Differential expression of galectin 3 and galectin 1 in colorectal cancer progression

Background & Aims: Galectins are beta-galactoside-binding proteins possibly involved in tumor progression. The aim of this study was to determine the pattern of galectin 3 and galectin 1 expression and involvement in colorectal cancer progression. Methods: Galectin 3 expression was examined immunohistochemically in 39 samples of normal mucosae, 25 adenomas, 87 carcinomas, and 39 lymph node metastases. Galectin 1 was analyzed in 25 samples of mucosae, 15 adenomas, 25 carcinomas, and 11 metastases. Western blot analysis was also performed. Results: All normal mucosae showed strong nuclear galectin 3 expression, which was down-regulated in the neoplastic progression, because only 60% of adenomas, 48% of carcinomas, and 44% of metastases were strongly positive (P < 0.0001). Cytoplasmic expression was down-regulated in adenomas (16%) but increased again in carcinomas (64%) (P < 0.0001). Galectin 1 expression was mainly detected in stromal cells and correlated with tumor progression from normal mucosae to adenomas and carcinomas (P < 0.0001). Conclusions: Galectin 3 expression is down-regulated in the initial stages of neoplastic progression, whereas a dissociated cytoplasmic expression increases in later phases of tumor progression. Galectin 1 in colorectal mucosa is predominantly a stromal product whose overexpression is associated with the neoplastic progression of colorectal cancer.