Comparison of O-Linked Carbohydrate Chains in MUC-1 Mucin from Normal Breast Epithelial Cell Lines and Breast Carcinoma Cell Lines:

Abstract

MUC-1 mucin is considered to be aberrantly glycosylated in breast, ovary, and other carcinomas in comparison with mucin from corresponding normal tissues. In order to clarify these differences in glycosylation, we have compared the O-linked carbohydrate chains from MUC-1 immunoprecipitated from [ 3 H]GlcN-labeled breast epithelial cell lines (MMSV1-1, MTSV1-7, and HB-2) derived from cells cultured from human milk, with three breast cancer cell lines (MCF-7, BT-20, and T47D). Analysis by high pH anion chromatography showed that the normal cell lines had a higher ratio of GlcN/GalN and more complex oligosaccharide profiles than the cancer cell lines. Structural analyses were carried out on the oligosaccharides from MTSV1-7 and T47D MUC-1, and the following structures were proposed. MUC-1 from T47D had rather a simple glycosylation pattern, with NeuAc␣2-3Gal␤1-3GalNAc-ol, Gal␤1-3GalNAc-ol, and GalNAc-ol predominating; in contrast, MUC-1 from MTSV1-7 had more complex structures, including a number of disialo, core 2 species, i.e. NeuAc␣2-3Gal␤1-4GlcNAc␤1-6[NeuAc␣2-3Gal␤1-3]GalNAc-ol and NeuAc␣2-3Gal␤1-4GlcNAc␤1-6[NeuAc␣2-3Gal␤1-4GlcNAc␤1-3Gal␤1-3]GalNAc-ol. Double-labeling experiments with [ 3 H]GlcN and 14 C-aminoacids and analysis of GalNAc or GalNAc-ol:protein ratios in MUC-1 showed that there was also a significant difference in the degree of glycosylation of the mucin between the two cell types. We conclude that MUC-1 from breast cancer cell lines has simpler, and fewer, carbohydrate chains than MUC-1 from normal breast epithelial cells, and that these differences, combined or separately, explain the differential tumor specificity of some MUC-1 antibodies and T cells.

Recombinant MUC1 mucin with a breast cancer-like O-glycosylation produced in large amounts in Chinese-hamster ovary cells

“…The O-glycans expressed on MUC1 from normal cells consist of long and branched, mainly core 2-based, oligosaccharides [7,8]. In contrast, MUC1 expressed by breast carcinoma cells has an increased proportion of shorter, non-branched, core 1-based O-glycans with a higher sialic acid content [9][10][11].…”

Responses of human T cells to peptides flanking the tandem repeat and overlapping the signal sequence of MUC1

“…3,4 Its extracellular domain consists largely of TR sequences of 20 amino acids, 1 each of which contains 5 potential O-glycosylation sites; and the glycoforms produced by cancer cells can differ from those expressed by normal tissues. 5 There have been reports of humoral and cellular immune responses to MUC1 in multiparous women and in cancer patients, 6 with the presence of a humoral response reportedly being a good prognostic factor for outcome in breast cancer patients. 7 These data together with the high level of expression in tumour cells have led to a focus on MUC1 as a potential target for tumour immunotherapy.…”

High Density O-Glycosylation on Tandem Repeat Peptide from Secretory MUC1 of T47D Breast Cancer Cells

“…The preponderance of sialylated core1-trisaccharide on carcinoma-associated MUC1, which can be regarded as a biosynthetic dead end product, has been shown to originate from the simultaneous up-regulation and overexpression of Gal␤1-3GalNAc/␣-3-sialyltransferase (7). Moreover, not only the chain length of the glycans but also their density has been described to be reduced on breast cancer cell-specific MUC1 (4).…”

“…Also, the widely distributed epithelial mucin MUC1 has been described to be aberrantly processed in cancer cells (2)(3)(4). In breast cancer, the nonexpression of the core2 enzyme, Gal␤1-3GalNAc/␤-6-N-acetylglucosaminyltransferase (5), leads to the truncation of polylactosamine-type chains found on the lactation-associated mucin (6) and to the accumulation of core-type chains (2)(3)(4).…”

“…In breast cancer, the nonexpression of the core2 enzyme, Gal␤1-3GalNAc/␤-6-N-acetylglucosaminyltransferase (5), leads to the truncation of polylactosamine-type chains found on the lactation-associated mucin (6) and to the accumulation of core-type chains (2)(3)(4). The preponderance of sialylated core1-trisaccharide on carcinoma-associated MUC1, which can be regarded as a biosynthetic dead end product, has been shown to originate from the simultaneous up-regulation and overexpression of Gal␤1-3GalNAc/␣-3-sialyltransferase (7).…”