Colon cancer mucin: a new ligand for the beta-galactoside-binding protein galectin-3.
Galectin-3, an endogenous beta-galactoside-binding lectin, is present on colon cancer cells and may play a role in metastasis. Galectin-3 binds poly-N-acetyllactosamine structures on glycoproteins, but its natural ligands remain to be fully defined. Galectin-3 bound to purified native and desialylated colon cancer mucin in a concentration-dependent manner, which was completely inhibited by 0.1 M lactose, the competitive inhibitory sugar for this protein. Mucin purified from highly metastatic LS-Lim6 human colon cancer cells bound galectin-3 to a 2-fold greater extent than mucin from low-metastatic parental cell line LS174T. Desialylation increased binding to mucin >4-fold. Mucin purified from LS-B colon cancer cells is fully glycosylated and bound >40-fold more galectin-3 than mucin purified from clonal cell line LS-C, which produces mucin lacking peripheral carbohydrate structures. Endogenous galectin-3 was detected by Western analysis in all cell lines, and its expression was related to mucin production and metastatic capacity. When serum from a patient with metastatic colorectal cancer was chromatographed on Superose 6, >70% of galectin-3 ligand was identified as circulating mucin. Colon cancer mucin is a newly identified ligand for galectin-3, and binding of galectin-3 to mucins depends on peripheral carbohydrate structures. Binding of this endogenous lectin to mucins; may influence cellular interactions that play a role in colon cancer metastasis.
Bresalier
R S
RS
Department of Medicine, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA.
Byrd
J C
JC
Wang
L
L
Raz
A
A
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D002240:Carbohydrate Sequence; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D005697:Galactosides / Q000378:metabolism*; D037502:Galectin 3; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008969:Molecular Sequence Data; D009077:Mucins / Q000737:chemistry / Q000378:metabolism*; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000943:Antigens, Differentiation; D005697:Galactosides; D037502:Galectin 3; D037102:Lectins; D008024:Ligands; D009077:Mucins; D009363:Neoplasm Proteins; D011134:Polysaccharides; D011994:Recombinant Proteins; C007816:beta-galactoside; C037199:poly-N-acetyllactosamine