[Frontiers in Bioscience E2, 1538-1547, June 1, 2010]

Scutellariae radix suppresses hepatitis B virus production in human hepatoma cells

Ya Ping Tseng1, Yi Chieh Wu1, Yann Lii Leu2 , Sheau Farn Yeh1, Chen Kung Chou3

1Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, R.O.C., 2Graduate Institute of Natural Product, Chang Gung University, Tao-Yuan, Taiwan, R.O.C., 3Department of Life Science, Chang Gung University, Tao-Yuan, Taiwan, R.O.C.

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Materials and methods
3.1. Preparation of herbal remedy
3.2. Cell culture
3.3. Detection of HBsAg
3.4. RNA isolation and northern blot analysis
3.5. Plasmids
3.6. Transient transfections and luciferase assay
3.7. Quantitative detection of HBV DNA by real-time light cycler PCR
3.8. Gel electrophoretic mobility shift assay
4. Results
4.1. HD-1S but not HD-1B is the active component in HD-7 that suppresses HBsAg production by HepA2 cells
4.2. HD-1S inhibited both wild type and lamivudine resistant HBV viral particle production by human hepatoma 1.3ES2 and M33 cells
4.3. HD-1S treatment reduced all four HBV viral transcript levels in 1.3ES2 cells
4.4. HD-1S selectively suppresses viral promoter activities of the large viral surface antigen and the core antigen in liver cells
4.5. HD-1S reduces DNA-binding activity of nuclear extract to the C/EBP/FTF and PPAR/hepatocyte nuclear factor-4 binding sequences in the HBV core promoter
4.6. Overexpression of PGC-1 overrides the suppressive activity of HD-1S on HBV core promoter activity
5. Discussion
6. Acknowledgements
7. References

1. ABSTRACT

The traditional Chinese medicine Xiao-Chai-Hu-Tang (HD-7) has been widely used to treat liver diseases in China and Japan. HD-7 consists of seven different ingredients, but which one provides the therapeutic benefits is still unknown. Here, we identified the "Minister herb" Scutellariae radix (HD-1S), but not the "King herb" Bupleuri radix (HD-1B) in HD-7, as the active component that suppresses HBV gene expression and virus production in human hepatoma cells. We have found that an aqueous extract of HD-1S not only suppressed wild-type virus but also lamivudine-resistant HBV mutant in human hepatoma cells. We show that HD-1S selectively suppresses HBV core promoter activity. Electrophoretic mobility shift assay analysis has revealed that HD-1S treatment decreases the DNA-binding activity of nuclear extract of HepA2 cells to a specific cis-element of the HBV core promoter, which includes the peroxisome proliferator-activated receptor binding site and HNF4. Furthermore, ectopic expression of PGC-1 abolished the suppression of HD-1S on HBV core promoter activity suggesting that HD-1S may act through modulating hepatic transcriptional machinery to suppress HBV viral gene expression and virus production.