Expression of p16 and Human Papillomavirus Infection in Precancerous Lesions.

Objectives: Evaluate the expression of p16INK4A in precancerous lesions of oral cavity and its association with HPV.
Methods: Formalin-fixed paraffin-embedded (FFPE) tissue samples obtained from 25 patients with oral dysplasias from Bosque University Oral Pathology Diagnostic Service . All FFPE samples were cut in 5-μm-thick sections and evaluated by hematoxylin and eosin (H & E) staining and the clinical diagnosis of oral precancerous lesions was confirmed by WHO criteria. Using immunohistochemical analysis, we determined the expression of p16INK4a in histologic samples, the reaction was considered positive when a chestnut-brown color was seen in the nucleus and cytoplasm and considering the parameters set by Kostopoulou positivity in 2011. All positive p16 cases were selected and performed between 6 and 10 cuts by sample of 8 microns thick, , were used for DNA extraction according to kit protocol (HT illustra DNA Extraction Kit (GE Healthcare)) and HPV positivity were evaluated by real-time PCR using the consensus GP5+/GP6+ primers
Results: There was p16 positive expression in 18/25 (72%). Patch positivity 4/18 (22%) samples, and focal positivity in 14/18 (78%) samples was observed. Two samples of patch positivity and 1 focal positivity was excluded because of insufficient tissue for DNA extraction. HPV positivity was evaluated by real-time PCR in 15 samples. 7/15 (46.6%) samples was HPV (+) and 8/15 (53.3%) samples was HPV (-).
Conclusions: Precancerous lesions of oral cavity may be expressing increased of p16 protein, it indicates that the cell is constantly in proliferation. A considerable number of these samples are HPV positive.