Department of Gastroenterology and Endocrinology, University Hospital, Philipps University, Marburg, Germany.
Department of Biology, Philipps University, School of Medicine, Marburg, Germany.
Oncogene. 2015 Jan 8;34(2):177-87. doi: 10.1038/onc.2013.530. Epub 2013 Dec 16.
Many solid cancers including pancreatic ductal adenocarcinoma (PDAC) are characterized by an extensive stromal reaction that is accompanied by infiltrating tumor-associated macrophages (TAMs). The role of TAMs in malignant tumors is only partially understood. Previously, we identified the transcription factor CUX1 as an important mediator of tumor progression in PDAC. Interestingly, we found that CUX1 is highly expressed not only in tumor cells but also in TAMs. On the basis of these data, we aimed to elucidate the effects of CUX1 in TAMs in vitro and in vivo. We analyzed the effects of CUX1 on cytokine expression using overexpression and knockdown strategies. The cytokine regulation by CUX1 was further assessed by reporter assays, DNA pulldown experiments and chromatin-immunoprecipitation. CUX1 expression in TAMs was analyzed in human pancreatic cancer tissues and in a genetic mouse model. Immunohistochemical analysis revealed strong expression levels of CUX1 in a distinct subset of TAMs in human PDAC tissues. Furthermore, its expression increased during tumor progression in a genetic mouse model of PDAC. Profiling experiments showed that CUX1 downregulates several NF-κB-regulated chemokines such as CXCL10, which have been associated with M1 polarization and inhibition of angiogenesis and tumor progression. We could demonstrate that CUX1 interacts with NF-κB p65, leading to reduced binding of NF-κB p65 to the chemokine promoters. In addition, CUX1 reduces acetylation of NF-κB p65 at K310 by recruiting HDAC1. Functionally, CUX1 expression in TAMs antagonizes T-cell attraction and enhances angiogenesis in vitro. We identified CUX1 as an important modulator of the TAMs phenotype and function by modulating NF-κB-dependent cytokines.
许多实体瘤，包括胰腺导管腺癌（PDAC），其特征为广泛的基质反应，伴随着浸润的肿瘤相关巨噬细胞（TAMs）。TAMs 在恶性肿瘤中的作用尚未完全了解。此前，我们发现转录因子 CUX1 是 PDAC 肿瘤进展的重要介质。有趣的是，我们发现 CUX1 不仅在肿瘤细胞中高度表达，而且在 TAMs 中也高度表达。基于这些数据，我们旨在阐明 CUX1 在体外和体内对 TAMs 的影响。我们使用过表达和敲低策略分析了 CUX1 对细胞因子表达的影响。通过报告基因分析、DNA 下拉实验和染色质免疫沉淀进一步评估了 CUX1 对细胞因子的调控作用。分析了 CUX1 在人胰腺癌细胞和遗传 PDAC 小鼠模型中的 TAMs 中的表达。免疫组织化学分析显示，在人 PDAC 组织中 CUX1 在一个独特的 TAMs 亚群中表达水平较高。此外，在 PDAC 的遗传小鼠模型中，其表达在肿瘤进展过程中增加。分析实验显示，CUX1 下调了几个 NF-κB 调节的趋化因子，如与 M1 极化、血管生成抑制和肿瘤进展相关的 CXCL10。我们证明 CUX1 与 NF-κB p65 相互作用，导致 NF-κB p65 与趋化因子启动子的结合减少。此外，CUX1 通过招募 HDAC1 来减少 NF-κB p65 上 K310 的乙酰化。功能上，TAMs 中的 CUX1 表达拮抗 T 细胞趋化作用并增强体外血管生成。我们通过调节 NF-κB 依赖性细胞因子，鉴定出 CUX1 是 TAMs 表型和功能的重要调节剂。
