Molecular signature in three types of hepatocellular carcinoma with different viral origin by oligonucleotide microarray

Chronic infection with hepatitis B or C virus (HBV or HCV) is the most clearly established risk factor for hepato-cellular carcinoma (HCC). One type of HCC (non-B, non-C HCC) also appears to develop in patients negative for both HBV and HCV. Using a supervised learning method, we investigated gene expression in 11 non-B, non-C HCCs with high-density oligonucleotide microarrays, and compared the patterns of gene expression with those of HBV-infected HCCs (B-type HCCs) and HCV-infected HCCs (C-type HCCs) in the previous dataset. Our gene selection identified 112 and 64 genes that were differentially expressed in non-B, non-C HCC in comparison with B- and C-type HCCs, respectively. In both gene selections, we found that the false discovery rate, the percentage of genes identified by chance, was less than 5%. Additionally, in combination with the previous data, our present data revealed a set of genes specific to each type of B- and C-type HCCs and non-B, non-C HCC. Among these, an interferon-induced gene, IFI27, was differentially expressed among all three types of HCCs, and this result was confirmed by RT-PCR. Thus, our present study provides a framework to characterize the molecular features in the three subtypes of HCC with different viral origin.