Enhanced expression of hepatitis B surface antigen by sodium butyrate in PLC/PRF/5 human hepatoma cells

The effect of butyric acid, a natural fermentation product of colonic bacterial flora, on hepatitis B surface antigen (HBsAg) expression was investigated in HBsAg-positive PLC/PRF/5 human hepatoma cells. By Northern blot analysis, the levels of HBsAg mRNA increased dose-dependently using sodium butyrate (0-2 mmol/l). In transient chloramphenicol acetyltransferase plasmid transfection experiments, the HBsAg-preS2 promoter activity as well as the HBV enhancer 1 activity was stimulated by sodium butyrate, whereas the HBsAg-preS1 promoter activity was not. These results indicate that butyric acid functions as a physiological regulator of HBsAg expression through the portal blood flow and possibly contributes to increased expression ratio of preS2/S to preS1 polypeptides recognized in persistant HBV infection.