Our body is made up of proteins. Measuring the abundances of these proteins has been the primary goal of scientists because they give us a way of understanding diseases. More careful analysis of proteins reveals that that no matter how similar proteins seem, they are not really the same. Proteins become modified through a process of post translational modification to yield the fine tuning of the proteins function.
One of the most common modification is the addition of short sugar chains called glycans. There are several places that glycans can attach on proteins. And even on a single site of attachment, a protein may have different copies of glycans to give different versions of the same protein. It turns out that glycans are very important for the proteins’ functions. Some function of glycans include changing the proteins structure, making the protein more interactive with other proteins, and allowing the protein to perform its function as a catalyst. There are many more functions, and researchers are only beginning to discover these roles.
The importance of glycan in protein function make them very important targets for diseases and as markers for diseases. There are many scientific publications that show glycosylation is changed in cancer.
The structures of glycans that are attached to proteins are altered in cancer. These alterations are measurable and can be structurally characterized. The full effects of these alterations are not yet known but they change the general characteristics of cells. For example, by altering the glycans on proteins on the cell surface, the cell may become more tumorigenic. They also may become more metastatic. We also know that the immune systems work by recognizing glycans. In fact, your own blood type is really determined by a glycan. There are further indications that changing the cell surface can even help the cancer cells evade the body’s own immune system.
If glycans are so important, why are we just learning about them? We’ve known about glycans for over 100 years but further study has been hindered by the difficulty to characterize and to measure. It used to take a whole PhD thesis to figure out a single structure. However, this is rapidly improving as new tools are being developed based on mass spectrometry, which enable measurement of all the different glycan structures that are associated with the protein, increasing our understanding of the roles of glycans.
We are currently working on rapid throughput analytical methods to determine what structures are altered specifically in different cancers. In turn, by knowing these changes and their effect on cancer tissues and cells we will be able to create therapeutics that can target specific glycans on cancer cells.