MTDH阳性肿瘤相关巨噬细胞经miR-18a-5p/HIF-1α/CCL18信号轴参与头颈鳞癌血管新生和转移的机制研究

Tumor-associated macrophages (TAMs) in tumor microenvironment function importantly and is intensively investigated in cancer malignant progression. Our previous results indicate that MTDH+ tumor associated macrophages (TAMs) overexpress cytokine CCL18, which enhances angiogenesis and metastasis in of squamous cell carcinoma of the head and neck (SCCHN). Moreover, a potential miR-18a-5p/HIF-1α/CCL18 signaling axis may exist in MTDH+ TAMs. Therefore, we hypothesize that MTDH+ TAMs may regulate the expression of CCL18 that binds to its receptor Nir1 on cell surfaces of SCCHN and vascular endothelial cells via miR-18a-5p/HIF-1α/CCL18 signaling axis. Moreover, CCL18/Nir1 bindings may enhance metastatic ability of SCCHN cells themselves and recruit vascular endothelial cells to form angiogenesis, which together promotes SCCHN metastasis. To confirm this hypothesis, both in vitro and in vivo experiments will be used to observe whether miR-18a-5p/HIF-1α/CCL18 signaling axis will participate in MTDH+ TAMs mediated angiogenesis and metastasis in SCCHN. In this program, we will focus on the molecular regulation mechanisms of the above signaling pathway in TAMs. Finally, the clinical significance of this signaling axis will be investigated in a large SCCHN specimens with intact clinical information. The success of this project will help us to confirm that MTDH/miR-18a-5p/HIF-1α/CCL18 signaling axis can serve as a molecular bridge to connect tumor cells, vascular endothelial cells and TAMs, which will deepen our understanding about immunological and inflammatory microenvironment in SCCHN and further benefit our future immunotherapy targeting TAMs.

微环境肿瘤相关巨噬细胞（TAMs）在肿瘤恶性进展中的作用备受关注。我们发现MTDH+ TAMs细胞可高表达CCL18，促进头颈鳞癌的血管新生和侵袭转移；MTDH+ TAMs细胞可能存在miR-18a-5p/HIF-1α/CCL18信号轴。据此推测MTDH+ TAMs细胞可能经miR-18a-5p/HIF-1α上调CCL18，结合肿瘤细胞和血管内皮细胞表面受体Nir1，增强头颈鳞癌细胞的侵袭转移，并招募血管内皮细胞促进血管新生，共同导致侵袭转移。为此，我们将经体内外实验进一步阐明miR-18a-5p/HIF-1α/CCL18信号轴是否参与MTDH+ TAM细胞介导的血管新生和转移，重点阐明该信号轴的内在调控机制并验证其临床价值。本项目将证实该信号轴可作为“分子桥梁”衔接肿瘤细胞、血管内皮细胞和TAMs细胞共同导致转移；加深对头颈鳞癌免疫炎性微环境的认识，为靶向TAMs的免疫治疗提供实验数据。

微环境肿瘤相关巨噬细胞（TAMs）在肿瘤恶性进展中的作用备受关注，本课题证实了TAMs源性MTDH可维持其M2型功能，敲除MTDH可引起M2型TAMs细胞分泌蛋白的改变，对TAMs细胞的M2型功能维持具有重要作用，但不影响TAMs细胞的M2型的转化。进一步，我们将MTDH+TAMs和MTDH-TAMs与头颈鳞癌高转移细胞686LN-M2按比例混合后进行裸鼠颏下成瘤，证明MTDH+TAMs在促进头颈鳞癌生长的同时，可促进其淋巴结转移。并通过免疫荧光染色检测上述686LN-M2体内移植瘤中血管内皮标志物CD31和淋巴内皮细胞标志物LYVE-1的表达，结果提示MTDH+TAMs处理组内CD31的密度较MTDH-TAMs处理组显著提高，MTDH+ TAMs可通过诱导头颈鳞癌的血管新生，进而促进头颈鳞癌转移。利用中和抗体阻断CCL18与头颈鳞癌细胞的结合，发现中和抗体能部分逆转CCL18所导致的改变，包括头颈鳞癌细胞迁移侵袭能力、EMT和“干性”增强。体外实验进一步确定miR-18a-5p可降低HIF1α蛋白的表达，MTDH+TAMs细胞中存在miR-18a-5p/HIF-1α/CCL18信号轴调节其功能。最后，我们构建了MTDH敲除小鼠荷瘤模型，发现MTDH部分敲除能影响肿瘤TAMs细胞的M2型极化，并拓展性的发现MTDH介导肿瘤细胞淋巴结中CD8+ T细胞的发育和转化，影响肿瘤和预后。本项目将证实该信号轴可作为“分子桥梁”衔接肿瘤细胞、血管内皮细胞和TAMs细胞共同导致转移；加深对头颈鳞癌免疫炎性微环境的认识。总而言之，该项目本项目的资助下共发表论文31篇（SCI 28篇）。团队新获国家自然科学基金资助3项，参与国家重点研发计划子各课题，授权8项专利。申请人入选湖南省高层次卫生人才，履新5个专科学会副主任委员或委员。牵头举办会议3次，派送5人出国学习交流，支持培养博、硕士27人。