Correlative fine specificity of several Thomsen-Friedenreich disaccharide-binding proteins with an effect on tumor cell proliferation.
Epithelial cancer cells show increased cell surface expression of mucin antigens with aberrant O-glycosylation, notably type I core (Galbeta1-3GalNAcalpha), termed Thomsen-Friedenreich disaccharide (TFD), a chemically well-defined carbohydrate antigen with a proven link to malignancy. Several TFD-binding proteins influence the proliferation of cells to which they bind. We studied the fine specificity of TFD-binding proteins and its relationship with epithelial tumor cell proliferation. Competitive binding assays against asialoglycophorin showed that Agaricus bisporus lectin (ABL) and human anti-TFD monoclonal antibody (mAb) TF1 were inhibited only by TFD and its alpha-derivatives. Peanut agglutinin (PNA), mAb TF2, and mAb TF5 were also inhibited by other carbohydrates such as lacto-N-biose (Galbeta1-3GlcNAc), lactose, and (Mealpha or beta) Gal, indicating lower recognition of the axial C-4 hydroxyl group position of GalNAc from TFD, and the major relevance of the terminal Gal on interaction of these three TFD-binding proteins. In the direct glycolipid-binding assay, ABL bound mostly to alpha-anomeric TFD-bearing glycolipids, whereas PNA interacted mainly with beta-linked TFD. Of the three anti-TFD mAbs analyzed, all bound N5b (terminal beta-TFD), but only TF2 interacted with N6 (terminal alpha-TFD). These findings indicate that TFD-binding proteins that stimulate the proliferation of epithelial tumor cell lines recognize mainly a terminal beta-Gal region of beta-linked TFD, whereas ABL, which inhibits the proliferation of these tumor cells, binds mainly to subterminal GalNAc of alpha-anomeric TFD.
Irazoqui
F J
FJ
Departamento de Química Biológica, CIQUIBIC-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina. irazoqui@dqb.fcq.unc.edu.ar
Jansson
B
B
Lopez
P H
PH
Nores
G A
GA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000276:immunology / Q000378:metabolism*; D001667:Binding, Competitive; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology*; D002417:Cattle; D002455:Cell Division; D004187:Disaccharides / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D037102:Lectins / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015295:Antigens, Tumor-Associated, Carbohydrate; D004187:Disaccharides; D006023:Glycoproteins; D037102:Lectins; C016467:Thomsen-Friedenreich antigen