Heart Drug May Be a Cancer Fighter

Jan. 8 -- WEDNESDAY, Jan. 7 (HealthDay News) -- Digoxin, a drug used for many years to treat irregular heart rhythms and heart failure, may also be a cancer-fighting agent, researchers report.

Cancer cells need to create new blood vessels to survive. But many of these cells are oxygen-deprived and need to switch on genes that produce a protein called hypoxia-inducible factor (HIF-1), which help cells survive in low-oxygen conditions.

Digoxin reduces HIF-1, causing cancer cells to die, the scientists from Johns Hopkins University found.

"Anytime you see alternative uses for existing drugs, that always generates a certain amount of excitement," said William Phelps, director of preclinical and translational cancer research at the American Cancer Society. "In the cancer field, we are always looking for any new compounds, so this is an exciting potential."

For the study, Dr. Gregg L. Semenza, director of the vascular program at the Johns Hopkins Institute for Cell Engineering, and his colleagues tested more than 3,000 U.S. Food and Drug Administration-approved drugs for their ability to reduce HIF-1 levels in cancer cells.

They identified 20 drugs that reduced HIF-1 by more than 88 percent; more than half are used to treat heart failure. The researchers then looked specifically at digoxin because it is commonly used and its side effects are well-documented.

The researchers found that prostate cancer cells treated in a laboratory with digoxin grew significantly slower. After three days of treatment, there were fewer cancer cells, and many cells had stopped growing altogether, compared with untreated cells.

"This is really exciting, to find that a drug already deemed safe by the FDA also can inhibit a protein crucial for cancer cell survival," Semenza said in a statement.

To see if digoxin would work on cancer cells in animals, and not just on isolated cancer cells in a lab, the researchers then gave mice with tumors daily injections of digoxin.

They found that in mice not given digoxin, tumors grew to the point where they could be felt after nine days. But, in mice treated with digoxin, tumors couldn't be felt until 15 to 28 days.