肝癌细胞旁分泌MBL2通过ITGB1-AKT/mTOR轴调控NK细胞诱导肿瘤免疫逃逸的机制研究

肝癌细胞逃避肿瘤微环境中免疫系统的监控是肿瘤转移的先决条件，其分子机制尚未明确。课题组前期采用基因测序技术筛选出肝癌细胞中表达下调的免疫调节相关基因甘露糖结合凝集素2（Mannose Binding Lectin 2,MBL2），进一步证实MBL2能旁分泌刺激NK细胞的活化，分泌颗粒酶B、穿孔素和细胞因子TNF-α、IFN-γ，同时调控T细胞杀伤癌细胞的功能；采用免疫共沉淀结合质谱分析技术证实MBL2可与NK细胞表面ITGB1结合，使用 MBL2重组蛋白能够激活NK细胞中的AKT/mTOR通路。我们推测：肝癌细胞下调MBL2蛋白的分泌，降低ITGB1-AKT/mTOR通路的活性，从而逃避NK细胞的免疫监视。本研究拟在体内外研究水平，探讨MBL2介导的抗癌功能，阐明ITGB1-AKT/mTOR信号轴参与肝癌免疫逃逸的机制，旨在为晚期肝癌患者的临床治疗提供早期干预靶点，开辟免疫治疗的新思路。

The immune escape of hepatocellular carcinoma (HCC) cells from the surveillance of the immune system in tumor microenvironment is a prerequisite for HCC metastasis, but its molecular mechanism is not yet clear. In our previous study, we used gene sequencing technology to screen out the immune-regulating-related gene ,mannose binding lectin 2 (MBL2), which was down-regulated in HCC cells, and further confirmed that the activation of NK cells , stimulated by MBL2 in a paracrine manner, can secrete granzyme B, perforin and cytokine TNF-α, IFN-γ, and also regulate the function of T cells to kill cancer cells. It is confirmed by co-immunoprecipitation combined with protein mass spectrometry analysis that MBL2 can bind to integrin beta‐1 (ITGB1) on the surface of NK cells. Furthermore, recombinant protein MBL2 can activate the AKT / mTOR axis in NK cells. We speculate that HCC cells can reduce the secretion of MBL2 protein by downregulating MBL2 gene expression, decreasing the activity of ITGB1-AKT / mTOR axis，thus avoiding the immune surveillance of NK cells. This study intends to investigate MBL2-mediated anti-tumor function in vivo and in vitro, and carify the mechanism of ITGB1-AKT / mTOR signal axis involved in immune escape of HCC, aiming to provide early intervention targets for clinical treatment of patients with advanced HCC and open up new ideas for immunotherapy.