The Role of HIF2 in Pancreatic Ductal Adenocarcinoma

项目总结/摘要 胰腺导管腺癌（PDAC）含有限制血液灌注的促结缔组织增生性基质， 输送营养物质、氧气和治疗药物，创造一个缺氧的微环境， 几乎所有形式的治疗，包括免疫调节治疗。癌症相关成纤维细胞（CAF）是 PDAC中基质的主要成分和生产者。缺氧诱导因子-1（HIF 1）和-2（HIF 2） 在低氧下稳定，并被假设介导治疗抗性和侵袭性 PDAC的生长，但在胰腺上皮隔室中HIF 1或HIF 2的缺失没有产生明显的 PDAC中的表型。因此，我们推断HIF可能通过其对PDAC病理学的作用而支持PDAC病理学。 在癌症相关成纤维细胞（CAF）中发挥作用，CAF是胰腺癌中的另一种主要细胞成分。 肿瘤的由于对HIF在间质区室中的作用知之甚少，我们建立了一个小鼠模型， 它利用两种重组酶，使我们能够完全时空控制肿瘤生长和HIF消融， 在咖啡馆。使用这个模型，我们发现CAFs中HIF 2的消除降低了肿瘤生长，并且增加了一倍。 胰腺癌动物的中位生存期。CAFs中HIF 2的丢失与更少的 肿瘤内M2巨噬细胞和调节性T细胞。此外，缺氧CAFs的条件培养基 即使在煮沸后，在离体测定中也产生类似的效果。这些初步数据表明HIF 2- CAF和免疫区室之间的依赖性串扰可能对PDAC的能力至关重要， 逃避免疫系统。基于这些初步的数据，我们建议确定分子机制， 这使得低氧CAFs能够通过三个目的调节胰腺癌的免疫微环境。 在目标1中，我们将确定CAF和CAF之间HIF 2依赖性串扰的分子介导剂。 巨噬细胞我们将使用质谱法鉴定CAFs分泌的HIF 2依赖因子 能够在巨噬细胞中诱导M2极化，并确定该因子如何在CAF中产生， 它是如何改变巨噬细胞功能的目标2将定义CAF和T之间的HIF 2依赖关系 淋巴细胞我们将探讨CD8+抑制和Treg转化是如何通过HIF 2信号调节的， 使用小鼠模型和共培养方法的CAF。最后，在目标3中，我们将重新使用HIF 2抑制剂， 他们目前在肾细胞癌到胰腺癌的适应症中作为增强免疫治疗的药物 应答这项拟议中的研究意义重大，因为胰腺癌对化疗没有反应。 我们的数据表明，HIF 2抑制可以大大改善免疫反应。这 这项研究是创新的，因为我们将首次描述免疫靶向分子， PDAC中缺氧微环境激活的通路。此外，我们将提供第一个机械 使用HIF 2抑制剂沿着免疫检查点的潜在治疗组合的评价 封锁是走向临床转化的第一步。

PROJECT SUMMARY/ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) contains a desmoplastic stroma that limits blood perfusion and thus the delivery of nutrients, oxygen, and therapeutics, creating a hypoxic microenvironment that is able to resist nearly all forms of treatment, including immunomodulating therapy. Cancer-associated fibroblasts (CAFs) are the main components and producers of stroma in PDAC. The hypoxia-inducible factors-1 (HIF1) and -2 (HIF2) are stabilized in low oxygen and have been hypothesized to mediate therapeutic resistance and aggressive growth of PDAC, but deletion of HIF1 or HIF2 in the pancreatic epithelial compartment produced no obvious phenotype in PDAC. Thus, we reasoned that HIF may instead be supporting PDAC pathobiology through its functions in cancer-associated fibroblasts (CAFs), which are the other major cellular component in pancreatic tumors. Since little was known about the role of HIF in the stromal compartment, we created a mouse model that exploits two recombinases enabling us complete spatiotemporal control of tumor growth and HIF ablation in CAFs. Using this model, we found that the abrogation of HIF2 in CAFs decreased tumor growth and doubled the median survival of animals with pancreatic cancer. The loss of HIF2 in CAFs correlated with fewer intratumoral M2 macrophages and regulatory T cells. Furthermore, conditioned media from hypoxic CAFs produced similar effects in ex vivo assays even after boiling. These preliminary data suggested a HIF2- dependent crosstalk between CAF and the immune compartment that may be critical to the ability of PDAC to evade the immune system. Building on this preliminary data, we propose to identify the molecular mechanisms that allow hypoxic CAFs to modulate the immune microenvironment of pancreatic cancer through three aims. In Aim 1, we will determine the molecular mediators of HIF2-dependent crosstalk between CAFs and macrophages. We will use mass spectrometry to identify the HIF2 dependent factor secreted from CAFs capable of inducing M2 polarization in macrophages and determine how this factor is produce in CAFs and how it alters macrophage function. Aim 2 will define the HIF2-dependent relationships between CAFs and T lymphocytes. We will explore how CD8+ suppression and Treg conversion is regulated by HIF2 signaling in CAFs using mouse models and co-culture methods. Lastly, in Aim 3, we will repurpose HIF2 inhibitors from their current indications in renal cell carcinoma to pancreatic cancer as a drug to enhance immunotherapy responses. The proposed research is significant because pancreatic cancer does not respond to immunotherapy, and our data suggests that HIF2 inhibition may greatly improve immune responses. This research is innovative because we will provide the first description of the immune-targeting molecular pathways activated by hypoxic microenvironment in PDAC. Further, we will offer the first mechanistic evaluation of a potential therapeutic combination using a HIF2 inhibitor along with immune checkpoint blockade as the first steps towards clinical translation.