Figure 5

The methylation status of the rRNA promoter in clinical prostate cancer relative to matched normal tissues. (a) The methylation status of each cytosine within each CpG dinucleotide spanning −158 to +29 bp of the human rRNA promoter in 20 human prostate cancers and matched normal tissues. The rRNA promoter region was amplified from bisulfite-treated genomic DNA and cloned. The 10–18 randomly selected clones from each sample were subjected to automated sequencing. (b) Quantitative analysis of methylation density at each CpG and all CpGs with respect to the +1 site of the rRNA promoter in individual tumors and matched normal prostate tissues is shown. The percentage of clones methylated and unmethylated at each position among clones is represented in this bar diagram. T and N denote prostate cancer and normal tissue, whereas Unmet and Met indicate unmethylated and methylated CpGs, respectively. The average percentage of methylation for all CpG sites at each CpG site, for prostate cancer (N=20; left-side bars) and matched normal tissues (N=20; right-side bars). Data are expressed as *P<0.05; ** P<0.01, measured by χ²-test.