Department of Clinical Laboratory, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Laboratory Medicine, Jinan, China.
Hepatol Commun. 2024 Feb 14;8(3). doi: 10.1097/HC9.0000000000000387. eCollection 2024 Mar 1.
The essential function of HBV DNA polymerase (HBV-DNA-Pol) is to initiate viral replication by reverse transcription; however, the role of HBV-DNA-Pol in HBV-associated HCC has not been clarified. Glycogen phosphorylase L (PYGL) is a critical regulator of glycogenolysis and is involved in tumorigenesis, including HCC. However, it is unknown whether HBV-DNA-Pol regulates PYGL to contribute to HCC tumorigenesis.
Bioinformatic analysis, real-time quantitative PCR, western blotting, and oncology functional assays were performed to determine the contribution of HBV-DNA-Pol and PYGL to HCC development and glycolysis. The mechanisms of co-immunoprecipitation and ubiquitination were employed to ascertain how HBV-DNA-Pol upregulated PYGL.
Overexpression of HBV-DNA-Pol enhanced HCC progression in vitro and in vivo. Mechanistically, HBV-DNA-Pol interacted with PYGL and increased PYGL protein levels by inhibiting PYGL ubiquitination, which was mediated by the E3 ligase TRIM21. HBV-DNA-Pol competitively impaired the binding of PYGL to TRIM21 due to its stronger binding affinity to TRIM21, suppressing the ubiquitination of PYGL. Moreover, HBV-DNA-Pol promoted glycogen decomposition by upregulating PYGL, which led to an increased flow of glucose into glycolysis, thereby promoting HCC development.
Our study reveals a novel mechanism by which HBV-DNA-Pol promotes HCC by controlling glycogen metabolism in HCC, establishing a direct link between HBV-DNA-Pol and the Warburg effect, thereby providing novel targets for HCC treatment and drug development.
HBV DNA 聚合酶（HBV-DNA-Pol）的基本功能是通过逆转录启动病毒复制；然而，HBV-DNA-Pol 在 HBV 相关 HCC 中的作用尚未阐明。糖原磷酸化酶 L（PYGL）是糖原分解的关键调节因子，参与包括 HCC 在内的肿瘤发生。然而，尚不清楚 HBV-DNA-Pol 是否通过调节 PYGL 促进 HCC 肿瘤发生。
通过生物信息学分析、实时定量 PCR、western blot 和肿瘤学功能测定，确定 HBV-DNA-Pol 和 PYGL 对 HCC 发生和糖酵解的贡献。采用共免疫沉淀和泛素化机制确定 HBV-DNA-Pol 如何上调 PYGL。
HBV-DNA-Pol 的过表达增强了 HCC 在体外和体内的进展。在机制上，HBV-DNA-Pol 与 PYGL 相互作用，并通过抑制 PYGL 泛素化来增加 PYGL 蛋白水平，该过程由 E3 连接酶 TRIM21 介导。HBV-DNA-Pol 通过与其更强的结合亲和力与 TRIM21 竞争，从而破坏了 PYGL 与 TRIM21 的结合，从而抑制了 PYGL 的泛素化。此外，HBV-DNA-Pol 通过上调 PYGL 促进糖原分解，导致葡萄糖更多地流入糖酵解，从而促进 HCC 发展。
本研究揭示了 HBV-DNA-Pol 通过控制 HCC 中的糖元代谢促进 HCC 的新机制，在 HBV-DNA-Pol 与沃伯格效应之间建立了直接联系，从而为 HCC 的治疗和药物开发提供了新的靶点。
