Discussion on differential gene expression between chronic hepatitis B and C hepatic lesion

Abstract

Background & Aims: Complementary DNA (cDNA) microarray technology allows simultaneous expression analysis of hundreds to thousands of genes. We applied the cDNA microarray technique to clarify gene expression profiles in chronic viral hepatitis tissue lesions. Methods: We made cDNA microarrays consisting of 1080 human cDNAs and analyzed gene expression using labeled cDNAs prepared from 6 normal, 12 chronic hepatitis B, and 14 chronic hepatitis C liver tissues. Relative expression ratios of individual genes were obtained by comparing hybridization of Cy5-labeled cDNAs from chronic hepatitis lesions and Cy3-labeled cDNA from normal liver tissue. Results: Hierarchical clustering analysis of the gene expression profiles in 26 patients showed that the patients were clustered into 2 groups with respect to similarities in differentially expressed genes. Hepatitis B and C virus infection, but not age, sex, or histology of hepatitis, were significant factors determining clustering (P < 0.05). In hepatitis B tissue lesions, genes involved in inflammation were predominant, whereas in hepatitis C, expression of anti-inflammatory response genes was relatively dominant. Conclusions: These findings shed new light on the possible differential molecular mechanisms in the pathogenesis of hepatitis caused by hepatitis B virus and hepatitis C virus infection, from which hepatocellular carcinoma frequently develops.