SSBP1调控线粒体生成影响肝癌NK细胞杀伤敏感性的作用及机制研究

Natural killer cells play important roles in anticancer immunosurveilance, which highly depend on the crosslink between activating receptors and ligands. It is generally considered that abnormality of mitochondrial biogenesis can promote cancer progression by regulating gene expression. Our previous findings have shown that the expression of SSBP1, an important regulator of mitochondrial biogenesis and three NK cell activating ligands, CD112, CD155 and MICA are positively associated with the prognosis of hepatocellular carcinoma (HCC). Moreover, the expression of SSBP1 is positively correlated with that of CD155 and MICA. Our preliminary cell studies have indicated that CD155 over expression increases the expression of CD155 and MICA, as well as mitochondrial biogenesis in HCC cells. Moreover, SSBP1 improve NK lysis of HCC cells. These findings raise our hypothesis that SSBP1 increases the sensitivity of HCC cells to NK lysis by promoting the expression of CD155 and MICA through mitochondrial biogenesis regulation. Based on this hypothesis, we will examine the alterations in mitochondrial biogenesis, NK cell ligand expression and lysis sensitivity, as well as mitochondrial retrograde signaling. We will explore the molecular mechanisms by which SSBP1 promotes the NK lysis of HCC on molecular, cell, animal and human tissue levels in our project. The data generated in our project will provide novel theoretical support for the current understanding on the molecular mechanisms of HCC development.

NK细胞在抗肿瘤免疫监视中发挥非常关键的作用，其杀伤肿瘤作用的发挥依赖激活性受体与配体的结合。线粒体生成异常可通过调控基因表达促进肿瘤恶性进展。我们前期发现线粒体生成重要调控蛋白SSBP1以及NK细胞激活配体CD112、CD155、MICA与肝癌预后显著正相关，SSBP1与CD155、MICA表达水平显著正相关。细胞实验表明SSBP1可促进肝癌表达CD155、MICA，促进线粒体生成，增强NK细胞杀伤敏感性。进而我们提出假设：SSBP1可通过调控线粒体生成调控CD155、MICA基因表达，进而影响肝癌细胞的NK杀伤敏感性。基于此，本项目拟通过干预SSBP1表达，利用各种生物学定量技术，检测线粒体生成、杀伤配体表达与NK杀伤活性、线粒体反向信号通路的变化，分别从分子、细胞、动物及组织学水平深入探讨SSBP1影响肝癌NK细胞杀伤敏感性的作用及机制。为深入理解肝癌分子病理机制提供新的理论支持。

NK细胞在抗肿瘤免疫监视中发挥非常关键的作用，其杀伤肿瘤作用的发挥依赖激活性受体与配体的结合。线粒体生成异常可通过调控基因表达促进肿瘤恶性进展，与多种肿瘤的发病风险和预后密切相关，其中线粒体-核逆向信号NF-κB等发挥了关键作用。我们前期发现肝癌（HCC）中线粒体生成重要调控蛋白SSBP1与杀伤配体CD155、MICA表达水平显著正相关，但其在肝癌中的关系及相互作用远未阐明。本项目研究发现HCC组织中SSBP1、CD155及MICA与患者预后显著相关，通过干预HCC细胞系SSBP1表达发现其具有增强肿瘤细胞杀伤敏感性的作用，且其作用通过上调CD155、MICA表达实现。进一步研究发现，HCC组织SSBP1与线粒体生成标志物显著相关，细胞研究发现SSBP1具有促进线粒体生成、减少活性氧生成、增加细胞氧耗及ATP生成的作用。通过线粒体清除的ρ0和线粒体生成增加的ρ+细胞模型，我们发现SSBP1通过调控线粒体生成影响HCC细胞CD155、MICA表达及杀伤敏感性。机制研究发现，SSBP1通过线粒体生成抑制了重要的线粒体-核逆向信号NF-κB，进而减少了MICA和CD155转录负调控因子GATA2的表达，促进CD155和MICA表达，从而增强HCC细胞杀伤敏感性。本项目的完成将为深入理解肝癌分子病理机制及开发新的免疫治疗策略提供理论支持。