No abstract

Nucleolin is multifunctional protein mainly present in nucleoli but also detected in cytoplasm and plasma membranes. Extranuclear nucleolin differs from the nuclear form by its glycosylation. Studies on expression of nucleolin in breast cancer suggest a possible association to the metastatic cascade. In the present study, Vicia villosa lectin (VVL) precipitation followed by subsequent polyacrylamide gel electrophoresis and mass spectrometry analysis demonstrates nucleolin as a VVL-positive glycoprotein expressed in melanoma. The presence of VVL-positive nucleolin in the melanoma cell membrane and cytoplasm was confirmed by confocal microscopy. Using bioinformatic peptide prediction programs, nucleolin was shown to contain multiple possible MHC class-I binding peptides in its sequence which makes nucleolin an interesting melanoma marker and target for immunodiagnostic and possibly therapeutic purposes.

A lot of experimental data has been produced which suggests that there is a crucial role for glycans during the different stages of melanoma progression. Malignant transformation is associated with various alterations in the glycosylation pattern of the protein glycans. The most common changes are associated with the presence of more branched and hypersialylated N-linked oligosaccharides, re-expression of fetal-type antigens and premature terminated glycans. Some of these changes may provide the tumor cells with an advantage in influencing their social behavior and facilitating metastasis formation so, glycan-target therapy in combination with existing protocols may have an important impact in the treatment of melanoma.