Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
Antimicrob Agents Chemother. 2012 Mar;56(3):1407-13. doi: 10.1128/AAC.05762-11. Epub 2012 Jan 9.
We previously showed that equilibrative nucleoside transporter 1 (ENT1) is a primary ribavirin transporter in human hepatocytes. However, because the role of this transporter in the antiviral mechanism of the drug remains unclear, the present study aimed to elucidate the role of ENT1 in ribavirin antiviral action. OR6 cells, a hepatitis C virus (HCV) replication system, were used to evaluate both ribavirin uptake and efficacy. The ribavirin transporter in OR6 cells was identified by mRNA expression analyses and transport assays. Nitrobenzylmercaptopurine riboside (NBMPR) and micro-RNA targeted to ENT1 mRNA (miR-ENT1) were used to reduce the ribavirin uptake level in OR6 cells. Our results showed that ribavirin antiviral activity was associated with its accumulation in OR6 cells, which was also closely associated with the uptake of the drug. It was found that the primary ribavirin transporter in OR6 cells was ENT1 and that inhibition of ENT1-mediated ribavirin uptake by NBMPR significantly attenuated the antiviral activity of the drug as well as its accumulation in OR6 cells. The results also showed that even a small reduction in the ENT1-mediated ribavirin uptake, achieved in this case using miR-ENT1, caused a significant decrease in its antiviral activity, thus indicating that the ENT1-mediated ribavirin uptake level determined its antiviral activity level in OR6 cells. In conclusion, our results show that by facilitating its uptake and accumulation in OR6 cells, ENT1 plays a pivotal role in the antiviral effectiveness of ribavirin and therefore provides an important insight into the efficacy of the drug in anti-HCV therapy.
我们之前的研究表明，核苷转运蛋白 1（ENT1）是人类肝细胞中利巴韦林的主要转运蛋白。然而，由于该转运蛋白在药物抗病毒机制中的作用尚不清楚，本研究旨在阐明 ENT1 在利巴韦林抗病毒作用中的作用。本研究使用丙型肝炎病毒（HCV）复制系统 OR6 细胞来评估利巴韦林的摄取和疗效。通过 mRNA 表达分析和转运试验鉴定 OR6 细胞中的利巴韦林转运蛋白。使用硝基苄基巯基嘌呤核苷（NBMPR）和针对 ENT1 mRNA 的 micro-RNA（miR-ENT1）来降低 OR6 细胞中的利巴韦林摄取水平。结果表明，利巴韦林的抗病毒活性与其在 OR6 细胞中的积累密切相关，而这也与药物的摄取密切相关。研究发现，OR6 细胞中的主要利巴韦林转运蛋白是 ENT1，NBMPR 抑制 ENT1 介导的利巴韦林摄取可显著减弱药物的抗病毒活性及其在 OR6 细胞中的积累。结果还表明，即使使用 miR-ENT1 轻微减少 ENT1 介导的利巴韦林摄取，也会导致其抗病毒活性显著降低，这表明 ENT1 介导的利巴韦林摄取水平决定了其在 OR6 细胞中的抗病毒活性水平。总之，我们的研究结果表明，ENT1 通过促进利巴韦林在 OR6 细胞中的摄取和积累，在利巴韦林的抗病毒有效性中发挥关键作用，这为利巴韦林在抗 HCV 治疗中的疗效提供了重要的见解。
