Epithelial-Mesenchymal Plasticity is Associated with Immunosuppressive Features in Canine Mammary Carcinomas

Epithelial-mesenchymal plasticity (EMP) is a cellular process activated in carcinoma cells to drive invasiveness, metastasis, and chemoresistance. Recently, we have demonstrated that activation of the EMP program also results in the assembly of an immunosuppressive tumor microenvironment and resistance to immunotherapy in an immunocompetent orthotopic murine model. However, it has yet to be shown whether these findings can be translated to canine carcinomas. Here, we show that in spontaneous canine mammary carcinomas (CMCs), which share similar histopathologic, molecular, and clinical features with human breast cancers, EMP activation is linked to the recruitment of immunosuppressive cells including regulatory T-cells and M2-like macrophages. Additionally, through transcriptomic profiling of CMCs, we identify that the glycoprotein CD109 is associated with EMP-mediated immunosuppression across canine, murine, and human breast cancer models. CD109 has been previously associated with tumorigenicity, but not immunosuppression in cancers of any species. Finally, we identified upregulation of several immunosuppressive paracrine factors across multiple canine carcinomas, including oral squamous cell carcinoma, urothelial carcinoma, and pulmonary carcinoma samples. These findings demonstrate for the first time that the EMP program is associated with immunosuppression in canine carcinomas, with direct translational implications for human breast cancers. Overall design: RNA-seq data from 15 formalin-fixed paraffin-embedded canine mammary carcinoma samples across three states: epithelial, heterogeneous, and quasi-mesenchymal.

上皮-间质可塑性（Epithelial-mesenchymal plasticity, EMP）是一类在癌细胞中被激活的细胞程序，可驱动肿瘤侵袭、转移与化疗耐药。近期本团队已证实，在免疫健全的原位小鼠模型中，EMP程序的激活还可促成免疫抑制性肿瘤微环境的形成，并引发免疫治疗耐药。但目前尚无研究证实该结论能否推广至犬类癌症。
本研究针对自发犬乳腺肿瘤（canine mammary carcinomas, CMCs）展开分析——这类肿瘤与人类乳腺癌在组织病理学、分子特征及临床表型上均具有高度相似性——结果显示，EMP激活与免疫抑制性细胞的招募存在显著关联，此类细胞包括调节性T细胞与M2样巨噬细胞。
此外，通过对犬乳腺肿瘤的转录组测序分析，本团队鉴定出糖蛋白CD109与EMP介导的免疫抑制相关，该关联在犬类、小鼠及人类乳腺癌模型中均成立。既往研究已证实CD109与多种癌症的致瘤性相关，但尚未有研究表明其在任何物种的癌症中与免疫抑制存在关联。
最后，本团队在多种犬类癌症样本（包括口腔鳞状细胞癌、尿路上皮癌及肺癌样本）中均检测到多种免疫抑制性旁分泌因子的上调表达。
本研究首次证实，EMP程序与犬类癌症的免疫抑制存在关联，该发现对人类乳腺癌的转化研究具有直接指导意义。
整体实验设计：本研究的RNA测序数据来自15份福尔马林固定石蜡包埋的犬乳腺肿瘤样本，样本涵盖上皮、异质性及准间质三种状态。