Molecular pathogenesis of keratocystic odontogenic tumors developing in nevoid basal cell carcinoma syndrome

Objective. The aim of this study was to investigate the molecular pathogenesis of keratocystic odontogenic tumors (KCOTs) that developed in nevoid basal cell carcinoma syndrome (NBCCS) patients. Study design. We analyzed germline and somatic mutations of the PTCH1 and its related genes, SMO and SUFU in 10 KCOTs that developed in 8 unrelated NBCCS patients. Methylation status of the PTCH1 promoter was also investigated by bisulfite sequencing. Results. Somatic mutations of PTCH1 were detected in 3 KCOTs. Two out of 3 somatic mutations were either identified as a polymorphism or located on the same allele as the germline mutation. Neither abnormal methylation of the PTCH1 promoter, loss of PTCH1, nor somatic mutation of SMO or SUFU was detected in any of the samples. Conclusions. Our results suggest that the tumorigenesis of most KCOTs associated with NBCCS cannot be explained by the classical 2-hit theory.