Sensitive and label-free DNA methylation detection by ligation-mediated hyperbranched rolling circle amplification

Area of Science:

• Molecular Biology
• Epigenetics
• Biotechnology

Background:

• Accurate DNA methylation detection is crucial for epigenetic analysis and early cancer diagnosis.
• Existing methods often require complex procedures like restriction enzymes or PCR amplification.
• There is a need for sensitive, specific, and simpler DNA methylation detection techniques.

Purpose of the Study:

• To develop a novel, sensitive, and specific method for DNA methylation detection.
• To utilize thermostable ligation and hyperbranched rolling circle amplification (HRCA) for signal enhancement.
• To enable rapid epigenetic evaluation and early cancer diagnosis without complex pre-amplification steps.

Main Methods:

• Employing a methylation-specific linear padlock probe that circularizes only in the presence of methylated DNA after bisulfite treatment.
• Utilizing thermostable ligation for methylated DNA discrimination.
• Implementing hyperbranched rolling circle amplification (HRCA) for signal amplification, with detection via SYBR Green I and a standard fluorometer.

Main Results:

• The developed method demonstrates excellent specificity and high sensitivity, with a detection limit of 0.8 fM.
• It exhibits a wide detection range spanning 4 orders of magnitude.
• The assay can distinguish methylation levels as low as 0.01% in a mixture, outperforming most current DNA methylation assays.

Conclusions:

• The ligation-mediated HRCA method provides a robust platform for sensitive and specific DNA methylation detection.
• This technique simplifies the process by avoiding restriction enzymes, PCR, and fluorescent probes.
• The method shows potential for analyzing genomic DNA in cancer cells, aiding in early diagnosis and research.