Altered glycosylation in Madin-Darby canine kidney (MDCK) cells after transformation by murine sarcoma virus

Abstract

The changes in glycosylation of an immortalized epithelial cell line (MDCK) before and after progression towards a more malignant phenotype have been studied. The parental MDCK-3 cells were immortalized after long-term passage in vitro and have shown no tendency for spontaneous acquisition of malignancy-related phenotypes such as tumorigenicity, invasion and metastasis. They conserved morphological and functional characteristics of the epithelial tissue of origin. The ras-MDCK cells acquired the fully malignant phenotype after transformation with a Harvey murine sarcoma virus; they were immortalized, invasive in vitro and produced invasive and also metastatic tumors after subcutaneous injection into nude mice. Using immobilized lectins and gel chromatography, before and after liberation of O-linked glycans from the peptide moieties and also after removal of terminal sialic acid, we have found differences in the glycosylpeptides of both whole cells and cell surface trypsinates from ras-MDCK cultures as compared to the parental MDCK-3 cultures: (i) more sialic acid in the N-linked tri- and tetra-antennary structures; (ii) more fucosylation in the N-glycosylpeptides; (iii) more bi-antennary N-glycosylpeptides and less O-linked glycans; and (iv) a lower molecular weight of the O-linked glycans probably due to a decreased sialylation. It is concluded that alterations in sialylation and fucosylation of the cell surface exposed glycans accompanied progression of MDCK-3 cells towards a more malignant phenotype.

Broadly neutralizing antibodies targeted to mucin-type carbohydrate epitopes of human immunodeficiency virus

“…Viral glycoproteins may thus obtain increased amounts of incompletely processed oligosaccharide chains, which will present themselves as carbohydrate neoantigens. Similar induction of neoglycosylation has previously been found for cytomegalovirus and HIV (1,2), and murine leukemia virus has been shown to effect alterations mediated by the ras oncogene in the glycosylation process in infected cells (5).…”

“…MAbs against the carbohydrate Tn epitope (GalNAc-Ser/ Thr) inhibited both HIV-1 and HIV-2 infection in vitro ( Table 2). Both an IgG2a (1E3) and an IgM (TKH6) MAb showed a dose-dependent inhibition of infection as evaluated by virus antigen production when the virus was preincubated with MAb prior to inoculation of either lymphocytic ( 5. Effect of MAb 1E3 on HIV111B infection of MT-4 cells when the viral inoculum was preincubated with MAb before (solid bars) or after (open bars) being mixed with the cells.…”

“…Additionally, specific bands at 140 precipitated with protein A-Sepharose. Lanes: 1, MAb 1E3; 2, MAb TKH2; 3, MAb B72.3; 4, positive control MAb 110-4; 5, negative control MAb a-GFAP (5). Precipitates were used for SDS-PAGE with 8% homogeneous gels and subsequent fluorography.…”

The invasive phenotypes

“…An increased brancing of the carbohydrate chains, and/or an increased sialylation, apparent from gel chromatography profiles and lectin chromatography of cell surface material, accompanied the conversion from the I-towards the I ÷ phenotype. This was found after virus transformation, oncogene transfection, mutagenesis, and epigenetic manipulation of a number of cell types [109][110][111]. As with the oncogene products, the precise role of the modified cell surface glycoproteins observed in these experiments is not yet clear for a number of reasons.…”

Enhanced CMP‐NeuAc:Galβ1, 4GlcNAc‐R α2, 6 sialyltransferase activity of human colon cancer xenografts in athymic nude mice and of xenograft‐derived cell lines

“…Some characteristic features of tumor cells, such as the ability to invade the neighboring tissues and to metastasize, as well as the ability to escape from immune-system recognition, have been related to the presence of altered oligosaccharide sequences on their surface (Collard et al, 1985;Dennis et al, 1987;Pettijon et al, 1988;Bolscher et al, 1989;Bresalier et al, 1990;Bruyneel et al, 1990). Among the most common alterations of cancer-cell surface glycoconjugates is the presence of highly branched and more heavily sialylated N-linked chains of glycoproteins (Smets and van Beek, 1984;Pierce and Arango, 1986;Hakomori, 1989).…”