PO.ET06.01 · 实验与分子治疗
致命的啃咬：理解巨噬细胞介导的胞啃作用后癌细胞的命运
Bites that kill: Understanding cancer cell fate after macrophage mediated trogocytosis
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
巨噬细胞疗法是靶向杀伤肿瘤内癌细胞的一条令人振奋的途径。巨噬细胞可吞噬（即整细胞吞入）濒死、死亡和异常的细胞。然而，据观察，在实体瘤中，巨噬细胞主要执行胞啃作用（trogocytosis）即“啃咬”，即撕下实体瘤细胞的部分。肿瘤中的胞啃作用被观察到具有矛盾性：一方面它使免疫细胞得以剥离癌细胞表面的抗原，从而允许癌症进展；另一方面，它可导致癌细胞死亡，有助于免疫治疗。这一双重性结果引出了一个问题：如何利用胞啃作用使其在免疫治疗中持续致命。我们观察到，嵌合抗原受体巨噬细胞（CAR-M）在与实体瘤细胞相互作用时，胞啃作用的发生率高于吞噬作用。我们用SKOV3细胞构建的3D肿瘤球体模型显示，在Her2CAR巨噬细胞作用下体积显著缩小，并伴有更高的胞啃作用。我在2D细胞培养中观察到，被胞啃的癌细胞通过Her2CAR巨噬细胞的特异性靶向而发生凋亡性细胞死亡。然而有趣的是，在共培养中死亡并非即刻发生，而是在持续的胞啃攻击之后发生。在共培养的最初2小时内，当胞啃作用显著高于吞噬作用时，并无癌细胞死亡。我们的3D肿瘤球体模型还显示，在与Her2CAR巨噬细胞共培养5天后球体直径减小。癌细胞死亡可被泛caspase抑制剂Q-VD-Oph阻断。延迟的癌细胞死亡提示，被胞啃的癌细胞克服了初始的、非致命的细胞膜丧失；然而持续的胞啃攻击使癌细胞在较晚时间点易于发生凋亡。细胞膜的持续丧失以及随后在维持稳态的同时进行的持续修复，对癌细胞而言是一个耗能的过程。因此，被胞啃癌细胞中持续应激的累积最终可将其推向凋亡。我目前正在研究被胞啃细胞中氧化应激的累积对凋亡激活的作用。此外，还观察到与Her2CAR巨噬细胞共培养3天后某些基因转录组谱的变化，提示被胞啃细胞可改变其对胞啃作用的转录组反应。当前正在研究被胞啃细胞中累积的应激是否导致这一转录组谱的变化。CAR-M为靶向肿瘤提供了一条有前景的途径。然而，其在实体瘤中的疗效有待提高。我们观察到持续的胞啃作用在较晚时间点将癌细胞推向凋亡。因此，要使胞啃作用在免疫治疗中致命，理解被胞啃细胞的反应并研究被胞啃细胞的命运至关重要。
查看英文原文 English abstract
Macrophage therapies are an exciting avenue for targeted cancer cell killing in tumors. Macrophages phagocytose (that is, whole cell engulfment) of dying, dead, and abnormal cells. However, it's been observed that in solid tumors, macrophages primarily perform trogocytosis or nibbling, where they tear away portions of solid tumor cells. Trogocytosis in tumors is observed to be paradoxical: while it allows immune cells to strip away antigen from the cancer cell surface and thus allowing cancer progression. Conversely, it can cause cancer cell death, aiding immunotherapy. This dichotomous result raises the question of how to leverage trogocytosis in immunotherapy to be consistently lethal. We observe higher rates of trogocytosis compared to phagocytosis with Chimeric Antigen Receptor macrophages (CAR-M) when interacting with solid tumor cells. Our 3D tumor spheroid model constructed with SKOV3 cells shows a significant reduction in size with Her2CAR macrophages, with higher trogocytosis. I observe trogocytosed cancer cells to undergo apoptotic cell death via specific targeting by Her2CAR macrophages in 2D cell cultures. However, interestingly, death is not immediate in the co-cultures; instead, it happens following sustained trogocytic attack. In the first 2 hours of co-culture, when trogocytosis is significantly higher than phagocytosis, there's no cancer cell death. Our 3D tumor spheroid model also shows a reduction in spheroid diameter with Her2CAR macrophages after 5 days of co-culture. The cancer cell death can be blocked with a pan-caspase inhibitor Q-VD-Oph. The delayed cancer death suggests that trogocytosed cancer cells overcome initial, non-lethal loss of cell membrane; however, continual trogocytic attack renders cancer cells susceptible to apoptosis at later timepoints. Continuous loss of the cell membrane, followed by continual repair while maintaining homeostasis, is an energy-expensive process for the cancer cells. Thus accumulation of sustained stress in the trogocytosed cancer cells can ultimately push them to undergo apoptosis. I am currently investigating oxidative stress accumulation for activation of apoptosis in trogocytosed cells. Further, a change in transcriptomic profile for certain genes following 3-day co-culture with Her2CAR macrophages is also observed, suggesting the trogocytosed cells can alter their transcriptomic response to trogocytosis. Under current investigation is whether accumulated stress in trogocytosed cells causes this change in transcriptomic profile. CAR-M presents a promising avenue for targeting tumors. However, their efficacy in solid tumors needs to be improved. We observe continual trogocytosis pushes cancer cells to apoptosis at later timepoints. Thus, to make trogocytosis lethal in immunotherapy, understanding the trogocytosed cell response and investigating the fate of trogocytosed cells is essential.
利益披露 Disclosure
I. Datta, None..
A. Rogers, None.