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Gene expression profiling of hepatocarcinogenesis in a mouse model of chronic hepatitis B

ABSTRACT: BACKGROUND: Hepatocellular carcinoma (HCC) is a common complication of chronic viral hepatitis. In support of this notion, we have reported that hepatitis B surface antigen (HBsAg)-specific CD8+ T lymphocytes critically contribute to inducing chronic liver cell injury that exerts high carcinogenic potential in a hepatitis B virus (HBV) Tg mouse model. The dynamics of the molecular signatures responsible for hepatocellular carcinogenesis are not fully understood. The current study was designed to determine the serial changes in gene expression profiles in a model of chronic immune-mediated hepatitis. METHODS: Three-month-old HBV Tg mice were immunologically reconstituted with bone marrow cells and splenocytes from syngeneic nonTg donors. Liver tissues were obtained every three months until 18 months at which time all mice developed multiple liver tumors. Nitrative DNA lesions and hepatocyte turnover were assessed immunohistochemically. Gene expression profiles were generated by extracting total RNA from the tissues and analyzing by microarray. RESULTS: The nitrative DNA lesions and the regenerative proliferation of hepatocytes were increased during the progression of chronic liver disease. In a gene expression profile analysis of liver samples, the chemokine- and T cell receptor (TCR)-mediated pathways were enhanced during chronic hepatitis, and the EGF- and VEGF-mediated pathways were induced in HCC. Among these molecules, the protein levels of STAT3 were greatly enhanced in all hepatocyte nuclei and further elevated in the cytoplasm in HCC tissue samples at 18 months, and the levels of phosphorylated TP53 (p-p53-Ser 6 and -Ser 15) were increased in liver tissues. CONCLUSIONS: HBV-specific immune responses caused unique molecular signatures in the liver tissues of chronic hepatitis and triggered subsequent carcinogenic gene expression profiles in a mouse model. The results suggest a plausible molecular basis responsible for HBV-induced immune pathogenesis of HCC.

ORGANISM(S): Mus musculus

PROVIDER: GSE103205 | GEO | 2017/08/29

SECONDARY ACCESSION(S): PRJNA400489

REPOSITORIES: GEO

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Project description:Although hepatitis B virus (HBV) has been established to cause hepatocellular carcinoma (HCC), the exact mechanism remains to be clarified. Type II ground glass hepatocytes (GGH) harboring the HBV pre-S2 mutant large surface protein have been recognized as morphologically distinct hallmark of HCC in advanced stages of chronic HBV infection. Considering its pre-neoplastic nature, we hypothesized that type II GGH may exhibit high genomic instability, which is important for the carcinogenic process in chronic HBV carriers. In this study we found that pre-S2 mutant LHBS directly interacted with importin 1, the key factor that recognizes cargos undergoing nuclear transportation mediated by the importin 1 associated nuclear pore complex (NPC). By interacting with importin 1, which inhibits its function as an NPC factor, pre-S2 mutant LHBS blocked nuclear transportation of an essential DNA repair and recombination factor Nijmegen breakage syndrome 1 (NBS1) upon DNA damage, thereby delaying formation of nuclear foci at the sites of DNA double strand breaks. Pre-S2 mutant LHBS was also found to block NBS1-mediated homologous recombination repair and induce multi-nucleation of cells. In addition, pre-S2 mutant LHBS transgenic mice showed genomic instability indicated by increased global gene copy number variations (CNV), which were significantly higher than those in hepatitis B virus X mice, indicating that pre-S2 mutant LHBS is the major viral oncoprotein inducing genomic instability in HBV-infected hepatocytes. Consistently, the human type II GGHs in HCC patients exhibited increased DNA double-strand breaks representing significant genomic instability. In conclusion, type II GGH harboring HBV pre-S2 mutant oncoprotein represents a high-risk marker for the loss of genome integrity in chronic HBV carriers and explains the complex chromosome changes in HCCs. Non-tumorous liver sections from four each the HBx and pre-S2 mutant LHBS transgenic mice and 3 double transgenic mice between 9 and 22 months old were examined for gene gain and loss.

Project description:Chronic infections by hepatitis B virus (HBV) and hepatitis C virus (HCV) appear to be the most significant causes of hepatocellular carcinoma (HCC). Aberrant promoter methylation is known to be deeply involved in cancer, including HCC. In this study, we analyzed aberrant promoter methylation on genome-wide scale in 6 HCCs including 3 HBV-related and 3 HCV-related HCCs, 6 matched noncancerous liver tissues and 3 normal liver tissues by methylated DNA immunoprecipitation-on-chip analysis. Candidate genes with promoter methylation were detected more frequently in HCV-related HCC. Candidate genes methylated preferentially to HBV-related or HCV-related HCCs were detected and selected, and methylation levels of the selected genes were validated using 125 liver tissue samples, including 61 HCCs (28 HBV-related HCCs and 33 HCV-related HCCs) and matched 59 matched noncancerous livers, and 5 normal livers, by quantitative methylation analysis using MALDI-TOF mass spectrometry. Among analyzed genes, preferential methylation in HBV-related HCC was validated in 1 gene only. However, 15 genes were found methylated preferentially in HCV-related HCC, which was independent from age. Hierarchical clustering of HCC using these 15 genes stratified HCV-related HCC as a cluster of frequently methylated samples. The 15 genes included genes inhibitory to cancer-related signaling such as RAS/RAF/ERK and Wnt/b-catenin pathways. It was indicated that genes methylated preferentially in HCV-related HCC exist, and it was suggested that DNA methylation might play an important role in HCV-related HCC by silencing cancer-related pathway inhibitors. we analyzed aberrant promoter methylation in 6 HCC clinical samples (including 3 HBV-related HCCs and 3 HCV-related HCCs) and their matched noncancerous tissues on genome-wide scale by the method. Candidate regions of promoter methylation preferentially to HBV-related HCC and HCV-related HCC were selected, and the methylation levels of these genes were measured quantitatively using MALDI-TOF mass spectrometry. Expression levels of these 6 pairs of HCC and 4 more pairs of HCCs and surrounding noncancerous tissues were analyzed by expression array and are reported in this Series. <br><br>This experiment was reloaded in November 2010 after additional curation. this dataset is part of the TransQST collection.

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Gene expression profiling of hepatocarcinogenesis in a mouse model of chronic hepatitis B

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