Loss of heterozygosity of the PTCH gene in ameloblastoma.

Ameloblastoma is a locally aggressive benign neoplasm derived from odontogenic epithelium, with high recurrence rates. Alterations in the Sonic Hedgehog signaling pathway, including PTCH gene mutations, have been associated with the pathogenesis of some odontogenic tumors. The purpose of the present study was to assess loss of heterozygosity at the PTCH locus in ameloblastoma. Twelve ameloblastomas were included, and loss of heterozygosity was assessed by using 3 microsatellite markers D9S252, D9S127, and D9S287 and 3 single-nucleotide polymorphisms rs112794371, rs111446700, and rs357564, all located at the PTCH gene locus. Furthermore, we investigated GLI1 and GLI2 transcription levels by quantitative reverse transcription polymerase chain reaction in 8 ameloblastomas and, concomitantly, PTCH protein levels by immunohistochemical analysis. Loss of heterozygosity at 9q21.33-9q.31 was detected in 4 (40.0%) of 10 informative cases of ameloblastoma. All 8 analyzed samples expressed GLI1 messenger RNA and 7 cases GLI2 messenger RNA. Interestingly, loss of heterozygosity at the PTCH locus was not correlated with GLI1 or GLI2 transcription levels, nor was there any correlation with PTCH protein expression. In conclusion, our findings suggest that loss of heterozygosity in the PTCH region may be relevant to the pathogenesis of ameloblastoma but may target a different gene than PTCH.