Division of Gastroenterology, Department of Medicine Department of Pathology, Kurume University School of Medicine Research Center for Innovative Cancer Therapy, Kurume University, Kurume Asakura Medical Association Hospital, Asakura, Japan.
Hepatol Res. 2012 Jun;42(6):591-600. doi: 10.1111/j.1872-034X.2011.00953.x. Epub 2012 Jan 6.
Hepatitis C virus (HCV) core protein critically contributes to hepatocarcinogenesis, which is often observed in liver cirrhosis. Since the liver cirrhosis microenvironment is affected by hypoxia, we focused on the possible driving force of HCV core protein on signal relay from hypoxia-inducible factor (HIF)-1α to vascular endothelial growth factor (VEGF).
Human hepatocellular carcinoma cells stably overexpressing HCV core (Core cells) and NS5A (NS5A cells) were established; empty vector-transfected (EV) cells were used as controls. Hypoxia was induced by oxygen deprivation or by using cobalt chloride (CoCl(2) ). YC-1 was used to inhibit HIF-1α expression. Protein analyses for cultured cells and liver tissues obtained from CoCl(2) -treated HCV core-transgenic (Core-Tg) mice were performed by western blot and/or immunocytochemistry. Cellular mRNA levels were evaluated by quantitative real-time reverse transcription-polymerase chain reaction.
Under hypoxia, the sustained expression of HIF-1α, but not HIF-2α, was profoundly observed in Core cells but, was faint in EV and NS5A cells. Immunocytochemistry revealed increased HIF-1α in the nucleus. HIF-1α mRNA levels were significantly higher in Core cells than in EV cells under both normoxia and hypoxia. The HIF-1α-targeted VEGF and Bcl-xL expressions were increased in Core cells under hypoxia and abolished by YC-1 treatment. Hypoxic liver samples of Core-Tg mice indicated significant increases in both HIF-1α and VEGF expression compared with the wild type.
Hepatitis C virus core protein has the distinct potential to transcriptionally upregulate and sustain HIF-1α expression under hypoxia, thereby contributing to increased VEGF expression, a key regulator in the hypoxic milieu of liver cirrhosis.
丙型肝炎病毒（HCV）核心蛋白在肝癌发生中起着至关重要的作用，这种情况经常发生在肝硬化中。由于肝硬化微环境受到缺氧的影响，我们专注于 HCV 核心蛋白对缺氧诱导因子（HIF）-1α到血管内皮生长因子（VEGF）信号转导的可能驱动力。
建立了稳定过表达 HCV 核心（Core 细胞）和 NS5A（NS5A 细胞）的人肝癌细胞系；空载体转染（EV）细胞作为对照。通过缺氧剥夺或使用氯化钴（CoCl(2)）诱导缺氧。使用 YC-1 抑制 HIF-1α的表达。通过 Western blot 和/或免疫细胞化学分析 CoCl(2)处理的 HCV 核心转基因（Core-Tg）小鼠的培养细胞和肝组织中的蛋白质。通过实时定量逆转录聚合酶链反应评估细胞内 mRNA 水平。
在缺氧条件下，Core 细胞中 HIF-1α的持续表达明显，但 EV 和 NS5A 细胞中的 HIF-2α表达微弱。免疫细胞化学显示核内 HIF-1α增加。Core 细胞在常氧和缺氧条件下 HIF-1α mRNA 水平明显高于 EV 细胞。在缺氧条件下，Core 细胞中的 HIF-1α靶向 VEGF 和 Bcl-xL 表达增加，并用 YC-1 处理后被消除。Core-Tg 小鼠的缺氧肝组织与野生型相比，HIF-1α和 VEGF 的表达均显著增加。
丙型肝炎病毒核心蛋白在缺氧下具有独特的转录上调和维持 HIF-1α表达的潜力，从而促进血管内皮生长因子（VEGF）表达增加，VEGF 是肝硬化缺氧微环境中的关键调节因子。
