RESUMO
BACKGROUND: The aim of this study was to identify the expression of MCM3, Ki-67 and p27 in normal mucosa, leucoplakia and oral squamous cell carcinoma (OSCC) and determine whether altered expression could serve as a prognostic marker of a malignant progression of dysplastic lesions. METHODS: The samples were collected from 37 patients with oral leucoplakia (13 with mild dysplasia - MLD, 12 with moderate dysplasia - MD and 12 with severe dysplasia - SD). Eleven samples of mouth floor mucocele (M) and 50 floor mouth and tongue samples OSCC of untreated patients were included in this study. Immunohistochemical expression of MCM3, Ki-67 and p27 of all the groups was analysed. Kruskal-Wallis and Dunn's test were used to determine differences among groups, and a Pearson's correlation test was used to evaluate the correlation between the proteins. RESULTS: Ki-67 expression was higher in OSCC than M (P < 0.001) and MLD (P < 0.01) groups, and there was a lower expression in M compared with MD and SD (P < 0.05). Regarding p27, its expression was lower in OSCC compared with M, MD and SD. MCM3 expression was lower in M compared with SD and OSCC (P < 0.001), and MLD showed a lower expression when compared SD (P < 0.01) and OSCC (P < 0.001). Moreover, a better correlation was observed between the proteins MCM3 and p27 than between Ki-67 and p27 proteins when all lesions were examined together. CONCLUSIONS: This study showed that MCM3 could be a better marker than Ki-67 for evaluation of dysplastic oral lesions.