Scientists have found that cancer stem cells that trigger the most lethal type of brain tumor also suppress an immune system attack on the disease.
Scientists from University of Texas M. D. Anderson Cancer Centre say that the effect can be greatly diminished by encouraging the stem cells to differentiate into other types of brain cell.
"We've known for years that glioblastoma and cancer patients in general have impaired immune responses," said senior author Amy Heimberger, an associate professor in M. D. Anderson's Department of Neurosurgery.
"Our research uncovers an important mechanism that shows how that happens. The cancer stem cells inhibit T cell response, and it is these T cells that recognize and eradicate cancer," she added.
First author Dr Jun Wei, an instructor in the Department of Neurosurgery said that glioblastoma stem cells suppress T cell response in three different ways: By producing immunosuppressive cytokines that prevent the responses of T cells. Inducing some T cells to become regulatory T cells, which act as brakes on the immune response. Killing T cells via apoptosis, or programmed cell suicide.
Wei said this immunosuppressive effect was reversed when the team placed the undifferentiated glioma stem cells in a culture medium that causes them to differentiate into the three types of neural cell.
"There are multiple research groups around the country, including ours, trying to develop vaccines or other immunotherapeutics against glioma stem cells," Heimberger said.
"Now we have to be cognizant that the stem cell may deliver a fatal blow back to the immune system, which will help us understand how to design immune-based therapies," she added.
The researchers said new drugs or combination therapies are needed, because after decades of research, little progress has been made in treating glioblastoma multiforme.
The study appears in journal Clinical Cancer Research.