ANN ARBOR---University of Michigan scientists have developed a new cancer-inhibiting peptide, or chain of amino acids, that has proven to be effective at preventing metastatic prostate cancer from spreading to other organs in laboratory rats.
Rats treated systemically with the new peptide developed smaller primary tumors and fewer lung metastases than untreated rats and showed no toxic side effects from the treatment. The peptide was effective even if primary tumors were allowed to grow to a large size before surgery and peptide treatment began. If future studies show the peptide works as well in people, it could be the basis for a new approach to cancer therapy.
In an article published in the Jan. 15 issue of Cancer Research, U-M scientists present results from an extensive series of experiments which document the peptide's ability to block cancer cells' invasive activity and limit the growth and spread of tumors in laboratory rats.
U-M scientist Donna L. Livant, Ph.D., created the peptide by changing just one amino acid in a short sequence of a common blood protein called fibronectin, which circulates freely through the body in blood plasma, lymph, serum and interstitial fluid around cells.
When tissue is damaged, fibronectin at the injury site fragments and diffuses outward. Unlike intact fibronectin, which is present everywhere in the body, these fragments bind to fibronectin receptors on cells surrounding damaged tissue, which stimulates them to invade and repair the injury.
The downside to this process, according to Livant---an assistant professor of cellular biology in the U-M Medical School---is that cancer cells can mutate so that intact fibronectin stimulates them to invade surrounding tissue also. "Cancer is the price we pay for our ability to heal from wounds," Livant said. "When intact fibronectin stimulates cancer cells to invade, they can easily reach the blood or lymphatic system and metastasize or spread to other parts
Contact: Sally Pobojewski
University of Michigan