An overwhelming majority of cancer deaths are in some way connected to metastasis even though the immune system is rather effective at scouring the bloodstream for traveling cancer cells. This is because cancer cells have found a way around the ever-watching eye of the immune system, by seizing control of myeloid-derived suppressive cells (MDSCs) from the bone marrow.
"There is a very intricate balance in the immune system that is usually anti-tumorigenic, meaning it eliminates tumors, but in some cases, if this balance is altered, these cells may actually help tumors grow and develop into full-blown metastatic disease," explained Hasan Korkaya, PhD from the Medical College of Georgia at Augusta University.
MDSCs are conveniently capable of suppressing the immune response. While immune regulation is vital in some situations, cancer cells take advantage of MDSCs, using their “powers” for “evil” instead of “good.” MDSCs are found in high levels in mouse models and humans with cancer, and researchers from the Medical College of Georgia are working on unveiling the role of MDSCs in cancer metastasis.
Cancer cells secrete cytokines just like the immune system to communicate with MDSCs, and two different types of MDSCs are evidently useful to the cancer agenda.
Monocytic cells facilitate the tumor cell transition into a stem cell-like state to enable them to leave the primary tumor, enter the bloodstream, travel to a new area of the body, and set up camp
Granulocytic cells expedite the transition back to cancer cells and the multiplication process to build a new population of tumors
The therapeutic plan of attack is to “re-school” MDSCs to shift their loyalty back to the immune system, attacking cancer cells instead of protecting them. Additionally, researchers are interested in identifying and targeting cytokines used by cancer cells to communicate with MDSCs, literally killing the messenger.
The present study was published in the journal Nature Communications.