Identifying and Targeting Metabolic Dependencies in the Pancreatic Tumor Microenvironment

项目总结/摘要 胰腺导管腺癌（PDAC）细胞保持增殖能力，尽管缺乏血管，营养， 微环境差;这种具有挑战性的微环境是由癌症相关的成纤维细胞建立的 （CAFs）。PDAC CAF主要来源于胰腺星状细胞（PSC），健康胰腺中的脂质储存细胞。 胰腺可以转分化为活化的CAF表型，并产生致密的促结缔组织增生的 基质。CAF衍生的组分产生氧气和营养不良的微环境，PDAC细胞可以在其中生长。 必须适应。这些适应机制仍然知之甚少， 治疗干预我们最近的研究结果表明，PSC衍生的CAFs的旁分泌脂质通量代表了 间质向癌细胞提供能量和促增殖信号的新机制， PDAC增长。具体来说，我们发现PDAC CAFs分泌丰富的溶血磷脂酰胆碱（LPC）， Ras转化细胞如PDAC细胞的优选脂肪酸清除底物; PDAC CAF 分泌组还含有高水平的溶血磷脂酸（LPA），一种具有多种细胞因子的已建立的有丝分裂原。 在肿瘤发生中起作用的下游效应物。我们初步的转录和脂质组学数据表明， PSC在胰腺肿瘤发生的背景下经历了戏剧性的脂质代谢转变，包括重塑 细胞内脂质组的变化以及在激活的CAF状态下大量脂质的分泌。这些结果提高了 PDAC CAF分泌以旁分泌方式“喂养”上皮细胞的特定脂质种类的可能性 隔室和刺激增殖。我们假设成纤维细胞通过分泌脂质发挥功能， 促进上皮细胞增殖和在不友好的伤口愈合反应的情况下存活。这 假设将以下列具体目标进行检验。目的1：了解基质衍生的 脂质对癌细胞脂质代谢的影响。将使用稳定同位素示踪方法来确定 旁分泌代谢流从基质细胞到癌细胞之间分泌的脂质，和改变PDAC细胞 将使用已建立的代谢测定来评估对基质来源的脂质的响应的代谢。目标二： 确定基质衍生脂质在PDAC细胞生长控制中的作用。建立体外培养， 共培养系统将用于分析促有丝分裂LPA效应物途径和生长能力的调节 对基质衍生脂质的反应。目的3：定义LPC-自分泌运动因子-LPA轴在 胰腺癌生长的微环境调节。LPA由LPC通过分泌产生 我们发现LPC由PDAC CAFs高水平分泌，ATX过表达， 在小鼠和人PDAC中。LPC-自分泌运动因子-LPA轴将在遗传学上和 在PDAC小鼠模型中进行体内试验，以确定其在PDAC进展中的作用。这些研究将 提高我们对PDAC细胞在营养不良肿瘤中存活和生长机制的理解 微环境，可能确定一种新的治疗干预途径。

PROJECT SUMMARY/ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) cells maintain proliferative capacity despite a hypovascular, nutrient- poor microenvironment; this challenging microenvironment is established by cancer-associated fibroblasts (CAFs). PDAC CAFs are predominantly derived from pancreatic stellate cells (PSCs), lipid-storing cells in healthy pancreas which can transdifferentiate to an activated CAF phenotype and generate a dense, desmoplastic stroma. CAF-derived components generate an oxygen- and nutrient-poor microenvironment to which PDAC cells must adapt. These adaptation mechanisms remain poorly understood, and may represent vulnerabilities for therapeutic intervention. Our recent results suggest that paracrine lipid flux from PSC-derived CAFs represents a novel mechanism by which the stroma provides energy and pro-proliferative signals to cancer cells to support PDAC growth. Specifically, we find that PDAC CAFs secrete abundant lysophosphatidylcholine (LPC), the preferred fatty acid scavenging substrate for Ras-transformed cells such as PDAC cells; the PDAC CAF secretome also contains high levels of lysophosphatidic acid (LPA), an established mitogen with multiple downstream effectors with roles in tumorigenesis. Our preliminary transcriptional and lipidomic data suggest that PSCs undergo a dramatic lipid metabolic shift in the context of pancreatic tumorigenesis, including remodeling of the intracellular lipidome and secretion of abundant lipids in the activated CAF state. These results raise the possibility that PDAC CAFs secrete specific lipid species that act in a paracrine manner to “feed” the epithelial compartment and stimulate proliferation. We hypothesize that fibroblastic cells function via secreted lipids to promote epithelial cell proliferation and survival in the context of an inhospitable wound-healing response. This hypothesis will be tested with the following specific aims. Aim 1: Understand the effect of stroma-derived lipids on cancer cell lipid metabolism. A stable isotope tracing approach will be used to determine the extent of paracrine metabolic flux from stromal cells to cancer cells among secreted lipids, and alterations to PDAC cell metabolism in response to stroma-derived lipids will be assessed using established metabolic assays. Aim 2: Determine the role of stroma-derived lipids in PDAC cell growth control. Established in vitro culture and co-culture systems will be used to analyze regulation of mitogenic LPA effectors pathways and growth capacity in response to stroma-derived lipids. Aim 3: Define the significance of the LPC-Autotaxin-LPA axis in microenvironmental regulation of pancreatic cancer growth in vivo. LPA is generated from LPC by secreted enzyme Autotaxin; we find that LPC is secreted at high levels by PDAC CAFs, and that ATX is overexpressed in mouse and human PDAC. The LPC-Autotaxin-LPA axis will be interrogated both genetically and pharmacologically in a PDAC mouse model in vivo to determine its role in PDAC progression. These studies will improve our understanding of PDAC cell survival and growth mechanisms in the context of a nutrient-poor tumor microenvironment, potentially identifying a novel route for therapeutic intervention.