[The p16 methylation in oral leukoplakia and oral squamous cell carcinoma]

To investigate p16 gene methylation in normal mucosa, leukoplakia with hyperplasia and dysplasia and oral squamous cell carcinoma.

20 patients of leukoplakia with hyperplasia, 11 patients of leukoplakia with mild dysplasia, 10 patients of leukoplakia with moderate dysplasia, 9 patients of leukoplakia with severe dysplasia, 10 patients with OSCC in low grade, 12 patients with OSCC in moderate grade, 8 patients with OSCC in high grade, and 10 normal individuals were studied on p16 methylation.

Rates of p16 methylation were 0 for normal individuals, 5% for patients of leukoplakia with hyperplasia, 18% for patients of leukoplakia with mild dysplasia, 10% for patients of leukoplakia with moderate dysplasia, 22% for patients of leukoplakia with moderate dysplasia, and 50% for patients with OSCC in low grade, 42% for patients with OSCC in moderate grade, and 63% for patients with OSCC in high grade. Rates of p16 methylation increased with tissue malignance increase and correlated positively to the tissue malignance. The rate (82%) of p16 methylation in OSCC patients with lymph node metastasis was significantly high than that (32%) of OSCC patients without lymph nodes metastasis. The methylated rates of p16 correlated positively to the lacking rates of p16 protein.

It was first reported that p16 methylation occurred in every stage of leukoplakia cancerization and OSCC progression. p16 can be one of the important molecular biological markers for leukoplakia cancerization and OSCC progression. p16 methylation is recommended as an important marker for diagnosis of OSCC.