Roles of Glial Autophagy in Breast Cancer Brain Metastasis

项目总结 预防和治疗乳腺癌的最新进展显著提高了乳腺癌的存活率 癌症患者。需要强调的是，随着乳腺癌患者存活率的增加， 隐匿性乳腺癌脑转移(BCBM)发生率明显增加。煤层气是关键因素之一 这导致了乳腺癌患者的致命性。自噬在肿瘤的发生和发展中起着重要的作用 癌症、神经退行性疾病、代谢紊乱和传染病。尽管如此， 自噬在肿瘤微环境中的作用，特别是神经胶质细胞自噬在大脑皮层脑膜瘤中的作用 调查过了。利用同基因小鼠，我们建立了脑内和颈动脉注射模型 BCBM与不同的小鼠乳腺癌细胞。我们观察到强健的星形胶质细胞增生，小胶质细胞的渗透，以及 小鼠BCBM模型中恶性细胞的失控生长。更重要的是，我们发现自噬增加 在反应性星形胶质细胞中，而不是在脑乳腺癌边缘的神经元中。使用特定于大脑的FIP200(和 自噬必需基因)条件性敲除小鼠，我们揭示了自噬在 星形胶质细胞与脑血肿的发生和发展。乳腺癌细胞激活STAT3启动大脑 转移，其过程依赖于肿瘤微环境星形胶质细胞的完整自噬。此外， 我们证实了在解剖的人类中星形胶质细胞自噬的增加和癌细胞中STAT3的激活 样本，表明我们的实验观察与临床重要性相关。我们的结果表明 先前未知的星形胶质细胞在肿瘤微环境中支持启动和 乳腺癌细胞在脑内的生长情况。为了便于机械论研究，我们生成了一个共文化模型，使用 人乳腺癌细胞系与人胚胎干细胞共同衍生的脑器官。我们的数据显示 转移性人乳腺癌细胞MDA-MB-231可在脑脏器中定植，而非 转移性MCF-7细胞不能生长。在这项提议中，我们将确定分子机制， 星形胶质细胞中的自噬被乳腺癌用于脑转移，使用的分子组合 生物学、细胞追踪法、脑注射、干细胞技术和小鼠遗传方法。我们的 拟议的研究将对理解反应性的基本机制产生重大影响 星形胶质细胞来调节脑微循环。我们的研究将为分层和治疗提出新的翻译方法 BCBM患者中。我们的研究结果也可能对肿瘤的研究有所帮助。 其他脑转移癌和原发脑瘤的微环境。

PROJECT SUMMARY Recent advance in the prevention and treatment of breast cancer significantly increase the survival of breast cancer patients. It will be highlighted that with the increased survival of breast cancer patients, however, the incidence of latent breast cancer brain metastasis (BCBM) significantly increased. BCBM is one of critical factors that contributes to the lethality of breast cancer patients. Autophagy is important in the initiation and progression of cancers, neurodegenerative diseases, metabolic disorders, and infectious diseases. Nevertheless, the functions of autophagy in tumor microenvironment, especially the roles of glial autophagy in BCBM, are not investigated. Using syngeneic mice, we established intracerebral and intracarotid artery injection models for BCBM with different mouse breast cancer cells. We observed robust astrogliosis, infiltration of microglia, and uncontrolled growth of malignant cells in mouse BCBM models. More importantly, we found increased autophagy in reactive astrocytes but not in neurons at the borders of brain-breast cancers. Using brain specific Fip200 (an autophagy essential gene) conditional knock out mice, we revealed the indispensable functions of autophagy in astrocytes for the initiation and progression of BCBM. Breast cancer cells activated Stat3 to initiate brain metastasis, the process of which depended on intact autophagy in tumor microenvironment astrocytes. Moreover, we confirmed the elevation of autophagy in astrocytes and activation of Stat3 in cancer cells in dissected human samples, suggesting a correlation of our experimental observation with clinical importance. Our results indicated a previously unrecognized mechanism for astrocytes in tumor microenvironment to support the initiation and growth of breast cancer cells in brain. To facilitate mechanistic studies, we generated a coculture model using human breast cancer cell lines with human embryonic stem cells derived cerebral organoids. Our data indicated that the metastatic human MDA-MB-231 breast cancer cells could colonize in cerebral organoids while the non- metastatic MCF-7 cells could not grow. In this proposal, we will determine the molecular mechanisms by which autophagy in astrocytes is utilized by breast cancer for brain metastasis, using a combination of molecular biology, cell tracing method, brain injections, stem cell technology, and mouse genetic approaches. Our proposed studies will have significant impact on understanding the fundamental mechanisms of reactive astrocytes to regulate BCBMs. Our research will raise new translational approach for stratification and treatment of BCBM patients. The results in our research might also shed light on the investigation of tumor microenvironment for other brain metastatic cancers and primary brain tumors.