DNA methylation detection using MS-qFRET, a quantum dot-based nanoassay.

Detection of aberrant promoter hypermethylation of tumor suppressor genes can be used as a prognostic or predictive marker for carcinogenesis. Since epigenetic modifying agents are FDA approved for treatment of patients with myelodysplastic syndrome, laboratory correlative tools to monitor response to this targeted therapy are important. Methylation specific quantum dot fluorescence resonance energy transfer (MS-qFRET) is a nanotechnology assay that enables the detection of methylation and its changes in a sensitive, quantifiable manner. It utilizes quantum dot-mediated fluorescence resonance energy transfer to achieve highly sensitive detection of DNA methylation. Template DNA is first treated with sodium bisulfite such that unmethylated cytosines are converted to uracil while methylated cytosines remain unconverted. Thereafter, the converted template is amplified using biotinylated methylation-specific primers. Quantum dots, functionalized with streptavidin, serve both as a scaffold to capture amplicons and as a donor for transferring energy to the Cy5 acceptor that is incorporated into the amplicons during PCR. Thus, the status of DNA methylation can be determined according to the level of FRET. In this report, MS-qFRET is validated in cell lines and then used to detect the status of p15(INK4B) methylation in clinical samples from eight patients with acute myeloid leukemia.