HOUSTON - Cancer-initiating cells that launch glioblastoma multiforme, the most lethal type of brain tumor, also suppress an immune system attack on the disease, scientists from The University of Texas M. D. Anderson Cancer Center report in a paper featured on the cover of the Jan. 15 issue of Clinical Cancer Research.
The researchers demonstrate that this subset of tumor cells, also known as cancer stem cells, stifles the immune response in a variety of ways, but 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, M.D., 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."
Definitions of cancer stem cells vary. To meet the researchers' definition, the cells had to express a marker called CD133, form neurospheres (little round balls) in culture, and be able to recreate glioblastoma multiforme when injected into the brain of a mouse. They also had to be capable of differentiating into specific types of brain cells - neurons, astrocytes and glial cells.
Glioblastoma stem cells have been implicated in tumor resistance to chemotherapy and radiation, and are the believed to be responsible for the relentless recurrence of the disease, said first author Jun Wei, Ph.D., an instructor in the Department of Neurosurgery.
Wei explained that the glioblastoma stem cells suppress T cell response three different ways by:
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University of Texas M. D. Anderson Cancer Center