AIBP通过HIF1-a介导的EMT抑制肝细胞癌侵袭转移的研究

It is crucial to clarify the molecular mechanisms underlying hepatocellular carcinoma(HCC) recurrence and metastasis, which have become the major obstacle in improving long term survival of HCC. Athough AIBP plays important roles in inhibiting angiogenesis, repairing damaged forms of antioxidant NADPH and stabliziing cell membrane structure, its biological role for tumor is still elusive. Based on the biological functions of AIBP, we hypothesize that AIBP may play a key role in inhibiting HCC invasion and metastasis. Our preliminary results showed that low expression of AIBP in HCC tissues was significantly associated with aggressive clinicopathological characteristics and poor prognosis of HCC patients after liver resection. Furthermore, AIBP did show the ability to inhibit HCC cells migration, invasion and metastasis by reducing epithelial-mesenchymal transition (EMT) both in vitro and in vivo experiments. Next, we will further validate the correlation between AIBP expression and HCC prognosis by larger HCC cohorts and adopt techniques such as IHC, IF, wound healing, transwell, IVIS Xenogen technique, HCC xenograft model and gene knock-out mouse technology to verify the new role of AIBP in suppression of HCC invasion and metastasis. Then, ten-pathway and protein chip joint databases，such as KEGG ，will be used to screen the targeted proteins of AIBP. The targeted protein will be further confirmed by Co-IP, gain- and loss- function assays and so on, to clarify the mechanism that AIBP inhibits HCC invasion and metastasis via HIF1-α mediated EMT.We also explore the potential application value of AIBP targeted intervention in the inhibition of HCC progression, which will provide important theoretical basis in developing new target drugs for HCC.

肝癌复发转移是制约病人长期生存的主要障碍，阐明其机制对改善肝癌生存结局至关重要。AIBP具有抑制血管生成、修复NAPDH和稳定细胞膜结构等重要功能，尚不清楚AIBP在肿瘤中的作用。我们推测AIBP很可能在抑制肝癌侵袭转移中发挥关键作用。前期研究显示肝癌组织中AIBP低表达与病人临床病理特征及不良预后密切相关。且证实AIBP能显著抑制肝癌细胞的侵袭转移与EMT。为此，本项目将继续扩大样本验证AIBP表达水平与肝癌预后的相关性；再利用IHC、细胞免疫荧光、划痕愈合、transwell、IVIS等方法及裸鼠原位成瘤、基因敲除鼠进一步验证AIBP低表达促进肝癌侵袭转移新作用；进而采用ten-pathway与蛋白芯片联合KEGG等数据库筛选策略筛选AIBP下游作用靶点，再利用Co-IP、功能回复-缺失等实验验证候选靶点，阐明AIBP低表达激活HIF1-α促进EMT介导的肝癌侵袭转移的作用机制。

肿瘤异常代谢产生的活性氧簇(Reactive oxygen species, ROS)可促进肿瘤的侵袭和转移。AIBP基因现在已被人类基因组组织基因命名委员会重新命名为NAD(P)HX表异构酶（NAXE）。NAXE可修复受损的抗氧化剂NADPH，是一种潜在的细胞ROS清除剂，其在肿瘤发展中的作用尚不清楚。我们发现NAXE在肝细胞癌(HCC)组织和细胞系中表达显著下调。NAXE下调与较差的临床病理特征相关，是肝切除术后肝癌患者整体和无瘤生存的独立危险因素。低表达NAXE可在血管浸润前或肝癌早期区别出预后较差的肝癌病人。NAXE在肝癌中低表达与微血管浸润显著相关，且联合MVI可以发现预后更差的肝细胞癌病人。此外，体外和体内实验均表明，抑制NAXE表达可通过诱导上皮间质转化(epithelial-mesenchymal transition, EMT)促进肝癌细胞的迁移、侵袭和转移，而过表达NAXE则会产生相反的效果。NAXE的低表达在机制上降低了NADPH水平，进而引起ROS水平升高和缺氧诱导因子1α (hypoxia inducible factor-1α， HIF-1α)的激活，从而通过促进EMT而促进肝癌的侵袭和转移。最后，我们在小鼠饮用水中添加N-乙酰-L-半胱氨酸（NAC，一种ROS清除剂）可消除NAXE敲减对肝癌异种移植瘤的促瘤作用。综上所述，我们的研究结果揭示了NAXE在HCC中通过清除过多的ROS和抑制促肿瘤信号通路的抑癌作用，为靶向氧化还原信号通路治疗HCC提供了一种新的策略。