IMMUNOHISTOCHEMICAL EVALUATION OF THE CA2-BINDING S-100 PROTEINS S-100A1, S-100A2, S-100A4, S-100A6 AND S-100B IN SALIVARY-GLAND TUMORS()

The Ca2+-binding S-100 proteins are involved in the regulation of a nu mber of cellular processes and an altered expression has been reported in several neoplastic tissues. Tissue specimens of normal salivary gl ands (n=23), pleomorphic adenomas (n=60), basal cell adenomas (n=6), c analicular ademomas (n=2), myoepitheliomas (n=2), adenoid cystic carci nomas (n=26) and adenocarcinomas NOS (n=11) were evaluated for the exp ression of S-100A1, S-100A2, A-100A4, S-100A6 and S-100B by using high ly specific polyclonal and monoclonal antibodies generated against the recombinant human protein. In normal salivary glands, the ductal cell s showed mild to intense immunoreactivity for S-100A1, S-100A2, S-100A 4 and S-100A6, while S-100B was observed in nerve fibers in the connec tive tissue. The normal myoepithelial cells were unreactive. In pleomo rphic adenoma, the luminal tumor cells of the duct-like structures sho wed moderate to intense immunoreactivity for S-100A2, while reactivity for S-100A1, S-100A4 and S-100A6 was relatively weak. The non-luminal cells, also termed neoplastic myoepithelial cells, showed immunoreact ivity for S-100B, while tumor cells in the solid, myxoid and chondroid areas were immunoreactive for S-100A1, S-100A4, S-100A6 and S-100B. T he non-luminally located tumor cells in basal cell adenomas and canali cular adenomas, and numerous tumor cells in clusters in myoepithelioma s were intensely reactive for S-100A2. In adenoid cystic carcinomas an d in adenocarcinomas not otherwise specified, the luminal cells formin g the tubular or cribriform structures were markedly positive for S-10 0A2 and/or S-100A6. Squamous metaplastic cells in salivary tumors show ed intense immunoreactivity for S-100A2. The results of the present st udy suggest that the majority of the tumor cells in salivary neoplasms , despite the most heterogeneous tumor cell differentiation, express S -100 proteins more heterogeneously than the normal glandular ducts. Th e salivary ducts in normal glands, the luminal tumor cells and squamou s metaplastic cells in the neoplastic lesions were intensely immunorea ctive for S-100A2 as compared to S-100A1, S-100A4 or S-100A6. In contr ast, the non-luminal tumor cells showed a rather heterogeneous express ion of the S-100 proteins.