Expression of Sialic Acid α2-3 and α2-6 in MCF Cells Upon Stimulation with Lipopolysaccharide

Protein sialylation is an important post-translational modification of glycoproteins that is also involved in tumor progression and metastasis. Increased expression of sialic acid can disrupt receptor-ligand interactions and protect tumor cells from the immune system. In this work, the expression of sialic acid α2-3 and α2-6 in MCF-7 stimulated with LPS at a concentration of 20 ng/ml cells was determined, by flow cytometry, fluorescence microscopy, and RT- qPCR. An increase in the expression of sialic acid α2-3 and α2-6 recognized by Maackia amurensis and Sambuccus nigra lectins was observed. While the percentage of cells expressing α2, 3 sialic acid recognized by the Maackia amurensis lectin remained at 20%, in the case of α2, 6 sialic acid recognized by the Sambucus nigra lectin, it was observed that 44% of the population expressed it after 2h of stimulation. The expression of ST3GAL1 and ST6GAL1 was evaluated by RT- qPCR, and the results obtained showed that Lipopolysaccharide did not produce significant changes in ST6GAL1 mRNA levels, while for ST3GAL1 it is observed that Lipopolysaccharide causes an increase in mRNA at 4 hours while at 2 and 6 hours it decreases. Our results suggest that lipopolysaccharide causes an increase in the expression of α2, 3 sialic acid at four hours after stimulation, decreasing at six hours of stimulation, while the expression of α2, 6 sialic acid increases at six hours of stimulation with LPS. Further studies are needed to evaluate the effect of protein sialylation caused by lipopolysaccharide.