INTRODUCTION: The most frequent type of oral cancer is the squamous cell carcinoma, which corresponds to 95% of the cases(9).The oral squamous papilloma is a benign neoplasia, commonly associated with infections caused by the human papilloma virus(21). The analysis of medical literature shows changes in cell cycle regulatory genes (p27, p21WAF/Cip1 and p16INK4a), but does not define their roles in oral carcinogenesis. Objective: Characterize the immuno-histochemical expression of p27, p21WAF/Cip1 and p16INK4a in oral normal squamous epithelium, oral squamous papilloma and oral squamous cell carcinoma. METHODS: Immuno-histochemical evaluation of p27, p21WAF/Cip1 and p16INK4a in 32 samples of oral normal squamous epithelium, 30 of oral squamous papilloma and 34 of oral squamous cell carcinoma. RESULTS: 97.06% of the oral squamous cell carcinoma group, 33.33% of the squamous papilloma group and 18.75% of the control group showed focal immunopositivity for p27. 100% of both control and oral squamous cell carcinoma groups and 90% of the oral squamous papilloma group showed focal immunopositivity for p21WAF/Cip1. 100% of both control and oral squamous papilloma groups and 94% of the oral squamous cell carcinoma group showed focal immunopositivity for p16INK4a. CONCLUSIONS: The study revealed a statistically significant difference for p27 expression when comparing the control and oral squamous papilloma groups with the oral squamous cell carcinoma group. p21WAF/Cip1 did not prove to be useful to differentiate the groups. p16INK4a showed diffuse immunopositivity in a minority of the oral squamous cell carcinoma cases. The oral squamous papilloma group behaved similarly to the control group as to the three markers.
Squamous cell carcinoma; Squamous papilloma; Immunohistochemistry; Cyclin-dependent kinase inhibitor p27; Oncogene protein p21; Cyclin-dependent kinase inhibitor p16
