RESUMEN
Polymorphous adenocarcinoma (PAC) is a malignant epithelial neoplasm that affects almost exclusively the minor salivary glands, generally described as having a relatively good prognosis. Aberrant nuclear factor erythroid 2 (NF-E2)-related factor (Nrf2) activation in tumor cells has been associated with induction of antioxidant enzymes, such as peroxiredoxin I (Prx I) and increased matrix metalloproteinase (MMP) expression. In this context, the aim of the present study was to evaluate the expression of Nrf2 and correlate it with Prx I and MMP-2 secretion in PAC. Thirty-one cases of PAC from oral biopsies were selected and immunohistochemically analyzed for Nrf2 and Prx I. MMP-2 quantification was performed on primary cell cultures derived from PAC. Oral squamous cell carcinoma (OSCC) cell cultures were used as control. A high immunoexpression of Nrf2 was observed in both the cytoplasm and the nucleus of neoplastic cells from PAC. Nuclear staining for Nrf2 suggested its activation in the majority of the PAC cells, which was confirmed by the high expression of its target gene, Prx I. Quantification of MMP-2 secretion showed lower levels in PAC cell cultures when compared to OSCC cell cultures (p < 0.05). In conclusion, although Nrf2 overexpression has been frequently associated with high-grade malignancies, such relationship is not infallible and, in fact, the opposite may occur in low-grade tumors, such as PAC of minor salivary glands.
Asunto(s)
Adenocarcinoma/metabolismo , Metaloproteinasa 2 de la Matriz/biosíntesis , Factor 2 Relacionado con NF-E2/biosíntesis , Peroxirredoxinas/biosíntesis , Neoplasias de las Glándulas Salivales/metabolismo , Glándulas Salivales Menores/patología , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/análisis , Femenino , Humanos , Masculino , Metaloproteinasa 2 de la Matriz/análisis , Persona de Mediana Edad , Factor 2 Relacionado con NF-E2/análisis , Peroxirredoxinas/análisisRESUMEN
Sterilization by gamma radiation is a method often used for bone and extracted teeth banking. The bond strength of human dentin submitted to gamma rays has not been reported. Therefore, the aim of this study was to assess the effect of gamma radiation on dentin shear bond strength and morphology. The roots were removed from extracted human bicuspids and their crowns divided into two groups: an untreated control and crowns submitted to gamma radiation sterilization. The crowns were mounted in epoxy resin and the buccal enamel removed exposing the subjacent dentin. SBMPPlus adhesive system was applied to a 3-mm diameter area after 15 s of 35% phosphoric acid etching. The samples were mounted in composite resin cylinders and stored in distilled water at 37 degrees C for 24 h until the shear test. Dental fragments from both groups were prepared for SEM analysis. There was no statistically significant difference between the results of the shear test for the two groups according to the Tukey test (p > 0.05). Scanning electron micrographs also did not show alterations. These results indicate that gamma radiation neither affected the shear bond strength of SBMPPlus nor altered the dentin surface morphology.