Gene expression studies of hepatitis virus-induced woodchuck hepatocellular carcinoma in correlation with human results

The lack of good molecular markers for diagnosis as well as treatment assessment has rendered the hepatocellular carcinoma (HCC) a major challenge in health care. In this study, woodchucks were used as an animal model for hepatitis virus-induced HCC, and gene expression studies were performed using a human oligonucleotide microarray. An analysis approach combing supervised significant analysis of microarray (SAM), prediction analysis of microarray (PAM), and unsupervised hierarchical cluster methodologies statistically determined 211 upregulated and 78 downregulated genes between liver cancer and non-cancer liver tissues, and demonstrated ≥93% accuracy in classifying the tissue samples. RT-PCR results confirmed the differential expression of selected sequenced woodchuck genes (SAT, IDH3B, SCD) in the microarray. Our study showed that differentially expressed genes were involved in transcription, RNA splicing, translation, cell cycle, metabolism, protein folding and degradation, apoptosis, immune response, metal binding, etc. Interestingly, some genes were involved with signaling pathways such as Ras/MAPK (MAPKAP1), Src-dependent pathways (CSK), hedgehog signaling pathway (HHIP), while Wnt signaling pathway may not be dominant in woodchuck HCC as shown by the downregulation of β-catenin (TNNB1) and the upregulation of CXXC4 and CSNK2B. Numerous genes found in this study were also differentially expressed in human HCC and many other human cancers including breast, prostate and lung cancers, etc., serving as tumor suppressors, promoters, prognostic markers or chemotherapy targets. In conclusion, this study has demonstrated the robustness of the data analysis and the potential of using human microarrays on woodchuck samples. In particular, some of the differentially expressed genes in the woodchuck HCC can be further explored for possible molecular imaging targets or biological markers in human HCC.