Role of galectins 1 and 3 in the recruitment of eosinophilic granulocytes into tumor tissue in gastric and colon cancers

Background : Gastric and colon tumors are often associated with eosinophilic infiltration of tumor tissue, the significance of which is still not entirely clear. The recruitment of eosinophils into the tissues can be in part regulated by galectins ― galactose-binding proteins which are expressed by a variety of tissues and are capable of exerting a broad range of effects. Aims : To evaluate the expression of galectin-1 and galectin-3 in tumor tissue, and gal-3 gene mRNA expression in blood eosinophils in patients with gastric and colon cancer with or without tissue eosinophilia. Materials and methods : The study included a total of 107 patients (84 males and 23 females, average age 60,9 ± 6,8) with verified gastric cancer (52 persons) and colon cancer (55 persons), who underwent treatment or were registered at the dispensary at the regional medical institution “Tomsk Regional Oncology Center” (Tomsk, Russia). The control group consisted of 15 men and 11 women of comparable age. The materials of the research included samples of gastric and colon tumors obtained during surgery, and eosinophilic granulocytes isolated from whole blood by immunomagnetic separation. Galectin-1 and galectin-3 expression in tumor tissue was evaluated by immunohistochemistry. The expression of gal-3 gene mRNA in eosinophils was determined by real-time reverse transcription polymerase chain reaction. Statistical analysis of the results was carried out using the non-parametric Mann-Whitney U test for independent samples with Benjamini-Hochberg procedure for multiple comparisons, and the Chi-square Pearson criterion with Yates correction. Results : In patients with gastric cancer and colon cancer, regardless of the presence of tissue eosinophilia, low expression of galectin-3 in the tumor tissue and high expression of gal-3 gene mRNA in peripheral blood eosinophils were found. Gastric and colon cancer patients with eosinophilic infiltration of tumor tissue were characterized by low expression of galectin-1 within tumor cells (in 64.0% cases, χ 2 = 4.890, р = 0.029; and in 73.9% cases, χ 2 = 5.981, p = 0.031 respectively). There was a statistically significant connection between the level of galectin-1 expression by tumor cells and the presence of tissue eosinophilia both in gastric (φ = 0.307) and colon cancer (φ = 0.330). Conclusion : Low expression of galectin 1 and 3 by tumor cells in gastric and colon cancer with tissue eosinophilia indicates the lack of a significant effect of these proteins on the process of recruiting eosinophilic granulocytes into tumor tissue. Increased expression of galectin-3 in blood eosinophils in gastric and colon cancer is not associated with the presence of eosinophilic infiltration of tumor tissue.