Specific myelomonocytic cells heavily infiltrate orthotopic lung tumors and display a hypoxia-driven micro-RNA expression signature that directs tumor-supporting functions and negatively impacts on clinical outcome. Mus musculus

Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the nature and dynamics of immune cells in the lung cancer micro-environment. Dendritic cells (DCs) represent a heterogenous and highly plastic immune cell system with a central role in controlling immune responses. The intratumoral infiltration and activation status of DCs emerge as clinically relevant parameters in lung cancer. In this study we used an orthotopic preclinical model of lung cancer to interrogate the transcriptome of lung tumor-infiltrating DCs and extract novel biologically and clinically relevant information. Lung tumor-infiltrating leukocytes expressing generic DC markers were found to predominantly consist of CD11b+ cells which, compared to peritumoral lung DC counterparts, strongly over-express the T cell inhibitory molecule PD-L1 and acquire classic markers of tumor-supporting macrophages (TAM) on their surface. Transcriptome analysis of these CD11b+ tumor-infiltrating DCs (TIDCs) indicates impaired anti-tumoral immunogenicity, confirms the skewing towards TAM-related features, and indicates exposure to a hypoxic environment. In paralled, TIDCs display a specific micro-RNA signature dominated by the prototypical lung cancer oncomir miR-31. Hypoxia was found to drive intrinsic miR-31 expression in CD11b+DCs. Conditioned medium of mir-31-overexpressing CD11b+DCs induces pro-invasive lung cancer cell shape changes and is enriched with the pro-metastatic factors S100A8 and S100A9. Finally, analysis of TCGA datasets reveals that the TIDC-associated miRNA signature has a negative prognostic impact in non-small cell lung cancer. Together, these data suggest a novel mechanism through which lung cancer co-opts the plasticity of the DC system to support tumoral progression. Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the nature and dynamics of immune cells in the lung cancer micro-environment. Dendritic cells (DCs) represent a heterogenous and highly plastic immune cell system with a central role in controlling immune responses. The intratumoral infiltration and activation status of DCs emerge as clinically relevant parameters in lung cancer. In this study we used an orthotopic preclinical model of lung cancer to interrogate the transcriptome of lung tumor-infiltrating DCs and extract novel biologically and clinically relevant information. Lung tumor-infiltrating leukocytes expressing generic DC markers were found to predominantly consist of CD11b+ cells which, compared to peritumoral lung DC counterparts, strongly over-express the T cell inhibitory molecule PD-L1 and acquire classic markers of tumor-supporting macrophages (TAM) on their surface. Transcriptome analysis of these CD11b+ tumor-infiltrating DCs (TIDCs) indicates impaired anti-tumoral immunogenicity, confirms the skewing towards TAM-related features, and indicates exposure to a hypoxic environment. In paralled, TIDCs display a specific micro-RNA signature dominated by the prototypical lung cancer oncomir miR-31. Hypoxia was found to drive intrinsic miR-31 expression in CD11b+DCs. Conditioned medium of mir-31-overexpressing CD11b+DCs induces pro-invasive lung cancer cell shape changes and is enriched with the pro-metastatic factors S100A8 and S100A9. Finally, analysis of TCGA datasets reveals that the TIDC-associated miRNA signature has a negative prognostic impact in non-small cell lung cancer. Together, these data suggest a novel mechanism through which lung cancer co-opts the plasticity of the DC system to support tumoral progression. Overall design: Orthotopic model of lung cancer by inoculating Lewis lung carcinoma (LLC) cells into the airways of immunocompetent syngeneic C57BL/6 hosts were used to study the transcriptomic differences between tumoral and peritumoral tissue.

靶向免疫调节通路为肺癌治疗开启了全新纪元。后续研究进展有赖于对肺癌肿瘤微环境中免疫细胞的本质与动态变化的更深入解析。树突状细胞（Dendritic Cells, DCs）是一类具有高度异质性与可塑性的免疫细胞群体，在调控免疫应答过程中发挥核心作用。DCs的瘤内浸润状态与激活水平已成为肺癌临床相关的评估参数。本研究采用肺癌原位临床前模型，对肺肿瘤浸润DCs的转录组进行解析，并挖掘具有生物学与临床价值的全新信息。研究发现，表达通用DC标志物的肺肿瘤浸润白细胞主要由CD11b+细胞构成；与瘤周肺DC相比，这类细胞高表达T细胞抑制分子PD-L1，并在表面获得肿瘤支持性巨噬细胞（Tumor-associated macrophages, TAM）的经典标志物。对这类CD11b+肿瘤浸润DCs（Tumor-infiltrating DCs, TIDCs）的转录组分析显示，其抗肿瘤免疫原性受损，证实其向TAM相关表型发生极化，并提示其处于缺氧微环境中。与此同时，TIDCs展现出以肺癌典型致癌microRNA（miR-31）为核心的特异性miRNA表达特征。研究证实缺氧可诱导CD11b+DCs内源性miR-31的表达。过表达miR-31的CD11b+DCs的条件培养基可诱导肺癌细胞发生促侵袭性形态改变，且富含促转移因子S100A8与S100A9。最后，对癌症基因组图谱（The Cancer Genome Atlas, TCGA）数据集的分析显示，TIDC相关miRNA特征谱对非小细胞肺癌具有不良预后预测价值。综上，本研究数据揭示了肺癌通过劫持DC系统的可塑性以促进肿瘤进展的全新机制。靶向免疫调节通路为肺癌治疗开启了全新纪元。后续研究进展有赖于对肺癌肿瘤微环境中免疫细胞的本质与动态变化的更深入解析。树突状细胞（Dendritic Cells, DCs）是一类具有高度异质性与可塑性的免疫细胞群体，在调控免疫应答过程中发挥核心作用。DCs的瘤内浸润状态与激活水平已成为肺癌临床相关的评估参数。本研究采用肺癌原位临床前模型，对肺肿瘤浸润DCs的转录组进行解析，并挖掘具有生物学与临床价值的全新信息。研究发现，表达通用DC标志物的肺肿瘤浸润白细胞主要由CD11b+细胞构成；与瘤周肺DC相比，这类细胞高表达T细胞抑制分子PD-L1，并在表面获得肿瘤支持性巨噬细胞（Tumor-associated macrophages, TAM）的经典标志物。对这类CD11b+肿瘤浸润DCs（Tumor-infiltrating DCs, TIDCs）的转录组分析显示，其抗肿瘤免疫原性受损，证实其向TAM相关表型发生极化，并提示其处于缺氧微环境中。与此同时，TIDCs展现出以肺癌典型致癌microRNA（miR-31）为核心的特异性miRNA表达特征。研究证实缺氧可诱导CD11b+DCs内源性miR-31的表达。过表达miR-31的CD11b+DCs的条件培养基可诱导肺癌细胞发生促侵袭性形态改变，且富含促转移因子S100A8与S100A9。最后，对癌症基因组图谱（The Cancer Genome Atlas, TCGA）数据集的分析显示，TIDC相关miRNA特征谱对非小细胞肺癌具有不良预后预测价值。综上，本研究数据揭示了肺癌通过劫持DC系统的可塑性以促进肿瘤进展的全新机制。实验整体设计：本研究通过将路易斯肺癌（Lewis Lung Carcinoma, LLC）细胞接种于免疫健全的同基因C57BL/6宿主的气道内，构建肺癌原位模型，以此分析肿瘤组织与瘤周组织的转录组差异。