Background & Aims

Pancreatic ductal adenocarcinoma (PDA) initiation and progression is 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.

Methods

Gnat3-null (Gnat3^-/-) mice were crossbred with animals harboring a Cre-inducible Kras^LSL-G12D/+ allele with either Ptf1a^Cre/+ (KC) or tamoxifen-inducible Ptf1a^CreERT/+ (KC^ERT) mice to drive oncogenic KRAS expression in the pancreas. Ex vivo organoid conditioned media generated from KC and Gnat3^-/-;KC acinar cells was analyzed for cytokine secretion. Experimental pancreatitis was induced in KC^ERT and Gnat3^-/-;KC^ERT 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.

Results

Ablation of Gnat3 in KC organoids increased release of tumor-promoting cytokines in conditioned media, including CXCL1 and CXCL2. Analysis of Gnat3^-/-;KC^ERT pancreata found altered expression of immunomodulatory genes in Cxcr2 expressing myeloid-derived suppressor cells (MDSC) and an increased number of granulocytic MDSCs (gMDSC), a subset of tumor promoting MDSCs. Importantly, expression levels of CXCL1 and CXCL2, known ligands for CXCR2, were also elevated in Gnat3^-/-;KC^ERT pancreata. Consistent with the tumor-promoting role of MDSCs, aged Gnat3^-/-;KC mice progressed more rapidly to metastatic carcinoma compared to KC controls.

Conclusions

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.

中文翻译：

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味觉 G 蛋白 GNAT3 抑制小鼠胰腺癌的进展。

背景与目标

胰腺导管腺癌（PDA）的发生和进展伴随着免疫抑制炎症反应。在这里，我们通过分析 GNAT3（MTC 表达的味觉通路 G 蛋白）在 PDA 进展过程中的作用，评估了化学感应信号在化生簇细胞 (MTC) 中的免疫调节作用。

方法

Gnat3 -null ( Gnat3 ^-/- ) 小鼠与携带 Cre 诱导型Kras ^LSL-G12D/+等位基因的动物与Ptf1a ^Cre/+ (KC) 或他莫昔芬诱导型Ptf1a ^CreERT/+ (KC ^ERT ) 小鼠杂交，以驱动胰腺中致癌的 KRAS 表达。从 KC 和Gnat3 ^-/-产生的离体类器官条件培养基；分析 KC 腺泡细胞的细胞因子分泌。^{在 KC ERT}和Gnat3 ^-/- ;KC ^ERT小鼠中诱导实验性胰腺炎以加速肿瘤发生，然后使用质谱流式细胞仪和单细胞 RNA 测序进行分析。为了研究 PDA 进展，KC 和Gnat3 ^-/- ;KC 小鼠年龄达到发病年龄或 52 周。

结果

KC 类器官中Gnat3的消除增加了条件培养基中促肿瘤细胞因子的释放，包括 CXCL1 和 CXCL2。对Gnat3 ^-/- ;KC ^ERT胰腺的分析发现，表达Cxcr2 的骨髓源性抑制细胞 (MDSC) 中免疫调节基因的表达发生改变，并且粒细胞 MDSC (gMDSC)（促进肿瘤的 MDSC 的一个子集）数量增加。重要的是，CXCL1 和 CXCL2（CXCR2 的已知配体）的表达水平在Gnat3 ^-/- ;KC ^ERT胰腺中也有所升高。与 MDSC 的促肿瘤作用一致，与 KC 对照相比，老年Gnat3 ^-/- ;KC 小鼠进展为转移癌的速度更快。

结论

通过Gnat3消融实现的味觉受损增强了 CXCL1/2 – CXCR2 轴，从而改变了 MDSC 群体并促进了转移性 PDA 的进展。