Fig. 2

PTGS pathway DNA methylation profiling in colorectal cancer. a Dissociation curve analysis of CRC patients and cell lines. A total of 64 patients (tumor and adjacent mucosae pairs) and five cell lines were analyzed with this method. Cell lines were compared to an unmethylated normal tissue. b DNA methylation beta values quantified with InfiniumMethylation450K arrays for a cohort of 98 CRC patients (both tumor and adjacent mucosae) and 50 matched healthy donors. Unlike gene expression, adjacent normal tissue of CRC patients displays normal methylation profiles compared with the mucosae from healthy donors, while tumors show a large number of abnormalities. c Unsupervised clustering analysis of the DNA methylation levels of 254 CRC tumors from in the Cancer Genome Atlas (TCGA). AKR1B1, PTGIS, and PTGER3 were the genes exhibiting the highest rates of hypermethylation in CRC. d DNA methylation analysis by dissociation curve and InfiniumMethylation450K array (Colonomics study and TCGA) provide similar results. White to red color scale represents the minimum and maximum percentage of hypermethylated tumors, respectively. Methylation status of the PTGS pathway genes in a panel of six colorectal cancer cell lines is represented. Genes frequently methylated in CRC tumors are also methylated in the analyzed cell lines. Red represents methylation in >75 % of the CpG sites. e Proportion of tumors with DNA methylation of the PTGS pathway genes in different cancer types. Data were obtained from TCGA