Researchers Inhibit Metastasis in Mice with Cancer

A modified version of a naturally occurring human protein can decrease the spread of human breast cancer implanted in mice. The new findings were reported in the June 2003 issue of Clinical Cancer Research.

The ability to adhere to other cells is what allows a cell that breaks away from a primary tumor to lodge in other parts of the body, or metastasize. The researchers decided that interfering with that ability to adhere might be a way of attacking metastases. They modified a human protein known as galectin-3, a member of the family of proteins called lectins that bind to sugar molecules on the surface of cells. Galactin is known to promote cell-to-cell adhesion.

The researchers left the sugar-binding region of Galactin intact but removed the part of the protein that normally allows cells to stick to one another. Next, they implanted portions of human-derived breast cancer tumors into the chest pads of nude mice, which have a low-functioning immune system. Then they injected the experimental animals with the truncated galectin-3, while the control mice were given sham injections.

By the end of the experiment, the cancer had spread to lymph nodes or other organs in four out of 20 experimental mice, versus 11 of 20 controls. Also, the post-treatment growth of the tumor fragments was significantly less than in the control animals.

"We are able to significantly reduce the spread of the disease and decrease tumor growth without any evidence of toxicity,” said senior author Gary Jarvis, Ph.D., associate professor of laboratory medicine at the University of California, San Francisco ( USA; www.ucsf.edu). Dr. Jarvis and colleagues are now working on functional studies that would determine the mechanism behind the reduction in metastasis they observed.




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