炎症微环境上调的Annexin A2通过增强骨内细胞粘附促进乳腺癌骨转移 的机制研究

Breast cancer with bone metastasis is the main obstacle to advanced breast cancer therapy. However, the molecular mechanism underlying breast cancer cells adhesion to bone forming metastasis has not been elucidated. Recent study has demonstrated that Annexin A2 could be induced by a variety of inflammation. Furthermore, Annexin A2 regulates the initial adhesion of hematopoietic stem cells to bone marrow, which was similar to tumor cells adhesion and homing to bone. Our previous work found that protein expression levels of Annexin A2 and its receptor were both up-regulated in strongly bone-metastatic MDA-MB-231 breast cancer cells than in weakly metastatic MCF7 cells. Moreover, Annexin A2 expression level in nude mice femurs with breast cancer metastasis was obviously higher than that in femurs without breast cancer metastasis. Here, we will carry out tumor cells-macrophages co-culture system, gene knockout, adhesion assays as well as animal experiments to reveal that interaction of inflammatory factors and Annexin A2 promotes breast cancer cells bone adhesion followed by bone metastasis, which will provide new targets for the treatment of breast cancer bone metastasis.

乳腺癌骨转移是制约晚期乳腺癌患者治疗的主要瓶颈，但乳腺癌细胞如何在骨内定植形成转移灶的机制尚未阐明。研究发现Annexin A2能够被多种炎症诱导表达，且其在造血干细胞粘附骨髓憩室的过程中起到关键作用，而肿瘤细胞骨内归巢的过程与造血干细胞相似。我们前期研究发现，与骨转移能力弱的MCF7细胞相比，骨转移能力强的MDA-MB-231细胞的Annexin A2及其受体表达均明显升高，乳腺癌骨转移裸鼠较对照鼠股骨内Annexin A2表达明显升高。本项目拟通过肿瘤细胞-巨噬细胞共培养体系、基因敲除, 粘附实验以及裸鼠体内乳腺癌骨转移瘤模型阐明炎症因子与Annexin A2相互作用进而增强肿瘤细胞骨内粘附，促进乳腺癌骨转移的具体分子机制，为治疗乳腺癌骨转移提供新的靶点。

一、项目背景.尽管Annexin A2与乳腺癌的相关性已被大量研究证实，但乳腺癌中Annexin A2高表达的原因目前仍不清楚。近年来炎症微环境在乳腺癌等恶性肿瘤的演进过程中的作用日趋成为研究热点。.已证实炎症因子IFN-γ可上调Annexin A2的表达。有研究发现Annexin A2是NF-κB通路的靶基因，激活NF-κB通路可上调Annexin A2的表达。上述研究提示乳腺癌微环境中的炎症因子很可能通过激活NF-κB通路，诱导Annexin A2的表达，进而促进乳腺癌的侵袭转移。.因此，Annexin A2是乳腺癌相关基因，具有促进乳腺癌增殖、迁移、侵袭等作用。Annexin A2既能够被炎症诱导表达，也能够激活炎症细胞。本项目中，我们推测在乳腺癌微环境中，IFN-γ、IL-6、TNFα等炎症因子通过激活NF-κB通路，上调Annexin A2的表达，加速乳腺癌的进展。.二、主要研究内容.TNFα、IL-6、IFN-γ等炎症因子通过激活NF-κB通路，上调Annexin A2的表达，促进乳腺癌的进展。.三、重要结果、关键数据和科学意义. 本研究结果显示，炎症因子IFN-γ、IL-6、TNFα不是单纯的促进乳腺癌MDA-MB-231细胞、MCF-7细胞的增殖，而是促进乳腺癌细胞的迁移和侵袭，抑制炎性通路NF-κB的表达，Annexin A2的表达同样受到抑制，提示Annexin A2在炎症因子促乳腺癌迁移和侵袭的过程中起到关键作用。进一步实施需要采用基因沉默技术抑制乳腺癌细胞中Annexin A2的表达，检测炎症因子的表达和乳腺癌细胞的生物学行为，并进一步在动物实验中验证。. 本研究创新性的采用IFN-γ、IL-6、TNFα处理乳腺癌细胞，检测细胞增殖、侵袭、迁移等生物学行为，以及Annexin A2的表达水平。并且进一步从基因水平通过强化表达IκBαM阻断了经典NF-κB信号通路，验证炎症因子是否通过NF-κB通路上调Annexin A2及Annexin A2受体的表达水平的关键技术，证实了肿瘤炎症微环境可以上调Annexin A2表达，促进乳腺癌的进展。