Comparative analysis of α2,3/2,6-linked N-acetylneuraminic acid and cytokeratin expression in head and neck squamous cell carcinoma

Abstract

Head and neck squamous cell cancer (HNSCC) requires precise characterization of their biological properties to better stratify treatment approaches. Some biological features of tumor cells are related to altered glycosylation of their surface. This study characterized alpha2,3/6-N-acetylneuraminic acid (NeuNAc) expression in adult squamous epithelia of primary and metastatic HNSCC in relation to expression of well established differentiation markers, such as cytokeratins. The expression of NeuNAc was assessed by plant lectins: Maackia amurensis agglutinin type 2 (MAA) and Sambucus nigra agglutinin (SNA) specific for alpha2,3NeuNAc and alpha2,6NeuNAc, respectively. Double labeling studies at the single-cell level were performed to compare alpha2,3/6NeuNAc linkage with expression of intermediate filaments. In studied normal adult epithelia, predominantly basal expression of alpha2,6NeuNAc and suprabasal expression of alpha2,3NeuNAc was seen, showing their differentiation-dependent linkage. The cells with markers of terminal differentiation (i.e. CK10+ alpha2,3NeuNAc+ alpha2,6NeuNAc-) prevailed in HNSCC, with increasing proportion from differentiation grade G1 to G3. High proportions of cytokeratin pCK37+ carcinoma cells occurred in all studied tumors and were accompanied by a hypersialylated phenotype (i.e. alpha2,3 NeuNAc+ alpha2,6NeuNAc+) not generally seen in non-transformed epithelia. It is hypothesized that these cells could be the pool for tumor spreading in the organism. Monitoring HNSCC using multiparameter phenotype analysis can produce new data important for the understanding of the biological behavior of HNSCC, and useful for the treatment rationalization.