结直肠癌（CRC）是一种常见的肿瘤类型，肝转移降低了CRC患者的长期生存率。自然杀伤（NK）细胞在抗肿瘤免疫中发挥着重要作用。本研究的目的是探讨miR-214-5p对结直肠癌肝转移中NK细胞的作用机制。我们收集了CRC肝转移和非转移组织的临床样本，并购买了人NK细胞系NK92和肝转移CRC细胞KM12L4用于研究。采用RT-qPCR、Western blot、CCK-8、Transwell、流式细胞术等方法评价miR-214-5p/USP27X/Bim通路调节NK细胞活性对CRC肝转移的影响。此外，我们还研究了miR-214-5p信号通路的潜在靶点和调控机制。在这项研究中，我们发现miR-214-5p在CRC肝转移组织中表达下调。转染miR-214-5p模拟物后，NK细胞活性显着增强，CRC肝转移细胞的增殖和迁移能力受到抑制，同时诱导肿瘤细胞凋亡。进一步的研究证明USP27X是miR-214-5p的潜在靶标，并通过去泛素化上调Bim水平。此外，miR-214-5p模拟物降低了USP27X和Bim的水平，从而增强NK细胞的抗肿瘤作用。总之，我们的研究结果表明，miR-214-5p通过调节USP27X/Bim通路促进NK细胞的抗肿瘤作用，从而抑制CRC肝转移。这一发现揭示了miR-214-5p在调节NK细胞免疫功能中的重要作用，为开发新的免疫治疗策略提供了新思路。在线版本包含补充材料，请访问10.1007/s10616-024-00642-1。©作者获得 Springer Nature B.V. 2024 的独家许可。Springer Nature 或其许可方（例如协会或其他合作伙伴）根据与作者或其他权利持有者签订的出版协议拥有本文的专有权;作者对本文已接受的手稿版本的自行存档仅受此类出版协议和适用法律的条款的约束。

Colorectal cancer (CRC) is a common tumor type, and liver metastasis reduces the long-term survival in CRC patients. Natural killer (NK) cells play an important role in anti-tumor immunity. The aim of this study was to investigate the mechanism of miR-214-5p on NK cells in CRC liver metastasis. We collected clinical samples of CRC liver metastasis and nonmetastatic tissues and purchased the human NK cell lines NK92 and liver metastatic CRC cells KM12L4 for research. RT‒qPCR, Western blot, CCK-8, Transwell, and flow cytometry methods were used to evaluate the effect of miR-214-5p/USP27X/Bim pathway regulating NK cell activity on CRC liver metastasis. In addition, we also investigated the potential targets and regulatory mechanisms of the signaling pathway of miR-214-5p. In this study, we found that miR-214-5p was downregulated in CRC liver metastasis tissues. After transfection of miR-214-5p mimic, the activity of NK cells was significantly enhanced, and the proliferation and migration ability of CRC liver metastasis cells were inhibited, while inducing tumor cell apoptosis. Further research proved that USP27X is a potential target for miR-214-5p and upregulates Bim level through deubiquitination. In addition, miR-214-5p mimic reduced the level of USP27X and Bim, thereby enhancing the antitumor effect of NK cells. In conclusion, our research results show that miR-214-5p promotes the antitumor effect of NK cells by regulating the USP27X/Bim pathway, thereby inhibiting CRC liver metastasis. This finding reveals the important role of miR-214-5p in regulating the immune function of NK cells, and provides new ideas for developing new immunotherapy strategies.The online version contains supplementary material available at 10.1007/s10616-024-00642-1.© The Author(s), under exclusive licence to Springer Nature B.V. 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.