Clinicopathological relevance of BRAF and SMO mutations in Chinese patients with ameloblastoma

Abstract

Ameloblastomas are benign tumors associated with recurrence and morbidity. Mutations in the V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) and smoothened (SMO) genes have been identified in ameloblastomas. The mutation rate of BRAF in different regions and mutation sites of SMO remains controversial. This study assesses the relationship between these mutations and clinicopathological features of ameloblastoma in Chinese patients. Ameloblastomas were surgically removed from 30 patients and BRAF gene polymorphisms were detected using DNA sequencing analysis. We also examined the relationship between BRAF or SMO mutations and clinicopathological parameters. BRAF V600E mutation was detected in 18 of 30 ameloblastomas. No significant correlation was found between BRAF V600E mutation and age, sex, location, histologic type, capsular invasion, or tumor recurrence. Five cases carried an SMO T364N mutation in exon 5, whereas six carried an SMO S590 T mutation in exon 10. The SMO mutation rate in patients aged ≤ 20 years was significantly higher than that in patients aged > 20 years. SMO T364N and S590 T mutations were closely related to age and capsular invasion. These findings indicate that BRAF V600E, SMO T364N, and SMO S590 T mutations play important roles in the pathogenesis of ameloblastoma. Key highlights The BRAF V600E mutation was highly prevalent in Chinese patients with ameloblastoma. SMO T364N and S590 T mutations are closely related to age and capsular invasion. The BRAF V600E, SMO T364N, and SMO S590 T mutations play important roles in the pathogenesis of ameloblastoma.