Mitochondrial lateral transfer during metastasis

项目摘要 巨噬细胞在癌症中扮演着矛盾的角色：它们可以杀瘤，但在许多癌症中，巨噬细胞 促进转移。越来越多的证据表明，巨噬细胞可以通过 发育和动态平衡中的非常规细胞接触介导的交流。我们最近做了 通过发现巨噬细胞也可以进行非常规的细胞接触，扩展了这些范例- 在肿瘤微环境中介导与肿瘤细胞的通讯，以及这些相互作用 会导致肿瘤转移。通过可视化和操纵高度迁移的黑色素瘤细胞及其 在体内微环境中，我们意外地发现肿瘤相关巨噬细胞在胞浆内转运 内容物以细胞接触依赖的方式转移到黑色素瘤细胞。值得注意的是，70%-80%的黑色素瘤细胞 在斑马鱼和小鼠模型中均收到从原发肿瘤中播散的巨噬细胞胞浆。 我们现在处于识别从巨噬细胞转移到肿瘤的关键成分(S)的理想位置 细胞的转移，以及这种转移是如何发生的。线粒体是动态细胞器，执行各种功能 基本的细胞功能。已有研究表明，线粒体可以在体内转移到肿瘤细胞，恢复它们的 呼吸和形成肿瘤的能力。虽然这些优雅的“原则证明”研究表明 线粒体在肿瘤微环境中可以发生侧向转移，供体基质细胞(S)则不能 线粒体的转移机制尚未明确，肿瘤细胞中线粒体的命运和功能尚未确定 并不具有特征性。令人兴奋的是，我们发现原代人类巨噬细胞可以转移线粒体 对于人类乳腺癌细胞和黑色素瘤细胞，巨噬细胞在两种癌症中被证明是 发挥促进肿瘤发生的作用。通过自发方式接收巨噬细胞线粒体的肿瘤细胞 在共培养中或通过直接注射纯化的巨噬细胞线粒体，线粒体转移显示增加 扩散。令人惊讶的是，我们发现在线粒体转移发生后，转移的线粒体仍然存在 作为与宿主线粒体网络在空间上不同的种群。此外，我们发现高水平的 当地的活性氧积累在转移的线粒体上，这表明了一个有趣的假说 转移的线粒体可能会向肿瘤细胞提供信号，而不是提供多余的线粒体 功能如前所述。为了检验这一假设，我们建议：(目标1)了解如何 线粒体动态重组以将线粒体转移到肿瘤细胞，并(目标2)确定如何 线粒体转移机械性地诱导癌细胞增殖。总而言之，这些实验将 揭示巨噬细胞线粒体转移是否能指导乳腺癌和黑色素瘤细胞成为 更健壮，更容易转移。我们的目标是定义免疫细胞如何在肿瘤微环境中发挥作用， 并为开发未来限制转移的免疫疗法提供基础。

Project Summary Macrophages play paradoxical roles in cancer: They can be tumoricidal, but in many cancers, macrophages promote metastasis. There has been growing evidence that macrophages can modulate cell behavior via unconventional cell contact-mediated communication in development and homeostasis. We have recently extended these paradigms by discovering that macrophages can also engage in unconventional cell contact- mediated communication with tumor cells within the tumor microenvironment, and that these interactions contribute to metastasis. By visualizing and manipulating highly migratory melanoma cells and their microenvironment in vivo, we unexpectedly found that tumor-associated macrophages transfer cytoplasmic contents to melanoma cells in a cell contact-dependent manner. Remarkably, 70-80% of melanoma cells that received macrophage cytoplasm disseminated from the primary tumor in both zebrafish and murine models. We are now ideally positioned to identify key component(s) that are transferred from macrophages to tumor cells for metastasis, and how this transfer occurs. Mitochondria are dynamic organelles that perform a variety of essential cellular functions. Mitochondria have been shown to transfer to tumor cells in vivo, restoring their respiration and ability to form tumors. While these elegant “proof of principle” studies demonstrated that mitochondrial lateral transfer can occur in the tumor microenvironment, the donor stromal cell(s) were not identified, the transfer mechanism was not defined, and the fates and functions of mitochondria in tumor cells were not characterized. Excitingly, we have found that primary human macrophages can transfer mitochondria to human breast cancer cells and melanoma cells, two cancers in which macrophages have been shown to play a pro-tumorigenic role. Tumor cells that receive macrophage mitochondria either by spontaneous mitochondrial transfer in coculture, or by direct injection of purified macrophage mitochondria, exhibit increased proliferation. Surprisingly, we find that after mitochondrial transfer occurs, the transferred mitochondria remain as a spatially distinct population from the host mitochondrial network. Furthermore, we found that high levels of local reactive oxygen species accumulate at transferred mitochondria, suggesting an intriguing hypothesis that transferred mitochondria may provide a signal to tumor cells, rather than providing excess mitochondrial function as has been previously described. To test this hypothesis, we propose to: (Aim 1) Understand how mitochondria dynamically reorganize for mitochondrial transfer to tumor cells and (Aim 2) Determine how mitochondrial transfer mechanistically induces cancer cell proliferation. Taken together, these experiments will reveal whether macrophage mitochondrial transfer can instruct breast cancer and melanoma cells to become more robust and metastatic. Our goals are to define how immune cells function in the tumor microenvironment, and to provide a basis for developing future immunotherapies that limit metastasis.