title: Ameloblastic carcinoma ex ameloblastoma: report of a case-possible involvement of CpG island hypermethylation of the p16 gene in malignant transformation.
abstract: Ameloblastic carcinoma is described in the updated World Health Organization (WHO) classification as a rare malignant lesion. Ameloblastic carcinoma meeting the WHO criteria may arise either as a result of malignant change in a pre-existing benign ameloblastoma (carcinoma ex ameloblastoma) or as a primary malignant ameloblastoma not preceded by an ordinary ameloblastoma (de novo carcinoma). We report a case of ameloblastic carcinoma ex ameloblastoma and examine how this case underwent malignant transformation. The DNA was extracted separately from benign and malignant areas in paraffin sections of the tumor. Direct sequencing showed no genetic mutation of exons 5-8 of the p53 gene. Hypermethylation of CpG islands of the p16 gene was detected in the malignant parts of the tumor. The results indicate that hypermethylation of p16 may have been involved in the malignant transformation of the ameloblastoma in the present case.
authors.affiliation: Department of Dental Science, Institute of Personalized Medical Science, Health Sciences University of Hokkaido, Sapporo City, Japan. yoshi-ab@hoku-iryo-u.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Abiko
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nagayasu
authors.forename: Maiko
authors.initials: M
authors.lastname: Takeshima
authors.forename: Mami
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Michiko
authors.initials: M
authors.lastname: Nishimura
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kusano
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kitajo
authors.forename: Masato
authors.initials: M
authors.lastname: Saitoh
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Kawakami
authors.forename: Itsuo
authors.initials: I
authors.lastname: Chiba
authors.forename: Tohru
authors.initials: T
authors.lastname: Kaku
mesh_terms: D000368:Aged; D000564:Ameloblastoma / Q000235:genetics* / Q000473:pathology; D015820:Cadherins / Q000032:analysis; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins / Q000032:analysis; D019942:Genes, p16; D016158:Genes, p53; D006801:Humans; D008297:Male; D008339:Mandibular Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: D015820:Cadherins; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C478985:PDRG1 protein, human