Biological applications of a chimeric probe for the assessment of galectin-3 ligands.
Beta1-6 branching of N-linked oligosaccharides has been correlated with the progression of different cancers. The leukoagglutinins of Phaseolus vulgaris (L-PHA) have been used to study this pattern of glycosylation whose biological significance is incompletely understood. The animal lectin, galectin-3, also binds to structures recognized by L-PHA. To develop a functional tool for the in situ identification of this pattern of glycosylation, human galectin-3 was fused to bacterial alkaline phosphatase (gal3/AP). Gal3/AP recognized both A and B blood group saccharides (B>A) and lactosamine derivatives. Gal3/AP recognition depended at least in part on the N-linked oligosaccharides of different glycoproteins. The presence and distribution of galectin-3 ligands were analyzed in both murine and human normal and tumor samples. Loss of apical expression of galectin-3 ligands was commonly found in carcinomas. Endothelial and inflammatory cells were enriched in galectin-3 ligands as compared with tumor cells; thus, gal3/AP is a suitable tool for studying tumor microenvironments. Comparative analysis of both gal3/AP and L-PHA binding patterns indicated that although similar, these patterns are not identical. The probe developed was useful for several immunoenzymatic assays and will allow the physiological and clinical significance of the expression pattern of galectin-3 ligands to be established. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
de Melo
Fabiana H M
FH
Faculdade de Medicina da Universidade de São Paulo, Avenida Dr. Arnaldo 455, 01246-903 São Paulo SP, Brazil.
Butera
Diego
D
Medeiros
Raphael S
RS
Andrade
Luciana N de S
LN
Nonogaki
Suely
S
Soares
Fernando A
FA
Alvarez
Richard A
RA
Moura da Silva
Ana M
AM
Chammas
Roger
R
D000469:Alkaline Phosphatase / Q000235:genetics*; D000818:Animals; D000911:Antibodies, Monoclonal; D045744:Cell Line, Tumor; D029968:Escherichia coli Proteins / Q000235:genetics; D037502:Galectin 3 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007124:Immunoenzyme Techniques; D008024:Ligands; D008546:Melanoma, Experimental / Q000378:metabolism; D051379:Mice; D009369:Neoplasms / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012513:Sarcoma, Experimental / Q000378:metabolism; D012680:Sensitivity and Specificity; D046888:Tissue Array Analysis
D000911:Antibodies, Monoclonal; D029968:Escherichia coli Proteins; D037502:Galectin 3; D006023:Glycoproteins; D008024:Ligands; D009844:Oligosaccharides; D011993:Recombinant Fusion Proteins; D000469:Alkaline Phosphatase