Endothelins are cytokines expressed in the microenvironment of several tumors. To identify which stromal cells in the melanoma microenvironment respond to endothelin, we injected murine melanoma cell lines B16F10, YUMM1.7, and YUMMER1.7 in a transgenic mouse that overexpresses endothelin 3 (Edn3) under the control of the keratin 5 promoter in the skin (K5-Edn3). All cell lines developed larger tumors in K5-Edn3 mice than in control animals. In YUMM1.7 tumors, the Edn3 receptor, endothelin receptor B (Ednrb), was expressed in several stromal cell types including immune cells. This result was validated by the identification of Ednrb-positive stromal cells in human melanoma from previously published RNA-seq data. Regulatory T cells (Tregs) and dendritic cell numbers were significantly higher in K5-Edn3 tumors when compared to control tumors. Edn3 increased Treg proliferation in vitro and the expression of FOXP3. YUMM1.7-GFP tumors in K5-Edn3 mice were sensitive to immune checkpoint inhibitor (anti-CTLA-4) as well as to Ednrb blockage (BQ-788). Our results indicate that Ednrb signaling has an important role in the melanoma microenvironment where it mediates immunosuppression resulting in escape from tumor immunity.

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Edn3过表达在黑色素瘤微环境中的免疫抑制作用

内皮素是在几种肿瘤的微环境中表达的细胞因子。为了确定黑色素瘤微环境中的哪些基质细胞对内皮素有反应，我们将小鼠黑色素瘤细胞系 B16F10、YUMM1.7 和 YUMMER1.7 注射到转基因小鼠体内，该小鼠在细胞内角蛋白 5 启动子的控制下过表达内皮素 3 (Edn3)。皮肤（K5-Edn3）。所有细胞系在K5-Edn3中都出现了较大的肿瘤小鼠比对照动物。在 YUMM1.7 肿瘤中，Edn3 受体、内皮素受体 B (Ednrb) 在包括免疫细胞在内的几种基质细胞类型中表达。通过从先前发表的 RNA-seq 数据中鉴定人黑色素瘤中的 Ednrb 阳性基质细胞来验证这一结果。与对照肿瘤相比， K5-Edn3肿瘤中的调节性 T 细胞 (Tregs) 和树突细胞数量显着增加。Edn3 增加体外 Treg 增殖和 FOXP3 的表达。K5-Edn3中的 YUMM1.7-GFP 肿瘤小鼠对免疫检查点抑制剂（抗 CTLA-4）以及 Ednrb 阻断剂（BQ-788）敏感。我们的研究结果表明，Ednrb 信号在黑色素瘤微环境中具有重要作用，它介导免疫抑制，从而导致肿瘤免疫的逃逸。