Biological Applications of a Chimeric Probe for the Assessment of Galectin-3 Ligands

Fabiana H. M. de Melo ¹, Diego Butera ¹, Raphael S. Medeiros ¹, Luciana N. de S. Andrade ¹, Suely Nonogaki ¹, Fernando A. Soares ¹, Richard A. Alvarez ¹, Ana M. Moura da Silva ¹ and Roger Chammas ^1*

¹ Laboratório de Oncologia Experimental, Faculdade de Medicina da Universidade de São Paulo, São Paolo, Brazil (FHMdM,RSM,LNdSA,RC); Laboratório de Imunopatologia, Instituto Butantan, São Paulo, Brazil (DB,AMMdS); Divisão de Patologia, Instituto Adolfo Lutz, São Paulo, Brazil (SN); Departamento de Patologia, Hospital A.C. Camargo, São Paulo, Brazil (FAS); NIGMS Consortium for Functional Glycomics, Core H, Oklahoma City, Oklahoma (RAA); and Center for Cell-based Therapy Research, Universidade de São Paulo, Ribeirão Preto, Brazil (RC)

^* To whom correspondence should be addressed. E-mail: rchammas{at}lim24.fm.usp.br.

Submitted on January 4, 2007
Accepted on 14 May 2007

	Abstract

1-6 branching of N-linked oligosaccharides has been correlated with the progression of different cancers. The leukoagglutinin 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. In order 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(LN)-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 to 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 to establish the physiological and clinical significance of the expression pattern of galectin-3 ligands. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Key Words: galectin-3, galectin-3 ligands, L-PHA, aberrant glycosylation

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