Old blood pressure drug inhibits skin cancer in mice

Scientists at Western University of Health Sciences have discovered that an FDA-approved beta blocker protects against the sun's cancer-causing rays.

Carvedilol is a beta blocker that was developed under the brand name Coreg by SmithKline Beecham and approved by the FDA to treat high blood pressure back in 2003. It went generic a few years later. But now it may find new life as a sunscreen, thanks to researchers at Western University of Health Sciences College of Pharmacy in Pomona, California, who have discovered that the drug seems to prevent sun-induced cell damage that leads to skin cancer.

The discovery, described during the recent American Society for Pharmacology and Experimental Therapeutics annual meeting in Chicago, happened serendipitously. A graduate student in the lab of Ying Huang, Ph.D., a professor at the college, was investigating whether beta blockers cause cancer. But he accidentally tested carvedilol’s anticancer effects, according to a press release. He was surprised to find that the drug seemed to protect against skin cancer.

So Huang’s team went on to test the drug in cell cultures, and then in mice, focusing on its effects against ultraviolet-B (UVB) rays, which damage the epidermal layer in ways that can lead to cancer. They discovered that the drug protects the cells from DNA damage and death.

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When hairless mice were exposed to UVB rays, those that received carvedilol developed fewer and less severe tumors than mice that did not get the drug, the research team reported. (For more, see video below.)

Some past research has suggested a link between beta blockers and improved cancer outcomes—but most studies have focused on the drugs’ ability to reduce stress-related tumor growth. One study in mice a few years back showed that blocking an adrenaline-induced pathway with beta blockers inhibited the growth of prostate tumors. A retrospective study of women with ovarian cancer done at the University of Texas M.D. Anderson Cancer Center found that patients who happened to be taking beta blockers for hypertension survived longer than those who were not on the drugs. But those findings are widely believed to be inconclusive.

The researchers at Western University of Health Sciences believe they have evidence that beta blockers act against molecules that have not yet been discovered. "We have preliminary data indicating that the cellular targets for carvedilol are not related to the beta-adrenergic receptors that are the commonly accepted targets for all beta blockers," said Bradley Andresen, Ph.D., co-leader of the research team. "They likely target unexpected mechanisms involved in cancer development."

The next step for the team will be to incorporate carvedilol into a skin cream or spray that could act against the sun’s harmful rays without affecting blood pressure or heart rate. They also hope to gain a better understanding of the drug’s effects against cancer so they can design safe and effective sunscreens.