2: To evaluate the role of EGFL6 in cancer initiation. We will use a novel genetic mouse model of HGSC to assess (i) the impact of EGFL6 knockout or (ii) the effect of EGFL6 neutralizing antibodies on HGSC initiation and growth. We have shown that the murine EGFL6 neutralizing antibody we developed has excellent therapeutic activity versus human cancer cell lines in mice. To translate these studies into clinical trials we developed a a panel of humanized EGFL6-blocking antibodies (hEGFL6-Ab). We propose SA3: To validate hEGFL6-Ab and determine if EGFL6 expression by patients' tumors predicts response to anti-EGFL6 therapy. Using in vitro assays and a novel humanized stroma- patient derived xenograft model we will identify the most effective hEGFL6-Ab. We hypothesize that patients whose tumor cells express EGFL6 and/or exhibit EGFL6 pathway activation will be most responsive to such therapy. Using expression analysis of hEGFL6-Ab responsive and non-responsive tumors, we propose to generate an algorithm to predict patients' responses to anti-EGFL6 therapy. IMPACT: These studies will 1) define the EGFL6 signaling cascade in ovarian cancer cells, 2) define requirements for cancer cell EGFL6 expression in HGSC initiation and growth, and 3) create and validate a novel humanized anti-EGFL6-Ab and an accompanying algorithm that identifies/stratifies patients who are most apt to respond to such therapy. Ultimately, the project will produce a promising therapeutic agent positioned for first-in-human clinical trials in ovarian cancer.