On the trail of the glycan codes stored in cancer-related cell adhesion proteins

Changes in the profile of protein glycosylation are a hallmark of ongoing neoplastic transformation. A unique set of tumor-associated carbohydrate antigens expressed on the surface of malignant cells may serve as powerful diagnostic and therapeutic targets. Cell-surface proteins with altered glycosylation affect the growth, proliferation and survival of those cells, and contribute to their acquisition of the ability to migrate and invade. They may also facilitate tumor-induced immunosuppression and the formation of distant metastases. Deciphering the information encoded in these particular glycan portions of glycoconjugates may shed light on the mechanisms of cancer progression and metastasis. A majority of the related review papers have focused on overall changes in the patterns of cell-surface glycans in various cancers, without pinpointing the molecular carriers of these glycan structures. The present review highlights the ways in which particular tumor-associated glycan(s) coupled with a given membrane-bound protein influence neoplastic cell behavior during the development and progression of cancer. We focus on altered glycosylated cell-adhesion molecules belonging to the cadherin, integrin and immunoglobulin-like superfamilies, examined in the context of molecular interactions.