[Hepatitis B surface antigen affects the expression of lipid metabolism-related genes in HepG2 cells]

To investigate the influence of hepatitis B virus (HBV)-encoded small surface protein (SHBs) on hepatic cell expression of host genes related to lipid metabolism.

The full-length SHBs gene was amplified from HBV genotype C by polymerase chain reaction (PCR) and cloned into the pcDNA3.1(+) expression vector for stable transfection into HepG2 cells (selected by G418 screening); cells transfected with empty vector served as control. The SHBs mRNA and protein levels were detected by reverse transcription-PCR and enzyme-linked immunosorbent assay. SHBs effects on expression of genes and proteins related to lipid metabolism were detected by real-time quantitative (q)PCR and western blotting, respectively.

The stably transfected cell line HepG2-pn3.1-SHBs was established successfully. qPCR showed that the HepG2-pn3.1-SHBs cells had significantly down-regulated transcription of the ECHS1, APOA1 and LPL genes (0.161+/-0.043 vs. control cells: 0.210+/-0.022, t = 2.479; 0.031+/-0.007 vs. 0.094+/-0.055, t = 2.752; 0.770+/-0.036 vs. 0.982+/-0.031, t = 10.914), but significantly up-regulated ACC and SREBP-1c genes (0.113+/-0.027 vs. 0.059+/-0.022, t = -3.757; 0.019+/-0.002 vs. 0.015+/-0.001, t = -4.330). The CPT1a and PPARa genes' expression was slightly, but not significantly, down-regulated in the HepG2-pn3.1-SHBs cells (0.028+/-0.005 vs. 0.030+/-0.004, t = 1.022; 0.014+/-0.004 vs. 0.015+/-0.002, t = 0.758). Western blotting showed similar expression trends for the corresponding proteins.

SHBs alters the expression of some host genes with known functions in fatty acid synthesis and decomposition; however, it remains unclear whether the hepatitis B surface antigen can directly contribute to development of hepatic steatosis.