Related Experiment Video
Updated: Aug 13, 2026
Characterization of Functionally Associated miRNAs in Glioblastoma and their Engineering into Artificial Clusters for Gene Therapy
Published on: October 4, 2019
Clustering of hypermethylated genes in neuroblastoma
Max M van Noesel1, Saskia van Bezouw, P A Voûte
1Department of Human Genetics, Academic Medical Center, Amsterdam, The Netherlands. m.vannoesel@erasmusmc.nl
Abstract:
CpG-island hypermethylation of gene promoters is a frequent mechanism for gene inactivation in tumors. Many neuroblastomas have hypermethylation and down-regulation of CASP8, leading to resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We recently found hypermethylation of the four TRAIL receptors in 9 neuroblastoma cell lines. Here, we analyzed methylation of 34 genes in 22 neuroblastoma cell lines. Of the 29 newly analyzed genes, only FLIP at chromosome band 2q33 was methylated in 8/22 cell lines. The FLIP protein is a negative regulator of Caspase 8. FLIP maps adjacent to CASP8, and their methylation patterns showed a moderate correlation. Furthermore, co-methylation patterns were observed for the TRAIL receptor pairs DCR1 and DCR2 and between DR4 and DR5. All four receptors co-localize in chromosome band 8p21. The 6 genes methylated in neuroblastomas appeared to occur in pairs. The genes within each pair have a strong sequence homology and originated from gene duplication. We found no evidence for regional spreading of methylation, given that we did not observe de novo methylation in additional local CpG islands. However, the gene pairs showed a striking co-regulation at the mRNA expression level. Down-regulation of FLIP strongly corresponds with down-regulation of CASP8, and this was also found for DCR1 and DCR2. Only a subset of the down-regulated genes was methylated. This suggests a mechanism of co-regulated transcriptional silencing of the gene pairs, followed by a methylation event that is less penetrating. The methylation pattern therefore supports a model in which CpG islands are not randomly targeted by methylation in cancer. Specific transcriptional silencing probably marks genes that can become methylated.
Insights
CpG island hypermethylation inactivates genes in neuroblastomas. Gene pairs like FLIP/CASP8 and TRAIL receptors show co-methylation and co-regulation, suggesting targeted silencing in cancer.
Area of Science:
- Oncology
- Epigenetics
- Molecular Biology
Background:
- CpG-island hypermethylation frequently inactivates tumor suppressor genes.
- Neuroblastomas often exhibit CASP8 hypermethylation, conferring resistance to TRAIL-induced apoptosis.
- Previous studies identified hypermethylation of TRAIL receptors in neuroblastoma cell lines.
Purpose of the Study:
- To investigate the methylation patterns of 34 genes in 22 neuroblastoma cell lines.
- To identify novel methylated genes and analyze co-methylation patterns.
- To explore the relationship between gene methylation and mRNA expression in neuroblastomas.
Main Methods:
- Analysis of CpG-island methylation status for 34 genes across 22 neuroblastoma cell lines.
- Correlation analysis of methylation patterns between genes, particularly those located in proximity or with sequence homology.
- Assessment of mRNA expression levels for methylated genes to evaluate co-regulation.
Main Results:
- FLIP, a negative regulator of Caspase 8, was methylated in 8/22 cell lines.
- Co-methylation patterns were observed for TRAIL receptor pairs (DCR1/DCR2 and DR4/DR5).
- Methylated genes occurred in pairs with sequence homology, suggesting origins from gene duplication. Co-regulation of mRNA expression was observed for these gene pairs, with methylation occurring in a subset of down-regulated genes.
Conclusions:
- CpG-island methylation in neuroblastomas is not random but targets specific gene pairs.
- Co-regulated transcriptional silencing likely precedes methylation, marking genes for inactivation.
- This methylation pattern supports a model of targeted gene silencing in cancer development.
