Galectin-1

Galectin-1 belongs to the family of galactoside-binding lectins and (comparable to Tiam1) is associated with functions such as cell growth, cell differentiation, inflammation, malignant transformation, and metastasis

The coding gene (galectin-1 gene, also LGALS1 or lectin- galactoside-binding-soluble) is located on chromosome 22q12.

The family of galectins consists of a number of structurally similar proteins that are characterized by their affinity for oligosaccharides containing beta-galactose (beta-galactosides). Each galectin (15 galectins have been identified so far) has at least one carbohydrate recognition domain (CRD).

In general, galectins are ascribed different functions in numerous biological processes. The proteins are involved in processes that influence the regulation of cell-cell adhesion, cell-matrix adhesion, proliferation, apoptosis and the immune response. Due to their expression in various tumors, they are also believed to play a role in tumor genesis and metastasis.

Galectin-1 is expressed in various soft tissues (liver, lung, skeletal muscles, etc.) but also in tumors. Sézary cells also express galectin-1 (Nicolay). The tissue-specific expression of galectin-1 is controlled by DNA methylation. Galectin-1 interacts with the extracellular matrix (ECM) of various normal and neoplastic tissues via its surface carbohydrate residues.

Intracellularly, galectin-1 is mainly located in the cytoplasm and nucleus.

Expression of galectin-1 has been observed in various tumor types. A correlation of galectin-1 expression with the aggressiveness of tumours and their metastasis potential (Rabinovich) has been demonstrated. Concerning the influence of galectin-1 on the growth processes of cells contradictory results have been found. Extracellularly, galectin-1 binds to the disaccharide N-acetyllactosamine (LacNAc; Galbeta1-4GlcAc). Certain glycoproteins such as the matrix proteins laminin and fibronectin are ligands for galectin-1. Accordingly, it has been shown on different cell types that extracellularly occurring galectin-1 increases the adhesion of cells to matrix proteins such as laminin or fibronectin. Using melanoma cells as an example, it was also shown that galectin-1 and galectin-3 lead to the formation of multicellular aggregates. For example, it could be shown that galectin-1 interacts with oncogenic Ras and thus plays a key role in the initiation of Ras-induced tumours (Paz et al.). Furthermore, an overexpression of galectin-1 increases the membrane association of Ras and leads to oncogenic transformation of cells (Paz et al.).

1. Nicolay JP et al (2016) The Sezary syndrome: from unresolved questions to new therapeutic approaches. JDDG 13: 256-265
2. Paz A et al (2001) Galectin-1 binds oncogenic H-Ras to mediate Ras membrane anchorage and cell transformation. Oncogene 20: 7486-7493.
3. Redleaf B et al (2004) Galectin-1(L11A) predicted from a computed Galectin-1 farnesyl-binding pocket selectively inhibits Ras-GTP. Cancer Res 64: 3112-3118.
4. Rubinstein N et al (2004) Targeted inhibition of galectin-1 gene expression in tumor cells results in heightened T-Cell mediated rejection; a potential mechanism of tumor-immune privilege. Cancer Cel 5: 241-251.
5. Rabinovich G A (2005) Galectin-1 as a potential cancer target. Br J Cancer 92: 1188-1192.