IMMUNOHISTOCHEMICAL EVALUATION OF TRANSGLUTAMINASE-C IN TUMORS OF SALIVARY-GLANDS

Transglutaminase C (TGase C), a family of Ca2+-dependent enzymes and a n essential component in the cross-linking of peptide bonds, has been found to be a marker of epithelial differentiation with a possible rol e in cellular apoptosis, extracellular matrix stabilisation and Ca2+ b inding, thereby having a potential role in tumour growth, differentiat ion and invasive behaviour. The expression of TGase C was evaluated in normal human salivary glands and their neoplastic lesions which inclu ded pleomorphic adenoma (n = 30), Warthin's tumour (n = 5), adenoid cy stic carcinoma (n = 10), acinic cell carcinoma (n = 5), mucoepidermoid carcinoma (n = 5) and control tissue specimens of normal oral mucosa and squamous cell carcinoma, using polyclonal antibody, the specificit y of which was determined by Western blotting, generated by immunising rabbits with purified transglutaminase. The TGase C was observed in t he epithelial cells in the control tissue specimens examined. Pleiomor phic adenoma revealed reaction products in luminal tumour cells, the n on-luminal or modified myoepithelial cells and their plasmacytoid vari ants, squamous metaplastic cells and chondroid cells. Adenoid cystic c arcinomas had tumour cells in the luminal cells of tubular and cribrif orm structures and the acinic cell carcinoma had from low to moderate immunoreactivity in the tumour cell component and a diffuse immunoreac tivity in the stroma for TGase C. Mucoepidermoid carcinoma showed no r eaction products in the mucous-producing cells, while intermediate and epidermoid cells had immunoreactivity in the cell cytoplasm. As the p resence of TGase C in salivary gland tumours was confined to those tum our cells which form the predominant histomorphology in each tumour su btype, it may be suggested that these enzymes may have a potential rol e in the regulation of cellular function in neoplastic salivary tissue s affecting tumour growth, differentiation and neoplastic behaviour. C opyright (C) 1996 Elsevier Science Ltd