Expression of fucosyltransferases contributes to melanoma invasive phenotype

During carcinogenesis aberrant N-glycosylation may lead to the development of subpopulations of tumor cells with altered adhesion properties and increased invasive potential. Biosynthesis of glycans and oligosaccharides is tissue-specific and developmentally regulated by number of glycosyltransferases of which fucosyl-, sialyl- and N-acetylglucosaminyltransferases often participate in synthesis of tumor type glycans. We analyzed the expression of selected glycosyltransferases (real-time PCR): fucosyltransferases FUT-1 and FUT-4, sialyltransferase SIAT4C and beta 1,6-N-acetylglucosaminyltransferase V (MGAT-5), in human melanoma cell lines: WM35 from primary tumor site and WM239, WM9, A375 from metastatic sites. In parallel their proliferation (crystal violet test) and adhesion to fibronectin and collagen IV (BD Biocoat assay) was assessed. Examined cell lines showed expression of all studied glycosyltransferases. The level of expression of fucosyltransferases was significantly higher in melanoma cell lines from metastatic site than from primary cell line: mRNA expression of FUT-1 was 100 times higher in A375 melanoma cell line from metastatic site (A375, solid tumor) than in WM35 primary cell line. The expression of FUT-4 in cell lines from metastatic sites: WM9 (lymph node) and WM239 (skin) was respectively 80 and 37 times higher than in WM 35 primary cell line. In all melanoma cell lines very low expression of MGAT-5 and high expression of SIAT4C was observed. Melanoma cells bound both to fibronectin and to collagen IV. LTA (Lotus tetragonolobus agglutinin), the lectin that specifically recognizes fucose residue of glycans and 20mM L-fucose by itself significantly reduced adhesion of all studied cell lines, both primary and metastatic, to fibronectin (20-50 %) and to collagen IV (20-50 %). In addition LTA reduced the proliferation (20-30 %) of metastatic cell lines (A375, WM9, WM239) and did not affect the growth of primary cell line (WM35). The results suggest that higher expression of fucosyltransferases (FUT-1, FUT-4) might be an important step in the formation of surface structures that facilitate metastasis of melanoma.