Expression of CD44 variant exons by normal oral epithelia.

Altered expression of CD44H an CD44 splice variants is associated with metastasis in several malignancies but its analysis requires knowledge of the normal pattern of expression which is tissue specific. There are considerable regional variations in epithelial differentiation within the mouth, including differences in cell surface glycoproteins. The aim of this study was to determine whether there are regional variations in the expression of CD44 variants in oral epithelia. Frozen and formalin-fixed paraffin-embedded sections of lip vermilion border, buccal mucosa, dorsum and ventrum of tongue, floor of mouth, gingiva and hard palate were stained immunohistochemically for CD44H and the produce of variant exons v3, v4/5, v6 and v9. Paraffin sections were subjected to microwave antigen retrieval. All epithelia stained strongly for all variants in basal, suprabasal and prickle cells and cornified and surface layers and the basal surface of basal cells were negative. Patterns of staining were identical in frozen and formalin-fixed tissue. Despite the structural heterogeneity within oral epithelium, no regional variation was detected.