Integrin expression in normal, hyperplastic, dysplastic, and malignant oral epithelium

We have examined the distribution of a range of integrin subunits in normal and lesional oral mucosa. The α2, α3, α6, β1β, and β4 subunits were highly expressed in normal epithelium, and there was weaker, more variable expression of α5 and αv. Expression of all subunits was highest in the basal layer of normal epithelium, but extensive staining above the basal layer was also observed, particularly in the floor of the mouth and the lateral margin of the tongue. In dysplastic lesions and hyperplastic epithelium adjacent to ulcers, suprabasal staining was even more pronounced. Staining patterns in squamous cell carcinomas showed considerable variation, both within and between individual tumours: in some areas there was staining reminiscent of normal epithelium, but uniform staining throughout tumour islands, and patchy and variable cytoplasmic and pericellular staining were also seen. Thirteen out of 17 carcinomas showed some loss of integrin expression: six out of ten moderately well differentiated tumours and all the poorly differentiated tumours. Focal loss of a6 and β4 was most commonly observed, but loss of α2 and β3 also occurred. Since integrins regulate not only keratinocyte adhesion, but also the initiation of terminal differentiation, the changes in integrin expression that we have observed may have significance for the behaviour of individual tumours.