N-Glycans influence the in vitro adhesive and invasive behaviour of three metastatic cell lines

Alterations in cellular glycosylation may play a key role in metastatic behaviour of tumour cells. We studied three metastatic cell lines, LOX (malignant melanoma), FEMX (malignant melanoma) and MA-11 (mammary carcinoma). These cell lines have a very different metastatic behaviour in vivo, and different glycans have been postulated to be partly responsible for these differences. To further investigate the functional role of carbohydrates, these three cell lines have been treated with tunicamycin, an inhibitor of the biosynthesis of N-glycans and benzyl- alpha-N-acetylgalactosamine (benzyl-alpha-GalNAc; BnGalNAc), an inhibitor of mature O-linked glycans. Various in vitro adhesion and invasion assays were undertaken for functional studies. Tunicamycin significantly inhibited adhesion to laminin, but only slightly affected cell adhesion to collagen IV. The same compound significantly decreased cellular invasiveness through a Matrigel invasion chamber. Moreover, tunicamycin reduced homotypic aggregation of cells. BnGalNAc had generally little effect on cell behaviour in in vitro assay. The effects of the inhibitors were, however, to some extent cell line-specific. We conclude that N-glycans, but probably not mature O-glycans have important in vitro functions in cell adhesion to laminin, cell invasion through Matrigel and cellular aggregation in the studied cell lines. These results support the view that carbohydrates are functionally involved in several steps of the metastatic process.