Clinical Assays: MethylScreen Technology
Orion scientists developed MethylScreen technology to meet the need for a clinical assay system to detect and quantify trace amounts of DNA methylation-based biomarkers in clinical samples. MethylScreen technology precisely identifies these biomarkers using a proprietary process that relies on restriction digestion and quantitative PCR, robust procedures routinely practiced in high-volume reference laboratories worldwide.
MethylScreen assays are capable of detecting trace amounts of tumor signal through the use of a combination of restriction enzymes selected to destroy normal copies of a locus, leaving intact disease-associated copies that are amplified and detected by quantitative PCR. A MethylScreen assay determines the concentration of a disease biomarker and quantifies the methylation density of the biomarker in a sample. MethylScreen technology demonstrates a high degree of sensitivity, sufficient to allow the detection of methylated biomarkers in accessible samples such as blood, urine, cell swabs, and biopsies.
MethylScreen technology combines the action of two classes of restriction enzymes - one class cuts methylated DNA and the other cuts unmethylated DNA - with the power of quantitative PCR, an accurate technique for quantifying intact gene fragments in a sample.
The results of two MethylScreen assays performed on tumor and normal specimens from both prostate and breast tissue are shown in step 4 above. The assays measure DNA methylation-based biomarkers for each cancer type. The unmethylated DNA (u) signal is very high compared to the methylated signal (m) in both normal samples (the green cycle threshold precedes the blue cycle threshold). However, in the tumors, a significant increase in methylation at each of the biomarkers is evident (the cycle threshold of the blue reaction precedes green reaction).