Researchers have recently discovered that certain cancer cells escape destruction by the immune system by hiding inside other cancer cells. The discovery, published in the journal eLifecould explain why some cancers may be more resistant than others.
We know that many cancers can suddenly come back and cause a relapse after a few years. This is also the reason why doctors prefer to speak of “remission” rather than “cure”. Also, for years, researchers have been trying to understand the different means used by certain cancers to avoid being detected by the immune system and therefore escape destruction.
Previous work has already revealed some of these techniques, such as hiding in fatty tissue or the ability to come into dormant state during chemotherapy. An exciting recent study reveals another equally devious one of these tricks.
“It was like seeing the devil”
Dr. Yaron Carmi and his PhD student, from Tel Aviv University, made the discovery while researching which T cells in the immune system might be most potent in killing cancers. For this work, they focused on melanoma and breast cancer. Very quickly, they realized that these cells, normally built to destroy these tumors, seemed ineffective in mice.
By scrutinizing these interactions in real time under the microscope, the researchers then observed a previously unsuspected phenomenon. In fact, the cancer cells that seemed to escape the attack of the T cells contained other cancer cells. The first cells could be destroyed by the immune system, but not the second nested below.
« It was like seeing the devil“, said Dr. Carmi. These cells could thus remain hidden “ for weeks or months » before emerging from their hiding place once the T cells have disappeared.
The researchers then examined human cells from breast cancers, cancers of the colon and melanomas and they observed the same phenomenon. However, blood cancers and glioblastomas (brain cancers) do not seem to be affected.
So the next step will be to independently confirm the results and then find a way to thwart this sleight of hand. Researchers have already tried without success. By blocking the genes involved in this defense mechanism, they unfortunately also blocked the ability of T cells to attack tumors.