E-cadherin expression in normal, hyperplastic and malignant oral epithelium.

E-cadherin is a calcium-dependent cell adhesion molecule which is important in cell-cell interactions in epithelium and plays a major role in maintaining the structure and integrity of epithelial sheets. The purpose of this study was to examine E-cadherin expression in normal and malignant oral epithelium. Ten specimens of normal oral epithelium, five specimens of hyperplastic epithelium and 15 squamous cell carcinomas were stained using a standard immunoperoxidase technique and a monoclonal antibody to E-cadherin. Normal and hyperplastic epithelium showed strong pericellular staining in the basal, suprabasal and prickle cell layers. The keratinising superficial layers were negative. E-cadherin expression did not correlate to the degree or pattern of keratinisation and was not altered in the hyperplastic epithelium. All cases of squamous cell carcinoma showed heterogenous staining with areas of loss or fragmentation of staining. No tumour was completely negative. The amount or pattern of loss showed no apparent correlation to the degree of tumour differentiation. These findings suggest that loss of E-cadherin is not essential for the acquisition of a malignant phenotype but may be important in the invasive process. This supports the view that E-cadherin may be the product of a tumour suppressor gene important in tumour progression.