外泌体CFH通过抑制补体活化促进肝癌转移

Exosome has been the subject of interest in intercellular communication. Exosomes confer the ability of cancer cells to exert a local effect on surrounding cells and a systemic influence on distant cells, via the transfer of exosomal contents. Exosome has garnered much attention also because of its potential diagnostic and therapeutic applications. Our findings revealed that exosomes derived from metastatic hepatocellular carcinoma (HCC) cells augmented the migratory and invasive potentials of naïve HCC cells. Demonstrated in an animal model, intravenous injection of metastasis-exosomes enhanced the incidence of distant metastasis from HCC primary tumor to lungs. Through proteomic profiling, complement factor H (CFH) was found to be highly expressed in exosomes of metastatic HCC cells. Knockdown of CFH reduced its cellular and exosomal expression in metastatic HCC cells resulting in reduced cell motility and oncogenic properties of exosomes. CFH is a major inhibitor of complement system of immune defense. Cancers cells aquire the ability to hijack the complement system to evade the cell defense mechanism. Indeed, we showed that metastatic-exosomes treated HCC cells showed reduced complement-mediated cytotoxicity when compared to cells treated with exosomes derived from CFH knockdown cells suggesting CFH protects HCC cells by evading complement attack. We hypothesize that exosomal CFH inhibits complement activation in the tumor microenvironment facilitating HCC tumorigenesis and metastasis. In this study, we aim to 1) demonstrate the functional role of exosomal CFH using cell culture and animal models, 2) dissect the role of exosomal CFH in the escape of complement-mediated cytotoxicity, and 3) evaluate the therapeutic effect of anti-CFH antibody. Our findings will provide an important paradigm for tumor-derived exosomes in driving metastasis, yield novel mechanistic insights into HCC metastasis and to establish a novel therapeutic strategy for the treatment of liver cancer.

外泌体一直是细胞间通讯的受关注话题，通过转移其内容物外泌体赋予癌细胞对周围细胞发挥局部作用和对远处细胞的全身性影响的能力。来源于转移性肝细胞癌（HCC）细胞的外泌体增了加HCC细胞的迁移和侵袭潜能及肝癌小鼠模型肺远端转移机率。蛋白质组学分析提示补体因子H（CFH）在转移性HCC细胞的外泌体中高度表达。敲除CFH抑制了HCC细胞运动性和各种致癌能力。CFH是人体免疫防御补体系统的主要抑制蛋白，癌细胞借此抑制补体系统来逃避免疫攻击。实验表明与CFH敲除细胞来源的外泌体处理的细胞相比，转移性外泌体处理的HCC细胞中出由补体介导的细胞毒减轻。我们推测外泌体CFH通过抑制肿瘤微环境中的补体激活来促进HCC肿瘤的发生和转移。我们将在本研究中1，利用细胞培养和动物模型证明外泌体CFH的功能作用; 2. 解析外泌体中CFH在帮助HCC细胞逃避免疫监视中的作用。3. 评估抗CFH抗体在HCC中的治疗效果。

背景 细胞外囊泡 (EV) 在肿瘤生长、癌症转移和血管生成中起着关键作用。在这里，我们的目的是鉴定有助于源自转移性肝细胞癌 (HCC) 细胞的 EV 功能的蛋白质。.方法 通过质谱法分析源自转移性 HCC 细胞和正常肝细胞的 EV 的蛋白质。蛋白质组学分析发现肌动蛋白相关蛋白 2/3 复合亚基 2 (ARPC2) 在转移性 HCC 细胞的 EV 中高度表达。分别使用免疫印迹和 TCGA 数据库检查 ARPC2 在 EV 和 HCC 组织中的表达。 EV-ARPC2 的功能作用通过敲除方法和各种体外和体内试验进行了研究。.结果 ARPC2 在转移细胞的 EVs 中高表达，但在非转移性 HCC 细胞和正常肝细胞中几乎检测不到。免疫金标记显示 EV 表面存在 APRC2。肝癌TCGA数据库分析显示ARPC2过表达与患者预后不良相关。 ARPC2 在转移性 HCC 细胞中被敲除。与对照细胞的 EV 相比，来自敲除细胞的 EV 在促进细胞生长、运动和转移方面表现出受损的活性。 APRC2抑制剂匹莫齐特也抑制转移细胞EV对小鼠肿瘤细胞肺定植的促进作用。.结论 本研究揭示了以前未报道的 ARPC2 在 EV 中的表达和功能。具有高表达 ARPC2 的 EV 可增强癌细胞的生长和转移。 ARPC2 可能为 HCC 患者的新型治疗提供一个前瞻性靶点。

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