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.
And levels of HIF-1 were lower in the tumors of treated mice, compared with untreated mice. The researchers also found that it was digoxin that reduced HIF-1 levels leading to slower tumor growth.
The report was published recently in the Proceedings of the National Academy of Sciences.
There have been previous studies showing that digoxin and other so-called digitalis-based drugs reduce the risk of dying from or developing some cancers, Semenza's team noted.
In one long-term follow-up of 175 breast cancer patients, those taking digitalis drugs had a 6 percent death rate, compared with 34 percent among those not taking these drugs. Another study of more than 9,000 patients taking digoxin found an association between high levels of the drug and a lower risk of leukemia and lymphoma and kidney and urinary tract cancers, according to the study.
Phelps said future research needs to focus on how these drugs slow tumor growth to see if it's different from how they work to control heart function. "If so, can you improve the class to more specifically hit this new target that has the anti-tumor effects?" he said.
To learn more about digoxin, visit the U.S. National Library of Medicine.
SOURCES: William Phelps, Ph.D., director, preclinical and translational cancer research, American Cancer Society, Atlanta; Dec. 16, 2008, Proceedings of the National Academy of Sciences
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