Targeting the fibroblast-immune cell crosstalk to relieve immune suppression in the pancreatic cancer microenvironment

摘要 胰腺癌的特征是广泛的纤维炎症反应或肿瘤间质。虽然免疫 细胞在间质中是丰富的，它们在很大程度上是免疫抑制的，因此胰腺癌是 对免疫疗法基本上没有反应。胰腺癌的基因工程小鼠模型 概括了胰腺癌的逐步进展，是研究前驱病变的理想选择，如 胰腺上皮内瘤变（PanIN）。PanIN期免疫浸润的分析显示， 免疫抑制在恶性进展之前很早就建立。的机制 胰腺癌中免疫抑制建立的基础仍然未知， 了解它们对于设计新的胰腺癌化疗方法至关重要。 癌我们以前使用单细胞RNA测序来表征人类中的基因表达谱， 胰腺癌免疫浸润。然后，我们绘制了微环境中潜在的细胞-细胞相互作用 基于配体和受体的相互表达。在预测的相互作用中，我们确定了WNT 胰腺癌T细胞区室中的信号传导激活，由肿瘤细胞表达的配体驱动 和癌症相关成纤维细胞（CAF）。我们和其他人以前曾将不适当的激活与 胚胎信号传导途径，包括WNT信号传导，作为胰腺癌的特征。WNT信号传导 是胰腺癌中激活的核心通路之一。我们以前的研究表明， 信号转导抑制胰腺癌的发生，但WNT在胰腺癌中的潜在作用 微环境，特别是免疫细胞中的微环境是未知的。CAF表达WNT家族的几种配体; 为了消除它们的表达，我们灭活了PORCN（PORCUPINE），这是一种跨膜酶， 胰腺成纤维细胞中WNT配体的酰化和分泌。然后我们将胰腺癌细胞 并观察到生长减少。为了确定WNT信号的T细胞活化是否对此重要， 为了达到这一效果，我们产生了编码蛋白质TCF 1的转录因子TCF 7失活的小鼠 CD 4 + T细胞。在这些动物中，我们观察到移植肿瘤生长减少，CAF改变， 表型，并增加抗肿瘤免疫的激活。在这份提案中，我们计划在我们初步的 数据来剖析胰腺癌中WNT信号传导驱动免疫抑制的机制。长期 我们的目标是设计靶向方法，可能逆转这种疾病的免疫抑制。

ABSTRACT Pancreatic cancer is characterized by an extensive fibroinflammatory reaction, or tumor stroma. While immune cells are abundant within the stroma, they are largely immune suppressive, and therefore pancreatic cancer is largely unresponsive to immunotherapy. Genetically engineered mouse models of pancreatic cancer recapitulate the stepwise progression of pancreatic cancer, and are ideal to study precursor lesions, such as pancreatic intraepithelial neoplasia (PanIN). Analysis of the immune infiltrates at the PanIN stage revealed that immune suppression is established very early on and precedes malignant progression. The mechanisms underlying the establishment of the immune suppression in pancreatic cancer remain unknown and understanding them is of fundamental importance to design new chemotherapy approaches for pancreatic cancer. We previously used single cell RNA sequencing to characterize gene expression profiles in the human pancreatic cancer immune infiltrate. We then mapped potential cell-cell interactions within the microenvironment based on reciprocal expression of ligands and receptors. Among predicted interactions, we identified WNT signaling activation in the T cell compartment of pancreatic cancer, driven by ligands expressed by tumor cells and cancer associated fibroblasts (CAFs). We and others have previously associated inappropriate activation of embryonic signaling pathways, including WNT signaling, as a characteristic of pancreatic cancer. WNT signaling is one of the core pathways activated in pancreatic cancer. We previously showed that ablation of epithelial WNT signaling inhibits the onset of pancreatic carcinogenesis, but the potential role of WNT in the pancreatic cancer microenvironment and specifically in immune cells is unknown. CAFs express several ligands of the WNT family; to ablate their expression, we inactivated PORCN (PORCUPINE), a transmembrane enzyme required for acylation and secretion of WNT ligands, in pancreatic fibroblasts. We then transplanted pancreatic cancer cells and observed reduced growth. To determine whether T cell activation of WNT signaling was important for this effect, we generated mice where the transcription factors TCF7, encoding for the protein TCF1, was inactivated in CD4+ T cells. In these animals, we observed reduced growth of transplanted tumors, alterations in the CAF phenotype, and increased activation of anti-tumor immunity. In this proposal, we plan to build on our preliminary data to dissect the mechanism of WNT signaling driven immune suppression in pancreatic cancer. The long term goal is to design targeting approaches that might reverse immune suppression in this disease.