Some Immune Cells Thought to Help Fight Mesothelioma and Other Cancers May Actually Aid Metastasis

• Nancy Meredith
• Mesothelioma, Treatments

The National Cancer Society reports that 90 percent of all cancer deaths occur when the cancer cells migrate beyond the primary cancer site to distant organs. Stopping tumor growth and preventing metastasis is especially critical for increasing survival in mesothelioma and other cancer patients. Now, researchers believe they have found yet another way cancer cells spread throughout a patient’s body.

According to an April 6 press release from the Georgia Cancer Center at Augusta University (http://jagwire.augusta.edu/archives/43129), a team of researchers report that while cytokines are primarily useful in helping fight cancer, they found that they can also lead to cancer metastasis. These “immature” immune cells may be hijacked by cancer cells to help the cancer spread beyond its primary site.

“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,” said Dr. Hasan Korkaya, molecular and cancer biologist at the Georgia Cancer Center and Medical College of Georgia at Augusta University.

Cancer spreads through the blood stream, but when cancer cells break free they have to get past the immune system where they are attacked and broken down. According to the researchers, the cancer cells use myeloid-derived suppressive cells (MDSCs) that come from the bone marrow, like a support system to dodge the immune system and metastasize.

The researchers note that MDSCs have been shown to suppress the immune system, however, their discovery that they also enable the spread of cancer is surprising. MDSCs seem to be directed by the cytokines secreted by the tumor. Cytokines, typically secreted by the immune system, can influence other cell types. The researchers found that tumors can also secrete cytokines that then signal the immature MDSCs to support the cancer growth.

“They are being schooled toward facilitating tumor cell growth and metastasis,” Korkaya said. The tumors continue to control the cytokines, according to the researchers, to keep the MDSCs from maturing, thus they can keep using them to grow the cancer.

In a recent study one researcher said, “Metastasis is currently incurable and remains one of the key targets of cancer research.” The physicians and patients in the mesothelioma community hope the researchers at Augusta University continue this line of research to help bring a solution to halting cancer’s uncontrolled growth.

Mesothelioma is diagnosed in close to 3,000 Americans each year. There is no cure for the asbestos-caused cancer.

To find out more, read the full study in the Feb. 20 issue of Nature Communications. http://www.nature.com/ncomms/2016/160524/ncomms11734/full/ncomms11734.html