Rogel Comprehensive Cancer Center, University of Michigan, Ann Arbor, Michigan; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan.
Rogel Comprehensive Cancer Center, University of Michigan, Ann Arbor, Michigan; Department of Pathology, University of Michigan, Ann Arbor, Michigan.
Cell Mol Gastroenterol Hepatol. 2021;11(2):349-369. doi: 10.1016/j.jcmgh.2020.08.011. Epub 2020 Aug 31.
BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDA) initiation and progression are accompanied by an immunosuppressive inflammatory response. Here, we evaluated the immunomodulatory role of chemosensory signaling in metaplastic tuft cells (MTCs) by analyzing the role of GNAT3, a gustatory pathway G-protein expressed by MTCs, during PDA progression.
Gnat3-null (Gnat3) mice were crossbred with animals harboring a Cre-inducible Kras allele with either Ptf1a (KC) or tamoxifen-inducible Ptf1a (KC) mice to drive oncogenic KRAS expression in the pancreas. Ex vivo organoid conditioned medium generated from KC and Gnat3;KC acinar cells was analyzed for cytokine secretion. Experimental pancreatitis was induced in KC and Gnat3;KC mice to accelerate tumorigenesis, followed by analysis using mass cytometry and single-cell RNA sequencing. To study PDA progression, KC and Gnat3;KC mice were aged to morbidity or 52 weeks.
Ablation of Gnat3 in KC organoids increased release of tumor-promoting cytokines in conditioned media, including CXCL1 and CXCL2. Analysis of Gnat3;KC pancreata found altered expression of immunomodulatory genes in Cxcr2 expressing myeloid-derived suppressor cells (MDSCs) and an increased number of granulocytic MDSCs, a subset of tumor promoting MDSCs. Importantly, expression levels of CXCL1 and CXCL2, known ligands for CXCR2, were also elevated in Gnat3;KC pancreata. Consistent with the tumor-promoting role of MDSCs, aged Gnat3;KC mice progressed more rapidly to metastatic carcinoma compared with KC controls.
Compromised gustatory sensing, achieved by Gnat3 ablation, enhanced the CXCL1/2-CXCR2 axis to alter the MDSC population and promoted the progression of metastatic PDA.
胰腺导管腺癌（PDA）的发生和进展伴随着免疫抑制性炎症反应。在这里，我们通过分析味觉通路 G 蛋白 GNAT3 在化生簇细胞（MTC）中的作用，评估了化学感觉信号在化生簇细胞中的免疫调节作用，GNAT3 由 MTC 表达。
将 Gnat3 基因敲除（Gnat3）小鼠与携带 Cre 诱导型 Kras 等位基因的动物进行杂交，该基因可在胰腺中驱动致癌性 Kras 表达，分别为 Ptf1a（KC）或他莫昔芬诱导型 Ptf1a（KC）小鼠。分析 KC 和 Gnat3;KC 腺泡细胞产生的外源性类器官条件培养基中的细胞因子分泌情况。在 KC 和 Gnat3;KC 小鼠中诱导实验性胰腺炎以加速肿瘤发生，然后使用质谱细胞术和单细胞 RNA 测序进行分析。为了研究 PDA 的进展，将 KC 和 Gnat3;KC 小鼠饲养至发病或 52 周。
在 KC 类器官中敲除 Gnat3 会增加条件培养基中促肿瘤细胞因子的释放，包括 CXCL1 和 CXCL2。对 Gnat3;KC 胰腺的分析发现，Cxcr2 表达的髓系来源抑制细胞（MDSC）中免疫调节基因的表达发生改变，并且粒细胞 MDSC 的数量增加，粒细胞 MDSC 是促肿瘤 MDSC 的一个亚群。重要的是，CXCL1 和 CXCL2 的表达水平，已知是 CXCR2 的配体，在 Gnat3;KC 胰腺中也升高。与 MDSC 的促肿瘤作用一致，与 KC 对照相比，年老的 Gnat3;KC 小鼠更快地进展为转移性癌。
Gnat3 缺失导致味觉感知受损，增强了 CXCL1/2-CXCR2 轴，改变了 MDSC 群体，并促进了转移性 PDA 的进展。
