HBx通过激活SMYD3/lncRNA-IHS正反馈信号通路促进肝癌侵袭转移的机制

The HBx protein is reported to play a key role in metastasis of HBV related hepatocellular carcinoma (HCC). However, the key point and signal pathway through which HBx promote HCC metastasis remain largely unknown. Our on-going NSF project found that HBx can activate the promoter of SMYD3 and increase its expression through NRF1. Meanwhile, we carried out lncRNAs microarray in HBx-overexpressing cell line and SMYD3-overexpressing cell line respectively and found lncRNA-IHS (lncRNA intersection between HBx microarray and SMYD3 microarray) was upregulated in both cell lines. Results from HCC tissues and cell function experiments indicated lncRNAs-IHS was related to invasion and metastasis of HCC. In addition, we also found that lncRNAs-IHS can increase the protein expression of SMYD3 through inhibiting SMYD3 protein degradation. Therefore, we hypothesize that in HCC, HBx promotes invasion and metastasis through SMYD3/lncRNAs-IHS positive feedback loop. In order to verify our hypothesis, our project will include reasonable experiment scheme in combination with abundant preliminary experiment data and clinical material. Our research will help to further elucidate the mechanism of HBx-mediated invasion and metastasis in HCC, and provide scientific evidence in developing an effective treatment against HBV related HCC.

乙肝病毒X蛋白（HBx）与HCC的侵袭转移密切相关，但HBx调控HCC侵袭转移的关键网络节点及信号通路，目前仍很不清楚。我们在研的国自然项目研究发现，HBx能够通过NRF1激活组蛋白甲基转移酶SMYD3启动子而促进其表达。同时，我们对HBx和SMYD3过表达HCC细胞模型进行lncRNAs芯片高通量筛选，发现lncRNA-IHS在两组细胞模型中均明显上调，并结合临床样本初步证实了lncRNA-IHS高表达与HCC侵袭转移的相关性。不仅如此，我们还发现lncRNA-IHS可在翻译后水平调控SMYD3蛋白表达，抑制SMYD3蛋白降解。综合以上前期研究，我们推测：在HCC中，HBx可能通过SMYD3/lncRNA-IHS正反馈信号通路促进癌细胞侵袭转移。本项目拟通过严谨的实验验证该科学假设，项目成果有望对HBx促进HCC侵袭转移的分子机制进一步完善，为寻找HBV相关HCC的治疗靶点提供科学依据。

lncRNAs是指生物体内一类不编码蛋白并且长度超过200个核苷酸的RNA。近年来许多研究均表明 lncRNAs与乙肝相关肝癌的发生、发展、侵袭和转移有密切联系。然而，lncRNAs对HBV相关HCC的作用与具体致癌机制仍有许多未知。此外，虽然SMYD3及PRMT9在肝癌中有所研究，但关于其在肝癌具体促癌转移机制仍有许多未知。本项目在执行过程中主要探讨是否存在lncRNAs参与调控HBV相关HCC的侵袭转移等生物学行为，以及阐明HBx调控lncRNAs的具体分子机制及SMYD3和PRMT9的具体促癌转移机制。在本项目中，我们的主要发现为：1.新型lncRNA（lncRNA-IHS）的高表达与HCC侵袭转移相关，并且阐明了lncRNA IHS通过调节ERK和AKT/GSK-3b信号通路来促进肝癌细胞的增殖转移。2.SMYD3-ANKHD1轴是一种调节肝癌细胞的侵袭及转移的新分子调控机制。3.PRMT9通过激活PI3K/Akt/GSK-3b/Snail信号通路促进肝细胞癌的侵袭和转移。该成果理清了HBX-SMYD3-lncRNA-在肝癌中的促癌机制，为进一步完善HBx蛋白的促癌机制提供实验证据，同时丰富了lncRNAs表观遗传调控机制及促癌机制。另外，SMYD3-ANKHD1相关研究成果为晚期肝癌的治疗提供了潜在靶点。我们的研究成果还为PRMT9的促癌机制提供实验证据。