Project description:Alcohol is a major risk factor for hepatocellular carcinoma (HCC) although the mechanisms underlying the alcohol-related liver carcinogenesis are still poorly understood. Alcohol is known to increase hepatocarcinogenesis possibly by inducing aberrant DNA methylation through the reduced provision of methyl groups within the hepatic one-carbon metabolism. Whether the epigenetically-regulated pathways in alcohol-associated HCC can be reversible or modifiable by nutritional factors is unknown. The aim of the present study was to investigate the genome wide promoter DNA methylation profiles along with array-based, gene expression profiles in non-viral, alcohol-associated HCC. From eight HCC patients the methylation status and transcriptional levels of all annotated genes were compared by analyzing HCC tissue and the cancer-free surrounding liver tissue, following curative surgery. After merging both the DNA methylation and gene expression data, we identified 159 hypermethylated-repressed, 30 hypomethylated-induced, 49 hypermethylated-induced and 56 hypomethylated-repressed genes. A number of potentially novel candidate tumor-suppressor genes (FAM107A, IGFALS, MT1G, MT1H, RNF180) demonstrated promoter hypermethylation and transcriptional repression in alcohol-associated HCC. Notably, promoter DNA methylation appeared as the regulatory mechanism for the transcriptional repression of genes controlling the retinol metabolic pathway (ADH1A, ADH1B, ADH6, CYP3A43, CYP4A22, RDH16) and SHMT1, a key gene within one-carbon metabolism. A genome-wide DNA methylation approach linked up with array-based gene expression profiles allowed identifying a number of novel, epigenetically-regulated candidate tumor-suppressor genes in alcohol-associated hepatocarcinogenesis. Retinol metabolism genes and SHMT1 are also epigenetically-regulated through promoter DNA methylation in alcohol-associated hepatocarcinogenesis. 16 samples (8 control samples from non-neoplastic liver tissue, 8 test samples from hepatocellular carcinoma) from 8 patients affected from hepatocellular carcinoma were analyzed.

Project description:Introduction: Hepatocellular carcinoma (HCC) is one of the most aggressive solid tumors and oncogenic pathways (e.g Akt, IGF signaling) are often activated in high proliferating HCC. Among several genetic alterations, epigenetic changes seem to be involved in the development and progression of HCC. DNA hypermethylation of promoter regions is almost always associated with transcriptional silencing and can lead to inactivation of tumor suppressor genes (TSG) in cancer cells. Aim: (1) To identify genes differently methylated in a subclass of HCC associated with proliferation and, (2) To correlate methylation changes with activation of molecular pathways. Methods: gDNA of 20 HCC, 8 cirrhotic and 8 normal liver samples was extracted and the methylation status was detected by the Illumina HumanMethylation27 BeadChip and immunohistochemistry of p-AKT, pIGF IR, p-S6 was analyzed. Results: Unsupervised clustering clearly classified normal livers, cirrhosis and HCC in 3 different groups. 961 genes were significantly hypermethylated in HCC compared to cirrhotic and 3942 genes showed hypermethylation in cirrhotic compared to normal liver tissue. 163 genes showed stepwise significant hypermethylation from normal to cirrhotic to HCC, including well described (p16, SOCS2, SFRP5, RBP1) and potential (SRD5A2, PCDH8, IGF-1R, UCHL1) TSGs, and the miR-10a. 133 genes were specifically hypermethylated in HCC. Among them the transcription factors GATA2, DLX1, and KLF14, all significantly inversely correlated to gene expression (p=0.003, p=0.03, and p=0.007, respectively). The methylation status of SOCS2 (p=0.025) and DLX1 (p=0.025) was significantly correlated to phosphorylation of IGFR1. Samples with RBP1 hypermethylation showed significantly higher AFP serum levels (p=0.018). Conclusion: Whole genome methylation analysis markedly classifies normal, cirrhotic and HCC samples. 8 TSGs play a key role in this stepwise progression of hypermethylation in the development of HCC and could be a promising point of action in anticancer therapy. Genomic DNA extracted from fresh frozen tissue specimens and cell lines was hybridized to genome-wide mthylation beadarray after bisulphite treatment. Keywords: DNA methylation, hepatocellular carcinoma, tissue, cell line

Project description:DNA methylation is critical for development and is strongly associated with gene regulation. Variation in the DNA methylome between closely related species may reveal unique functional adaptation. We have implemented a novel inter-primate DNA methylation genome-wide analysis between human, chimpanzee and rhesus macaque to identify human species-specific Differentially Methylated Regions (human s-DMRs) in orthologous loci. We analysed the peripheral blood cell DNA methylomes of these primates and identified 22,758 hypomethylated and 15,858 hypermethylated human s-DMRs. These s-DMRs are globally enriched within weak promoter, enhancer and transcribed regions via comparison with ChromHMM segmentation. Human s-DMRs, (both hypo- and hypermethylated) are found to be more prevalent in CpG Island shores than within the islands themselves (?2 P = 1.80 x 10-32). Examining human-specific Transcription Factor Binding Site motif change within CpG islands, we show gain and loss, in hypomethylated and hypermethylated s-DMRs, respectively, of CTCF motifs. Epigenetically the most divergent human-specific locus was the immunological Leukotriene B4 receptor (LTB4R, aka BLT1 receptor), due to collocating hypomethylated s-DMRs within the promoter CpG island and shore, as well as inverse increased gene body methylation. This gene is vital in host immune responses and associated with the pathogenesis of a wide range of human inflammatory diseases. This finding was supported by additional neutrophil-only DNA methylome and lymphoblastoid H3K4me3 chromatin comparative data. Functional investigation of the consequences of these epigenetic differences identified this receptor to have increased expression, and have a higher response to the LTB4 ligand in human versus rhesus macaque peripheral blood mononuclear cells. This result further emphasises the exclusive nature of the human immunological system, its divergent adaptation even from closely related primates, and the power of comparative epigenomics to identify and understand human uniqueness. DNA methylome analysis of pooled Human, Chimpanzee and Macaque

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DNA methylation profiles in alcohol-associated hepatocellular carcinoma

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