Immunohistochemical analysis of the p53 tumor suppressor gene product in oral leukoplakia

Abstract

Squamous Cell Carcinoma (SCC) is the most frequent malignancy in the oral cavity. p53 protein has been reported to be expressed at high levels in malignant lesions, while the level in premalignant lesions has yet to be determined. In this study, oral leukoplakia and oral SCC were examined. Seventy-four incision or excision samples from 43 cases diagnosed as leukoplakia, and 41 samples from 37 SCC cases in the oral cavity, were obtained. All samples (formalin-fixed, paraffin embedded) were examined immunohistochemically for overexpression of p53 protein with monoclonal antibody BP 53-12. As the result, 1. Twenty-two out of 43 leukoplakia cases, and 29 out of 37 oral SCC cases, were positive for p53 protein. 2. p53 protein was overexpressed in premalignant lesions, especially in the cases with moderate and severe epithelial dysplasia. 3. There was a relation between p53 protein expression and pathological features of leukoplakia (epithelial dysplasia), statistically. 4. There was a relation between p53 protein expression and clinical features of leukoplakia, statistically. 5. Malignant transformation during clinical observation was seen in 11 cases. Nine out of 11 cases were positive for p53 even before malignant transformation. Since in cancer-development cases, p53 staining was detected even before malignant transformation of oral leukoplakia to squamous cell carcinoma, it is indicated that p53 accumulation occurred at a early stage of cancer-development. In conclusion, immunohistochemical analysis of p53 protein is suggested to be useful diagnostic procedure for oral leukoplakia, which may develop into oral SCC.