Dataset Information

Multiplexed methylation profiles of tumor suppressor genes and clinical outcome in oligodendroglial tumors.

ABSTRACT: Aberrant methylation has been associated with transcriptional inactivation of tumor-related genes in a wide spectrum of human neoplasms. The influence of DNA methylation in oligodendroglial tumors is not fully understood. Genomic DNA was isolated from 61 oligodendroglial tumors for analysis of methylation using methylation-specific multiplex ligation-dependent probe amplification assay (MS-MLPA). We correlated methylation status with clinicopathological findings and outcome. The genes found to be most frequently methylated in oligodendroglial tumors were RASSF1A (80.3%), CASP8 (70.5%), and CDKN2A (52.5%). Kaplan-Meier survival curve analysis demonstrated longer duration of progression-free survival in patients with 19q loss, aged less than 38 years, and with a proliferative index of less than 5%. Methylation of the ESR1 promoter is significantly associated with shorter duration of overall survival and progression-free survival, and that methylation of IGSF4 and RASSF1A is significantly associated with shorter duration of progression-free survival. However, none of the methylation status of ESR1, IGSF4, and RASSF1A was of prognostic value for survival in a multivariate Cox model. A number of novel and interesting epigenetic alterations were identified in this study. The findings highlight the importance of methylation profiles in oligodendroglial tumors and their possible involvement in tumorigenesis.

SUBMITTER: Kuo LT

PROVIDER: S-EPMC4971911 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Multiplexed methylation profiles of tumor suppressor genes and clinical outcome in oligodendroglial tumors.

Kuo Lu-Ting LT Lu Hsueh-Yi HY Lee Chien-Chang CC Tsai Jui-Chang JC Lai Hong-Shiee HS Tseng Ham-Min HM Kuo Meng-Fai MF Tu Yong-Kwang YK

Cancer medicine 20160701 8

Aberrant methylation has been associated with transcriptional inactivation of tumor-related genes in a wide spectrum of human neoplasms. The influence of DNA methylation in oligodendroglial tumors is not fully understood. Genomic DNA was isolated from 61 oligodendroglial tumors for analysis of methylation using methylation-specific multiplex ligation-dependent probe amplification assay (MS-MLPA). We correlated methylation status with clinicopathological findings and outcome. The genes found to b ...[more]

PMID: 27367901

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Project description:Purpose: The most clearly established genetic hallmark in oligodendroglial tumors (OTs) is the combined loss of 1p/19q, a molecular alteration characteristic of tumors responding to therapy. Markers of tumoral progression have not yet been studied. Experimental Design: Novel markers of tumoral progression in OTs were sought through gene expression profiling analysis. Results: Unsupervised hierarchical cluster analysis classified OTs into two main groups associated with tumoral grade, independent of histological subtype and 1p/19q status. Differential gene expression analysis between low- and high-grade OTs revealed that only cell cycle-related genes were significantly upregulated in high-grade OTs. Among the deregulated genes, NDRG2 downregulation was detected in high-grade OTs with combined loss of 1p/19q. Expression analysis revealed low transcript levels of NDRG2 relative to non-tumoral brain tissue in 45% (9/20) of high-grade OTs. Furthermore, the low transcript levels of NDRG2 were significantly associated with a worse clinical outcome in patients. Transcript levels of NDRG2 were associated with promoter hypermethylation, which was detected in 38.4% (10/26) of high-grade OTs. The treatment of glioma cell lines T98 and LN18 with demethylating agents increased the mRNA expression levels of NDRG2 relative to the control cell line. Additionally, cell proliferation was significantly reduced and cell cycle was arrested in G1 phase after treatment with demethylating agents. Conclusions: Taken together, our results suggest that NDRG2 is a candidate tumor suppressor gene in OTs whose inactivation could be involved in tumoral progression and worse patient survival. The microarray study involved 28 glioma samples including oligodendrogliomas and oligoastrocytomas WHO grade II and III. Six non-tumoral brain tissues were used as controls, two of which were purchased from Stratagene (La Jolla, CA) and Clontech (Mountain View, CA). RNAs from several cell lines (Universal Human RNA, Stratagene, La Jolla, CA) was used as a standard reference in all hybridizations

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

Multiplexed methylation profiles of tumor suppressor genes and clinical outcome in oligodendroglial tumors.

Publications

Multiplexed methylation profiles of tumor suppressor genes and clinical outcome in oligodendroglial tumors.

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