Significant association of promoter hypomethylation with colorectal cancer.

Colorectal cancer (CRC) is one of the most common and serious types of malignancy worldwide. The embryonic ectoderm development (EED) gene is important to maintain transcriptional repressive states of genes over successive cell generations. The present study aimed to investigate the association between methylation and CRC. A total of 111 CRC tissue samples, 111 paired para-tumor tissues and 20 colorectal normal tissues were obtained for methylation assay, which was performed using a quantitative methylation-specific polymerase chain reaction. The percentage of methylated reference was calculated to represent the DNA methylation level. A dual-luciferase reporter gene assay was used to detect the gene promoter activity of a fragment. The current results revealed a significant difference in the methylation levels among tumor, para-tumor and normal colorectal tissues (tumor vs. para-tumor vs. normal, 5.03±4.61 vs. 8.65±11.50 vs. 40.12±45.31; F=45.014; P<0.0001). The dual-luciferase reporter gene assay demonstrated that the transcriptional activity of recombinant pGL3- plasmid was significantly higher compared with that of the pGL3-Basic control vector (fold-change, 3.15; P=0.014), which suggests the fragment can promote gene expression. In conclusion, the present study demonstrated that hypomethylation may be an important factor associated with CRC.