von Olshausen Gesa, Quasdorff Maria, Bester Romina, Arzberger Silke, Ko Chunkyu, van de Klundert Maarten, Zhang Ke, Odenthal Margarete, Ringelhan Marc, Niessen Carien M, Protzer Ulrike
Department of Internal Medicine I, University Hospital rechts der Isar, Technical University of Munich, Munich, Germany.
Molecular Infectiology, Institute for Medical Micro biology, Immunology and Hygiene, University Hospital Cologne, Cologne, Germany.
Oncotarget. 2018 Sep 21;9(74):33947-33960. doi: 10.18632/oncotarget.26103.
Hepatitis B virus (HBV) infection is a prominent cause of hepatocellular carcinoma (HCC) but the underlying molecular mechanisms are complex and multiple pathways have been proposed such as the activation of the Wnt-/β-catenin-signalling and dysregulation of E-cadherin/β-catenin adherens junctions. This study aimed to identify mechanisms of how HBV infection and replication as well as HBV X protein (HBx) gene expression in the context of an HBV genome influence Wnt-/β-catenin-signalling and formation of adherens junctions and to which extent HBx contributes to this. Regulation of E-cadherin/β-catenin junctions and β-catenin-signalling as well as the role of HBx were investigated using constructs transiently or stably inducing replication of HBV+/-HBx in hepatoma cell lines. In addition, HCC and adjacent non-tumorous tissue samples from HBV-infected HCC patients and drug interference in HBV-infected cells were studied. Although HBV did not alter overall expression levels of E-cadherin or β-catenin, it diminished their cell surface localization resulting in nuclear translocation of β-catenin and activation of its target genes. In addition, HBV gene expression increased the amount of phosphorylated c-Src kinase. Treatment with Src kinase inhibitor Dasatinib reduced HBV replication, prevented adherens junction disassembly and reduced β-catenin-signalling, while Sorafenib only did so in cells with mutated β-catenin. Interestingly, none of the HBV induced alterations required HBx. Thus, HBV stimulated β-catenin-signalling and induced disassembly of adherens junctions independently of HBx through Src kinase activation. These pathways may contribute to hepatocellular carcinogenesis and seem to be more efficiently inhibited by Dasatinib than by Sorafenib.
乙型肝炎病毒（HBV）感染是肝细胞癌（HCC）的一个主要病因，但其潜在的分子机制很复杂，并且已经提出了多种途径，如Wnt-β-连环蛋白信号通路的激活以及E-钙黏蛋白/β-连环蛋白黏附连接的失调。本研究旨在确定在HBV基因组背景下HBV感染与复制以及HBV X蛋白（HBx）基因表达如何影响Wnt-β-连环蛋白信号通路和黏附连接的形成，以及HBx在其中的贡献程度。使用在肝癌细胞系中瞬时或稳定诱导HBV+/-HBx复制的构建体，研究了E-钙黏蛋白/β-连环蛋白连接和β-连环蛋白信号通路的调节以及HBx的作用。此外，还研究了来自HBV感染的HCC患者的HCC和相邻非肿瘤组织样本以及HBV感染细胞中的药物干扰。虽然HBV没有改变E-钙黏蛋白或β-连环蛋白的总体表达水平，但它减少了它们在细胞表面的定位，导致β-连环蛋白的核转位及其靶基因的激活。此外，HBV基因表达增加了磷酸化c-Src激酶的量。用Src激酶抑制剂达沙替尼处理可减少HBV复制，防止黏附连接的解体并减少β-连环蛋白信号通路，而索拉非尼仅在β-连环蛋白突变的细胞中才会如此。有趣的是，HBV诱导的改变均不需要HBx。因此，HBV通过Src激酶激活独立于HBx刺激β-连环蛋白信号通路并诱导黏附连接的解体。这些途径可能有助于肝细胞癌的发生，并且似乎达沙替尼比索拉非尼更有效地抑制这些途径。
