Cell proliferation and apoptosis in keratocystic odontogenic tumors.

OBJECTIVES: Keratocystic odontogenic tumors (KOTs), also known as odontogenic keratocysts, were recently classified as a benign neoplasia due to the aggressive clinical behavior. Although several studies have shown the high proliferative activity of the epithelial lining, few studies have evaluated apoptosis in KOTs. Therefore, the aim of this study is to evaluate and compare the proliferation index (PI) and the apoptotic index (AI) of the epithelial lining in sporadic KOTs, KOTs associated with the Nevoid Basal Cell Carcinoma Syndrome (NBCCS KOTs), and dentigerous cysts. MATERIAL AND METHODS: A total of 11 sporadic KOTs, 15 NBCCS KOTs, and 11 dentigerous cysts were evaluated. The PI was assessed by immunohistochemical detection of the cell proliferation marker Ki-67. The AI was assessed by morphological evaluation of sections stained by methyl green-pyronin. The TUNEL assay was used to confirm the occurrence of apoptosis. Differences in the PI and the AI between sporadic KOTs, NBCCS KOTs, and dentigerous cysts were analyzed using the Kruskal-Wallis test. Differences in the PI and the AI between the epithelial layers of each lesion were analyzed using the Wilcoxon test. RESULTS: The PI and AI were higher in sporadic and NBCCS KOTs than in dentigerous cysts. No difference in these indexes was observed between sporadic and NBCCS KOTs. In dentigerous cysts, the PI was higher in the basal layer. In sporadic and NBCCS KOTs, the PI was higher in suprabasal layer. No difference in the AI was observed between the basal layer and the suprabasal layer in the three lesions. The AI was higher in the superficial layer of sporadic and NBCCS KOTs. CONCLUSIONS: The present study demonstrates that the epithelial lining of KOTs shows a distinct pattern of cell proliferation and apoptosis, reflecting its high cell turnover and reinforcing its classification as an odontogenic tumor.

Cell proliferation and apoptosis in ameloblastomas and keratocystic odontogenic tumors.

A high proliferative activity of the odontogenic epithelium in ameloblastoma (AM) and keratocystic odontogenic tumor (KOT) has been demonstrated. However, no previous study has simultaneously evaluated cell proliferation and apoptotic indexes in AM and KOT, comparing both lesions. The aim of this study was to assess and compare cell proliferation and apoptotic rates between these two tumors. Specimens of 11 solid AM and 11 sporadic KOT were evaluated. The proliferation index (PI) was assessed by immunohistochemical detection of Ki-67 and the apoptotic index (AI) by methyl green-pyronine and in situ DNA nick end-labelling methods. KOT presented a higher PI than AM (p<0.05). No statistically significant difference was found in the AI between AM and KOT. PI and AI were higher in the peripheral cells of AM and respectively in the suprabasal and superficial layers of KOT. In conclusion, KOT showed a higher cell proliferation than AM and the AI was similar between these tumors. These findings reinforce the classification of KOT as an odontogenic tumor and should contribute to its aggressive clinical behavior.

Cell proliferation and apoptosis in ameloblastomas and keratocystic odontogenic tumors

A high proliferative activity of the odontogenic epithelium in ameloblastoma (AM) and keratocystic odontogenic tumor (KOT) has been demonstrated. However, no previous study has simultaneously evaluated cell proliferation and apoptotic indexes in AM and KOT, comparing both lesions. The aim of this study was to assess and compare cell proliferation and apoptotic rates between these two tumors. Specimens of 11 solid AM and 11 sporadic KOT were evaluated. The proliferation index (PI) was assessed by immunohistochemical detection of Ki-67 and the apoptotic index (AI) by methyl green-pyronine and in situ DNA nick end-labelling methods. KOT presented a higher PI than AM (p<0.05). No statistically significant difference was found in the AI between AM and KOT. PI and AI were higher in the peripheral cells of AM and respectively in the suprabasal and superficial layers of KOT. In conclusion, KOT showed a higher cell proliferation than AM and the AI was similar between these tumors. These findings reinforce the classification of KOT as an odontogenic tumor and should contribute to its aggressive clinical behavior.

Uma elevada atividade proliferativa do epitélio odontogênico em ameloblastoma (AM) e tumor odontogênico ceratocístico (TOC) tem sido demonstrada. Entretanto, não há estudos prévios avaliando simultaneamente os índices de proliferação celular e apoptótico em AM e TOC, comparando ambas as lesões. O objetivo desse estudo foi avaliar e comparar os índices de proliferação celular e apoptótico entre esses dois tumores. Onze amostras deAM sólido e 11 amostras de TOC esporádico foram avaliadas. O índice de proliferação celular foi avaliado por meio da imunomarcação para o antígeno Ki-67 e o índice apoptótico pelas técnicas demetyl-green-pironina e TUNEL. O TOC apresentou um índice de proliferação celular maior que o AM (p<0,05). Nenhuma diferença estatística foi encontrada no índice apoptótico entre AM e TOC. Os índices de proliferação celular e apoptótico foram maiores nas células da camada periférica do AM e, respectivamente, nas camadas suprabasal e superficial do TOC. Em conclusão, o TOC apresentou proliferação celular maior que o AM e o índice apoptótico foi similar entre estes tumores. Estes achados reforçam a classificação do TOC como um tumor odontogênico e podem contribuir para o seu comportamento clínico agressivo.