Differential Activity of MAPK signalling Defines Fibroblast Subtypes in Pancreatic Cancer (scRNA-Seq)

Fibroblast heterogeneity is increasingly recognised across cancer conditions. Given their important contribution to disease progression, mapping fibroblasts' heterogeneity is critical to devise effective anti-cancer therapies. Cancer-associated fibroblasts (CAFs) represent the most abundant cell population in pancreatic ductal adenocarcinoma (PDAC). Whether CAF phenotypes are differently specified by PDAC cell lineages remains to be elucidated. Here, we reveal an important role for the MAPK signalling pathway in defining PDAC CAF phenotypes. We show that epithelial MAPK activity promotes the myofibroblastic differentiation of CAFs by sustaining the expression and secretion of TGF-ß1. We integrate single-cell profiling of post-perturbation transcriptional responses from mouse models with cellular and spatial profiles of human tissues to define a MAPKhigh CAF (mapCAF) phenotype. We show that this phenotype associates with basal-like tumour cells and reduced frequency of CD8+ T cells. In addition to elevated MAPK activity, this mapCAF phenotype is characterized by TGF-b signalling, hypoxia responsive signatures, and immunoregulatory gene programs. Furthermore, the mapCAF signature is enriched in myofibroblastic CAFs from various cancer conditions and correlates with reduced response to immune checkpoint inhibition in melanoma Altogether, our data expand our knowledge on CAF phenotype heterogeneity and reveal a potential strategy for targeting of myofibroblastic CAFs in vivo. Overall design: Single cell transcriptomic analysis of vehicle treated and Meki treated mouse PDAC

成纤维细胞异质性在各类癌症中日益得到广泛认知。鉴于其对疾病进展的重要贡献，解析成纤维细胞异质性对于开发高效抗癌治疗方案至关重要。癌症相关成纤维细胞（Cancer-associated fibroblasts, CAFs）是胰腺导管腺癌（pancreatic ductal adenocarcinoma, PDAC）中含量最为丰富的细胞群。胰腺导管腺癌细胞谱系是否会差异化决定癌症相关成纤维细胞的表型，这一问题仍有待阐明。本研究揭示了丝裂原活化蛋白激酶（MAPK）信号通路在定义胰腺导管腺癌相关成纤维细胞表型中的关键作用。研究发现，上皮细胞的MAPK活性通过维持转化生长因子β1（transforming growth factor-β1, TGF-β1）的表达与分泌，促进癌症相关成纤维细胞的肌成纤维样分化。我们整合了小鼠模型经扰动后的转录反应单细胞测序数据，以及人类组织的细胞与空间转录组图谱，以此定义了高MAPK活性的癌症相关成纤维细胞（MAPKhigh CAF, mapCAF）表型。研究表明，该表型与基底样肿瘤细胞密切相关，并伴随CD8+ T细胞浸润频率降低。除MAPK活性升高外，该mapCAF表型还具有TGF-β信号通路活化、缺氧应答特征以及免疫调节基因程序等典型特征。此外，mapCAF特征基因集在多种癌症的肌成纤维样癌症相关成纤维细胞中富集，且与黑色素瘤患者对免疫检查点阻断治疗的应答降低显著相关。综上，本研究拓展了我们对癌症相关成纤维细胞表型异质性的认知，并揭示了一种在体内靶向肌成纤维样癌症相关成纤维细胞的潜在策略。
整体实验设计：对经赋形剂处理与Meki处理的小鼠胰腺导管腺癌样本开展单细胞转录组分析。