A new study from the University of Michigan (UM) suggests a group of immune cells, known as myeloid derived suppressor cells, could be giving cancer a hand by bolstering cancer stem cells - the small number of cells within a tumor that drive its growth.
The researchers report their work in the September 4th online issue of the journal Immunity.
The researchers behind this latest study say not only do myeloid derived suppressor cells help cancer stem cells to thrive, but also they suppress the immune system.
They hope their study will help find new drugs that target both these features, as senior author Dr. Weiping Zou, a Professor of surgery, immunology and biology at UM Medical School, explains:
"This cell and its mechanisms are not good for your body and it helps the cancer by allowing the stem cells to thrive. If we can identify a therapy that targets this, we take away the immune suppression and the support for cancer stem cells. Essentially, we kill two birds with one stone."
Compared to control (left), immune cells (right) promoted tumor sphere formation, an indication of cancer stemness.
Image credit: University of Michigan Comprehensive Cancer Center
The researchers found a number of ways that myeloid derived suppressor cells appeared to help cancer stem cells. For instance, they enhanced expression of cancer stem cell genes and also spurred metastasis, where cancer cells migrate to other parts of the body.
The vast majority of cancer deaths are due to metastasis.
The results also showed that myeloid derived suppressor cells suppressed the immune system by inhibiting T cell activation. T cells help fight disease by eliminating cancer cells and cells infected with viruses and bacteria.
The team believes the immune cells bolster the "stemness" of the cancer cells and strengthen the features that make them so lethal. Without this support, they suggest, the cancer stem cells would not thrive.
Funds from the National Cancer Institute, the Ovarian Cancer Research Fund and the Marsha Rivkin Center for Ovarian Cancer Research helped finance the study.
In 2011, another team at the University of Michigan found that a type of normal stem cell fuels ovarian cancer by encouraging cancer stem cells to grow.Written by Catharine Paddock PhD