EPITHELIAL P53 GENE-EXPRESSION AND MUTATIONAL ANALYSIS, COMBINED WITHGROWTH FRACTION ASSESSMENT, IN ORAL LICHEN-PLANUS

The immunohistochemical detection of epithelial p53 protein expression in oral lichen planus (OLP) biopsies was supplemented with molecular analysis for mutations of the p53 gene using the polymerase chain reac tion - single stranded conformational polymorphism (PCR-SSCP) techniqu e, p53 protein expression, in the basal epithelial cell layer, as dete cted by the DO7 and 1801 antibodies, was significantly more frequent i n OLP compared with other oral keratoses and normal mucosa, as was the growth fraction, The 10 OLP biopsies that had the most frequent p53 s taining (plus a case of OLP found in continuity with a SCC) were scree ned by the PCR-SSCP technique. but no mutations were detected in the p 53 gene (exons 5-9). The p53 overexpression in the OLP samples may be a physiological response to the hyper-proliferative state. as revealed by the growth fraction determination. This may usefully serve to prot ect against mutagenesis, and so be a factor in the low incidence of ca rcinoma associated with OLP.