A novel method to quantify local CpG methylation density by regional methylation elongation assay on microarray.

Area of Science:

• Epigenetics
• Molecular Biology
• Cancer Genomics

Background:

• DNA methylation analysis is vital for clinical diagnostics and therapeutics.
• Current methods often analyze limited CpG sites, overlooking regional methylation density.
• Methylation density, rather than single CpG sites, is critical for gene silencing.

Purpose of the Study:

• To develop a novel, quantitative method for analyzing CpG methylation density.
• To overcome limitations of existing site-specific methylation analysis techniques.
• To assess the methylation density of key genes in colorectal cancer.

Main Methods:

• Developed a microarray-based hybridization technique incorporating Cy5-dCTP into Cy3-labeled DNA.
• Utilized Taq DNA Polymerase for quantitative analysis of methylation.
• Quantification achieved by measuring the Cy5/Cy3 signal ratio, proportional to methylation density.
• Introduced the regional methylation elongation assay on microarray (RMEAM).

Main Results:

• RMEAM enables precise quantification of regional methylation density.
• The method demonstrated high throughput potential.
• Applied RMEAM to determine methylation density in the promoter regions of MLH1, TERT, and MGMT in colorectal carcinoma patients.

Conclusions:

• RMEAM provides quantitative analysis of regional methylation density, representing all allelic methylation patterns.
• The technique is simple, rapid, specific, and high-throughput.
• This method is valuable for studying epigenetic alterations in diseases like cancer.