LSECtin对胃癌肝转移能力的影响及其机制的研究

Instead of randomly metastasizing to the various tissues and organs of the body, tumor cells specifically go to certain organs. Accumulated evidence has shown that the adhesion of tumor cells and endothelial cells plays an important role in organ specific metastasis. However, progress toward clarifying the specific adhesion molecules involved in organ-specific metastasis has proven difficult. LSECtin is an adhesion molecule which shows high and specific expression on hepatic and lymph node sinusoidal endothelial cells. LSECtin family, such as selectin, mannose receptor have shown to be involved in tumor metastasis. Our previous studies have shown that LSECtin play an important role in liver metastasis of the colon carcinoma. In this study, we aimed to determine the role of LSECtin in gastric cancer metastasis to the liver. The downstream target genes of LSECtin in gastric cancer cell will be detected by Microarray Gene Expression Profiling and ChIP-DSL Promoter Array, the metastasis-related target genes will be identified by bioinformatics technology, and the transcriptional regulatory sites of target gene promoter will be detected by Luciferase Assay. Then the metastasis-related target gene in gastric cancer will be confirmed by gene silencing and overexpression experiments. LSECtin targeted gene promoter will be detected by ChIP to investigate the molecular mechanisms of LSECtin influencing invasion and metastasis of colon cancer. Finally, the influence of LSECtin and its targeted gene on growth and metastasis of gastric cancer xenografts will be detected by whole-body fluorescence imaging in vivo, in order to assess the feasibility of using exogenous LSECtin and its targeted gene inhibitors to inhibit invasion and metastasis of gastric cancer cells to liver, which will provide a new idea for the treatment of gastric cancer.

肿瘤细胞与靶器官内皮细胞的粘附在肿瘤转移中起重要作用。目前对内皮细胞的特征粘附分子所知有限。已知，LSECtin是肝脏和淋巴结窦内皮细胞特异高表达的粘附分子，两者正是肿瘤高转移的靶器官；LSECtin同家族的某些成员已经被证明参与肿瘤转移；我们的前期研究发现：LSECtin与结肠癌肝转移密切相关。因而，推测LSECtin可能在肿瘤肝转移中发挥重要作用。胃癌也是易于转移到肝脏的肿瘤之一。本研究拟利用基因表达谱芯片和ChIP-DSL启动子芯片技术探测LSECtin在胃癌细胞中调控的下游靶基因；采用生物信息学确定与转移相关的靶基因；利用Luciferase实验验证LSECtin与靶基因的特异性结合；通过沉默和过表达上述靶基因，研究LSECtin对胃癌肝转移的作用；利用整体实验检测LSECtin及其靶基因在活体内对胃癌肝转移的影响，为胃癌的治疗提供新思路。

肿瘤细胞与靶器官内皮细胞的粘附在肿瘤转移中起重要作用。目前对内皮细胞的特征粘附分子所知有限。前期实验证明LSECtin参与了结肠癌肝转移。本研究证明：①ELISA方法检测发现胃癌患者血清中LSECtin 浓度明显高于正常人，胃癌肝转移患者血清中LSECtin的浓度明显高于未发生转移的患者；重组LSECtin蛋白能够与胃癌细胞结合，肝脏中的LSECtin亦能够结合胃癌细胞。Transwell侵袭、平板克隆形成和划痕等实验发现LSECtin蛋白能够促进胃癌细胞的侵袭和迁移。采用表达谱芯片检测胃癌细胞株发现经LSECtin蛋白诱导后FN1上调。利用转录因子数据库预测、筛选并鉴定发现可能与FN1的启动子结合的转录因子为STAT1。采用Human Circular RNA Array V2芯片及miRNA 数据库预测并验证发现hsa_circ_0056281/hsa-miR-513c-5p/STAT1和hsa_circ_0077417/hsa-miR-146a-5p/STAT1两条调控轴可能与LSECtin参与的胃癌肝转移有关。②发现lncRNA HNRNPKP2是参与DC-SIGNR介导胃癌发生肝转移的关键lncRNAs分子；CXCR4是lncRNA HNRNPKP2的功能性靶基因而参与胃癌侵袭转移。③DC-SIGN/LEF1-TCF1/miR-185反馈环路存在于结肠癌细胞中，并且与结肠癌的侵袭转移密切相关。④DC-SIGNR通过上调金属硫蛋白和MMP9参与了结肠癌肝转移。结果表明：LSECtin, DC-SIGNR和DC-SIGN参与胃肠道（肝）转移,为临床诊断提供理论依据和治疗胃肠道（肝）转移提供了理论依据。