Researchers at Tel Aviv University announced on Monday their discovery of immune system cells that, despite the fact that their primary function is to attack and kill cancer cells, actually act as “double agents” that increase and intensify the aggressiveness and threat of a tumor.
Their study examined for the first time the development of a glioblastoma cancerous tumor in animal models with a normal immune system, in order to best simulate the development of the tumor in humans.
Glioblastoma is the most common type of brain cancer, and one of the most violent and deadly cancers in humans; the average life expectancy of glioblastoma patients is 12 to 15 months from the time of detection.
The study examined the development of cancer cells in animal models with functioning immune systems. This allowed the cancer to grow gradually, to the point of the development of a massive tumor, which enabled the close monitoring of its development, and throughout the process, of the interaction between the cancer cells and different immune system cells.
In the study, the researchers found that cells called neutrophils play a critical role in interacting with the cancerous growth. Neutrophils are immune system cells that originate in the bone marrow, and whose purpose is to “swallow” or kill bacteria and fungi and fight the infections caused by them. “Neutrophils are the front-line soldiers of the immune system,” says Dr. Dinorah Friedmann-Morvinski, who led the research.
“When a tumor begins to develop, the neutrophils are among the first to mobilize and attack it in order to eliminate it.”
The researchers also found that the neutrophils remain in close proximity to the tumor throughout its development, and are continuously and consistently recruited from the bone marrow. The surprising thing that was discovered during this study is that the neutrophils “change sides:” Whereas at first, with the onset of the initial tumor, the neutrophils fight it, over time the neutrophils recruited to the cancerous area begin to support its development.
Moreover, the researchers found that the process by which the neutrophils change their properties can take place remotely, even before they progress towards the tumor itself.
“The study showed that the change in the properties of neutrophils takes place in the bone marrow itself – where there is no tumor at all: the cancerous tumor is located only in the brain, and from there it succeeds in changing the properties of the cells it recruits,” adds Dr. Friedmann-Morvinski.
“The new findings may also shed light on immunotherapeutic therapies, which have been gaining a lot of momentum in recent years. In one type of immunotherapy treatment, T cells are removed from the patient’s body, processed, and returned to the body with increased healing abilities. One of the major problems today is that even these cells that have been sent to heal are suppressed and their actions stifled. If we know how to change the interaction between neutrophils and T cells so that they are not suppressed, this will have implications for the effectiveness of immunotherapy.”
The study was published in the prestigious journal Cell Reports.