MicroRNA-26a在肝细胞癌门静脉癌栓形成中的作用和分子机制研究

Recurrence and metastasis of hepatocellular carcinoma are the main factors influencing its the prognosis. Therefore, to explore the molecular mechanisms of HCC metastasis is of great significance. My previous research found that miR-26a inhibit the growth, invasion and metastasis of HCC in vitro and in vivo by inhibiting IL-6-stat3 signaling pathway. Tumor metastasis and recurrence mostly depends on tumor angiogenesis. Further studies confirmed that miR-26a can significantly inhibit the expression of VEGF in HCC cells and endothelial cells proliferation, migration and tube formation, through directional inhibition of HGF-cMet signaling pathways, eventually inhibit angiogenesis of HCC. Tumor angiogenesis promotes the formation of PVTT. Previous studies and preliminary experiments have confirmed that miR-26a is closely related to vascular invasion and portal vein thrombosis of HCC. At the same time, we further found that miR-26a inhibits the expressions of uPA, PAR, VEGF, MMP2 and infiltration of Tregs cell in PVTT tissue thus regulate formation of PVTT. But the specific mechanism is unclear, yet to be confirmed. Based on miR-26a of the molecular mechanism of liver cancer metastasis and angiogenesis, along the preliminary studies, we continue to explore in-depth study on the impact and molecular mechanism of miR-26a in formation of portal vein tumor thrombus in hepatocellular carcinoma and to further elucidate how miR-26a to inhibit the expressions of those genes and Tregs cells infiltrating promoting PVTT, which thereby provide new cellular and molecular mechanisms and intervention targets in inhibiting portal vein thrombosis of hepatocellular carcinoma.

肝癌转移和复发严重影响肝癌预后，探索肝癌转移的关键调控环节意义重大。本人前期研究证实miR-26a通过抑制IL-6-stat3通路抑制体外和体内HCC的生长，侵袭和转移，而肝癌复发和转移在很大程度依赖肿瘤的血管发生，进一步研究证实miR-26a通过定向抑制HGF-cMet通路抑制HCC血管生成。血管的生成又促进门静脉癌栓(PVTT)形成，前期研究及预实验结果均发现 miR-26a 与PVTT有无、分级呈负相关，同时也发现miR-26a 可抑制 PVTT 组织中uPA、PAR、VEGF、MMP2 的表达和Tregs 细胞浸润进而调控 PVTT 的形成，但具体机制仍不清，有待进一步证实。本项目沿着前期研究的思路，进一步阐明miR-26a如何通过抑制这些促进PVTT形成的分子表达和Tregs 细胞浸润进而影响PVTT的形成，从而为肝细胞癌门静脉癌栓的治疗提供新的细胞分子机制和干预靶点。

肝细胞癌是一种具有强烈侵袭门静脉倾向的肿瘤。门静脉癌栓(PVTT)一旦形成，患者预后很差，探索抑制PVTT机制对于改善肝癌预后意义重大。目前对PVTT机制的研究尚少。本人前期研究证实miR-26a通过抑制IL-6-stat3通路和HGF-cMet通路抑制肿瘤生长，转移和血管生成。基于前期发现，在本项研究中，我们发现microRNA-26a的表达与肝癌中PVTT的存在有关。miR-26a在PVTT组织和细胞系中显著下调，同时与PVTT的有无和PVTT的分级均呈负相关。miR-26a和门静脉癌栓联合可作为肝癌患者的独立预后预测指标。生存分析证实：有门静脉癌栓的肝癌患者较无门静脉癌栓的患者的生存期和无瘤生存期都短，低miR-26a有门静脉癌栓的患者生存期和无瘤生存期最短，预后最差。进一步研究发现，miR-26a过表达抑制了肝癌细胞系和门静脉癌栓细胞的生长、迁移和侵袭。利用过表达miR-26a稳转细胞系构建皮下瘤模型和原位肝肿瘤模型，进一步证实miR-26a能够抑制肝癌细胞和门静脉癌栓细胞在体内成瘤、可以抑制原位瘤的门静脉癌栓形成、肝内转移和肺转移。我们通过体外和体内细胞验证以及组织炎症证实SMAD1是miR-26a的直接下游作用靶点，而且我们还发现miR-26a通过部分靶向抑制SMAD1进而影响其下游EMT信号传导途径中的蛋白质分子的表达来发挥抑制PVTT细胞的增殖，迁移和侵袭的作用。这些发现提示miR-26a在调节肝癌PVTT生长和侵袭中的重要作用和分子机制，并为肝细胞癌PVTT的治疗提供了潜在的治疗靶点。