Neutralizing Stromal NetrinG1 to Intercept Pancreatic Cancer

项目概要-项目2 大多数胰腺癌（PC）患者不能存活一年，不到10%的患者存活五年。这是 不幸的是，考虑到PC多年来的缓慢增长速度， 诊断前的潜在干预。遗传性家族性PC患者（约占PC病例的10%），以及 暴露于诱变剂，并表现出诱发性临床疾病，如胰腺炎和新发 糖尿病，是PC的高风险，并将大大受益于改善早期发现，癌症预防， 和/或拦截策略。拟议的项目通过加入气候变化框架公约癌症问题小组， 在“代理识别和筛选”会议上的预防拦截目标代理发现计划（CAP-IT） 阶段据我们所知，该提案是第一个采用基质靶向策略来阻断进展的提案 癌前组织转移到明显的PC这项建议利用了我们在研究结缔组织增生方面的工作-一种独特的 PC的微环境富含基质成纤维细胞和致密的细胞外基质（ECM）。 我们已经定义了不同的肿瘤促进和肿瘤抑制成纤维细胞（TPFs和TSFs）亚群， 在表型上可以可逆地相互转化。我们已经证明TPF出现在早期癌前组织中， 其特征在于表达Netrin G1（NetG 1）。NetG 1依赖性信号传导对癌前细胞至关重要 像肿瘤一样茁壮成长从机制上讲，我们已经证明，NetG 1 + TPF为 癌前启动的上皮细胞（IEC）和肿瘤，使它们能够在营养不良的环境中生存。 促结缔组织增生环境和逃避免疫监视诱导免疫抑制 微环境虽然一些支持是通过TPF分泌营养素和趋化因子提供的; 由TPF生成的ECM提供支持。重要的是，我们已经证明， 一种抑制NetG 1的抗体（mAb）可以逆转所有这些促肿瘤特性，并阻断 的PC。尽管商业mAb足以用于概念验证实验，但其效力不够， 临床候选人靶向不同NetG 1表位的一大组mAb，其结合亲和力高于 上面提到的那个已经产生了。在目标1中，我们将确定哪些新的mAb在功能上 根据区分这两类的分子标记的表达，将TPF恢复为TSF。 在目标2中，将使用共培养实验来鉴定降低TPF提供营养的能力的mAb。 支持IEC，并评估相同的mAb是否会降低TPF产生的ECM的能力， 促进IEC增长。新的IEC模型将被设计成与所见的功能丧失遗传变异平行 在PC高危人群中。在目标3中，可以拦截从 将评价它们的毒性特征和抑制PanIN形成的能力， PC的前体，在KC小鼠中，PC的模型。这些研究预计将产生靶向这些药物的新药物。 用于PC预防和/或拦截的基质。

PROJECT SUMMARY - PROJECT 2 Most patients with pancreatic cancer (PC) do not survive one year and less than 10% survive five years. This is unfortunate, given the slow rate of growth of PC over many years, and the large window of opportunity for potential intervention prior to diagnosis. Patients with hereditary familial PC (~10% of PC cases), as well as those exposed to mutagens and presenting with predisposing clinical conditions like pancreatitis and new onset of diabetes, are at high risk for PC and would benefit greatly from improved early detection, cancer prevention, and/or interception strategies. The proposed project addresses this unmet need by joining the FCCC Cancer Prevention-Interception Targeted Agent Discovery Program (CAP-IT) at the “Agent Identification and Screening” stage. The proposal is the first, to our knowledge, to employ a stroma-targeting strategy to intercept progression of precancerous tissue to overt PC. This proposal exploits our work in studying desmoplasia – a unique microenvironment enriched in stromal fibroblasts and dense extracellular matrix (ECM) that characterizes PC. We have defined distinct subsets of tumor-promoting and tumor-suppressing fibroblasts (TPFs and TSFs), which can reversibly interconvert in phenotype. We have shown that TPFs arise in early precancerous tissue, and are characterized by expression of Netrin G1 (NetG1). NetG1-dependent signaling is essential for premalignant cells to thrive as tumors. Mechanistically, we have shown that NetG1+ TPFs provide nutritional support to premalignant initiated epithelial cells (IECs) and tumors, allowing them to survive in the nutrient-poor desmoplastic environment and escape immunosurveillance by inducing an immunosuppressive microenvironment. While some support is delivered via TPF secretion of nutrients and chemokines; additional support is provided by the TPF-generated ECM. Critically, we have shown that a commercial monoclonal antibody (mAb) that inhibits NetG1 reverts all of these tumor-promoting properties and intercepts the formation of PC. Although the commercial mAb is sufficient for proof-of-concept experiments, it is not sufficiently potent as a clinical candidate. A large panel of mAbs targeting diverse NetG1 epitopes, with higher binding affinities than the one above-mentioned, has been generated. In Aim 1, we will determine which of the new mAbs functionally reverts TPFs to TSFs, based on the expression of molecular markers that distinguish between the two classes. In Aim 2, co-culture experiments will be used to identify mAbs that reduce the ability of TPFs to provide nutritional support to IECs, and assess whether the same mAbs decrease the ability of the ECM, produced by TPFs, to enhance IEC growth. New IEC models will be engineered that parallel the loss of function genetic variants seen in populations at high risk for PC. In Aim 3, the lead candidate mAbs that can intercept the transition from precancer to cancer in vitro will be evaluated for their toxicity profiles and ability to inhibit formation of PanINs, the precursor of PC, in KC mice, a model of PC. These studies are expected to yield novel agents that target the stroma for PC prevention and/or interception.