A molecule already implicated in a number of diverse cellular functions can suppress the growth of tumors in the liver, a Mayo Clinic Cancer Center study has found. Its name is IQGAP1, and when the molecule is active in the cells that surround a tumor cell, this "tumor microenvironment" becomes less hospitable to cancer growth. When the molecule is deficient, cancer thrives.
Results of the study appear in the Journal of Clinical Investigation. The findings give new insight into cancer metastasis, the ability of a tumor to spread from its primary site to distant organs such as the brain, lung or liver. The results also point to new targets for preventing or treating liver metastases, the major cause of death from cancer.
"Tumor cells are intelligent -- they talk to the cells in their surroundings to change the way they behave and make the environment supportive of cancer growth. If we can disrupt the communication between the tumor cells and the tumor microenvironment, we can prevent tumor growth or metastasis in the liver," says senior study author Ningling Kang, Ph.D., a biochemist and molecular biologist at Mayo Clinic.
For certain solid tumors, about 70 to 90 percent of the tumor mass is made up of microenvironment -- a complex mix of noncancerous cells, secreted extracellular matrix proteins, and tumor-promoting signaling molecules. This tumor microenvironment supports tumor growth and drug resistance. Mechanisms regulating the tumor microenvironment are not well understood.
IQGAP1 controls the shape and movement of cells. To study the effects of this molecule on liver metastases, Dr. Kang and her colleagues implanted tumor cells into the livers of mice genetically engineered to lack the molecule.