The hypermethylation of the CDKN2A and CHFR promoter region is a key regulatory mechanism of CDKN2A and CHFR expression in esophageal squamous cell carcinoma

BACKGROUND: The aim of this study was to evaluate the correlation between CDKN2A and CHFR expression and the methylation status of the CpG island in the promoter region of esophageal squamous cell carcinoma (ESCC) cell lines, radioresistant ESCC cell lines and ESCC clinical tissue specimens. METHODS: To determine whether the methylation of CHFR and CDKN2A occurs in ESCC and enhanced in radioresistant ESCC cell lines, the DNA methylation of the following was analyzed by pyrosequencing and quantitative real-time polymerase chain reaction (PCR): (I) 28 ESCC tissues; (II) the ESCC cell lines KYSE-150 and KYSE-180; and (III) the radioresistant ESCC cell lines KYSE-150-radioresistance and KYSE-180-radioresistance. RESULTS: The methylation of CDKN2A and CHFR was found to be enhanced in the radioresistant ESCC cell lines KYSE-150-radioresistance and KYSE-180-radioresistance (P<0.05), and the expression of CDKN2A and CHFR was found to decrease correspondingly (P<0.05). The methylation of CDKN2A and CHFR was found to be higher in the ESCC tissue and paracarcinoma tissue than in the adjacent benign tissue. The overall survival rates for ESCC patients were significantly correlated with the levels of CDKN2A and CHFR expression (P<0.05). CONCLUSIONS: Our findings suggest that the hypermethylation of the CDKN2A and CHFR promoter region is a key regulatory mechanism of CDKN2A and CHFR expression in ESCC. Hypermethylated CDKN2A and CHFR are potential biomarkers for predicting the radioresistance of ESCC.