Correlation between DNA methylation and expression status of miR-125b1 in breast cancer cell lines. A- Schematic representation of the locus of miR-125b1. Circles represent the CTCF binding sites, open circles represent the CpG island (CGI) present upstream of miR-125b1 and arrows represent the transcription start site. The regions amplified by PCR for the chromatin immunoprecipitation (ChIP) assay are represented in arrows and named by regions as RI to RIV. B- Assessment of DNA methylation status using MS-PCR of miRNAs in the breast cancer cell lines SK-BR-3, MDA-MB-231 and MCF7. As a control for the technique, we assessed the methylation state of DNA from non-tumorigenic epithelial cell line MCF 10A. DNA from lymphocytes was methylated in vitro by SssI methyltransferase, and used as a positive methylated DNA. M represents methylated, and U represents non-methylated. C- Determination of the DNA methylation status using sodium bisulfite and sequencing in breast cancer cell lines. Black boxes represent methylated CpGs, and white boxes represent non-methylated CpGs. D- Expression analysis of miR-125b1 in breast cancer cell lines compared with MCF 10A.P < 0.001 Student's t-test.
Soto-Reyes et al. BMC Cancer 2012 12:40 doi:10.1186/1471-2407-12-40