自然杀伤（NK）细胞发挥重要的肿瘤免疫监视作用，但肿瘤发生时NK细胞无法有效向肿瘤迁移，如何促进NK细胞进入实体肿瘤是提升免疫治疗效果的关键问题。本课题基于意外发现的矛盾现象：Styk1激酶在肿瘤细胞系和免疫缺陷荷瘤鼠中促进肿瘤进展，而在免疫健全的肿瘤模型小鼠和神经胶质瘤患者中表现为抗肿瘤作用，提示抗肿瘤作用发生可能在免疫细胞。进一步研究发现Styk1敲除小鼠中肿瘤浸润的NK细胞减少，且Styk1缺失能抑制NK细胞迁移，由此提出“Styk1促进NK细胞在肿瘤组织内的浸润，发挥抗肿瘤免疫作用”的假说。由于Styk1的胞外区缺失，本项目将研究Styk1激酶活性对趋化因子受体胞内信号通路的调控。申请人拟采用Styk1全敲除及NK细胞条件性敲除小鼠，探讨Styk1缺失对肿瘤进程及NK细胞肿瘤浸润的影响。并通过测序、蛋白相互作用及质谱实验筛选Styk1激酶的底物，为肿瘤的免疫治疗提供新思路。

Natural killer (NK) cells play an important role in tumor surveillance, but the antitumor effects of NK cells are limited by impaired NK cell infiltration, and how to promote NK cells migrating to solid tumors is a key strategy of NK cell immunotherapy. This subject is based on an unexpected paradox phenomenon in our previous study: Styk1 kinase promotes tumor proliferation and metastasis in tumor cell lines and immunodeficient tumor-bearing mice, but exhibits anti-tumor effects in spontaneous breast cancer mouse model and glioma patients. These data suggested that Styk1 inhibit tumor progression through regulating immune cells. The proportion of tumor-infiltrating NK cells was decreased significantly in Styk1 deletion mice, and we further confirmed the effect of Styk1 deletion on NK cell migration in vitro and in vivo. This project proposes that Styk1 promotes the infiltration of NK cells in tumor tissues and exerts anti-tumor immunity. Styk1 lacks the extracellular domain, it could not directly transmit extracellular chemokine signaling. So, we aim to study how Styk1 kinase regulates the intracellular downstream signaling pathway of chemokine receptors in tumor-infiltrating NK cells. This project intends to use Styk1 total knockout and NK cell-specific knockout mice, spontaneous tumor and xenograft models to investigate the effects of Styk1 deletion on tumor progression and NK cell tumor infiltration. The substrates of Styk1 kinase were screened by sequencing, protein interaction and mass spectrometry experiments. Our study aims to explore the key factors enhancing the capacity of NK cells tumor infiltration, providing new ideas and targets for clinical therapy.