Northwestern Medicine researchers have discovered a "two-faced" group of cells at work in human colon cancer, with opposing functions that can suppress or promote tumor growth. These cells are a subset of T-regulatory (Treg) cells, known to suppress immune responses in healthy individuals
In this previously unknown Treg subset, the presence of the protein RORγt has been shown to differentiate between cancer-protecting and cancer-promoting properties.
The Northwestern team, led by Khashayarsha Khazaie, research associate professor at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University, recently reported their findings in the journal Science Translational Medicine.
"The subset of Tregs that expand in human colon cancer is different from the Tregs that abound in healthy individuals in their ability to suppress inflammation," said Khazaie. "Since their discovery, Tregs have been assumed to be harmful in cancer based on the knowledge that they suppress immunity. More recent clinical studies have challenged this notion. Our work shows that Tregs, by suppressing inflammation, are normally very protective in cancer; it is rather their switch to the expression of RORγt that is detrimental."
The Northwestern team's work builds on observations, which demonstrated that the transfer of Tregs from healthy mice to mice with colitis or colitis-induced cancer actually protected the mice from colitis and colitis-induced cancer.
After identifying the abnormal Treg subset in mice with hereditary colon cancer, Khazaie and lead author Nichole Blatner, research assistant professor at Lurie Cancer Center, worked with Mary Mulcahy, MD, associate professor of hematology and oncology, radiology, and organ transplantation, and David Bentrem, MD, Harold L. and Margaret N. Method Research Professor in Surgery, of Northwestern University Feinberg School of Medicine, to look for the same cells in colon cancer patients.
"To our delight, we found the same Treg alterations in cancer patients," said Khazaie.