Identification of DNA methylation changes in esophageal cancer before/after chemoradiation therapy using an MCA-microarray and bisulfate pyrosequencing

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Tumor and adjacent normal tissue biopsy specimens were obtained before/after treatment from 34 patients(124 samples) treated with a uniform CRT protocol. We analyzed genomewide DNA methylation of 12 non-treated test samples(T and matched ADJ : 6 each) by methylated CpG island amplification and microarray(MCAM) method, and selected candidate genes that were highly methylated in T compared to ADJ. CYP26C1 was selected by unsupervised hierarchical clustering after MCAM in test samples, and was also ranked in the top 5 of both molecular & cellular function networks as a drug metabolism category. CYP26C1 DNA methylation was significantly higher in T than ADJ in both test and validation samples. CYP26C1 has a CpG island in promoter area, which is highly methylated in T of ESCC patients.