In order to grasp the role H3K27me3 marks in prostate cancer progression in 34 patients, we investigated H3K27me3 mark binding to determine whether it correlates with tumor progression. First, to examine the epigenetic signature of H3K27me3 in prostate cancer, we mapped the global promoter occupancy profile of H3K27me3 in prostate cancer compared to normal biopsies using ChIP-on-chip methods.