IL-4 suppresses the expression and the replication of hepatitis B virus in the hepatocellular carcinoma cell line Hep3B.
IL-4 has been known as a Th2 cytokine and can act on B cells, T cells, and monocytes. In this study we demonstrate that IL-4Rs are expressed on human hepatocellular carcinoma (HCC) cells. We found that IL-4 suppresses hepatitis B surface Ag (HBsAg) mRNA and HBsAg production in the Hep3B cell line, which contains an integrated hepatitis B virus (HBV) genome and constitutively secretes HBsAg. When Hep3B cells are further transfected with the plasmid pHBV3.6 that contains >1 U of HBV genome, IL-4 could suppress the production of all HBV RNA and secreted HBsAg and hepatitis B virus e Ag. Furthermore, an endogenous DNA polymerase activity assay shows a decrease in HBV DNA after IL-4 treatment. Using luciferase reporter assays we have demonstrated that IL-4 could suppress the activity of the surface promoter II and the core promotor (CP). To delineate how IL-4 suppressed the transcription of HBV genes, we have examined the effect of IL-4 on the expression of transcription factors that are known to bind to the core upstream regulatory sequence, which colocalizes with enhancer II of the HBV genome. Our results demonstrate that IL-4 suppresses the expression of C/EBPalpha. Furthermore, overexpression of C/EBPalpha blocked 43 and 30% of the IL-4-mediated suppression of CP activity and IL-4-induced suppression of pregenomic RNA, respectively. Finally, we have demonstrated that mutations affecting the C/EBPalpha-binding sites on core upstream regulatory sequence/enhancer II completely abolish the IL-4-mediated suppression of CP activity. Thus, down-regulation of C/EBPalpha may be involved in the anti-HBV effect of IL-4 in Hep3B cells.
Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Sue-Jane
SJ
Lin
Pei-Yun
PY
Shu
Chungming
C
Chang
Ah-Kau
AK
Ng
Cheng-po
CP
Hu
D000998:Antiviral Agents / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000276:immunology* / Q000821:virology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D051790:G-Box Binding Factors; D015967:Gene Expression Regulation, Viral / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis / Q000235:genetics; D006513:Hepatitis B e Antigens / Q000096:biosynthesis / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000276:immunology / Q000821:virology; D011401:Promoter Regions, Genetic / Q000276:immunology; D021122:Protein Subunits / Q000096:biosynthesis / Q000235:genetics; D020871:RNA Stability / Q000276:immunology; D012367:RNA, Viral / Q000096:biosynthesis; D019948:Receptors, Interleukin-4 / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000276:immunology; D014162:Transfection; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics; D014779:Virus Replication / Q000235:genetics / Q000276:immunology*
D000998:Antiviral Agents; D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D021122:Protein Subunits; D012367:RNA, Viral; D019948:Receptors, Interleukin-4; D014157:Transcription Factors; D014764:Viral Proteins; D015847:Interleukin-4