Hypermethylation of MGMT and DAPK gene promoters is associated with tumorigenesis and metastasis in oral squamous cell carcinoma

Background/purpose quamous cell carcinoma (OSCC) is the fourth major cause of mortality among males in Asia. The tumorigenesis of OSCC is a multi-step process characterized by sequential morphological changes. The extent of lymph node metastasis is a major determinant in the prognosis of cancer. Hypermethylation is an important pathway for repression of gene transcription in cancer cells and a promising marker for cancer detection. It is also found in early metastatic cancer patients. als and methods four histologically confirmed OSCC tissues and corresponding nontumorous tissues were enrolled in this study. DNA was extracted. The promoter methylation status of the p16, death-associated protein kinase (DAPK), MGMT, and glutathione S-transferase genes in OSCC tissues was evaluated by a methylation-specific polymerase chain reaction analysis. s ncies of promoter hypermethylation of p16, DAPK, and MGMT in OSCC tissue were 67.2%, 45.3%, and 31.3%, respectively. No methylation was found in normal oral mucosa. Methylation rates of MGMT (50%) and DAPK (55.6%) in metastasized OSCC were higher than those of MGMT (23.9%) and DAPK (41.3%) in nonmetastasized OSCC. No glutathione S-transferase P methylation was found in any tissue samples. sions udy supports the hypothesis that hypermethylation of p16 gene promoters may indicate a high risk of oral cancer, and hypermethylation of the MGMT and DAPK genes may be a major indicator of early OSCC metastasis.