Dynamics of the gene expression profiles responsible for the carcinogenesis are not fully understood.

The current study was designed to determine the serial changes of gene expression profiles and genetic and epigenetic modifications responsible for hepatocarcinogenesis in the model of chronic immune-mediated hepatitis. METHODS: Three-month-old HBV transgenic mice were immunologically reconstituted with bone marrow cells and splenocytes from syngeneic nontransgenic donors. Liver tissues were obtained every find protocol three months until 18 months at which time all mice developed multiple liver tumors. Oxi-dative DNA damage and hepatocyte turnover were assessed immunohistochemically. Gene expression profiles were developed by extracting total RNA from the tissues and analyzing by microarray (44 K genes, Agilent). Genomic DNA was enriched for methylated fragments and the epigenetic changes were detected, and targeted gene exomes were captured and sequenced using next-generation sequencing technology (HiSeq 2000, Illumina). RESULTS: Oxidative DNA damage (8-OHdG and 4-HNE) and hepatocyte turnover (PCNA) were increased during the progression of chronic liver disease. In a gene expression profile analysis of liver samples, nine of

gene groups with different time courses were identified by K-means clustering (P < 0.01). Although the expression levels of one group with 119 genes (cluster #2) were not changed find more in inflamed tissue at early time points (< 3 months) and chronic SAHA HDAC phases (6 – 12 months), the levels were decreased in noncan-cerous tissues in the late phase (15 – 18 months) and further

reduced in liver tumors. Of the cluster #2 genes, the hyper-methylated sites were seen at CpG islands around the coding sequences and multiple non-synonymous mutations above 1% frequency were detected in Cyp26a1, Nr2f6 and Hsd3b7 genes, all of which were involved in the catalytic and binding activity of iron, DNA or steroid. CONCLUSIONS: Chronic immune-mediated hepatitis enhances oxidative DNA damage and hepatocellular turnover in which hypermethylation and non-synonymous mutations were induced in three genes with catalytic properties of a cluster down-regulated in the late phase of liver disease. The resulting molecules may be primarily involved in malignant transformation of hepatocytes in the process of tumor development. Disclosures: Shuichi Kaneko – Grant/Research Support: MDS, Co., Inc, Chugai Pharma., Co., Inc, Toray Co., Inc, Daiichi Sankyo., Co., Inc, Dainippon Sumitomo, Co., Inc, Ajinomoto Co., Inc, MDS, Co., Inc, Chugai Pharma., Co., Inc, Toray Co., Inc, Daiichi Sankyo., Co., Inc, Dainippon Sumitomo, Co., Inc, Ajinomoto Co.