Global DNA hypomethylation is associated with the development and poor prognosis of tongue squamous cell carcinoma.

Backgrounds Oral cancer is the 4th leading cause of cancer death for males and the top cancer in young adult males in Taiwan. Tongue squamous cell carcinoma (TSCC) is a common oral cancer and generally associated with poor prognosis. Global DNA hypomethylation at the 5 position of cytosine (5mC) is a well-known epigenetic feature of cancer. Therefore, the purpose of this study was to investigate the relationship of the global 5mC content with the tumorigenesis and prognosis of patients with TSCC. Methods The levels of global 5mC were evaluated by immunohistochemistry using tissue microarray slides of 248 surgically resected TSCC and 202 corresponding tumor adjacent normal (TAN) tissues. Results We found that the level of 5mC in TSCC (P 50 years, P = 0.013), with moderate or poor cell differentiation (P = 0.044), early stage of disease (I-II, P = 0.046), small tumor size (T1–T2, P = 0.005), without lymph node involvement (P = 0.041), and ever received postoperative radiotherapy (P = 0.009). Conclusions Global hypomethylation was an independent biomarker for the development and poor prognosis of TSCC.