NQO1抑制剂Dicoumarol通过促进HBx降解来阻止cccDNA转录

StephenW

Dicoumarol, an NQO1 inhibitor, blocks cccDNA transcription by promoting degradation of HBx

    Sheng-Tao Cheng
    Jie-Li Hu
    Ji-Hua Ren
    Hong-Zhong Zhou
    Ai-Long Huang
    Juan Chen
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Open AccessPublished:September 25, 2020DOI:https://doi.org/10.1016/j.jhep.2020.09.019
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Highlights

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    Dicoumarol, a competitive NADPH quinone oxidoreductase (NQO1) inhibitor, is identified as an inhibitor of HBx expression.
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    NQO1 stabilises HBx protein by inhibiting 20S proteasome-mediated protein degradation.
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    NQO1 knockdown or dicoumarol treatment blocks cccDNA transcription by establishing a repressive chromatin structure.
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    Dicoumarol exhibits potent antiviral activity in HBV-infected hepatocytes and a humanised liver mouse model.

Background & Aims
Current antiviral therapies help keep HBV under control, but they are not curative, as they are unable to eliminate the intracellular viral replication intermediate termed covalently closed circular DNA (cccDNA). Therefore, there remains an urgent need to develop strategies to cure CHB. Functional silencing of cccDNA is a crucial curative strategy that may be achieved by targeting the viral protein HBx.
Methods
We screened 2,000 small-molecule compounds for their ability to inhibit HiBiT-tagged HBx (HiBiT-HBx) expression by using a HiBiT lytic detection system. The antiviral activity of a candidate compound and underlying mechanism of its effect on cccDNA transcription were evaluated in HBV-infected cells and a humanised liver mouse model.
Results
Dicoumarol, an inhibitor of NAD(P)H:quinone oxidoreductase 1 (NQO1), significantly reduced HBx expression. Moreover, dicoumarol showed potent antiviral activity against HBV RNAs, HBV DNA, HBsAg and HBc protein in HBV-infected cells and a humanised liver mouse model. Mechanistic studies demonstrated that endogenous NQO1 binds to and protects HBx protein from 20S proteasome-mediated degradation. NQO1 knockdown or dicoumarol treatment significantly reduced the recruitment of HBx to cccDNA and inhibited the transcriptional activity of cccDNA, which was associated with the establishment of a repressive chromatin state. The absence of HBx markedly blocked the antiviral effect induced by NQO1 knockdown or dicoumarol treatment in HBV-infected cells.
Conclusions
Herein, we report on a novel small molecule that targets HBx to combat chronic HBV infection; we also reveal that NQO1 has a role in HBV replication through the regulation of HBx protein stability.
Lay summary
Current antiviral therapies for hepatitis B are not curative because of their inability to eliminate covalently closed circular DNA (cccDNA), which persists in the nuclei of infected cells. HBV X (HBx) protein has an important role in regulating cccDNA transcription. Thus, targeting HBx to silence cccDNA transcription could be an important curative strategy. We identified that the small molecule dicoumarol could block cccDNA transcription by promoting HBx degradation; this is a promising therapeutic strategy for the treatment of chronic hepatitis B.

StephenW

NQO1抑制剂Dicoumarol通过促进HBx降解来阻止cccDNA转录

    程胜涛
    胡杰丽
    任继华
    周鸿中
    黄爱龙
    陈娟
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开放获取发布时间：2020年9月25日DOI：https：//doi.org/10.1016/j.jhep.2020.09.019
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强调

    •
    Dicoumarol是一种竞争性NADPH醌氧化还原酶（NQO1）抑制剂，被确定为HBx表达抑制剂。
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    NQO1通过抑制20S蛋白酶体介导的蛋白质降解来稳定HBx蛋白。
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    NQO1组合式或双香豆酚处理可通过建立抑制性染色质结构来阻断cccDNA转录。
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    地香豆酚在HBV感染的肝细胞和人源化的肝小鼠模型中表现出强大的抗病毒活性。

背景与目标
当前的抗病毒疗法有助于使HBV受到控制，但它们无法治愈，因为它们无法消除称为共价闭合环状DNA（cccDNA）的细胞内病毒复制中间产物。因此，迫切需要制定治疗CHB的策略。 cccDNA的功能沉默是关键的治愈策略，可通过靶向病毒蛋白HBx实现。
方法
我们通过使用HiBiT裂解检测系统筛选了2,000种小分子化合物抑制HiBiT标记的HBx（HiBiT-HBx）表达的能力。在HBV感染的细胞和人源化的肝小鼠模型中评估了候选化合物的抗病毒活性及其对cccDNA转录的影响的潜在机制。
结果
Dicoumarol是NAD（P）H：醌氧化还原酶1（NQO1）的抑制剂，可显着降低HBx表达。此外，双香豆酚在感染了HBV的细胞和人源化肝小鼠模型中显示出对HBV RNA，HBV DNA，HBsAg和HBc蛋白的有效抗病毒活性。机理研究表明，内源性NQO1结合并保护HBx蛋白免受20S蛋白酶体介导的降解。 NQO1敲低或双香豆酚处理可显着减少HBx向cccDNA的募集，并抑制cccDNA的转录活性，这与抑制性染色质状态的建立有关。 HBx的缺乏显着阻断了NQO1敲低或双香豆酚处理在HBV感染的细胞中诱导的抗病毒作用。
结论
在本文中，我们报道了一种靶向HBx的新型小分子，以对抗慢性HBV感染。我们还揭示了NQO1通过调节HBx蛋白稳定性在HBV复制中具有作用。
放置摘要
当前的乙型肝炎抗病毒治疗方法无法治愈，因为它们无法消除共价闭合的环状DNA（cccDNA），后者一直存在于被感染细胞的细胞核中。 HBV X（HBx）蛋白在调节cccDNA转录中起重要作用。因此，靶向HBx以沉默cccDNA转录可能是重要的治疗策略。我们发现小分子双香豆酚可以通过促进HBx降解来阻止cccDNA转录。这是治疗慢性乙型肝炎的有前途的治疗策略。

StephenW

https://www.journal-of-hepatolog ... 8278(20)33661-8/pdf