PO.TB10.11 · 肿瘤生物学
靶向癌症相关成纤维细胞中的 GABA 信号以减轻胰腺癌中的免疫抑制
Targeting GABA signaling in cancer associated fibroblasts to reduce immunosuppression in pancreatic cancer
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
胰腺导管腺癌（PDAC）是一种治疗选择极少的致命性疾病。这在很大程度上归因于被称为基质的非肿瘤细胞区室的扩增。癌症相关成纤维细胞（CAFs）是构成 PDAC 肿瘤基质的主要细胞类型之一，由于其产生大量细胞因子、生长因子和代谢物，因而具有极强的免疫抑制性。因此，理解 CAFs 如何在肿瘤微环境中施加严重的免疫抑制，对于使 PDAC 能够接受免疫治疗至关重要。利用一种新的 3D 培养方法，我们的数据支持这样一种观点：PDAC CAFs 从头（de novo）产生谷氨酸代谢物和抑制性神经递质 gamma-氨基丁酸（GABA），并且我们在从患者组织（10 例患者）分离的肿瘤间质液（TIF）中检测到 GABA（约 27µM）。令人惊讶的是，CAFs 缺乏谷氨酸脱羧酶（将谷氨酸转化为 GABA 的经典酶）的表达，这促使我们探索 GABA 合成的替代性、非经典途径。我们发现，来自患者 PDAC 肿瘤的 CAFs 表达非经典合成途径的酶（ODC1、DAO、ALDH1A1 和 ALDH9A1），且与正常成纤维细胞相比表达程度更高。同时，我们通过探索旁分泌信号证明，用 GABA 处理 CAFs 导致 p-p70、p-JNK、p-MTOR 和 p-AKT 蛋白（参与克服 PDAC 中代谢应激的关键信号枢纽）表达的变化。此外，GABA 处理增加了 CAFs 产生促肿瘤细胞因子，如 TGFbeta、IL8 和 IL6。在 PDAC 的临床前原位小鼠肿瘤模型中，通过 ALDH1A1 抑制 GABA 合成、以及通过 GABAB 受体抑制剂抑制 GABA 信号，可减少肿瘤负荷、增加抗肿瘤 T 细胞和 NK 细胞的流入，并在肿瘤外植体中阻断促肿瘤细胞因子的产生。在转化层面，我们已获取了 10 例患者的配对血浆、TIF 和组织，并将比较它们的代谢、免疫和空间转录组谱与详尽注释的临床参数，以开发改进的诊断检测。总体而言，我们揭示了一个由 GABA 驱动的新信号回路，它在控制极具免疫抑制性的 PDAC 微环境中发挥作用。
查看英文原文 English abstract
Pancreatic ductal adenocarcinoma (PDAC) is a devasting disease with few therapeuticoptions. This is due, in large part, to the expansion of the non-tumor cellular compartmentknown as the stroma. Cancer-associated fibroblasts (CAFs) are one of the major celltypes that populate the stroma of PDAC tumors and are extremely immunosuppressivebecause they produce large amounts of cytokines, growth factors and metabolites. Thus,understanding how CAFs impart severe immunosuppression in the tumormicroenvironment is critical to make PDAC amenable to immunotherapies. Using a novel3D culturing method, our data support the notion that PDAC CAFs produce the glutamatemetabolite and inhibitory neurotransmitter gamma aminobutyric acid (GABA), de novo ,and we detected GABA (~27µM) in tumor interstitial fluid (TIF) isolated from patient tissue(10 patients). Surprisingly, CAFs lacked expression of glutamate decarboxylase, thecanonical enzyme responsible for converting glutamate into GABA, which led us toexplore alternative, non-canonical pathways for GABA synthesis. We found that CAFsderived from patient PDAC tumors expressed the enzymes of the non-canonicalsynthesis pathway (ODC1, DAO, ALDH1A1 and ALDH9A1), and to a greater degreewhen compared to normal fibroblasts. In parallel, we demonstrated that, by exploringparacrine signaling, GABA treatment of CAFs resulted in changes in expression of p-p70,p-JNK, p-MTOR and p-AKT proteins, key signaling hubs involved in overcomingmetabolic stress in PDAC. In addition, GABA treatment increased the production of pro-tumor cytokines, such as TGFbeta, IL8, and IL6, by CAFs. In preclinical orthotopic murinetumor models of PDAC, inhibition of GABA synthesis through ALDH1A1, and GABAsignaling through GABAB receptor inhibitors, reduced tumor burden, increased influx ofanti-tumor T and NK cells, and blocked production of pro-tumor cytokines in tumorexplants. Translationally, we have acquired patient matched plasma, TIF, and tissue from10 patients, and will compare their metabolic, immune, and spatial transcriptomic profileswith well annotated clinical parameters, in order to develop improved diagnostic tests.Overall, we have uncovered a novel signaling circuit driven by GABA that plays a role incontrolling the extremely immunosuppressive PDAC microenvironment.
利益披露 Disclosure
A. Musa de Aquino, None..
M. Graves, None..
K. Langley, None..
P. Sajjakulnukit, None..
N. Steele, None..
J. Clark, None..
R. Francescone, None..
D. B. Vendramini-Costa, None..
G. Cognet G, None..
D. Kwon, None.