DISTRIBUTION OF P53 ONCOGENE PROTEINS IN ORAL MALIGNANT LESIONS

Abstract

Immunohi5tochemical determination ofoncogene proteins in human tumors is becoming increasingly important/or obtaining a better understanding ofprocess of tumorigenesis. TIlenuclear p53 protein has been detected in a variety ofturnors and has been implicated as a diagnostic marker for malignancy detection. In current study, the distribution of p53 was determined in paraffin-embedded sections obtainedfrom oral squamous cell carcinoma (SeC)
and oral malignant melanoma (llfM). Normal oral mucosa, hyperplastic/dysplastic oral lesions and benign pigmented lesions were included/or comparison. Expression ofp53 was detected by meum- ofimmunohistochemistry method using ami-p53 monoclonal antibody, which was specific to all known forms ofhuman p53. Results showed that only 1/15 normal oral mucosa had a few nuclear p53+ cells scattered in the basal cell layer in all section. Positive cells werenot found in an)' of the benign hyperplastic lesions but 8/11 dysplastic lesions had afew p53+ cells (approximately 5% to 10%)spreadin the dysplastic region ofthe sections. Nuclear p53 staining was found in 19/22 oral sec samples examined Numerous malignant cells (approximately 90% to 95%) were strongly positive for p53 oncogene, in these sections. In pigmentedlesions, p53+ cells werepresent in the majorityofbenignpigmented lesions. Each section had over 95% melanocytes stained positively for the antigen.
Malignant melanomasshowedstrong immunoreactivity in all the samples examined Approximately up to 90% to 95% of malignant melanocytes were p53 positive. It is concluded that expression of p53 oncogene WU5 more enhanced in dysplastic oral lesions than was expressed in benign and normal oralmucosa. TIle highestlevel ofp53 expression WU"found in oral sec sections. Accordingly, p53 expression corresponded to the aggressiveness of tumor cells in oral mucosal lesions. Secondly, p53 expression in malignant melanoma was not associated with increasing malignancy and provided inadequate indication of malignancy development in pigmented lesions. Finally, archives of paraffin embedded lesions provided useful sources for detection of specific tumor markers, in a variety of pathologicalconditions.