Significance of leptin, Galectin-1 and Galectin-3 in tumor lymphangiogenesis

Leptin, Galectin-1 and Galectin-3 are essential players in tumorigenesis, angiogenesis, and metastasis, but their lymphangiogenic role is unclear. Here, the associations of leptin, Galectin-1 and Galectin-3 with markers of lymphangiogenesis were evaluated in colorectal cancer (CRC).

A total of 120 patients with CRC were included in the study. The expressions of leptin, Galectin-1, Galectin-3, and vascular endothelial growth factor- C (VEGF-C) were analyzed in CRC tissue and compared with lymphatic vessel density (LVD). Also, the concentrations of Galectin-1 and Galectin-3 were determined in the sera of CRC patients (n=38).

LVD positively correlated with the intensity of leptin or Galectin-1 expression (as defined by intensity score, IS) in tissues. Although there was no significant association between tissue expression of Galectin-3 and LVD, serum Galectin-3 concentrations were markedly decreased in patients with high LVD. The positive correlation was observed between intensity of VEGF-C and leptin expressions. No significant relationship was found between VEGF-C and Galectin-1 expression, while the intensity of VEGF-C expression positively correlated with Galectin-3 expression in tumor tissue. Further, high leptin expression, determined by a total score (sum of percentage score (PS) and IS) > 4, was related to regional lymph node metastasis and TNM stages, indicating a more aggressive CRC phenotype.

The results suggest that leptin and Galectin-1 are involved in the formation of new lymphatic vessels in tumor, either dependently or independently of VEGF-C. It seems that high leptin expression reflects regional metastases and progression of CRC.