New role for sugars on proteins

In a ground-breaking study published in the top journal, Cell, Dr. James Dennis, senior investigator at the Samuel Lunenfeld Research Institute at Mount Sinai Hospital, has discovered a new role for sugars on proteins.

Every cell in the human body is controlled by signaling networks that are responsive to external stimuli. The stimuli are received by protein receptors on the cell surface. These proteins act as interpreters for cells, receiving messages from the outside and then instructing the cells to divide or to move.

Most of the important proteins that decorate the outside of human cells have complex sugars attached to them. Researchers at the Samuel Lunenfeld Research Institute have known that changes in these sugars are often associated with diseases such as cancer, diabetes and autoimmune diseases such as Multiple Sclerosis.

"Our research shows that the sugar composition of these receptor proteins controlled the amount of time the protein was available to interact with the external messages, in effect, changing the likelihood that a receptor could be activated," states Dr. Dennis. "This explains how cells can adapt in their nutrient environment. However, when this normal adaptation becomes imbalanced, cancer cells can grow and promote metastasis."

Dr. Dennis' team continues to research the effects of changing the sugars associated with the key proteins that act as receptors for hormones and growth factors. These are the same types of proteins that are targeted by a new generation of anti-cancer drugs such as Herceptin (trastuzumab).

"These findings may lead to a new class of drug treatments as well as strategies to improve the effectiveness of existing anti-receptor drugs," states Dr. Jim Woodgett, Director of Research, Samuel Lunenfeld Research Institute.