CHARACTERIZATION OF SUGAR RECEPTOR EXPRESSION BY NEOGLYCOPROTEINS IN ORAL AND OROPHARYNGEAL SQUAMOUS-CELL CARCINOMAS

Recognition of the carbohydrate part of cellular glycoconjugates by su gar receptors like lectins may contribute to biosignaling and interact ions between normal and transformed cells. Such recognitions may be es sential for establishing phenotypic characteristics in neoplastic cell s, including metastasis-associated properties. To evaluate various gly coconjugates in tumor diagnosis and clinical therapy, a panel of 18 bi otinylated neoglycoproteins was prepared. This included conjugates of a histochemically inert carrier protein and crucial sugar moieties suc h as D-glucuronic acid, alpha- and beta-N-acetyl-galactosamine, beta-N -acetyl-glucosamine, melibiose, lactose, maltose, cellobiose, mannose, mannose-6-phosphate, fucose, rhamnose, and xylose. In so doing the di azo derivative of the respective p-aminophenyl glycosides was coupled with galactose, beta-N-acetyl-galactosamine or beta-N-acetyl-glucosami ne via an epoxy group-containing aliphatic spacer. Other glycoconjugat es used were the proteoglycan heparin and the sulfated fucan fucoidan. Labeling was effected with cyanogen bromide activation and aminoalkyl ation for specific detection of endogenous sugar receptors, especially lectins. Tissues studied were paraformaldehyde-fixed, paraffin-embedd edd surgical biopsies from patients with different stages of squamous cell carcinomas (SCCs) of the oral cavity (n = 16) and oropharynx (n = 17), including three lymph node metastases from oropharyngeal primary tumors. Semiquantitative binding differences of probes to tumor stage s were evaluated statistically by the Mann-Whitney U-Wilcoxon rank sum W test. Specific binding of a probe to cytoplasmic and nuclear struct ures was detected with apparent quantitative differences. Overall, the cytoplasmic compartment revealed a higher intensity of histochemical reaction than did nuclear structures, indicating a comparatively highe r density of specific carbohydrate receptors. Significant and highly s ignificant two-tailed P values were noted for tissue types and stages of SCCs of the oropharynx but not the oral cavity.