Isolation and partial characterization of surface components of cell line MDA-MB-231 derived from a human metastatic breast carcinoma

Neuraminidase (Vibrio cholerae) treatment of human metastatic mammary carcinoma MDA-MB-231 cells grown in culture released 0.60-0.63 mg of N-acetylneuraminic acid from 10(9) cells. Incubation of intact cells with a modified trypsin and fractionation by gel filtration gave mainly O-glycopeptides. The presence of O-glycosyl-linked chains having one or two carbohydrate residues was confirmed by treatment of the glycopeptide fractions with galactose oxidase, followed by reduction with alkaline sodium borotritide and fractionation. The major glycopeptide fraction, which consisted of 53% carbohydrate and 47% protein, and a minor glycopeptide fraction each inhibited hemagglutination by peanut lectin. These results suggest the presence of O-beta-D-galactopyranosyl-(1 leads to 3)-O-(2-acetamido-2-deoxy-alpha-D-galactopyranosyl)-(1 leads to 3)-L-serine (threonine) residues. The absorptive capacities for anti-HLA-A2 and anti-HLA-B8 antisera were slightly greater for intact than for lyophilized cells, which suggested that masking of these major histocompatibility antigens did not occur in intact cells.