Hypomethylation of the ETS motif and promoter region of PARP1 in BRCA-mutated ovarian cancer. A, Location of PARP1 core promoter CpG sites. Genomic coordinates are shown, along with the primer-amplified fragments, GC percentage, location of individual CpG dinucleotides (dashes), CpG island (green bar), and the PARP1 RefSeq gene (exon 1 shown as a blue box and intron shown as an arrowed line). The arrow indicates the transcriptional direction. B, Changes of methylation patterns in the core promoter region of PARP1 (each group, n = 10). The circles correspond to CpG sites denoted by the black dashes in (A). Closed circles, methylation; open circles, unmethylation. Ten individual clones were sequenced for each sample. Red circles show a methylation of cytosine that located in a CpG within an ETS motif. C, Summary of the promoter DNA methylation pattern in ovarian cancer and normal tissues. The y-axis shows the mean methylation sites (each group n = 10). Red circles show a methylation of cytosine that located in a CpG within an ETS motif. D, Overall methylation percentage within the promoter region from ovarian cancer and normal tissues (each group n = 10). E, Correlation between the relative PARP1 mRNA levels and the total number of methylated sites for each sample. Open circles, ovarian cancer tissues. Closed circles, normal ovarian tissues (each group n = 10). * P < 0.05 ovarian cancer vs. normal tissues.