Methylation frequencies of cell-cycle associated genes in epithelial odontogenic tumours.

OBJECTIVE: The benign epithelial odontogenic tumours constitute a group of lesions derived from epithelial elements of the tooth-forming apparatus. This group includes lesions of different biological behaviour, such as ameloblastoma, calcifying cystic odontogenic tumour (CCOT) and adenomatoid odontogenic tumour (AOT). The pathogenesis of these neoplasms remains uncertain and the occurrence of methylation in cell-cycle related genes may be involved in their development. The aim of this study was to investigate the methylation status of P16, P21, P27, P53 and RB1 genes in epithelial odontogenic tumours.
DESIGN: Methylation-specific polymerase chain reaction (MSP) was used to evaluate the presence of methylation in 13 samples of ameloblastoma, six samples of CCOT, three samples of AOT and 14 samples of dental follicles, included as control.
RESULTS: Our results showed a distinct methylation profile in each group. In ameloblastoma, the highest methylated genes were P16 and P21, while in CCOT the P21 and RB1 genes were the most commonly methylated genes. Only the P16 and P21 genes were methylated in the AOT samples. In the dental follicle samples, P16, P27 and RB1 genes were commonly methylated. A high percentage of the odontogenic tumours analysed showed methylation of the P21 gene, in contrast to dental follicles.
CONCLUSIONS: Epithelial odontogenic tumours show a distinct methylation profile in cell-cycle associated genes. In addition to this, the current findings show that epigenetic alterations are common events in epithelial odontogenic tumours.