Prp19诱导上皮间质转化促进肝癌侵袭转移的分子机制研究

Invasion and metastasis is the pivotal factor that impinging on the prognosis of patients with hepatocellular carcinoma (HCC). Epithelial-mesenchymal transition (EMT) triggerred by EMT transcription factors plays critical roles in tumor invasiveness and metastasis. Mounting evidence has demonstrated that activity of EMT transcription factors is subject to regulation of ubiquitination. Our previous work had found that pre-mRNA processing factor 19 (Prp19) may function as the effector of deubiquitinating enzyme UCH37 to facilitate invasion and metastasis of HCC. In contrast to normal hepatocyte and paracancerous tissue, Prp19 expression was significantly higher in most hepatoma cells and HCC tumor tissues. Overexpression of Prp19 in HCC tumor tissue was positively correlated with vascular invasion, tumor capsule breakthrough and dismal prognosis. In vitro and ex vitro functional analysis displayed that Prp19 upregulated Twist1 expression and facililated EMT of HCC cells, enhancing motility and invasiveness of HCC cells. Following works will enlarge clinical specimens to verify the relationship between Prp19 expression and prognosis of HCC, and the important role of Prp19 in induction of EMT. Mechanism pertinent to regulation of Twist1-mediated EMT by Prp19 will be explored in detail using co-immunoprecipitation, laser confocal microscopy and gene trunction mutant. The functional domain within Prp19 in the modulation of EMT will be identified. Furthermore this regulation-mediated by Prp19 will be testified in several animal models. This work will contribute to enrich understanding of the biological characteristics and invasion-related mechanisms of HCC, and provide the underlying therapeutic target for individualized management of HCC

侵袭转移是影响肝癌患者预后的重要因素。上皮间质转化（EMT）在肿瘤侵袭转移中发挥了重要作用，主要由EMT转录因子介导。大量证据表明EMT转录因子的活性易受到泛素化修饰调控。我们前期工作发现信使RNA前体剪接因子Prp19可能作为去泛素化酶UCH37的效应因子，参与肝癌侵袭转移。相对于正常肝细胞与癌旁组织，Prp19在肝癌细胞系及肝癌组织中表达明显升高。且Prp19高表达与脉管侵袭、包膜突破、不良预后正相关。体内外功能研究显示Prp19可上调Twist1表达并促进肝癌细胞EMT，有利于肝癌细胞迁移侵袭。本课题将进一步扩大临床样本，明确Prp19表达与肝癌预后的关系，及对EMT的关键调节作用；采用免疫共沉淀、激光共聚焦、分段基因突变等方法深入探讨Prp19诱导EMT及调控Twist1的分子机制，明确其促EMT的结构基础，并在多种动物模型中进行验证，有助于深入了解肝癌的生物学特性和侵袭转移机制。

本项目首次证实了Prp19在肝癌中高表达，高表达的Prp19与血管侵犯、肿瘤包膜突破等侵袭特性密切相关。肝癌中Prp19高表达也提示预后不良。体内外功能研究验证了Prp19增加肝癌细胞迁移侵袭的潜能。Prp19通过正向调控Twist1表达，促进肝癌细胞的上皮间质转化。后续机制研究阐明了Prp19与TAK1结合，上调TAK1的K-63泛素化修饰，激活p38/MAPK，促进Twist1丝氨酸位点的磷酸化，抑制其经泛素蛋白酶体途径降解，导致Twist1在肝癌细胞内积聚，从而诱导EMT发生，促进肝癌侵袭。该研究有助于了解肝癌的生物学特性及其侵袭相关分子机制，并为寻找肝癌潜在的治疗靶点提供新的理论依据。