Galectin-4 in normal tissues and cancer |
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Authors: | Margaret E Huflejt Hakon Leffler |
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Institution: | (1) Sidney Kimmel Cancer Center, 10835 Altman Row, San Diego, CA 92121, USA |
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Abstract: | Galectin-4 belongs to a subfamily of galectins composed of two carbohydrate recognition domains within the same peptide chain.
The two domains have all the conserved galectin signature amino acids, but their overall sequences are only approximately
40% identical. Both domains bind lactose with a similar affinity as other galectins, but their respective preferences for
other disaccharides, and larger saccharides, are distinctly different. Thus galectin-4 has a property of a natural cross-linker,
but in a modified sense since each domain prefers a different subset of ligands. Similarly to other galectins, galectin-4
is synthesized as a cytosolic protein, but can be externalized. During development and in adult normal tissues, galectin-4
is expressed only in the alimentary tract, from the tongue to the large intestine. It is often found in relatively insoluble
complexes, as a component of either adherens junctions or lipid rafts in the microvillus membrane, and it has been proposed
to stabilize these structures. Strong expression of galectin-4 can be induced, however, in cancers from other tissues including
breast and liver. Within a collection of human epithelial cancer cell lines, galectin-4 is overexpressed and soluble in those
forming highly differentiated polarized monolayers, but absent in less differentiated ones. In cultured cells, intracellular
galectin-4 may promote resistance to nutrient starvation, whereas—as an extracellular protein—it can mediate cell adhesion.
Because of its distinct induction in breast and other cancers, it may be a valuable diagnostic marker and target for the development
of inhibitory carbohydrate-based drugs. Published in 2004.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | galectin-4 galectins carbohydrate specificity promoter breast cancer epithelial cells |
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