分泌型miR-103对肝癌血管生成与转移的调控作用及机制

Metastasis is responsible for frequent relapse and high mortality of cancer, but its underlying mechanisms remain unclear. Angiogenesis has been considered to be essential for metastasis. To date, the number of tumor vessels has been found to be positively correlated with the incidence of tumor metastasis and recurrence. However, other characters of tumor angiogenesis, such as vascular pattern and vascular permeability, are less analyzed. Recently, Emerging evidence shows that secreted miRNAs could be diagnostic biomarkers for diseases, including cancer. However, the function and underlying mechanism of secreted miRNAs in tumor angiogenesis and metastasis remain largely unknown. Based on RNA sequencing, we have identified a bunch of differentially secreted miRNAs between HCC patients with and without recurrence, and revealed that miR-103, one of the miRNAs that displayed high level in serum of patients with recurrence, was secreted by tumor cells and transferred to endothelial cells. To date, the function of secreted miR-103 has not been reported. Further study suggested that secreted miR-103 increased vascular permeability in vitro. With these findings, we will further investigate: 1) the effects and mechanism of secreted miR-103 in the regulation of vascular number, pattern and permeability, and tumor metastasis; 2) the regulatory mechanism of the expression and secretion of miR-103; 3) the feasibility of miR-103 as an anti-tumor target. The results obtained will reveal the novel function of secreted miR-103 and its underlying mechanism, and provide a potential target for anti-tumor therapy.

转移是肿瘤病人高死亡率的主要原因，血管生成是转移的关键。血管数量越多，越有利于肿瘤的转移。然而，影响肿瘤血行转移的其它因素如血管结构、血管通透性等，却常被忽略。近年来，将分泌型miRNA作为肿瘤标记物正成为研究热点。但是，分泌miRNA的生物学功能及其分泌机制仍不清楚。我们前期在有、无复发的肝癌病人血清中筛选到差异表达的分泌型miRNA，其中，血清中高水平的miR-103与肝癌病人的复发显著相关。至今，分泌型miR-103的功能未见报道。前期体外实验提示：miR-103经由肝癌细胞分泌，可进入内皮细胞，提高血管通透性。以此为基础，我们拟鉴定：1）分泌型miR-103对肝癌血管数量、结构、通透性及肿瘤转移的作用与其机制；2）调控miR-103表达及分泌的分子机制；3）分泌型miR-103作为抗肝癌治疗靶点的潜在可能。研究结果将有助于理解分泌型miRNA的作用方式及机制，发掘新的肿瘤治疗靶点。

肝癌易转移，死亡率极高。揭示肝癌转移机制，开发精准治疗策略是国际前沿研究重点和难点。我们发现肝癌血管结构具有明显异质性：除毛细管状血管，存在新型的肿瘤包绕型血管VETC。VETC肝癌在血管内皮的包裹中成块释放入血，并不需要运动侵袭；保留组织结构的转移团块转移效率更高。具有毛细管状血管（非VETC）的肝癌则以侵袭依赖的模式转移。本项目围绕肝癌血管结构及不同转移模式的调控机制展开，重点关注miR-103等非编码分子及其蛋白网络的作用，发现：1）miR-103等新型分子是干预侵袭依赖转移的高效靶点。非编码RNA，如miRNA及lncRNA，在血管生成和转移中的作用及机制不明。我们发现癌细胞高表达miR-103，促进癌细胞运动侵袭；还可以外泌体递送miR-103至内皮细胞，提高血管通透性，促进癌细胞入血；lncUTGF被促转移因子TGFβ诱导表达；lncUTGF则结合TGFβ下游的SMAD2和SMAD4，上调其水平，正反馈促进TGFβ的信号传导及其介导的肿瘤转移。干预癌细胞中miR-103或lncUTGF的表达，可抑制肝癌转移。2）鉴定调控肝癌转移的“双刃剑”，为肝癌转移的精准治疗提供靶点。雄激素受体AR在VETC肝癌中的水平明显低于非VETC肝癌；AR抑制VETC介导的侵袭非依赖转移，但却通过上调Rac1促进侵袭依赖的转移，揭示了AR在肝癌不同转移模式中发挥双重且对立的作用。而且，AR表达联合Rac1抑制剂可明显延长VETC肝癌荷瘤小鼠的生存时间，而AR抑制剂则显著抑制非VETC肝癌移植瘤的转移。进一步发现临床药物索拉非尼可显著延长VETC肝癌患者的生存时间，降低其死亡风险，但是对非VETC肝癌则无明显效果。这些结果为抗转移分子靶向药物的研发以及基于肿瘤血管结构异质性的个体化治疗提供了理论依据。作为第一/通讯作者（含共同）发表SCI论文4篇，其中，1篇ESI高被引及编辑亮点推介，1篇封面论文，1篇获专题评述。