Alteration of DNA methylation status induced by epidermal growth factor in gastric cancer cell line, MKN-74

DNA methylation dynamics are an important key to understanding various biological events, particularly regulation of gene expressions. To test the hypothesis that epidermal growth factor (EGF) signaling may influence DNA methylation status in cancer cells, which will show several altered biological characters compared with those before EGF-stimulation, we evaluated DNA methylation status with/without EGF-stimulation. The specific alteration of biological character in the gastric cancer cell line, MKN-74, by EGF was demonstrated by DNA synthesis, apoptosis and morphology, revealing that high concentrations of EGF (10 nM) altered the morphology accompanying a moderate increase of cell growth with induction of apoptosis, while low concentrations of EGF (0.1 nM) induced a high increase of cell growth without either morphological change or apoptosis. Although DNA synthesis is almost the same between 0.1 nM of EGF (164%) and 10 nM of EGF (172%), 0.1 nM of EGF showed higher methyltransferase activity than 10 nM of EGF did with a significant difference. In addition, the studies for both the methyl-base uptake into DNA incorporated with DNA synthesis and the methyl-base accepting capacity in DNA showed that a high concentration of EGF (10 nM) induced the demethylated status of the DNA compared with that of 0.1 nM EGF. Thus, we demonstrated that DNA methylation status is affected by EGF-stimulation with alteration of cell biological character.