Niu Y, Wu Z, Shen Q, Song J, Luo Q, You H, Shi G, Qin W. Hepatitis B virus X protein co-activates pregnane X receptor to induce the cytochrome P450 3A4 enzyme, a potential implication in hepatocarcinogenesis.
Dig Liver Dis 2013;
45:1041-8. [PMID:
23891548 DOI:
10.1016/j.dld.2013.06.004]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/16/2013] [Accepted: 06/10/2013] [Indexed: 02/05/2023]
Abstract
BACKGROUND
Hepatitis B virus X protein is a key regulator of hepatocarcinogenesis. The pregnane X receptor is a xenobiotic nuclear receptor that plays a role in the regulation of drug-metabolizing enzymes including the cytochrome P450 3A4, an enzyme important for the bioactivation of the liver carcinogen aflatoxin B1.
AIMS
To identify novel host factor that interacts with hepatitis B virus X protein and the functional interaction between hepatitis B virus X protein and pregnane X receptor in hepatocarcinogenesis.
METHODS
Co-immunoprecipitation, glutathione S-transferase pull-down, and chromatin immunoprecipitation were utilized to assess the interaction between hepatitis B virus X protein and pregnane X receptor. The functional relevance of hepatitis B virus X protein-pregnane X receptor interaction was investigated in cell cultures and hepatocellular carcinoma samples.
RESULTS
We observed that hepatitis B virus X protein and pregnane X receptor co-localize in hepatic cells. Pregnane X receptor interacted with hepatitis B virus X protein via the ligand-binding domain of pregnane X receptor. Functionally, hepatitis B virus X protein increased the transcriptional activity of pregnane X receptor. Pregnane X receptor was able to recruit hepatitis B virus X protein to the CYP3A4 gene promoter. In clinic samples, the expression of pregnane X receptor was high in hepatitis B virus-associated liver cirrhosis and stage I hepatocellular carcinoma, but low in state II and stage III hepatocellular carcinoma.
CONCLUSION
We revealed a novel function of hepatitis B virus X protein in co-activating pregnane X receptor. The increased expression of pregnane X receptor and its target gene CYP3A4 are potential biomarkers for the early stage of hepatitis B virus-associated hepatocarcinogenesis.
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