TGF-β与Notch信号通路调控乳腺癌内皮间质转化的作用与机制研究

Tumor angiogenesis plays a pivotal role in tumor invasion and metastasis. Endothelial-mesenchymal transition (EndMT), as an important process of angiogenesis, is of great concern. However, how EndMT is involved in the angiogenesis of breast cancer and its regulatory mechanisms remain to be been fully elucidated. Our preliminary study demonstrated that tumor-associated macrophages (TAMs) could induce endothelial cells to undergo EndMT by secreting CCL18 probably through activating the TGF-β and Notch signaling pathways in the microenvironment of breast cancer. Moreover, endothelial progenitor cells were found in the initiating cells of breast tumor, which could differentiate into functional vascular endothelial cells. In the present study, the models of induction of EndMT from endothelial cells and induced differentiation of vascular endothelial progenitor cells of breast cancer into vascular endothelial cells in vitro were conducted. By using immunohistochemical double-staining, RNA interference, angiogenesis in vitro, animal experiment and combining clinical sample analysis, we investigate the role of EndMT in angiogenesis of breast cancer both in normal and tumorous endothelial cells. This study was aimed at determining the mechanism and key signaling pathway regulating EndMT to evaluate the potential therapeutic strategies of EndMT for anti-tumor angiogenesis, which is desirable for developing novel targets for anti-angiogenesis in breast cancer.

肿瘤血管生成在肿瘤侵袭、转移中至关重要，其中内皮间质转化(EndMT)作为血管生成的重要环节而备受关注，但EndMT如何参与乳腺癌血管生成、其本身的调控机制等目前尚不明确。我们前期研究发现乳腺癌微环境中肿瘤相关巨噬细胞可通过分泌CCL18诱导内皮细胞发生EndMT，其机制可能与激活了Notch与TGF-β信号通路有关；同时也发现乳腺肿瘤启动细胞中存在内皮祖细胞，能分化成有功能的血管内皮细胞。在此基础上，本课题建立体外诱导内皮细胞EndMT模型及乳腺癌血管内皮祖细胞向血管内皮细胞分化模型，通过免疫组化双染、RNA干扰、体外血管生成实验、动物实验，结合临床样本分析，从正常内皮细胞及肿瘤分化内皮细胞两方面探讨EndMT在乳腺癌血管生成中的作用，明确调控EndMT的关键信号通路，阐明EndMT的发生机制，评价干预EndMT是否具有抗肿瘤血管生成的潜在治疗作用，为抗血管生成治疗乳腺癌提供新靶点。

自本项目获得资助以来，课题总体进展情况良好，各项研究工作按计划实施，并取得预期结果,在内皮间质转化促进乳腺癌血管生成的研究方面取得较大的进展。肿瘤血管生成在肿瘤侵袭、转移中至关重要，目前研究认为肿瘤血管可以由正常内皮和分化的肿瘤癌干细胞构成。其中内皮间质转化(EndMT)作为血管生成的重要环节而备受关注，但EndMT如何参与乳腺癌血管生成、其本身的调控机制等目前尚不明确。我们前期研究发现乳腺癌微环境中肿瘤相关巨噬细胞可通过分泌CCL18诱导内皮细胞发生EndMT，其机制可能与激活了Notch与TGF-β信号通路有关；同时也发现乳腺肿瘤启动细胞中存在内皮祖细胞，能分化成有功能的血管内皮细胞。本项目以此EndMT为切入点，探讨EndMT过程在上述的两种乳腺癌肿瘤血管新生的方式的影响和机制。我们通过对86例乳腺癌患者临床标本免疫组化双染分析，发现EndMT标志物与微血管密度呈现正相关，提示较差的临床预后。为了验证这两种乳腺癌肿瘤血管形成方式，我们构建了体外TGF-β1诱导正常内皮细胞及乳腺癌分化血管内皮细胞EndMT模型，通过RNA干扰，体外血管形成实验，发现这两种细胞发生EndMT后，血管形成能力加强，其机制与激活了Notch与TGF-β信号通路有关。我们进一步通过小鼠移植瘤模型及背部血管窗模型，通过体视显微镜直接观察肿瘤周围血管形成情况，发现当TGF-β1受抑制后，EndMT过程受抑制，肿瘤以及周围血管生长受抑制。该研究通过阐明EndMT的发生机制，验证干预EndMT具有抗肿瘤血管生成的潜在治疗作用，有望为抗血管生成治疗乳腺癌提供新的靶点和思路。迄今为止，已经在SCI收录杂志上发表相关论文8篇。