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A real-time PCR assay for DNA-methylation using methylation-specific blockers
Susan E Cottrell1, Jürgen Distler, Nancy S Goodman
1Epigenomics Inc, 1000 Seneca Street, Suite 300 Seattle, WA 98101, USA.
Nucleic Acids Research
|January 15, 2004
Summary
This study introduces HeavyMethyl, a novel real-time PCR assay for detecting cancer DNA methylation biomarkers in bodily fluids. The assay accurately identifies minute amounts of methylated DNA, crucial for early cancer diagnosis.
Area of Science:
- Molecular Biology
- Biochemistry
- Oncology
Background:
- DNA methylation biomarkers show promise for cancer diagnosis via circulating tumor DNA.
- Detection assays must identify low tumor DNA levels amidst normal DNA.
- Real-time PCR is a suitable platform for methylation detection.
Purpose of the Study:
- To develop and validate a real-time PCR assay (HeavyMethyl) for sensitive methylation detection.
- To assess the assay's ability to detect low concentrations of methylated DNA.
- To evaluate the clinical utility of HeavyMethyl for cancer diagnosis.
Main Methods:
- Developed HeavyMethyl assay utilizing methylation-specific oligonucleotide blockers and probes.
- Tested assay sensitivity using unmethylated and artificially methylated DNA.
- Analyzed methylation differences in DNA from colon cancer tissues and patient serum.
Main Results:
- HeavyMethyl assays achieved limits of detection as low as 30 pg (GSTP1) and 60 pg (Calcitonin) of methylated DNA.
- Neither assay amplified unmethylated DNA, demonstrating high specificity.
- Significant methylation differences were observed between normal colon tissue and adenocarcinomas; methylation was detected in serum DNA of colon cancer patients.
Conclusions:
- HeavyMethyl technology enables successful analysis of very low concentrations of methylated DNA.
- The assay is well-suited for detecting circulating tumor DNA in patient serum for cancer diagnosis.
- This technology holds potential for non-invasive cancer detection and monitoring.