Does glycosylation of melanoma cells influence their interactions with fibronectin?

Cell surface integrins, especially those binding to fibronectin (FN), participate in processes of tumor cell invasion and metastasis. Changes in glycosylation of cell surface adhesion proteins are often associated with malignant transformation of cells. In this study we examined the influence of swainsonine (SW) on adhesion, wound healing and haptotactic migration on FN, comparing the responses of different human melanoma cell lines: primary WM35 and metastatic WM9, WM239 and A375. We also examined the role of alpha subunits in adhesion to FN. All of the antibodies inhibited adhesion to FN but with different efficiencies depending on the cell line. Adhesion was mediated mainly by integrin alpha(5)beta(1) (WM9, A375), alpha(3)beta(1) (WM35, A375, WM239). Scratch wound repair was significantly faster on FN-coated wells than on plastic for all cells except for WM9. A375 and WM9 had the greatest migration ability, both expressing the highest level of alpha(5)beta(1) integrin. It seems very likely that adhesion to FN can be accomplished by many different integrins, but for effective migration alpha(5)beta(1) integrin is responsible. Only A375 and WM239 cell lines reacted to SW treatment. In the presence of SW WM239 and A375 cells had 70% and 40% increased adhesion to FN, and their migration was decreased 40% and 50%, respectively. Interestingly, although most of the cell lines share a common profile of integrins, each line interacted with FN differently. They differed mainly in the repertoire of integrins used for adhesion, and in the manner in which glycosylation affected these processes. The influence of SW was observed in two metastatic cell lines indicating the contribution of glycosylation status to the progression of melanoma. The lack of reaction to SW in WM9 cells may suggest that there is a threshold in the expression level of the highly branched N-glycans that may influence the adhesion and migration properties of the cell.

Rat submandibular gland during the maturation process: changes in enzyme activities, protein and lectin-binding profiles.

The total protein glycosylation profile and specific activity of lysosomal enzymes were investigated in rat submandibular glands isolated from very young (1-month), young (1.5-months) and adult rats (3-months) rats. The specific activity of lysosomal hydrolases (i.e. acid phosphatase, arylsulfatases A and B, beta-N-acetyl-D-glucosaminidase, beta-galactosidase and beta-glucuronidase) decreased in parallel to increasing age of the animals. Furthermore, the thermal stability of acid phosphatase and beta-N-acetyl-D-glucosaminidase was influenced by the age of rats. Age-related changes in protein profile regarding the intensity of particular bands as well as the appearance of certain proteins limited to special age groups were also demonstrated as revealed by Coomassie and lectin staining. Moreover, the marked age-related increase in structures Man (alpha1-2, alpha1-3, alpha1-6) Man, Fuc (alpha1-6) GlcNAc as well as Gal (beta1-3) GlcNAc was observed, whereas staining with terminal NeuAc and GlcNAc showed an inverse correlation. The reaction with (beta1-6) branched N-glycans and Gal (beta1-3) Gal structures was limited to 1-month-old rats. No significant changes in a specific reaction with NeuAc (alpha2-3) Gal were observed. We speculate that the observed differences with respect to protein and glycosylation profiles between 1-month-old rats and older ones could be caused by a modification of the diet composition as well as by the functional and morphological maturation of the rat submandibular gland.