Cancer cells hid from the immune system using an “invisibility cloak” made of ribosomes
On the outside, cancer cells look completely normal, causing the immune system to fail to recognize and fight them. However, the mechanism by which the cells avoid immune surveillance has long remained a mystery. Now scientists at the Netherlands Institute of Oncology have discovered that cancer cells can modify ribosomes to create an “invisibility cloak” to remain undetected.
One of the main tasks of the immune system is to identify and destroy potentially dangerous cells. Cancer cells, however, do everything they can to survive and avoid immune surveillance. For this reason, many patients with oncopathologies do not respond to immunotherapy or become resistant to it.
The authors of the study, presented in the journal Cell, found that cancer cells bypass the immune system by modifying their ribosomes. Recall that each cell of the human body contains a million ribosomes, which synthesize protein molecules from amino acids. Previously, ribosomes were thought to be the same structures that produce proteins as directed by the cell nucleus.
Now scientists have discovered a special subtype of ribosomes with a so-called P-strand (one of the mobile elements of ribosomes). It plays a key role in how cells respond to immune system signals by participating in the regulation of processes controlled by cytokines - small protein molecules that help cells communicate and coordinate the body's defense responses.
Healthy cells use P-stranded ribosomes to accumulate more antigens - proteins for recognizing threats - on their surface to become more visible to the immune system. Cancer cells, in turn, reduce the number of these ribosomes. This affects the synthesis of certain proteins and reduces the amount of antigens on their surface.
“By altering ribosomes, cancer cells create a kind of “invisibility cloak” that allows them to hide from the immune system. The findings change the view of ribosomes as passive and identical machines,” said Liam Faller, co-author of the research paper.
Because ribosomes are among the oldest and most important components of cells, the fact that they are more diverse and dynamic than thought is of great importance to biological research. For example, understanding the precise mechanisms by which ribosomes change could improve the effectiveness of immunotherapy (provided medics learn how to block this ability).
The results of this study also provide new insights into the interaction between cancer cells and the immune system and new strategies for treating cancer and other diseases associated with immune dysfunction.