Exosomes分泌途径在调节肝癌细胞microRNA表达谱中的作用与机制

Exosomes carrying multiple signal molecules including miRNAs play a part in intercellular signal transduction. In prophase clinical research ,we found some tumor suppressor miRNAs highly enriched in circulating tumor-derived exosomes isolated from patients with hepatocellular carcinoma, while their expression was negatively correlated to tissues of HCC. In our further study ,Vps4, one of the exosome secretory pathway components, showed differential expression between hepatocellular carcinoma and normal adjacent tissues. More over, Vps4 overexpression caused an up-regulation of some tumor suppressor miRNAs and sequentially inhibited downstream target genes of them as a result, revealing that the exosome secretory pathway might be a new mechanism in regulation of miRNA profiles and self-protection in hepatocellular carcinoma cells. To elucidate the mechanism, we plan to carry out researches as follow. First, stress treatment and direct intervention are adopted to components of the exosome secretory pathway in hepatocellular carcinoma cells, aiming to investigate whether or how the exosome secretory pathway regulates cellular and exosomal miRNA profiles and biological characteristics of tumor cells. The next step, exosomes derived from treated HCC cells are co-cultured with untreated HCC cells, exploring their effects on recipient cells. The project aims at revealing the molecular mechanisms of the exosome secretory pathway in hepatocellular carcinoma cells, also could provide new strategies for treatment of liver cancer.

Exosomes可携带miRNA等多种信号分子参与细胞间信号转导。我们在前期临床研究中发现，肝癌患者外周血肿瘤源性exosomes中高度富集某些抑癌的miRNA，与肝癌组织中呈负相关；进一步研究发现exosomes调控分子Vps4在肝癌及癌旁中差异性表达；上调Vps4可导致肝癌细胞某些抑癌miRNA水平升高并影响其下游靶基因表达。提示exosomes可能为肝癌细胞调节自身miRNA表达谱和自我保护的新途径。为深入阐明其作用与机制，本课题拟开展以下研究：①通过外源刺激处理和直接干预肝癌细胞exosomes分泌途径的调控分子，分析该途径在调控细胞内和exosomes中miRNA谱的变化和对肿瘤细胞生物学特性的影响；②将处理后肝癌细胞分泌的exosomes作用于未处理的肝癌细胞，观察其对受体细胞的影响。本项目旨在揭示exosomes分泌途径对肝癌细胞生物学行为的影响，为肝癌的治疗提供新思路。

肝癌的发生发展是一个多因素参与、多步骤的复杂过程， microRNAs（miRNAs）调控异常是导致肝癌发生的重要原因。近年来，exosomes 中的 miRNAs受到学者们的广泛关注， exosomes 可转运 miRNAs 至受体细胞内并影响其生理过程，因此这类 exosomal miRNAs 可能参与肿瘤发生的分子机制。然而，exosomes能否作为载体参与miRNAs 表达谱的调控尚无相关报道。本研究结合细胞、动物模型和临床样本，分析了 exosomes 在调控肝癌细胞 miRNAs 表达谱的作用与机制，并且研究了 exosomes 调控分子 Vps4A 在肝癌的表达、临床意义和调控exosomal miRNAs 的相关机制。主要结果如下：1. Exosomes 参与调控肝癌细胞 miRNAs 表达谱。2. Exosomes 调控分子 Vps4A 是肝癌的一个新的抑癌基因。3. 肝癌源性 exosomes 可促进母代肝癌细胞的生物学行为，而 Vps4A 则可抑制这一过程。4. 肝癌源性 exosomes 可转运 miRNAs 至受体细胞内， Vps4A 参与其过程的调控并可引起下游 PI3K/Akt 信号通路的改变。以上研究结果不仅发现了 Vps4A 新的功能和调控作用，还揭示了 exosomes 作为调控肝癌 miRNA 表达谱的新机制，加深了人们对肝癌发生发展的认识，为研制以靶向 exosomal miRNAs 为目标的新型防治策略奠定理论基础。