[The alterations of glycosylation in malignant diseases]

The universal feature characteristic of cancer cells are the alterations in protein and lipid glycosylation. The most frequent changes in glycosylation during malignant transformation are: disappearance or appearance of structures containing sugar residues in the tumor cell, synthesis of highly branched and heavily sialylated glycans, the premature termination of synthesis resulting in the formation of incompleted glycoforms and the expression of fetal antigens. There are many factors that cause such changes in glycosylation during the malignancy, but the most common and important mechanism is the change in the expression of enzymes involved in glycans synthesis. The changes in the structure of glycans are rather quantitative than qualitative, and depend on the nature of genetic processes occurring in normal or tumor cells.