Laboratory of Experimental Cancer Research, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg.
University of Strasbourg, Strasbourg, France.
Cancer Res. 2018 Oct 1;78(19):5631-5643. doi: 10.1158/0008-5472.CAN-18-0441. Epub 2018 Aug 13.
Elucidation of the underlying molecular mechanisms of immune evasion in cancer is critical for the development of immunotherapies aimed to restore and stimulate effective antitumor immunity. Here, we evaluate the role of the actin cytoskeleton in breast cancer cell resistance to cytotoxic natural killer (NK) cells. A significant fraction of breast cancer cells responded to NK-cell attack via a surprisingly rapid and massive accumulation of F-actin near the immunologic synapse, a process we termed "actin response." Live-cell imaging provided direct evidence that the actin response is associated with tumor cell resistance to NK-cell-mediated cell death. High-throughput imaging flow cytometry analyses showed that breast cancer cell lines highly resistant to NK cells were significantly enriched in actin response-competent cells as compared with susceptible cell lines. The actin response was not associated with a defect in NK-cell activation but correlated with reduced intracellular levels of the cytotoxic protease granzyme B and a lower rate of apoptosis in target cells. Inhibition of the actin response by knocking down CDC42 or N-WASP led to a significant increase in granzyme B levels in target cells and was sufficient to convert resistant breast cancer cell lines into a highly susceptible phenotype. The actin response and its protective effects were fully recapitulated using donor-derived primary NK cells as effector cells. Together, these findings establish the pivotal role of actin remodeling in breast cancer cell resistance to NK-cell-mediated killing. These findings establish the pivotal role of the actin cytoskeleton in driving breast cancer cell resistance to natural killer cells, a subset of cytotoxic lymphocytes with important roles in innate antitumor immunity. .
阐明癌症免疫逃逸的潜在分子机制对于开发旨在恢复和刺激有效抗肿瘤免疫的免疫疗法至关重要。在这里，我们评估了肌动蛋白细胞骨架在乳腺癌细胞对细胞毒性自然杀伤 (NK) 细胞的抵抗中的作用。相当一部分乳腺癌细胞通过在免疫突触附近迅速而大量地积累 F-肌动蛋白来对 NK 细胞的攻击做出反应，我们将这个过程称为“肌动蛋白反应”。活细胞成像提供了直接证据，表明肌动蛋白反应与肿瘤细胞对 NK 细胞介导的细胞死亡的抵抗有关。高通量成像流式细胞术分析表明，与敏感细胞系相比，对 NK 细胞高度抵抗的乳腺癌细胞系中，具有肌动蛋白反应能力的细胞明显富集。肌动蛋白反应与 NK 细胞激活缺陷无关，但与细胞内细胞毒性蛋白酶 granzyme B 水平降低和靶细胞凋亡率降低相关。通过敲低 CDC42 或 N-WASP 抑制肌动蛋白反应会导致靶细胞中 granzyme B 水平显著增加，并足以将耐药乳腺癌细胞系转化为高度敏感表型。使用供体来源的原代 NK 细胞作为效应细胞可以完全再现肌动蛋白反应及其保护作用。这些发现确立了肌动蛋白重塑在乳腺癌细胞抵抗 NK 细胞介导的杀伤中的关键作用。这些发现确立了肌动蛋白细胞骨架在驱动乳腺癌细胞对自然杀伤细胞（具有重要固有抗肿瘤免疫作用的细胞毒性淋巴细胞的亚群）的抵抗中的关键作用。
