Supplementary Data from COOH-Terminal Truncated HBV X Protein Plays Key Role in Hepatocarcinogenesis

Abstract Purpose: X protein (HBx), a product of hepatitis B virus, has been closely associated with the development of hepatocellular carcinoma (HCC). Based on observations that the COOH-terminal truncated HBx was frequently detected in HCC, the aim of this study is to evaluate the function of COOH-terminal truncated HBx in hepatocarcinogenesis. Experimental Design: Expression pattern of HBx was analyzed by immunohistochemistry on tissue microarray containing 194 pairs of HCCs and their matched nontumor liver tissues. MIHA and HepG2 cells transfected with full-length (X2) and COOH-terminal truncated HBx (X1) were tested for their ability to grow in soft agar and form tumors in vivo. Proliferation and apoptosis were assessed using 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt and terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling assays, respectively. To gain additional insight, the expression profile of HepG2-X2 and HepG2-X1 were compared using cDNA microarray. Results: COOH-terminal truncated HBx was frequently detected in HCCs (79.3%, n = 111), and our in vitro and in vivo studies showed that the truncated rather than the full-length HBx could effectively transform immortalized liver cell line MIHA. Interestingly, expression profiling revealed differential expression of key genes implicated in the control of cell cycle and apoptosis. Conclusions: These findings strongly suggest that the COOH-terminal truncated HBx plays a critical role in the HCC carcinogenesis via the activation of cell proliferation.

To facilitate profiling mitochondrial transcriptomes, we developed a third-generation human mitochondria-focused cDNA microarray (hMitChip3) and its bioinformatic tools. hMitChip3 consists of the 37 mitochondrial DNA-encoded genes, 1098 nuclear DNA-encoded and mitochondria-related genes, and 225 controls, each in triplicate. The bioinformatic tools included data analysis procedures and customized database for interpretation of results. The database associated 645 molecular functions with 946 hMitChip3 genes, 612 biological processes with 930 genes, 172 cellular components with 869 genes, 107 biological chemistry pathways with 476 genes, 23 reactome events with 227 genes, 320 genetic disorders with 237 genes, and 87 drugs targets with 55 genes. To test these tools, hMitChip3 was used to compare expression profiles between human melanoma cell lines UACC903 (rapidly dividing) and UACC903(+6) (slowly dividing). Our results demonstrated internal gene-set consistency (correlation R > or = 0.980 +/- 0.005) and interexperimental reproducibility (R > or = 0.931 +/- 0.013). Expression patterns of 16 genes, involved in DNA, RNA, or protein biosyntheses in mitochondrial and other organelles, were consistent with the proliferation rates of both cell lines, and the patterns of 6 tested genes were verified by quantitative reverse transcription PCR (RT-PCR). Thus, hMitChip3 and its bioinformatics software provide an integrated tool for profiling mitochondria-focused gene expression.