肿瘤相关巨噬细胞通过分泌细胞因子TGF-β2促进甲状腺乳头状癌的转移

Papillary thyroid carcinoma (PTC) has become one of the most common cancers. Up to 30-50% of PTC patients showed lymph node metastasis when diagnosed and lymph node metastasis had been associated with poor prognosis. However, the molecular mechanism of PTC metastasis is still unknown. Tumor-associated macrophage (TAM) is one of the most important cellular components in the tumor microenvironment, playing an important role in promoting tumor metastasis. Nevertheless, their roles in PTC are rarely investigated. In our previous work, abundant macrophages were found to filtrate into the PTC tumors and there was a positive correlation between TAM density and PTC lymph node metastasis as well as TNM Stages III/VI. It established the relationship between TAM and PTC. In addition, the cytokine profile showed the isolated TAM presented with high level cytokine of TGF-β2. Based on these results, we speculated that TAM may facilitate PTC cell metastasis through releasing high level of TGF-β2 Therefore, our project will further investigate 1) the role of the culture-medium of isolated TAM in the promotion of PTC development and progression, 2) the role of TGF-β2 and its receptor in promotion of PTC metastasis, 3) the relationship between the cytokine of TGF-β2and the clinic -pathological features of PTC patients by perceptive clinical trial analysis. Our project will aim to explore the molecular mechanism of PTC metastases from the aspect of tumor environment. It might provide a potential target for the prevention and treatment of the PTC metastases.

甲状腺乳头状癌（PTC）是最常见的内分泌肿瘤，其淋巴结转移率高达30%-50%，是预后不良的重要指标，目前其转移的分子机制理解十分欠缺。已知肿瘤相关巨噬细胞（TAM）在恶性肿瘤的发生发展中发挥重要作用。我们前期研究观察到TAM在PTC中呈散在分布，TAM密度与PTC淋巴结转移、TNM分期显著相关，提示TAM可能参与PTC的转移。抗体芯片结果提示TAM高分泌细胞因子TGF-β2。我们在上述重要发现的基础上提出假设，TAM可能通过分泌细胞因子TGF-β2作用于PTC细胞从而促进其发生发展。本项目将进一步展开以下工作：1）验证TAM可通过分泌细胞因子作用于PTC细胞 2）探讨TAM分泌的TGF-β2在PTC发生发展中的作用 3）随访研究分析TAM及分泌的TGF-β2与PTC 临床特征的关系。本课题不仅有利于阐明在肿瘤微环境层面PTC发生转移的分子机制，也将为PTC转移的预防和治疗提供一个新的靶点

近年来甲状腺肿瘤发病率快速增长，已经成为人体最常见肿瘤之一，其中以甲状腺乳头状癌（PTC）为主,次之为甲状腺滤泡癌（FTC）。已知甲状腺肿瘤中淋巴结转移及浸润是预后不良的危险因素。本研究从肿瘤微环境角度重点研究肿瘤相关巨噬细胞（TAM）对甲状腺肿瘤转移和浸润的作用及其相关分子作用机制。主要成果如下：成功分离甲状腺乳头癌癌中的TAM和PTC细胞，收集培养上清进行生物学行为实验阐明TAM可通过分泌细胞因子促进甲状腺乳头状癌转移；接着经体外实验证实与PBMC和PTC细胞相比，TAM确实可显著高表达和高分泌细胞因子TGF-β2；然而功能实验未发现外源性重组人细胞因子TGF-β2对PTC细胞的生物学行为有显著影响，提示TGF-β2可能不为TAM促进PTC细胞转移的效应分子（后已证实细胞因子CXCL8为TAM促进PTC转移的效应细胞因子）。进一步对甲状腺滤泡癌（FTC）和甲状腺腺瘤(FA)中的TAM进行研究发现，TAM在FTC和FA组织中分布密度不同，在FTC中显著增加；抗体芯片结果提示细胞因子CCL15可在FTC组织中显著表达，其表达量显著高于FA；体外实验证实外源性细胞因子CCL15可招募巨噬细胞，且可诱导巨噬细胞表面的CCL15受体CCR1表达增加；原代分离FTC细胞，收集其培养上清进行趋化及抑制实验提示FTC可通过分泌细胞因子招募巨噬细胞，并证实细胞因子CCL15为其效应分子之一；最后组织标本免疫组化结果提示FTC组织的CCL15表达量和TAM密度成正相关，从组织学层面证实FTC可通过分泌细胞因子CCL15招募TAM，从而促进FTC的浸润，该特征为FTC和FA的术前细针穿刺的鉴别诊断提供了新的依据。本研究是对肿瘤相关巨噬细胞在甲状腺肿瘤转移和浸润的作用及其作用机制的成功探讨，发现并证实TAM在甲状腺肿瘤的转移和浸润中发挥重要作用，提示TAM可能作为甲状腺肿瘤转移和浸润的标记，可为鉴别诊断提供线索和为治疗提供一个新的靶点。