Increased galectin-3 expression in gastric cancer: correlations with histopathological subtypes, galactosylated antigens and tumor cell proliferation.

Galectin-3 represents an endogenous galactoside-binding lectin which may be involved in tumor cell adhesion and proliferation. In order to evaluate its biological significance in human gastric cancer, we investigated its expression in the stomach of a large series of patients (n = 193) by immunohistochemical staining with the monoclonal antibody Mac-2. Compared to normal tissues, primary gastric adenocarcinomas showed a slight increase in galectin-3 expression. However, there was no correlation of membrane-bound and cytoplasmic galectin-3 with histopathological differentiation parameters (according to the WHO and Laurén classifications) or tumor progression (as documented by pTNM staging). Nuclear galectin-3 reactivity was significantly stronger in diffuse-type cancer compared to the intestinal-type tumors. Galectin-3 binds to terminal GalNAcalpha(1-3) bound to polylactosamine chains and related glycotopes. Therefore, the strong coexpression of membrane/cytoplasmic galectin-3 with Griffonia simplicifolia agglutinin I (GSA I) binding sites (Galalpha1-3Gal-, GalNAcalpha-) on carcinoma cells seems to be interesting. On the other hand, nuclear galectin-3 immunoreactivity did not correlate with the incidence of Ki-67-positive tumor cells. A prognostic value of galectin-3 regarding patient survival could not be established.