A genome-wide study of DNA methylation modified by epigallocatechin-3-gallate in the CAL-27 cell line.

In order to gain greater understanding of the mechanisms underlying the effect of epigallocatechin-3-gallate (EGCG) on DNA methylation and its chemopreventative action in oral squamous cell carcinoma (OSCC), a genome­wide methylation and mRNA expression screen was performed in the CAL­27 cell line with and without EGCG (100 µM) treatment. A total of 761 differentially methylated gene loci were identified following treatment with EGCG. Comparison of gene expression profiling in OSCC samples revealed 184 transcripts with a significant difference (P<0.05) and a fold change difference >2 compared with controls. Gene ontology analysis of differentially methylated loci and functional annotation of the differentially expressed genes indicated that the main pathways involved were metabolic, mitogen­activated protein kinase (MAPK), wnt, and cell cycle pathways. In conclusion, the present study indicates that EGCG can affect the methylation status and gene expression in the CAL­27 cell line. Additionally, the changes in several important signaling pathways may reveal the antitumor mechanism of EGCG.