Park E-H, Koh S S, Srisuttee R, Cho I-R, Min H-J, Jhun B H, Lee Y-S, Jang K L, Kim C-H, Johnston R N, Chung Y-H
Department of Nanomedical Engineering, BK21 Nanofusion Technology Team, Pusan National University, Miryang, Republic of Korea.
Cancer Gene Ther. 2009 May;16(5):453-61. doi: 10.1038/cgt.2008.95. Epub 2008 Dec 19.
Although reovirus has been used in tests as a potential cancer therapeutic agent against a variety of cancer cells, its application to hepatocellular carcinoma cells, in which the hepatitis B virus (HBV) X (HBX) protein of HBV plays a primary role, has not yet been explored. Here, we describe experiments in which we use reovirus to treat Chang liver carcinoma cells expressing either a vector only (Chang-vec) or a vector encoding HBX protein (Chang-HBX). Although Chang-vec cells readily support reoviral proliferation and undergo apoptosis, Chang-HBX cells are highly resistant to reoviral infection and virus-induced apoptosis, even though HBX protein induces activation of Ras and inactivation of PKR, which are normally thought to enhance reoviral oncolysis. The resistance of Chang-HBX cells to reovirus may instead be explained by HBX-induced downregulation of death receptor 5 and activation of Stat1. Phosphorylated Stat1 activates interferon (IFN)-stimulated regulatory element (ISRE)- and IFN-gamma-activated sequence (GAS)-mediated transcription, leading to the production of IFN-beta, whereas the reduced expression of Stat1 with its siRNA results in a decrease in IFN-beta production, by which Chang-HBX cells eventually succumb to reovirus infection. This result further indicates that HBX induces the establishment of an antiviral state through Stat1 activation. Thus, it appears that active Ras does not override the antiviral effect mediated by the activation of Stat1. Accordingly, we report that HBX, an oncoprotein of HBV, can prevent reoviral oncolysis of hepatocellular carcinoma. This suggests there may be limits to the practical application of reovirus in the treatment of human cancers already expressing other oncoviral proteins.
尽管呼肠孤病毒已被用于测试作为针对多种癌细胞的潜在癌症治疗剂，但其在乙型肝炎病毒（HBV）X（HBX）蛋白起主要作用的肝癌细胞中的应用尚未得到探索。在此，我们描述了使用呼肠孤病毒治疗仅表达载体（Chang-vec）或编码HBX蛋白的载体（Chang-HBX）的张氏肝癌细胞的实验。尽管Chang-vec细胞很容易支持呼肠孤病毒增殖并发生凋亡，但Chang-HBX细胞对呼肠孤病毒感染和病毒诱导的凋亡具有高度抗性，即使HBX蛋白诱导Ras激活和PKR失活，而通常认为这会增强呼肠孤病毒的溶瘤作用。Chang-HBX细胞对呼肠孤病毒的抗性反而可能由HBX诱导的死亡受体5下调和Stat1激活来解释。磷酸化的Stat1激活干扰素（IFN）刺激的调节元件（ISRE）和IFN-γ激活序列（GAS）介导的转录，导致IFN-β的产生，而用其小干扰RNA降低Stat1的表达会导致IFN-β产生减少，由此Chang-HBX细胞最终屈服于呼肠孤病毒感染。这一结果进一步表明HBX通过Stat1激活诱导抗病毒状态的建立。因此，似乎活跃的Ras不会超越由Stat1激活介导的抗病毒作用。据此，我们报告HBV的癌蛋白HBX可以阻止呼肠孤病毒对肝癌细胞的溶瘤作用。这表明呼肠孤病毒在治疗已经表达其他致癌病毒蛋白的人类癌症中的实际应用可能存在局限性。
