Lipid composition of hepatitis B virus surface antigen particles and the particle-producing human hepatoma cell lines

More than 90% of lipids of hepatitis B virus surface antigen (HBsAg) particles produced by two human hepatoma cell lines (huGK-14 and PLC/PRF/5) were composed of phospholipids, with phosphatidylcholine being the dominant component, accounting for more than 80% of total membrane lipids. Analysis of subclass compositions of phospholipids of HBsAg particles and the host cell lines revealed that 1,2-diacyl glycerophosphocholine was preferentially incorporated into the membrane of the HBsAg particles, although both host cell lines contained extremely high concentrations (more than 60% of total phospholipids) of ether-linked phospholipids. Phospholipids of other hepatoma cell lines (HuH-7, Hep-G2, and huL-1) which were not associated with hepatitis B virus (HBV) infection, were composed mostly of 1,2-diacylglycerophospholipids. Activities of dihydroxyacetone-phosphate acyltransferase, which is known to be an obligatory enzyme in ether lipid biosynthesis, were found to be elevated by three- to fourfold in both huGK-14 and PLC/PRF/5 cells compared to those of other hepatoma cell lines. The results suggest a possible relationship between HBV-induced hepatocellular carcinogenesis and the drastic change in the metabolism of membrane phospholipids.