Wnt/β-catenin信号途径对肿瘤相关巨噬细胞的调控及其在肝癌进展中的作用和机制研究

Tumor-associated macrophages (TAMs) are the key cell population during hepatocellular carcinoma (HCC) development. Recent many experimental studies show that macrophages possess heterogeneity on its origin, polarization and function. However, which macrophage subsets contribute to HCC progression and the detailed molecular mechanism of regulation on macrophages heterogeneity during HCC development is not well understood. Recently, literature and our work found that the molecules involving in canonical Wnt signaling were expressed significantly in M2 macrophages, activated Wnt signaling might promote the M2 macrophages activation. Using co-culture system, we found the reduced hepa1-6 cells growth, invasion and metastasis when they were cultured with the conditional medium-derived from si-β-catenin M2 macrophages, indicating that si-β-catenin M2 macrophages abrogate pro-tumor TAMs phenotype. Based on these studies, we propose that whether Wnt signaling might control HCC development through regulation of M2 macrophages activation. In the current project, by using conditional β-catenin deficient mice, that is the key transcription factor of Wnt signaling, and several tumor models including HCC, we intend to explore the role of Wnt signaling on macrophages activation during HCC progression, and reveal its down-stream molecules and the detailed molecular mechanism on regulation of macrophages heterogeneity in HCC. Furthermore, we expect to provide the enough evidence on the relationship between Wnt and related signaling on regulation of macrophage heterogeneity in tumorgenesis. Finally, these studies will bring forth more new strategies and targets for the treatment of HCC. Therefore, our studies are of important theoretical significance and potential application value.

肿瘤相关巨噬细胞（TAMs）是肝癌发生发展中的关键细胞亚群。最新研究表明巨噬细胞（Mφ）有起源、极化和功能异质性。哪种Mφ亚群调控肝癌进展？机制如何？文献和我们课题组近期工作均表明Wnt信号相关分子高表达于M2型Mφ，激活Wnt信号可促进M2型Mφ极化。利用体外共培养体系，我们发现β-catenin敲低的M2型Mφ培养上清，可显著抑制肝癌细胞的生长、侵袭和转移，表明其削弱了TAMs表型。据此，我们提出Wnt/β-catenin信号可能通过调控M2型TAMs活化而参与肝癌进展。本课题拟利用髓系细胞特异剔除Wnt信号关键转录因子β-catenin小鼠，建立原发性肝癌等肿瘤模型，探索Wnt信号在肝癌进展中对TAMs的调控作用，鉴定其下游分子和机制，明确与其他信号间的cross-talk，从而全面揭示Wnt信号在肝癌中对TAMs的调控和分子机制，为靶向肝癌治疗提供新思路和靶点，具有重要的研究意义。

肝癌是我国最常见的恶性肿瘤之一，发病率和死亡率高。既往肝癌的研究多聚焦于肝癌细胞本身的改变，对于肝癌微环境的关注较少。我们团队前期研究和同行的研究均显示肿瘤微环境中的肿瘤相关巨噬细胞（TAMs）参与肿瘤进程，表现为促肿瘤发展的M2表型，且与肝癌的分期及预后正相关。但是，巨噬细胞亚群在肿瘤中具有起源、极化和功能异质性。肝癌巨噬细胞亚群在肝癌微环境中起源是什么？不同起源巨噬细胞是否向M2型极化？其下游调控肝癌进展的机制和分子网络是什么？均有待进一步研究。根据文献及我们的前期研究结果，我们提出Wnt/b-catenin信号通路可能是调控肝癌TAMs亚群进而促肝癌发生发展的重要分子机制。本课题利用髓系细胞特异剔除Wnt信号关键转录因子b-catenin小鼠，建立原发性肝癌等肿瘤模型，探索Wnt信号在肝癌进展中对TAMs的起源和M2极化调控机制。研究结果显示，髓系来源的TAMs中，Wnt信号的激活可促进M2型巨噬细胞活化，提示Wnt信号可能参与巨噬细胞活化的调控。M2型巨噬细胞敲低b-catenin可削弱巨噬细胞促进肝脏肿瘤生长、侵袭和转移的能力。髓系细胞特异性Wnt信号剔除小鼠肝癌生长显著受抑制，其机制一方面是通过影响肝脏kuffer细胞增殖，另一方面是通过减少单核细胞募集和分化来抑制肝癌进展。我们构建靶向肿瘤相关巨噬细胞递送miRNAs的给药系统，该载体有望靶向巨噬细胞调控 Wnt 信号活性，达到肝癌治疗的目的。本研究从肿瘤微环境的角度揭示肝癌发生发展的分子机制，而且有望通过对巨噬细胞Wnt/b-catenin信号通路的干预，为开发肝癌免疫治疗的新方法提供理论基础，具有重要的理论意义和潜在的应用价值。