| Viral hepatitis B continues to be a significant global problem. Interferon-α (IFN-α) has proven effective in the treatment of chronic hepatitis B patients. However, sustained responses were observed in only one-third of chronic hepatitis B patients. To date, mechanisms underlying anti-viral function of IFN have not been fully elucidated. Because of the shortage of the ability on recognizing the genes and the scarceness of the tools for systemic research on the functions of hundreds and thousands of genes, mechanisms on anti-viral function of host cell after hepatitis B virus (HBV) infection, and the interaction between anti-viral function and the replication of HBV still remain unclear.In order to identify changes in transcription of host cell brought about by the replication of HBV and interactions between HBV infection and interferon treatment in liver-derived cells, and to study the mechanisms on the repression against the replication of HBV by cellular genes induced by IFN-α, cDNA microarray analysis on an HBV-genome transfected hepatoblastoma cell line (HepG22.2.15) and its parental (HepG2) cell line were performed. Isolated mRNA from two cell lines before or after the treatment with IFN-α (5×103IU/ml) for 6 hours, 24 hours and 48 hours respectively, was hybridized with the cDNA microarray of the 14,000 human genes. After hybridization and scanning of the arrays, the data were analyzed using ArrayGauge software. The microarray data were further checked by RNA slot analysis.Comparison of gene expression profiles from HepG22.2.15 and HepG2 cell lines before the IFN-α treatment showed that 89 genes were up or down –regulated more than 3 magnitudes, which may reveal the genes that are responsive to viral DNA replication and viral secretion. Among 21 genes with known functions, 14 were down-regulated, while 7 were up-regulated. Six hours after treatment with IFN-α, marked changes in mRNA expression were observed in both HepG22.2.15 and HepG2 cells, with 34 and 83 genes 3 fold up- or down-regulated separately. A moderate increase in changes of cellular gene expression were detected at 24 hours when 48 and 103 genes were 3 fold up- or down-regulated respectively. Nearlly half of these genes can be classified into functional categories, including interferon related proteins, cell signal transduction, kinase, phosphanase and ligand-receptor etc. A great number of the differentially regulated genes are new ESTs or the unknown genes. It is predicted that other IFN-inducible proteins and new mechanisms of this pleotropic cytokine may be revealed, and these new ESTs or cellular genes identified could serve as new targets for anti-HBV drug development or for novel therapies. In order to further clarify the relationship between IFN-α treatment, HBV replication and cellular gene expression, 23 cellular genes were picked out from the results of microarrays to analyze the different effect of IFN-α on the expression of these genes in two cell lines. Results showed that the expression of 3 genes (vascular endothelial growth factor, tyrosine phosphate 1E, serine protein with IGF-binding motif), which repressed by HBV replication before the IFN-α treatment in HepG22.2.15, were up-regulated, while two genes of interferon-induced kinases and two proto-oncogenes were further down- regulated. The up-regulated genes in HepG22.2.15 cell line suggested that under IFN-α treatment, these repressed cellular genes in HBV infected hepatocytes could be partially restored, while the down- regulated genes were most likely the cellular genes which could not be restored under interferon treatment.From the results of the cDNA microarrays, a novel IFN-α inducible gene with function unknown, ISG12, was found significantly up-regulated both in HepG22.2.15 and HepG2 cell lines induced by IFN-α. In order to understand the funtion of ISG12, and further clarify the relationship between ISG12, IFN-α and HBV, Northern blot analysis was carried out to elucidate the changes of HBV and ISG12 mRNA during the treatment of IFN-α. It is...
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