Genome-wide single base resolution profiling of 5-methylcytosine in human breast tissue

The underlying biological mechanisms through which epidemiologically defined breast cancer risk factors contribute to disease risk remain poorly understood. Here we investigated the impact cancer risk factors have on the normal breast epigenome by analyzing DNA methylation genome-wide (Infinium 450K array) in cancer-free women. We tested the relation of established breast cancer risk factors with DNA methylation adjusting for potential variation in cell-type proportions. Non-diseased breast tissue (n=18) DNA was subjected to bisulfite conversion with an input of 4ug per sample using the TrueMethyl® kit v.1.1 (Cambridge Epigenetix) protocol optimized for Illumina HumanMethylation450 arrays.