The immune system is actually quite capable of eliminating abnormal cells. As a safety mechanism, special features are built into healthy cells so that the immune system recognizes them and prevents an unintentional attack. Cancer cells, on the other hand, subtly manipulate these safety mechanisms so that the immune system ignores them. Immunotherapies have changed cancer treatment in recent years.
These include treatments that prevent cancer cells from interfering with the immune system. In the process, artificially produced proteins block so-called “immune checkpoints” that enable immune cells to successfully attack cancer cells.
“However, success in many tumors has been limited. That’s why we’re looking for new approaches to intervene more effectively in anti-tumor immune responses,” explains Professor Heinz Laubli from the Department of Biomedicine at the University of Basel and the University Hospital Basel. His team, together with the newly crowned Nobel Prize winner Professor Carolyn Bertozzi from Stanford University, reports on a promising new approach in the journal Science Translational Medicine.
The researchers were able to significantly boost the anti-tumor immune response by altering sugar molecules on the surface of cancer cells in mice.
Your attention is drawn to sugar molecules on the surface of cancer cells as well as cells in their immediate vicinity. These sialic acid-containing sugars are also found on healthy cells and play an important role in cell-to-cell communication. Tumors, on the other hand, increase the amount of these sugars on their surface.
Certain immune cells known as macrophages recognize these sialic acid sugars and inadvertently become traitors, giving the impression that all is well with other nearby immune cells.
Experiments by the research team on mice have now shown that sialic acid sugars can be removed or at least greatly reduced with the help of an enzyme. This means that the macrophages no longer prevent the tumor from being attacked by the immune system.
Through more detailed analysis, the researchers were able to identify in mice which receptor on macrophages recognizes sialic acid sugar. If a human equivalent receptor can be found, this could be another interesting target in the fight against cancer cells using the patient’s own immune system.