Alterations of p16INK4a tumour suppressor gene in mucoepidermoid carcinoma of the salivary glands

Mucoepidermoid carcinoma (MEC) is common in the salivary glands, but alterations of the p16INK4a tumour suppressor gene are largely unknown. The aim of this study was to analyse p16INK4a gene alterations in MEC, and evaluate their significance for carcinogenesis. Thirty-eight salivary glands with MEC and six normal salivary glands were studied for p16INK4a alterations. In the MEC-affected group, there were 23.7% (9/38) and 13.2% (5/38) cases of homozygous deletion, and 5.3% (2/38) and 2.6% (1/38) cases of point mutation in p16INK4a exon 1 and exon 2, respectively. Hypermethylation of the p16INK4a gene promoter was found in 13 cases (13/38, 34.2%). Alterations of the p16INK4a gene were not found in the normal salivary glands. These findings suggest that the main mechanisms of inactivation of the p16INK4a gene in MEC of the salivary glands are promoter hypermethylation and homozygous deletion.