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Updated: Jun 30, 2026
08:38
Targeted DNA Methylation Analysis by Next-generation Sequencing
Published on: February 24, 2015
CpG methylation is maintained in human cancer cells lacking DNMT1.
1The Johns Hopkins Oncology Center, and Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
Nature
|May 9, 2000
Summary
DNA methyltransferase 1 (DNMT1) is not solely responsible for genomic methylation in human cancer cells. Other enzymes maintain methylation, indicating DNMT1 has regional specificity.
Area of Science:
- Molecular Biology
- Cancer Research
- Epigenetics
Background:
- Aberrant DNA methylation, particularly hypermethylation, is a hallmark of cancer, often leading to the silencing of tumor suppressor genes.
- The precise mechanisms driving this abnormal methylation are not fully understood, with DNA methyltransferase 1 (DNMT1) being the presumed primary enzyme responsible for genomic methylation.
Purpose of the Study:
- To investigate the role of DNMT1 in maintaining global genomic methylation and specific gene methylation in human colorectal carcinoma cells.
- To determine if DNMT1 is the sole enzyme responsible for aberrant methylation in cancer.
Main Methods:
- Disruption of the DNMT1 gene in human colorectal carcinoma cells using homologous recombination.
- Measurement of cellular DNA methyltransferase activity.
- Analysis of overall genomic methylation levels.
- Assessment of methylation status at specific loci, including juxtacentromeric satellites and the p16INK4a tumor suppressor gene.
Main Results:
- Cells lacking DNMT1 showed significantly reduced cellular DNA methyltransferase activity.
- Overall genomic methylation decreased by only 20% in DNMT1-deficient cells.
- Juxtacentromeric satellite regions were significantly demethylated, but most analyzed loci, including p16INK4a, remained fully methylated and silenced.
- These findings suggest the presence of alternative methylating activities in human cells.
Conclusions:
- DNMT1 exhibits unexpected regional specificity in its methylation activity within human cells.
- Enzymes other than DNMT1 play a crucial role in maintaining the methylation status of the majority of the human genome, even in the context of cancer.
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