ABERRANT GLYCOSYLATION BASED ON THE NEO-EXPRESSION OF POLY-N-ACETYLLACTOSAMINE STRUCTURES IN SQUAMOUS-CELL CARCINOMAS OF THE HEAD AND NECK

An immuno- and lectin-histochemical study was performed to investigate the aberrant expression of blood group-related antigens and poly-N-ac etyllactosamine structures in squamous cell carcinomas of the maxillar y sinus, the larynx, the apipharynx, the hypopharynx, the oral cavity, the parotid gland and the tonsil from 52 patients using monoclonal an tibodies against A, B and H antigens, and six lectins, UEA-I, PNA, VVA -B-4, PWM, LEA and DSA. In addition, GSA-II staining following endo-be ta-galactosidase digestion procedure was also applied. A, B and H anti gens were expressed in most normal epithelial cells of head and neck o rgans, and depended on the patient blood type. However, in squamous ce ll carcinoma, A antigen was not detected in eight out of 25 individual s of blood groups A and AB, although B antigen was consistently expres sed in carcinoma cells from all the B and AB individuals. On the other hand, H antigen was expressed in carcinoma cells not only from all bl ood group O individuals, but from 32 out of 35 individuals of blood gr oups A, B and AB. T and Tn antigens, which are recognized by PNA and V VA-B-4, were strongly expressed in carcinoma cells from 40 and 42 out of 52 individuals respectively. Reactivity with GSA-II staining follow ing endo-beta-galactosidase digestion, which recognizes linear poly-N- acetyllactosamine structures, was found in a few malignant cells from 21 individuals. Staining with anti-A, -B and -H monoclonal antibodies and UEA-I lectin was diminished after endo-beta-galactosidase digestio n in some cases. Lectins specific for poly-N-acetyllactosamine, such a s PWM, LEA and DSA, exhibited reactivity in some malignant cells from 30, 22 and 32 out of 52 individuals respectively. These results sugges ted that the expression of the blood group-related antigens is suppres sed and immature carbohydrate chains, that is H, T and Tn antigens, ar e accumulated in squamous cell carcinomas of the head and neck. The re sults further suggested that poly-N-acetyllactosamine structures are s imultaneously synthesized along with the deletion of A antigen and the accumulation of precursors.