Wang Heng-Yi, Yang Sheng-Li, Liang Hui-Fang, Li Chang-Hai
Department of Surgery, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China.
Department of General Surgery, Liyuan Hospital, Tongji Medical College, Huazhong Science and Technology University, Wuhan 430077, China.
Int J Mol Sci. 2014 Feb 26;15(3):3507-18. doi: 10.3390/ijms15033507.
Growing evidence has shown that hepatic oval cells, also named liver progenitor cells, play an important role in the process of liver regeneration in various liver diseases. Oval cell proliferation has been reported in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) and chronic liver disease. Studies have found expression of HBV surface and core antigens in oval cells in the livers of patients with HCC, suggesting that HBV infection of oval cells could be a mechanism of human hepatocarcinogenesis. In addition, there is evidence of multiplication of HBV in oval cell culture. However, little research has been performed to explore the role of HBV-encoded proteins in the proliferation of hepatic oval cells. Previously, we successfully transfected the HBV x (HBx) gene, one of the four genes in the HBV genome, into a rat LE/6 oval cell line. In this study, we tested whether or not the transfected HBx gene could affect oval cell proliferation in vitro. Our results show that overexpression of HBx promotes the proliferation of oval cells and increases cyclin D1 expression, assessed at both the mRNA and protein levels. We also found that HBx activated the PI-3K/Akt and MEK/ERK1/2 pathways in HBx-transfected oval cells. Furthermore, the HBx-induced increases in cyclin D1 expression and oval cell proliferation were completely abolished by treatment with either MEK inhibitor PD184352 or PI-3K inhibitor LY294002. These results demonstrated that HBx has the ability to promote oval cell proliferation in vitro, and its stimulatory effects on cell proliferation and expression of cyclin D1 depend on the activation of the MEK/ERK and PI3K/Akt signaling pathways in cultured oval cells.
越来越多的证据表明，肝卵圆细胞，也被称为肝祖细胞，在各种肝脏疾病的肝再生过程中发挥着重要作用。在乙型肝炎病毒（HBV）相关的肝细胞癌（HCC）和慢性肝病中已报道有卵圆细胞增殖。研究发现，HCC患者肝脏中的卵圆细胞表达HBV表面抗原和核心抗原，这表明卵圆细胞的HBV感染可能是人类肝癌发生的一种机制。此外，有证据表明HBV在卵圆细胞培养物中增殖。然而，很少有研究探讨HBV编码蛋白在肝卵圆细胞增殖中的作用。此前，我们成功地将HBV基因组中的四个基因之一的HBV x（HBx）基因转染到大鼠LE/6卵圆细胞系中。在本研究中，我们测试了转染的HBx基因是否会影响体外卵圆细胞的增殖。我们的结果表明，HBx的过表达促进了卵圆细胞的增殖，并在mRNA和蛋白质水平上增加了细胞周期蛋白D1的表达。我们还发现，HBx激活了转染HBx的卵圆细胞中的PI-3K/Akt和MEK/ERK1/2信号通路。此外，用MEK抑制剂PD184352或PI-3K抑制剂LY294002处理可完全消除HBx诱导的细胞周期蛋白D1表达增加和卵圆细胞增殖。这些结果表明，HBx具有促进体外卵圆细胞增殖的能力，其对细胞增殖和细胞周期蛋白D1表达的刺激作用取决于培养的卵圆细胞中MEK/ERK和PI3K/Akt信号通路的激活。
