CpG Island Methylation Profile in Malignant Ameloblastoma

Objectives: Malignant ameloblastoma is a very rare tumor, in which the pattern of an ameloblastoma and cytological features of malignancy are shown by the primary jaw lesion and/or by any metastatic growth. The tumor often arises as a result of malignant changes in a pre-existing benign ameloblastoma. Hypermethylation of CpG island is associated with silencing of various tumor suppressor genes. The present study observed the CpG island methylation profile of the p15,p16,E-cadherin at both benign and malignant areas in the malignant ameloblastoma. . Methods: We used two cases of malignant ameloblastoma probably arising as a result of malignant changes in a benign ameloblastoma. Twenty cases of squamous cell carcinoma were also used. In order to observe the CpG island methylation profile,DNA was extracted from the paraffin sections. In the malignant ameloblastoma, DNA was extracted from benign and malignant parts, separately. The methylation profiles of the p15, p16, E-cadherin were assessed using CpG WIZTM amplification kits (Sreologicals Corp,GA). Results: Aberrant CpG island methylation of p16 was detected at malignant parts in the malignant ameloblastomas. The frequencies of hypermethylation of genes in squamous cell carcinoma were as follows: p15, 35%; p16,25%; E-cadherin,15%. Conclusions: The result indicates that the CpG island methylation of p16 may be associated with the malignant change in the ameloblastoma.