Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Beijing, China.
Antimicrob Agents Chemother. 2010 May;54(5):2070-7. doi: 10.1128/AAC.01764-09. Epub 2010 Feb 22.
Heat stress cognate 70 (Hsc70) is a host protein associated with hepatitis B virus (HBV) replication. The goal of this study was to investigate whether Hsc70 could be an anti-HBV drug target. Our results showed that introducing Hsc70 increased HBV replication in HBV(+) human hepatocytes (HepG2.2.15 cells). The coiled-coil region on Hsc70 (nucleotides 1533 to 1608; amino acids 511 to 536) was the key sequence for HBV replication. Knockdown of Hsc70 expression by RNA interference (RNAi) largely inhibited HBV replication with no cytotoxicity to the host. Using an Hsc70 mRNA screening assay, the natural compound oxymatrine (OMTR) was found to be a selective inhibitor for Hsc70 expression. Then, OMTR was used to investigate the potential of Hsc70 as an anti-HBV drug target. OMTR inhibited Hsc70 mRNA expression by 80% and HBV DNA replication by over 60% without causing cytotoxicity. The anti-HBV effect of OMTR appeared to be mediated by destabilizing Hsc70 mRNA. The half-life (T(1/2)) of Hsc70 mRNA decreased by 50% in OMTR-treated hepatocytes. The Hsc70 mRNA 3'-untranslated-region (UTR) sequence was the element responsible for OMTR's destabilization activity. OMTR suppressed HBV de novo synthesis at the reverse transcription stage from pregenomic RNA (pgRNA) to DNA and was active against either wild-type HBV or strains resistant to lamivudine, adefovir, and entecavir. Therefore, host Hsc70 could be a novel drug target against HBV, and OMTR appears to inhibit HBV replication by destabilizing Hsc70 mRNA. As the target is not a viral protein, OMTR is active for either wild-type HBV or strains resistant to reverse transcriptase (RT) inhibitors.
热休克同源物 70（Hsc70）是一种与乙型肝炎病毒（HBV）复制相关的宿主蛋白。本研究旨在探讨 Hsc70 是否可作为抗 HBV 药物靶点。研究结果显示，在 HBV（+）人肝细胞（HepG2.2.15 细胞）中，引入 Hsc70 可增加 HBV 复制。Hsc70 的卷曲螺旋区（核苷酸 1533 至 1608；氨基酸 511 至 536）是 HBV 复制的关键序列。通过 RNA 干扰（RNAi）敲低 Hsc70 表达可显著抑制 HBV 复制，而对宿主无细胞毒性。采用 Hsc70 mRNA 筛选检测，发现天然化合物氧化苦参碱（OMTR）可选择性抑制 Hsc70 表达。随后，采用 OMTR 探讨 Hsc70 作为抗 HBV 药物靶点的潜力。OMTR 可抑制 Hsc70 mRNA 表达 80%，抑制 HBV DNA 复制超过 60%，而无细胞毒性。OMTR 的抗 HBV 作用似乎是通过使 Hsc70 mRNA 不稳定来介导的。用 OMTR 处理的肝细胞中 Hsc70 mRNA 的半衰期（T(1/2)）降低 50%。Hsc70 mRNA 3'-非翻译区（UTR）序列是 OMTR 不稳定活性的负责元件。OMTR 可抑制从前基因组 RNA（pgRNA）到 DNA 的逆转录阶段的 HBV 从头合成，对野生型 HBV 或拉米夫定、阿德福韦酯和恩替卡韦耐药株均有活性。因此，宿主 Hsc70 可能成为一种新型抗 HBV 药物靶点，OMTR 似乎通过使 Hsc70 mRNA 不稳定来抑制 HBV 复制。由于该靶点不是病毒蛋白，OMTR 对野生型 HBV 或耐药于逆转录酶（RT）抑制剂的株均有活性。
