乳腺癌转移是全球妇女癌症死亡的主要原因。肿瘤相关巨噬细胞（TAMs）被视为治疗乳腺癌转移的潜在靶点，因为它们促进肿瘤生长和发展。甘草酸（GA）是甘草中最重要的植物化学物质之一，在临床前试验中表现出有希望的抗癌功效。然而，GA对TAM极化的调节作用仍不明确。本研究旨在探讨GA在调节M2型巨噬细胞极化和抑制乳腺癌转移中的作用，并进一步探讨其作用机制。在体外使用IL-4 / IL-13处理RAW 264.7和THP-1细胞作为极化的M2型巨噬细胞。在体内应用4T1小鼠乳腺癌模型和尾静脉乳腺癌转移模型研究GA对乳腺癌生长和转移的影响。体外研究表明，GA显著抑制了IL-4 / IL 13诱导RAW 264.7和THP-1巨噬细胞M2型极化，而不影响M1型极化。GA强烈降低了M2型巨噬细胞标志物CD206和Arg-1的表达，并降低了M2型巨噬细胞中的前血管生成分子VEGF、MMP9、MMP2和IL-10的水平。GA还增强了M2型巨噬细胞中JNK1/2的磷酸化。此外，GA显著抑制了M2型巨噬细胞对4T1癌细胞和HUVECs的增殖和迁移。有趣的是，JNK抑制剂取消了GA对M2型巨噬细胞的抑制作用。动物研究表明，GA显著抑制了BALB/c小鼠乳腺肿瘤的生长、血管生成和肺转移。在肿瘤组织中，GA减少了M2型巨噬细胞的数量，但增加了M1型巨噬细胞的比例，并伴随着JNK信号的激活。在尾静脉乳腺癌转移模型中发现了类似的结果。本研究首次证明了GA通过激活JNK1/2信号通路有效抑制乳腺癌生长和转移，通过抑制巨噬细胞M2极化。这些发现表明，GA可能成为未来开发抗乳腺癌药物的领先化合物。版权所有©2023 Elsevier GmbH。保留所有权利。

Breast cancer metastasis is leading cause of cancer death among women worldwide. Tumor-associated macrophages (TAMs) have been considered as potential targets for treating breast cancer metastasis because they promote tumor growth and development. Glycyrrhetinic acid (GA) is one of the most important phytochemicals of licorice which has shown promising anti-cancer efficacies in pre-clinical trials. However, the regulatory effect of GA on the polarization of TAMs remains elusive.To investigate the role of GA in regulating the polarization of M2 macrophages and inhibiting breast cancer metastasis, and to further explore its underlying mechanisms of action.IL-4 / IL-13-treated RAW 264.7 and THP-1 cells were used as the M2-polarized macrophages in vitro. A 4T1 mouse breast cancer model and the tail vein breast cancer metastasis model were applied to study the effect of GA on breast cancer growth and metastasis in vivo.In vitro studies showed that GA significantly inhibited IL-4 / IL 13-induced M2-like polarization in RAW 264.7 and THP-1 macrophages without affecting M1-like polarization. GA strongly decreased the expression of M2 macrophage markers CD206 and Arg-1, and reduced the levels of the pro-angiogenic molecules VEGF, MMP9, MMP2 and IL-10 in M2 macrophages. GA also increased the phosphorylation of JNK1/2 in M2 macrophages. Moreover, GA significantly suppressed M2 macrophage-induced cell proliferation and migration in 4T1 cancer cells and HUVECs. Interestingly, the inhibitory effects of GA on M2 macrophages were abolished by a JNK inhibitor. Animal studies showed that GA significantly suppressed tumor growth, angiogenesis, and lung metastasis in BALB/c mice bearing breast tumor. In tumor tissues, GA reduced the number of M2 macrophages but elevated the proportion of M1 macrophages, accompanied by activation of JNK signaling. Similar results were found in the tail vein breast cancer metastasis model.This study demonstrated for the first time that GA could effectively suppress breast cancer growth and metastasis by inhibiting macrophage M2 polarization via activating JNK1/2 signaling. These findings indicate that GA could be served as the lead compound for the future development of anti-breast cancer drug.Copyright © 2023 Elsevier GmbH. All rights reserved.