肝癌外泌体来源miR-148a调控微环境中巨噬细胞极化的作用及机制研究

High level of tumor-associated macrophage (TAM) infiltration is an important characteristic of the microenvironment of hepatocellular carcinoma (HCC), and the polarized degree of M2 macrophage is closely related to the clinic prognosis. However, intercellular communication between HCC cells and macrophages in the microenvironment and the mechanism to induce M2 polarization of macrophages are not entirely clear. Recently, we discovered that the abnormally highly-expressed miR-148a in TAM was able to activate the STAT3 signal pathway which modulated the phenotypic polarization, and might play critical roles in the TAM polarization and HCC progression. Besides, HCC cell-derived exosome also highly-expressed and delivered miR-148a to the TAM. Combined with the relevant research evidences, scientific hypotheses are raised: HCC cell-derived exosomal miR-148a activates the STAT3 signal pathway of macrophages in microenvironment and then facilitates the M2 polarization of macrophages and formation of tumor-promoting microenvironment. In vivo and vitro experiments and clinical specimen detection will be utilized in this project to systematically estimate the role of HCC cell-derived exosomal miR-148a in modulating the TAM polarization and tumor microenvironment formation, and elucidate the mechanism of miR-148a to modulate M2 polarization of macrophages and to be proactively discharged by HCC cells. The results can help to find new strategies for TAM-targeting immunotherapy and provide optimized schemes for miR-148a-based treatment for HCC.

肿瘤相关巨噬细胞（TAM）大量浸润是肝癌微环境的重要特征，其M2型极化与临床预后密切相关。但肝癌细胞与微环境中巨噬细胞间通讯的方式及引发其M2型极化的机制，尚不完全清楚。新近我们发现，作为肝癌细胞内的低表达性抑癌因子，miR-148a在TAM中却呈高表达，并能激活调控表型极化的STAT3通路，可能是TAM极化及肝癌进展的关键调控分子；而肝癌外泌体也高表达并能传递miR-148a给TAM。由此我们提出科学假说：肝癌外泌体来源miR-148a能活化微环境中巨噬细胞内STAT3通路，促进其M2型极化和促癌微环境形成。本项目拟通过体内外实验和临床样本检测，系统地研究肝癌外泌体来源的miR-148a在TAM极化和促癌微环境形成中的作用，阐明miR-148a调控TAM极化及肝癌细胞主动外排miR-148a的机制，以期从中寻找肝癌靶向TAM治疗新的策略，并为基于miR-148a的肝癌治疗提供优化方案。

肿瘤相关巨噬细胞（TAM）大量浸润是肝癌微环境的重要特征，其M2型极化与临床预后密切相关。但肝癌细胞与微环境中巨噬细胞间通讯的方式及引发其M2型极化的机制，尚不完全清楚。新近我们发现，作为肝癌细胞内的低表达性抑癌因子，miR-148a在TAM中却呈高表达，并能激活调控表型极化的STAT3通路，可能是TAM极化及肝癌进展的关键调控分子；而肝癌外泌体也高表达并能传递miR-148a给TAM。由此我们提出科学假说：肝癌外泌体来源miR-148a能活化微环境中巨噬细胞内STAT3通路，促进其M2型极化和促癌微环境形成。本项目拟通过体内外实验和临床样本检测，系统地研究肝癌外泌体来源的miR-148a在TAM极化和促癌微环境形成中的作用，阐明miR-148a调控TAM极化及肝癌细胞主动外排miR-148a的机制，以期从中寻找肝癌靶向TAM治疗新的策略，并为基于miR-148a的肝癌治疗提供优化方案。研究发现，在体外共培养模型中，肝癌TAM中异常升高的miR-148a，能够促进其M2极化，抑制T细胞增殖、刺激微血管形成。机制上，因Tyr705和Ser727位点磷酸化而激活的STAT3，介导了miR-148a对M2型TAM的促进作用；同时肝癌细胞产生的外泌体中高表达成熟体miR-148a，其传递对TAM中miR-148a含量的升高起关键作用。动物模型中，我们发现过表达miR-148a的巨噬细胞促进肝癌瘤体生长，而删除巨噬细胞可以增强agomiR-148a瘤内注射的疗效。本项目证明，miR-148a活化STAT3通路是肝癌TAM发生M2极化的关键调控机制，而肝癌外泌体miR-148a是促进微环境中TAM发生M2型极化的重要细胞间通讯方式，靶向抑制肝癌微环境中的“外泌体/miR-148a/STAT3”轴，具有重要的科学理论意义和潜在的临床应用价值。