Methylation analysis of the ERα promoter by MSP in MDA-MB-231 cells.

<p>(A) A 2.5 kb genomic sequence of the ERα promoter, analyzed by the online program, <a href="http://www.urogene.org/methprimer" target="_blank">www.urogene.org/methprimer</a>, revealed the presence of a high GC percentage CpG islands (blue) between relative positions 2000 and 2500. Position 2000 indicates the transcription start site (TSS, arrow). A region of high CpG (red vertical bars) density was chosen for MSP analysis. This region includes 28 CpG dinucleotides. (B), Methylation analysis of the ERα promoter by MSP in breast cancer cell lines. Sensitivity of the utilized MSP primers was determined by a dilution series of methylated DNA with unmethylated DNA. At least 1% of methylated DNA (∼0.1 ng) can be detected with the ER MSP primers. In each set, M primer pairs anneal only to sequences that are methylated before bisulfite treatment, whereas the U primer pairs anneal only to sequences that are unmethylated.