Unknown,Transcriptomics,Genomics,Proteomics

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Genome-wide DNA methylation profiles of human hepatocellular carcinoma

ABSTRACT: 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

ORGANISM(S): Homo sapiens

SUBMITTER: Yujin Hoshida

PROVIDER: E-GEOD-44970 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Genome-wide methylation analysis and epigenetic unmasking identify tumor suppressor genes in hepatocellular carcinoma.

Revill Kate K Wang Tim T Lachenmayer Anja A Kojima Kensuke K Harrington Andrew A Li Jinyu J Hoshida Yujin Y Llovet Josep M JM Powers Scott S

Gastroenterology 20130905 6

<h4>Background & aims</h4>Epigenetic silencing of tumor suppressor genes contributes to the pathogenesis of hepatocellular carcinoma (HCC). To identify clinically relevant tumor suppressor genes silenced by DNA methylation in HCC, we integrated DNA methylation data from human primary HCC samples with data on up-regulation of gene expression after epigenetic unmasking.<h4>Methods</h4>We performed genome-wide methylation analysis of 71 human HCC samples using the Illumina HumanBeadchip27K array; d ...[more]

PMID: 24012984

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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.

Project description:BACKGROUND & AIMS: In approximately 70% of patients with hepatocellular carcinoma (HCC) treated by resection or ablation, disease recurs within 5 years. Although gene expression signatures have been associated with outcome, there is no method to predict recurrence based on combined clinical, pathology, and genomic data (from tumor and cirrhotic tissue). We evaluated gene expression signatures associated with outcome in a large cohort of patients with early stage (Barcelona-Clinic Liver Cancer 0/A), single-nodule HCC and heterogeneity of signatures within tumor tissues. METHODS: We assessed 287 HCC patients undergoing resection and tested genome-wide expression platforms using tumor (n = 287) and adjacent nontumor, cirrhotic tissue (n = 226). We evaluated gene expression signatures with reported prognostic ability generated from tumor or cirrhotic tissue in 18 and 4 reports, respectively. In 15 additional patients, we profiled samples from the center and periphery of the tumor, to determine stability of signatures. Data analysis included Cox modeling and random survival forests to identify independent predictors of tumor recurrence. RESULTS: Gene expression signatures that were associated with aggressive HCC were clustered, as well as those associated with tumors of progenitor cell origin and those from nontumor, adjacent, cirrhotic tissues. On multivariate analysis, the tumor-associated signature G3-proliferation (hazard ratio [HR], 1.75; P = .003) and an adjacent poor-survival signature (HR, 1.74; P = .004) were independent predictors of HCC recurrence, along with satellites (HR, 1.66; P = .04). Samples from different sites in the same tumor nodule were reproducibly classified. CONCLUSIONS: We developed a composite prognostic model for HCC recurrence, based on gene expression patterns in tumor and adjacent tissues. These signatures predict early and overall recurrence in patients with HCC, and complement findings from clinical and pathology analyses. Center and peripheral portions of hepatocellular carcinoma tumors as well as surrounding non-tumor cirrhotic liver tissues were obtained from fresh frozen surgically resected tissues, and isolated total RNA samples were analyzed for genome-wide expression profiles.

Project description:Tumor suppressor genes (TSGs) are sometimes inactivated by transcriptional silencing through promoter hypermethylation. To identify novel methylated TSGs in melanoma, we carried out global mRNA expression proﬁling on a panel of 12 melanoma cell lines treated with a combination of 5-Aza-2-deoxycytidine (5AzadC) and an inhibitor of histone deacetylase, Trichostatin A. Reactivation of gene expression after drug treatment was assessed using Illumina whole-genome microarrays. After qRT-PCR conﬁrmation, we followed up 8 genes (AKAP12, ARHGEF16, ARHGAP27, ENC1, PPP1R3C, PPP1R14C, RARRES1, and TP53INP1) by quantitative DNA methylation analysis using mass spectrometry of base-speciﬁc cleaved ampliﬁcation products in panels of melanoma cell lines and fresh tumors. PPP1R3C, ENC1, RARRES1, and TP53INP1, showed reduced mRNA expression in 35–59% of the melanoma cell lines compared to melanocytes and which was correlated with a high proportion of promoter methylation (>40–60%). The same genes also showed extensive promoter methylation in 6–25% of the tumor samples, thus conﬁrming them as novel candidate TSGs in melanoma. We sought to identify melanoma TSGs silenced by promoter methylation by carrying out an array-based analysis in a well-annotated panel of 12 cell lines after combined treatment with 5AzadC and an inhibitor of histone deacetylase, Trichostatin A (TSA). Expression profiles were generated for each cell line before and after drug treatment using Illumina Sentrix Human-6 Expression version 2 BeadChips. Genes reactivated in all 12 cell lines were removed from further analysis since they are likely responding to drug treatment as part of the ‘‘cellular stress response,’’ or due to promoter demethylation of genes normally silenced in the melanocytic lineage. Genes were further ﬁltered to identify those with an average of >4-fold increased expression in at least four samples in the panel of 12 lines and >10-fold increase in at least one of the cell lines.

Dataset Information

Genome-wide DNA methylation profiles of human hepatocellular carcinoma

Publications

Genome-wide methylation analysis and epigenetic unmasking identify tumor suppressor genes in hepatocellular carcinoma.

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