Montalbano Roberta, Honrath Birgit, Wissniowski Thaddeus Till, Elxnat Moritz, Roth Silvia, Ocker Matthias, Quint Karl, Churin Yuri, Roederfeld Martin, Schroeder Dirk, Glebe Dieter, Roeb Elke, Di Fazio Pietro
Department of Visceral, Thoracic and Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
Division of Gastroenterology, Philipps University of Marburg, Marburg, Germany.
Oncotarget. 2016 Apr 12;7(15):20312-23. doi: 10.18632/oncotarget.7950.
HBV represents the most common chronic viral infection and major cause of hepatocellular carcinoma (HCC), although its exact role in liver tumorigenesis is unclear. Massive storage of the small (SHBs), middle (MHBs) and large surface (LHBs) HBV envelope proteins leads to cell stress and sustained inflammatory responses. Cannabinoid (CB) system is involved in the pathogenesis of liver diseases, stimulating acute and chronic inflammation, liver damage and fibrogenesis; it triggers endoplasmic reticulum (ER) stress response. The aim of our work was to investigate the activation of ER stress pathway after ectopic HBV envelope proteins expression, in liver cancer cells, and the role exerted by CB receptors. PCR, immunofluorescence and western blotting showed that exogenous LHBs and MHBs induce a clear ER stress response in Huh-7 cells expressing CB1 receptor. Up-regulation of the chaperone BiP/GRP78 (Binding Immunoglobulin Protein/Glucose-Regulated Protein 78) and of the transcription factor CHOP/GADD153 (C/EBP Homologous Protein/Growth Arrest and DNA Damage inducible gene 153), phosphorylation of PERK (PKR-like ER Kinase) and eIF2α (Eukaryotic Initiation Factor 2α) and splicing of XBP1 (X-box binding protein 1) was observed. CB1-/- HepG2 cells did not show any ER stress activation. Inhibition of CB1 receptor counteracted BiP expression in transfected Huh-7 and in HBV+ PLC/PRF/5 cells; whereas no effect was observed in HBV- HLF cells. These results suggest that HBV envelope proteins are able to induce the ER stress pathway. CB1 expression is directly correlated with ER stress function. Further investigations are needed to clarify the involvement of cannabinoid in HCC progression after HBV infection.
乙肝病毒（HBV）是最常见的慢性病毒感染，也是肝细胞癌（HCC）的主要病因，尽管其在肝脏肿瘤发生的确切作用尚不清楚。乙肝病毒包膜蛋白的小分子（SHBs）、中分子（MHBs）和大分子（LHBs）大量蓄积会导致细胞应激和持续的炎症反应。大麻素（CB）系统参与肝脏疾病的发病机制，刺激急性和慢性炎症、肝损伤和纤维化；它引发内质网（ER）应激反应。我们研究的目的是探讨肝癌细胞中异位表达乙肝病毒包膜蛋白后内质网应激途径的激活情况，以及CB受体发挥的作用。聚合酶链反应（PCR）、免疫荧光和蛋白质印迹法显示，外源性LHBs和MHBs在表达CB1受体的Huh-7细胞中诱导明显的内质网应激反应。观察到伴侣蛋白BiP/GRP78（结合免疫球蛋白蛋白/葡萄糖调节蛋白78）和转录因子CHOP/GADD153（C/EBP同源蛋白/生长停滞和DNA损伤诱导基因153）上调，蛋白激酶R样内质网激酶（PERK）和真核起始因子2α（eIF2α）磷酸化，以及X盒结合蛋白1（XBP1）剪接。CB1基因敲除的HepG2细胞未显示任何内质网应激激活。抑制CB1受体可抵消转染的Huh-7细胞和乙肝病毒阳性的PLC/PRF/5细胞中BiP的表达；而在乙肝病毒阴性的HLF细胞中未观察到影响。这些结果表明，乙肝病毒包膜蛋白能够诱导内质网应激途径。CB1表达与内质网应激功能直接相关。需要进一步研究以阐明大麻素在乙肝病毒感染后肝癌进展中的作用。
