Role of galectins in lung cancer

Abstract

Lung cancer is the leading cause of cancer-associated mortality worldwide and is also associated with a poor prognosis. As in numerous other types of cancer, galectins have been demonstrated to be involved in the progression of lung cancer. Galectins belong to a superfamily of lectins, which are carbohydrate-binding proteins. There are at least 15 members in the galectin family, however, only galectin-1, -2, -3, -4, -7, -8, -9, -10, -12, and -13 are found in humans. Galectins are able to mediate interactions between cells, including homotypic and heterotypic interactions; they also facilitate the bindings between cells and extracellular matrix components. These cell-cell and cell-matrix interactions, as well as the galectin signaling on the cell surface, are able to modulate signaling pathways and thereby influence cellular functions and behaviors. Galectin-1, -3, -4, -7, -8 and -9 are associated with lung cancer. These galectins are associated with tumor invasion, migration, metastasis and progression, and may serve important roles in the tumor microenvironment of lung cancer. The majority of galectins are associated with the progression of lung cancer, with the exception of galectin-9, which is associated with enhanced anticancer immunity. Therefore, galectins may be potential targets for developing novel lung cancer therapies.

Keywords: galectin; lung cancer; malignancy; tumor microenvironment.

Figure 1.

Classification of galectins into prototypical (dimeric), tandem-repeat and chimeric galectins. Prototypical (dimeric) galectins possess two identical CRDs. Tandem-repeat galectins possess two distinct CRDs. Chimeric galectins possess a single CRD, and may aggregate to form its common appearance with multiple identical CRDs. CRD, carbohydrate-recognition domains.

Figure 2.

Galectins are able to mediate cell-cell and cell-matrix interactions, and thereby modulate signaling pathways and influence cellular behavior.

Figure 3.

Roles of galectins in lung cancer. Galectins affect the progression of lung cancer in multiple aspects, including tumor migration, tumor progression, metastasis, tumor invasion, drug resistance, sphere-formation and the interactions between cells in the tumor microenvironment.