Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Identification of Candidate Tumor Suppressor Genes Inactivated by Promoter Methylation in Melanoma

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

SUBMITTER: Derek Nancarrow

PROVIDER: E-GEOD-32492 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Identification of candidate tumor suppressor genes inactivated by promoter methylation in melanoma.

Bonazzi Vanessa F VF Irwin Darryl D Hayward Nicholas K NK

Genes, chromosomes & cancer 20090101 1

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 confirmat ...[more]

PMID: 18803327

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Project description:Purpose: Discovery of curative therapies for renal cell carcinoma (RCC) is hampered by lack of authentic preclinical models. Tumorgrafts, generated by direct implantation of patient-derived tissues into mice, have demonstrated superior ability to predict therapeutic response. We evaluated âtissue slice graftsâ (TSGs) as an improved tumorgraft model of RCC. Experimental Design: Cores of fresh RCC were precision-cut at 300-Î¼m and implanted under the renal capsule of RAG2-/-Î³C-/- mice. Engraftment rate, histology, biomarker expression, genetic fidelity and metastatic potential were evaluated. Magnetic resonance imaging (MRI) was tested as a non-invasive method to measure tumor volume, and response to a targeted therapy was determined. Results: All 13 cases of RCC engrafted and displayed characteristic histology and biomarkers. TSG volume quantified non-invasively by MRI highly correlated with graft weights, providing a unique tool for monitoring orthotopic growth. Moreover, in 2 cases, cancer cells from TSGs metastasized to clinically relevant sites, including bone. Microarray analysis and DNA sequencing demonstrated a high degree of correlation of global gene expression and VHL status between TSGs and parental tumors. Treatment of TSGs with sunitinib significantly decreased graft weight and mean vessel density compared to controls. Conclusions: The TSG model of RCC faithfully recapitulates tumor pathology, gene expression, genetic mutation and drug response. The high engraftment rate and metastatic potential of this authentic model, in conjunction with the ability to generate large first-generation animal cohorts and to quantitate tumor volume at the orthotopic site by MRI, proffer significant advantages compared to other preclinical platforms. Three pairs of tissue slice graftes and parent tumors were included in the study. Tissue slice grafts and parent tumors were preserved in Allprotect tissue reagent (Qiagen, Valencia, CA) at -20Â°C prior to RNA extraction using an AllPrep DNA/RNA/Protein Mini Kit (Qiagen, Valencia, CA). The quality of RNA was determined using an Agilent 2100 Bioanalyzer (Agilent Biotechnologies, Santa Clara, CA). Microarray hybridization was performed using Illumina Human HT-12 v4 Beadchips (Illumina Inc., San Diego, CA) according to the manufacturerâs directions. Expression data was rank invariant normalized using BeadStudio software (Illumina Inc.).

Dataset Information

Identification of Candidate Tumor Suppressor Genes Inactivated by Promoter Methylation in Melanoma

Publications

Identification of candidate tumor suppressor genes inactivated by promoter methylation in melanoma.

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