Expression of p53 protein in oral submucous fibrosis, oral epithelial hyperkeratosis, and oral epithelial dysplasia

Background and purpose: In our previous study, positive p53 staining was ob served in 47 of 81 (58%) cases of oral squamous cell carcinoma associated w ith areca quid (AQ) chewing and cigarette smoking. This study looked for ex pression of p53 protein in premalignant oral lesions in patients who chewed AQ or smoked cigarettes, or both. Methods: Expression of p53 protein was examined in histologic sections of o ral submucous fibrosis (OSF, n = 50), epithelial hyperkeratosis (EH, n = 10 ), epithelial dysplasia (ED, n = 10), and normal oral mucose (NOM, n = 10) with antibodies against p53 protein using an immunoperoxidase technique. Results: Positive p53 staining was observed in 30 (60%) OSF specimens. four (40%) EH specimens, seven (70%) ED specimens, and none of the NOM specimen s. Only four (8%) of the OSF specimens and none of the EH specimens had mor e than 25% p53-positive keratinocytes. However, in four (40%) of the ED spe cimens, more than 50% of the keratinocytes were p53-positive. The degree of p53 staining increased with the morphologic transformation of normal-appea ring epithelial cells into dysplastic epithelial cells. There was no signif icant correlation between expression of p53 in OSF epithelium and the clini cohistologic parameters of patients with OSF. Conclusions: These results demonstrate that p53 is often present in precanc erous lesions of patients who chew AQ and smoke cigarettes. We suggest that p53 may play a role in dysplastic cell transformation in premalignant oral lesions.