Aberrant DNA methylation of ribosomal RNA genes in lung cancer

Aberrant epigenetic modification of rDNA has been reported in cancers. Here we analyzed DNA methylation of rRNA genes in lung cancer and correlated methylation levels with different chromatin states. In general, methylation of rDNA ranged from 10% to 30% at individual CpG sites in the promoter region. In primary lung cancers a significant increased rDNA methylation was observed at 19 analyzed CpGs (1.2-fold increase, p < 0.001). Moreover, we report an increased methylation of rDNA towards the 28S region of rRNA genes. Polymerase I- and CTCF-associated rDNA exhibited reduced methylation compared to global rDNA. I…