Mitochondrial lateral transfer during metastasis

项目摘要 巨噬细胞在癌症中发挥着自相矛盾的作用：它们可以杀肿瘤，但在许多癌症中，巨噬细胞 促进转移。越来越多的证据表明，巨噬细胞可以调节细胞行为， 非传统的细胞接触介导的通信在发展和稳态。我们最近 通过发现巨噬细胞也可以参与非常规的细胞接触， 在肿瘤微环境中与肿瘤细胞介导的通讯，这些相互作用 有助于转移。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转移细胞质， 内容物以细胞接触依赖性方式与黑色素瘤细胞接触。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接受从原发肿瘤播散的巨噬细胞胞质。 我们现在处于理想的位置，以确定从巨噬细胞转移到肿瘤的关键成分 转移的细胞，以及这种转移是如何发生的。线粒体是动态的细胞器， 基本细胞功能的一部分。线粒体已被证明在体内转移到肿瘤细胞，恢复其功能。 呼吸和形成肿瘤的能力。虽然这些优雅的"原理证明"研究表明， 线粒体侧向转移可发生在肿瘤微环境中，供体基质细胞不发生 虽然已经鉴定，但转移机制尚未确定，并且线粒体在肿瘤细胞中的命运和功能 没有被描述。令人兴奋的是，我们发现原代人类巨噬细胞可以将线粒体 人类乳腺癌细胞和黑色素瘤细胞，这两种癌症中的巨噬细胞已被证明是 发挥促肿瘤作用。接受巨噬细胞线粒体的肿瘤细胞， 共培养中的线粒体转移，或通过直接注射纯化的巨噬细胞线粒体，表现出增加的 增殖令人惊讶的是，我们发现线粒体转移发生后， 作为与宿主线粒体网络在空间上不同的群体。此外，我们发现，高水平的 局部活性氧在转移的线粒体中积累，这表明了一个有趣的假设， 转移的线粒体可以向肿瘤细胞提供信号，而不是提供过量的线粒体， 如前所述的功能。为了验证这一假设，我们建议：（目标1）了解如何 线粒体动态重组线粒体转移到肿瘤细胞和（目的2）确定如何 线粒体转移在机制上诱导癌细胞增殖。综合起来，这些实验将 揭示巨噬细胞线粒体转移是否可以指导乳腺癌和黑色素瘤细胞成为 更健壮和转移性。我们的目标是确定免疫细胞如何在肿瘤微环境中发挥作用， 并为开发限制转移的未来免疫疗法提供基础。

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.