The development of hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) involves complex interactions between viral factors and host genetics. A hallmark event in HBV-HCC progression is the integration of the HBV gene into the hepatocyte genome. This integration frequently results in truncation of the HBV X (HBx) gene, yielding C-terminal carboxy-truncated HBx (Ct-HBx), which exhibits stronger oncogenic potential than its wild-type counterpart. Previous work identified plasminogen activator inhibitor-1 (PAI-1) as a key effector of Ct-HBx, but the underlying mechanisms and clinical implications remained unclear.
To address this, we investigated the mechanisms by which the genetic predisposition and expression of PAI-1 influence Ct-HBx-induced hepatocarcinogenesis and to identify novel predictive and prognostic biomarkers for HBV-HCC. The comprehensive study combined mechanistic experiments in hepatoma cell lines with large-scale clinical cohort analyses.
ATAC-seq revealed that Ct-HBx more potently upregulates histone acetyltransferases (GCN5, KAT6A) and chromatin remodelers (BAF155, ATRX) than wild-type HBx (WT-HBx). This enhances chromatin accessibility of the -1kb promoter and the 3’UTR of PAI-1, increasing its expression. In addition, our co-transfection experiment demonstrated that Ct-HBx and WT-HBx almost equally upregulated the expression of the -1kb promoter- or the 3’UTR-regulatory gene, regardless of their functional polymorphic genotypes. Thus, Ct-HBx specifically upregulates the expression of PAI-1 in two ways: (i) Ct-HBx is more potent than WT-HBx in opening chromatin at regulatory regions by upregulating the expression of histone acetyltransferases and chromatin remodeling factors; and (ii) it trans-activates the regulatory regions to express PAI-1, with an almost equal trans-activation capacity to that of WT-HBx.
The genetic polymorphic genotypes in the promoter region (rs2227631-G) and in the 3’UTR region (rs11178-T and rs1050955-A) increased the risk of HBV-HCC. These three genetic polymorphic genotypes increased the transcription and mRNA stability of PAI-1, thus increasing the expression of PAI-1, respectively. Previous studies did not investigate the biological functions of SNPs. Here, we demonstrated, for the first time, that the functional polymorphic genotypes rs2227631-GG and rs11178-TT of PAI-1 increased the risk of HBV-HCC by promoting the expression of PAI-1 and participating in the immunoselection of HBV mutations. Specifically, the polymorphic genotypes predisposing to higher PAI-1 expression were often associated with higher frequencies of HCC-risk HBV mutations. Importantly, the interaction between these genotypes and HCC-risk HBV mutations multiplicatively elevated HBV-HCC risk.
Longitudinal monitoring in a nested cohort revealed that serum concentration of PAI-1 increased consecutively in HBV-infected subjects who eventually developed HCC but not in those without HCC; furthermore, PAI-1 levels increased significantly after HCC occurred.
Furthermore, in a postoperative cohort study, rs2227631-GG at the PAI-1 promoter was associated with increased expression of PAI-1 in tumors; the same was true for rs11178-TT at the 3’UTR. rs2227631-GG and rs11178-TT were independent risk factors for poor postoperative prognosis in patients with HBV-HCC. In addition, higher PAI-1 expression in tumors significantly predicts a poorer prognosis in patients with HBV-positive HCC, but not in HBV-negative HCC.
In conclusion, this study elucidates a novel epigenetic pathway wherein Ct-HBx promotes HBV-HCC by opening chromatin to upregulate PAI-1. PAI-1 levels and its functional genotypes serve as promising biomarkers for predicting HCC risk and postoperative prognosis. To the best of our knowledge, this is the first study to investigate the mechanisms by which Ct-HBx promotes the expression of PAI-1 and to characterize the effects of genetic predispositions and expression of PAI-1 and its interactions with HBV mutations on the development of HBV-HCC, indicating that PAI-1 might be a novel prognostic and predictive biomarker for HBV-HCC.
Reference
Title of original paper: Effect of plasminogen activator inhibitor-1 transcriptionally upregulated by C-terminal truncated hepatitis B virus X on the development of hepatocellular carcinoma
Journal: Chinese Medical Journal
DOI: https://doi.org/10.1097/CM9.0000000000004121
About Guangwen Cao from Second Military Medical University
Dr. Guangwen Cao is the chairman, professor, and PhD supervisor at Department of Epidemiology, Second Military Medical University (Shanghai, China). He is the principal scientist of the national key basic research program (973 Program), the National Outstanding Youth Scholar, and a professor for “Chang-Jiang scholar award scheme” of the Department of Education. The major research interests are to elucidate the mechanisms by which cancers develop and metastasize, trace the source of emerging infectious diseases, and handle devastating disasters. Dr. Cao has published 182 papers in professional English journals, including 152 papers as the first or corresponding author.
Funding information
This study was supported by the 2030 Key Program for Chronic Diseases in China (2023ZD0500100), the National Natural Science Foundation of China (82473715 and 82204112), and the Three-Year Public Health Program of the Shanghai Health Commission (GWV-10.1-XK17).
Chinese Medical Journal
Experimental study
People
Effect of plasminogen activator inhibitor-1 transcriptionally upregulated by C-terminal truncated hepatitis B virus X on the development of hepatocellular carcinoma
17-Jun-2026
None