Análise da imunoexpressão da proteína aldeído desidrogenase 1 em lesões odontogênicas epiteliais benignas

Abstract

Odontogenic cysts and tumors are heterogeneous lesions that arise from remnants of odontogenesis. Among these, the dentigerous cyst (DC), the odontogenic keratocyst (OK), the ameloblastoma (AM), and the adenomatoid odontogenic tumor (AOT) are odontogenic lesions of epithelial origin that have different biological profiles and have been extensively investigated. Stem cells (SC) are the main source for the generation and maintenance of cell diversity and disturbances in their regulation can lead to the production of altered SC, the socalled tumor stem cells (TSC). Among the markers of TSC, the aldehyde dehydrogenase-1 protein (ALDH1) has been evaluated in several neoplasms and its high expression has been associated with diagnostic and prognostic information. The aim of this study was to analyze the presence, quantity and distribution of TSC in the tumor parenchyma, cystic capsule and stroma, through the immunohistochemical expression of ALDH1 in odontogenic cysts and tumors of epithelial origin. The sample consisted of 80 cases (20 DCs, 20 OKs, 20 AMs and 20 AOTs) and the immunoreactivity was evaluated through the percentage of positive cells and intensity of immunostaining, with scores from 0 to 3. The final score was determined by the formula ''immunoexpression score = intensity × percentage of cells '', being defined as low expression the scores from 0 to 4 and high expression the scores from 6 to 9, in cystic capsule and tumor parenchyma. The expression of ALDH1 was also analyzed in the stroma of the lesions, with scores 0 = negative and 1 = positive. The data were submitted to nonparametric tests, considering a level of significance of 5% (p<0.05). Immunoexpression of ALDH-1 exhibited nuclear and nucleo-cytoplasmic marking. When the lesions were compared regarding the medians of the obtained scores, the expression pattern and the intensity of immunoexpression of ALDH-1 in the epithelial component of the lesions, a significantly higher expression of ALDH-1 was observed in KOs compared to AMs (p < 0.0001) and AOTs (p <0.0001), and higher expression of ALDH-1 was observed in DCs compared to AMs (p <0.0001) and AOTs (p <0.0001). When evaluating stroma and cystic capsule, immunoreactivity was observed in all cases of odontogenic cysts studied and in 85% and 90% of AMs and AOTs, respectively. The expression of ALDH-1 in the odontogenic lesions studied suggests the presence of SCs in them, highlighting the odontogenic cysts for presenting higher epithelial expressions compared to odontogenic tumors.