和厚朴酚调节肿瘤相关巨噬细胞极化及阻断免疫抑制微环境抑制乳腺癌肺转移的机制

Breast cancer is the tumor with the highest incidence in women worldwide and the leading cause of death from cancer, and 90% of death induced by breast cancer results from metastasis. Tumor-associated macrophage (TAM) is the most abundant immune cell in the microenvironment of breast cancer and is independent factor of poor prognosis. TAM induces the formation of immunosuppressive microenvironment, and participates in most aspects of tumor metastasis. Targeting the tumor microenvironment is the advantage of traditional Chinese medicine in treating tumors. Honokiol, the active ingredient of Chinese medicine Magnolia, can inhibit tumor growth and metastasis, but the mechanism relating to TAM and immunosuppressive has not been researched. We have previously found that Honokiol could inhibit M2 polarization of macrophage, yet promote M1 polarization, and inhibit breast cancer migration promoted by TAM. So we assume that Honokiol inhibits breast cancer lung metastasis by regulating TAM polarization and blocking the immunosuppressive microenvironment. This project is to observe the regulation of Honokiol on TAM polarization, the secretion of immunosuppressive factors, and the expression of immunosuppressive cells from various dimensions, moreover, to explore its effects on JAK/STAT and PI3K/Akt signaling pathways. In summary, the purpose of the study is to elucidate the mechanism by which Honokiol inhibits breast cancer metastasis and increases the efficacy of chemotherapy, which is helpful to lay the foundation for the research and clarification of mechanism of traditional Chinese medicine against tumor metastasis, and to provide new candidate compound and a scientific basis for clinical combination of medication.

乳腺癌是全球女性发病率第一的肿瘤和癌症致死的主因，90%以上乳腺癌导致的死亡源于发生转移。肿瘤相关巨噬细胞（TAM）是乳腺癌肿瘤微环境中丰度最高的免疫细胞及预后不良的独立因素。TAM可诱导免疫抑制微环境的形成，参与肿瘤转移的多个环节。靶向调节肿瘤微环境是中医药治疗肿瘤的优势，中药厚朴的活性成分和厚朴酚有抗肿瘤和转移作用，但未见涉及TAM及免疫抑制机制的研究。前期我们发现和厚朴酚抑制巨噬M2型极化并促进M1型极化，抑制TAM促乳腺癌迁移的作用，推测和厚朴酚通过调节TAM极化、阻断免疫抑制微环境抑制乳腺癌肺转移。本项目拟从多个维度观察和厚朴酚对TAM极化、免疫抑制性因子分泌、免疫抑制细胞表达的调节，探讨其对JAK/STAT和PI3K/Akt信号通路的作用，阐明和厚朴酚抑制乳腺癌肺转移并增加化疗疗效的机制，为中药抗肿瘤转移的研发和机制阐明奠定基础，为临床联合用药提供新候选化合物和科学依据。

转移是乳腺癌相关死亡的主要原因。与其他类型的乳腺癌相比，三阴性乳腺癌(TNBC)的复发和转移发生率更高。肺转移常发生在TNBC转移中，使TNBC预后恶化。由于对内分泌和靶向治疗不敏感，转移性TNBC患者通常只能采用化疗治疗，然而受耐药性和副作用的限制化疗效果不好。尽管最近一项临床三期研究表明新型抗体药物偶联物曲妥珠单抗对于Her2低转移性乳腺癌患者的无进展和总生存期优于化疗。然而抗体-药物偶联物在客观反应率、耐药性和对HER2零表达的TNBC的适用性方面仍然作用有限。因此寻找治疗TNBC的有效方法仍是迫切且必要的。由于肿瘤相关巨噬细胞(TAMs)在肿瘤进展和转移中发挥重要作用，是肿瘤治疗的重要靶点。既往研究已证实厚朴酚具有抑制肿瘤生长和进展的作用，但我们致力于研究和厚朴酚通过调节巨噬细胞极化以及招募发挥抑制TNBC肺转移中的作用和机制。本研究中我们发现和厚朴酚降低了IL13引起的M2标志物如CD206、Arg1和CCL2的表达增加，来自和厚朴酚处理的M2巨噬细胞的条件培养基抑制TNBC细胞的侵袭和迁移能力。和厚朴酚可显著通过抑制信号器和转录激活因子(STAT)6和STAT3的激活抑制巨噬细胞的M2型极化。同时，和厚朴酚通过促进STAT1磷酸化增加了LPS/ IFN-γ诱导的M1标记物如CD11c、iNOS和IL12的表达。此外，和厚朴酚降低了肺组织中M2/M1巨噬细胞的比例和IL-10/IL-12的基因表达，从而抑制了小鼠乳腺癌的增殖和转移。同时，和厚朴酚可通过CCL2/CCR2途径减少肺组织巨噬细胞的招募和浸润。这些结果表明厚朴酚可能通过调节巨噬细胞的极化和募集抑制TNBC肿瘤进展和肺转移。本研究从和厚朴酚影响TAM及免疫抑制微环境的视角为中药抗肿瘤转移的研发和机制阐明奠定基础，为肿瘤临床治疗现行的联合用药提供有效化合物和科学依据。