Tumor-associated macrophages (TAMs) in the tumor microenvironment influence tumor initiation, invasion and metastasis. Several studies have shown that Wnt5a is mainly expressed in the tumor stroma, especially in TAMs. However, whether Wnt5a regulates the polarization and biological function of TAMs in colorectal cancer (CRC) is incompletely understood. Immunofluorescence staining was performed to detect CD68 and Wnt5a expression in colorectal tissues from patients (63 CRC specimens VS 20 normal tissues). RT-qPCR, flow cytometry, ELISA and inhibitors were carried out to explore the role of Wnt5a in the polarization of TAMs. Clone formation and transwell assays were performed to determine the effects of Wnt5a–treated macrophages on tumor proliferation, migration and invasion in vitro. Finally, a xenograft model was applied to confirm the effects of Wnt5a+ TAMs on CRC tumorigenesis. We found that high Wnt5a+CD68+/CD68+ TAMs ratio was significantly associated with poor prognosis in CRC patients and Wnt5a+ TAM was an M2-like TAM subtype. Subsequently, we found that Wnt5a induced macrophages to secrete IL-10, which then acted as an autocrine cytokine to induce M2 polarization of these macrophages. IL-10 neutralizing antibody completely reversed the pro-M2 effect of Wnt5a. Mechanistically, the CaKMII-ERK1/2-STAT3 pathway was required for Wnt5a-mediated IL-10 expression in macrophages. Furthermore, Wnt5a-induced M2 macrophages promoted CRC cells proliferation, migration and invasion; knockdown of Wnt5a in TAMs significantly impaired the pro-tumor functions of TAMs. Our data indicate that Wnt5a could induce M2 polarization of TAMs by regulating CaKMII-ERK1/2-STAT3 pathway–mediated IL-10 secretion, ultimately promoting tumor growth and metastasis of CRC.

中文翻译：

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Wnt5a通过IL-10诱导的肿瘤相关巨噬细胞的M2极化促进结直肠癌的进展。

肿瘤微环境中的肿瘤相关巨噬细胞（TAM）影响肿瘤的发生，侵袭和转移。多项研究表明，Wnt5a主要在肿瘤基质中表达，尤其是在TAM中。但是，Wnt5a是否在大肠癌（CRC）中调节TAM的极化和生物学功能尚不完全清楚。进行了免疫荧光染色以检测患者大肠组织中的CD68和Wnt5a表达（63个CRC标本与20个正常组织）。进行了RT-qPCR，流式细胞仪，ELISA和抑制剂研究Wnt5a在TAMs极化中的作用。进行了克隆形成和transwell分析，以确定经Wnt5a处理的巨噬细胞对体外肿瘤增殖，迁移和侵袭的影响。最后，应用异种移植模型以确认Wnt5a + TAM对CRC肿瘤发生的影响。我们发现，高Wnt5a + CD68 + / CD68 + TAMs比例与CRC患者的预后差显着相关，而Wnt5a + TAM是M2样TAM亚型。随后，我们发现Wnt5a诱导巨噬细胞分泌IL-10，然后IL-10用作自分泌细胞因子，诱导这些巨噬细胞的M2极化。IL-10中和抗体完全逆转了Wnt5a的pro-M2效应。从机制上讲，CaKMII-ERK1 / 2-STAT3途径是Wnt5a介导的IL-10在巨噬细胞中表达所必需的。此外，Wnt5a诱导的M2巨噬细胞促进CRC细胞增殖，迁移和侵袭。在TAM中敲低Wnt5a会大大损害TAM的促肿瘤功能。