Avaliação da expressão das proteínas p53, bcl-2 e antígeno de proliferação celular ki-67 em lesões hiperplásicas, cancerizáveis e carcinomas de células escamosas bucais

Abstract

Leukoplakia is the most common oral premalignancy; however, their clinical and pathological characteristics are not specific. The association of the clinical and morphologic parameters with the analysis of imunohistochemical markers expressed in the induction or inhibition of the cellular proliferation and apoptosis are being studied to elucidating the process of oral carcinogenesis. The aim of this work was to evaluate, immunohistochemically the expression of the p53, bcl-2 and ki-67 proteins in 20 paraffin embedded oral tissues of inflammatory fibrous hiperplasias, 20 of leukoplakias, being ten with epithelial dysplasia and 20 of oral squamous cells carcinoma. A descriptive analysis of the results obtained in HE and immunohistochemically was done and, with the aid of the program Image Pro Plus, a quantitative analysis of the demarcations. The data of the immunohistochemical studies were appraised estatistically. The results showed that the expression of the p53 protein (DO-7) was more common in the group of the leukoplakias, most in the suprabasal region and with focal distribution. The group of the carcinomas was more expressive for the antibodies anti-p53 (PAb-240) and anti-Ki-67, with prevalence of the demarcations in the outlying and central areas and with diffuse distribution. Larger immunopositivity for the bcl-2 protein was observed in the group of hyperplasias, with prevalence for the basal and parabasal region with focal distribution. The difference of the positive areas among the markers p53 (DO-7) and p53 (PAb-240) was significant in the leukoplakias and in the hyperplasias; however, there was no difference statistically significant observed in the carcinomas. The demarcation of the studied proteins was observed more commonly in the suprabasal region in the leukoplakias with epithelial dysplasia but it was also found in leukoplakias without epithelial dysplasia. Leukoplakias and carcinomas were similar statistically as for the relative areas of the markers p53 clones DO-7 and PAb-240 and Bcl-2. The expression detected in this study for these markers in all the lesions suggests that the loss of the regulation of apoptosis and the cellular proliferation occurs in an initial phase of the development of the premalignant lesions including those where it is not possible to detect any alteration morphologically. These data reinforce the importance of the immunomarkers study involved in oral carcinogenesis for evaluation of the prognostic of premalignant and malignant lesions and the indication of more efficient therapeutical and preventive procedures.