Purpose

Targeting tumor-infiltrating macrophages limits progression and improves chemotherapeutic responses in pancreatic ductal adenocarcinoma (PDAC). Protease-activated receptor (PAR)1 drives monocyte/macrophage recruitment, and stromal ablation of PAR1 limits cancer growth and enhances gemcitabine sensitivity in experimental PDAC. However, the functional interplay between PAR1, macrophages and tumor cells remains unexplored. Here we address the PAR1-macrophage-tumor cell crosstalk and assess its contributions to tumor progression.

Methods

PAR1 expression and macrophage infiltration were correlated in primary PDAC biopsies using gene expression datasets and tissue microarrays. Medium transfer experiments were used to evaluate the functional consequences of macrophage-tumor cell crosstalk and to assess the contribution of PAR1 to the observed responses. PAR1 cleavage assays were used to identify a macrophage-secreted PAR1 agonist, and the effects of candidate proteases were assessed in medium transfer experiments with specific inhibitors and/or recombinant agonist.

Results

PAR1 expression correlates with macrophage infiltration in primary PDACs, and macrophages induce mesenchymal transition of PDAC cells through PAR1 activation. Protease profiling identified macrophage-secreted matrix metalloprotease 9 (MMP9) as the relevant PAR1 agonist in PDAC. PAR1 and/or MMP9 inhibition limited macrophage-driven mesenchymal transition. Likewise, preventing mesenchymal transition by silencing ZEB1 or by pharmacological inhibition of the MMP9/PAR1 axis significantly reduced the ability of tumor cells to survive the anti-tumor activities of macrophages.

Conclusion

Macrophages secrete MMP9, which acts upon PDAC cell PAR1 to induce mesenchymal transition. This macrophage-induced mesenchymal transition supports the tumor-promoting role of macrophage influx, explaining the dichotomous contributions of these immune cells to tumor growth.

中文翻译：

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巨噬细胞分泌的 MMP9 通过 PAR1 激活诱导胰腺癌细胞间质转化。

目的

靶向肿瘤浸润性巨噬细胞可限制进展并改善胰腺导管腺癌 (PDAC) 的化疗反应。蛋白酶激活受体 (PAR)1 驱动单核细胞/巨噬细胞募集，PAR1 的基质消融限制癌症生长并增强实验性 PDAC 中的吉西他滨敏感性。然而，PAR1、巨噬细胞和肿瘤细胞之间的功能相互作用仍未得到探索。在这里，我们解决了 PAR1-巨噬细胞-肿瘤细胞串扰并评估其对肿瘤进展的贡献。

方法

使用基因表达数据集和组织微阵列，PAR1 表达和巨噬细胞浸润在初级 PDAC 活检中相关。培养基转移实验用于评估巨噬细胞-肿瘤细胞串扰的功能后果，并评估 PAR1 对观察到的反应的贡献。PAR1 裂解测定用于鉴定巨噬细胞分泌的 PAR1 激动剂，并在具有特定抑制剂和/或重组激动剂的培养基转移实验中评估候选蛋白酶的作用。

结果

PAR1 表达与原代 PDAC 中的巨噬细胞浸润相关，巨噬细胞通过 PAR1 激活诱导 PDAC 细胞的间质转化。蛋白酶分析将巨噬细胞分泌的基质金属蛋白酶 9 (MMP9) 鉴定为 PDAC 中相关的 PAR1 激动剂。PAR1 和/或 MMP9 抑制限制了巨噬细胞驱动的间充质转化。同样，通过沉默 ZEB1 或通过药物抑制 MMP9/PAR1 轴来阻止间充质转化显着降低了肿瘤细胞在巨噬细胞的抗肿瘤活性下存活的能力。

结论

巨噬细胞分泌 MMP9，其作用于 PDAC 细胞 PAR1 以诱导间质转化。这种巨噬细胞诱导的间充质转化支持巨噬细胞流入的肿瘤促进作用，解释了这些免疫细胞对肿瘤生长的二分贡献。