THE EXPRESSION OF C-ERBB-2 PROTEIN IN THE KERATINOCYTES OF ORAL MUCOSAL LICHEN-PLANUS

The expression of the c-erbB-2 protein was studied in the keratinocyte s from patients with: (i) oral mucosal lichen planus (OLP) (n = 26); ( ii) oral mucosal squamous cell carcinoma (OMSCC) which had arisen in m ucosa affected by OLP (n = 5); and (iii) normal oral mucosa (n = 5). C -erbB-2 protein was expressed on the cell membranes of the keratinocyt es of nucleated epithelium in the stratum spinosum. The antigenic dete rminant recognized represents the cytoplasmic domain of a cell surface receptor which binds an as yet uncharacterized heparin binding ligand of unknown function.(1,2) The specimens from the five normal subjects showed positive immunohistochemical staining with the monoclonal c-er bB-2 protein antibody, the OMSCC specimens were negative, and 23 of 26 of the OLP specimens were positive. The lack of c-erbB-2 expression i n the three OLP and in the five OMSCC specimens may indicate a genetic alteration, or masking of the expression of c-erbB-2. The absence of expression in OLP specimens might be an indicator of the possibility o f future neoplastic transformation.