Estudo da correlação das proteínas INGs com a P53 em lesões odontogênicas epiteliais benignas

Abstract

INGs (inhibitor of growth gene) proteins play a role of tumor suppressors and can act via p53-dependent or independent pathways in signaling cell cycle and apoptosis. The aim of this study is to evaluate correlation between expression of proteins of ING proteins and expression of protein p53 in dental follicles (DF), odontogenic keratocysts (OK), adenomatoid odontogenic tumors (AOT) and solid ameloblastomas (AMBs). The sample was intentional and non-probabilistic, consisting of 20 cases of solid AMBs, 20 cases of AOT, 20 cases of OKs and 10 samples of DFs. The specimens were subjected to immunohistochemical method, using antibodies anti-Ing3, anti-Ing4, anti-Ing5 and antip53. Quantitative analysis was performed taking into account cytoplasmic and / or nuclear location for ING proteins and nuclear location for the p53 protein. The analysis of ING1 and ING2 immunoexpressions was performed in a previous study and the results were considered only for the correlation analysis. Data were analyzed by Statistical Package for Social Sciences for Windows (SPSS version 22.0; IBM, USA). Kruskal Wallis test was used to compare the immunoexpression between the groups of lesions, and Spearman test was used to investigate correlations. Values of p ≤ 0.05 were considered significant. This study showed a reduction in nuclear and cytoplasmic expression of ING3, ING4 and ING5 in odontogenic keratocysts (OKs) and ameloblastomas (AMBs). In addition, in some cases, loss of INGs nuclear expression was negatively correlated with p53 expression. Correlation analyzes may indicate existence of compensatory mechanisms between all the ING proteins in dental follicles (FDs) and adenomatoid odontogenic tumors (TOAs). These mechanisms seem to be less evident in COs and AMBs. The results of this study showed a reduction in ING3 expression in AMBs (p = 0.003); a reduction in ING4 expression, in OKs (p = 0.02) and in AMBs (p = 0.001); and a reduction in ING5 nuclear expression, also in OK (p = 0.09) and in AMBs (p = 0.012). Positive correlations were found between p53 nuclear expression with ING1 cytoplasm / nucleus expression (r = 0.603; p = 0.05) in OKs, and with ING3 cytoplasm / nucleus expression (r = 0.475; p = 0.034) and also ING4 cytoplasm / nucleus expression (r = 0.448; p = 0.047) in AMBs. Finally, this study suggests that reduction in the expression of INGs proteins seems to be an event that occurred in etiopathogenesis of more aggressive odontogenic lesions. Futhermore, nuclear / cytoplasmic expression of INGs proteins is not related to increase in p53 expression in OKs and AMBs, which indicates that loss of expression of these proteins may results in functional changes independently of p53.