Lectin histochemistry of laryngeal squamous cell carcinomas

The Tissue Architecture of Oral Squamous Cell Carcinoma Visualized by Staining Patterns of Wheat Germ Agglutinin and Structural Proteins Using Confocal Microscopy

OBJECTIVES

Tissue architecture and cell morphology suffer profound alterations during oral cancer and are important markers for its progression and outcome. For precise visualization of tissue architecture in oral cancer, we used confocal microscopy to examine the staining pattern of wheat germ agglutinin, a lectin that binds membrane glycoproteins, and the staining patterns of structural proteins.

MATERIALS AND METHODS

Paraffin sections of oral squamous cell carcinoma were stained with fluorescently labeled wheat germ agglutinin and with antibodies against structural proteins, which were revealed by immunohistochemistry with tyramide signal amplification.

RESULTS

Membrane localization of wheat germ agglutinin was markedly decreased in the basal layers and in regions of tumor invasion, accompanied by cytoplasmic redistribution of E-cadherin, β-actin and syndecan-1. Wheat germ agglutinin staining clearly identified tumor clusters within the surrounding stroma, and tumor cells with elongated morphology.

CONCLUSIONS

Our results suggest that the wheat germ agglutinin staining pattern is indicative of the degree of cell cohesion in oral squamous cell carcinoma, which decreases in basal layers and invasive tumor clusters with more migratory morphologies. Wheat germ agglutinin staining in combination with confocal microscopy could constitute, therefore, a valuable tool for the study of tissue architecture in oral cancer.

Age-related alterations in the carbohydrate residue composition of the cell surface in the unexposed normal human epidermis

BACKGROUND

The results of the very few histochemical studies that have been performed so far on the lectin-binding profile of normal human epidermis are mostly controversial; thus, the carbohydrate residue composition of the cell surface in the latter still remains in dispute and the possible alterations in the epidermal lectin-binding profile are unknown.

OBJECTIVE

To investigate the influence of age on the carbohydrate residue composition of the cell surface in unexposed normal human epidermis by means of lectin histochemistry.

METHODS

Biopsy specimens obtained from the sun-protected (unexposed) buttock skin, divided into 5 age groups of 18 subjects each, were fixed in buffered formalin (10%) and embedded in paraffin. 4-mum sections were processed for histochemistry using a panel of six biotinylated lectins.

RESULTS

In the unexposed normal human epidermis the concentration and distribution of cell surface beta-D-galactose, D-galactose-beta-(1,3 N-acetylo-D-galactosamine), beta(1,4 D-N-acetylo-D-glucosamine) and alpha-D-N-acetylo-D-galactosamine were almost identical in all age groups, whereas those of alpha-D-mannose, alpha-D-glucose and alpha-L-fucose revealed significant age-related differences.

CONCLUSION

These findings may be due to an age-related decline in synthesis and/or transport of monosaccharides from the cytoplasm to the surface of epidermal cells. Thus, the corresponding lectins concanavalin A and Ulex europaeus agglutinin-I can only be used in comparative histochemical studies of the carbohydrate residue composition of the cell surface in the normal and pathological epidermis of individuals of the same age, whereas Ricinus communis agglutinin-I, peanut agglutinin, wheat germ agglutinin and Dolichos biflorus agglutinin, whose binding to carbohydrates is not affected by aging can be used in histochemical studies of carbohydrate residue composition of the cell surface in the normal and pathological epidermis in human subjects of any age.

Qualitative and quantitative alterations of cell surface carbohydrate residues during epidermal morphogenesis

The purpose of this study was to investigate the carbohydrate residue composition of cell surface in the developing epidermis and to define the chronological sequence of its alterations in human fetuses from the 10th to the 20th weeks of gestation and at the 23rd week of gestation, using a panel of six biotinylated lectins: Concanavalin A, Ulex europaeus agglutinin-I, Ricinus communis agglutinin-I, Peanut agglutinin, Wheat germ agglutinin, and Dolichos biflorus agglutinin. Distinct qualitative and quantitative alterations in the expression of cell surface carbohydrate residues were found during epidermal morphogenesis prior to keratinization (10th to 20th weeks). At the 23rd week of gestation, the already keratinized fetal human epidermis revealed a pattern of cell surface glycosylation very similar to that of the adult human epidermis. Further studies are now warranted to answer the question regarding whether the glycosylation pattern in the developing human epidermis is disturbed in fetuses with genodermatoses and whether these disturbances might be important for prenatally diagnosing the latter.